Journal of Environmental Protection, 2011, 2, 342-358
doi: 10.4236/jep.2011.24038 Published Online June 2011 (http://www.SciRP.org/journal/jep)
Land Use Impact on Bioavailable Phosphorus in
the Bronx River, New York
Jingyu Wang, Hari Pant
1Environmental Geographic and Geological Sciences Department, Lehman College, New York, USA.
Received March 23rd, 2011; revised April 21st, 2011; accepted May 24th, 2011.
ABSTRACT
Various forms of phosphorus (P) could become bioavailable such as from desorption, dissolution and enzymatic hy-
drolysis. Potential bioavailable P estimation is critical to minimize eutrophication in freshwater systems. Thus, this
study was conducted to predict potential bioavailable P in the water columns and sediments and their relations with
enzymatic hydrolysis, and estimate impacts of land use and anthropogenic activities on P bioavailability, P transport
and water quality in the Bronx River, New York, USA. In sediment samples collected in 2006, total P (TP), total inor-
ganic P (IP), total organic P (OP) and bioavailable P (BAP) were in highest concentrations in sites located at Bronx
River Valley upstream in Westchester (site 2), Troublesome Brook (TB, site 4), Sprain Brook (SB, site 7b) and Bronx
River estuary near Sound View Park (site 14) respectively. Also, phosphodiesterase and native phosphatases (PDEase
and NPase) hydrolyzed distinguishingly high amounts of OP or enzymatically hydrolysable P (EHP) in samples from
sites 4, 7b, 10 (New York Botanical Garden) and 14. Microbial P was in negative values (caused by different bacteria
and microorganisms could not be paralyzed by chloroform), and the most negative concentrations were appeared at
sties 4 and 14. Spatial comparisons among different locations showed distinguished characteristics in tributaries and
estuary. In sediments collected in 2007, TP, BAP and IP were in highest concentrations at sites 7-SB, 11-Bronx Zoo,
12-East Tremont Ave Bridge where fresh and saline water meets, 13-estuary facing Hunts Point Waste Water Treatment
Plant (HP WWTP) and 14-estuary along Sound View Park. Besides, PDEase-P highest c o ncent r at i o ns a pp e ar e d at sti es
7, 13 and 11, NPase-P concentrations were highest at 7 and 11. Microbial P was highest at sties 11 and 14. Spatial
variations showed that high er P content and more intense en zymatic hydrolysis in silty clay fin er sediments at site 7, 11
and 13. Temporal variations between the two years’ data showed land use and other anthropogenic factors’ impacts on
P transport in river and deposit in sediments. Analysis of the river water samples showed that average solub le reactive
P (SRP, 67 µg·l–1) in 2006 and SRP (68µg·l–1) in 2007 both were greater than background P concentration in most
natural water (42 µg·l–1). Wate r T P (TPwater) peaks showed at sites 7 and 13 in 2006; TPwater were highest at sites 6 and
13 in 2007; showing high P content in water columns at TB and estuary downstream in both years. Similarly, native
phosphatases hydrolyzed substantial amounts of OP in the water samples at optimal temperature in both years, indi-
cating potential threats to river water quality as the rise in water temperature may be imminent due to global climate
change. Overall, incidental sewer overflows at Yonkers, oil spill at East Tremont Avenue Bridge, urban constructions at
Woodlawn Metro-North train station, fertilizer application at WC lawns and gardens, animal manure from the zoo,
combined sewer overflows (CSOs), storm water runoff from Bronx River parkway, and potential pollutants from East
River all appeared to be influencing spatial and temporal variations on P transport in the river. Research data from
this study could be shared among United States Environmental Protection Agency (USEPA), New York City Depart-
ment of Environmental Protection (NYCDEP), New York State Department of Environmental Conservation (NYSDEC)
and Bronx River Alliance to help make effective enviro nmenta l policies on P app lication, in turn, improve wa ter quality
of the Bronx River and restore its ecology.
Keywords: Potential Bioavailable P, Enzymatic Hydrolysis, Microbial P, Enzymatical l y Hy drolysable P , Sp at ial and
Temporal Variations
1. Introduction
Streams-nutrients occur naturally in water refereed to
‘background’ concentration. Anthropogenic discharges
such as artificial fertilizers, manure, and septic systems

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York343
effluent elevated concentrations. In U.S., five studied
nutrients including nitrate, ammonia, total nitrogen, or-
thophosphate, and total phosphorus exceeded back con-
centrations at 90% of sampled streams draining agricul-
ture and urban watersheds [1]. The highest total phos-
phorus concentrations were in streams in urban and ag-
ricultural areas, and the median concentration (250 µg·l–1)
was around 6 times greater than background concentra-
tions (42 µg·l–1). In urban area, P sources were runoff
from urban storm water runoff, golf courses, residential
lawns, construction sites, sewage overflow (treated
wastewater effluent), and septic-system drainage. In ag-
ricultural area, P sources were associated with fertilizers
and manure intensive applications [1-3]. Phosphorus
from different natural and anthropogenic sources dis-
charged to river has temporal and spatial variations [4].
Bioavailable P (BAP) is the total available P that could
be transformed into an available form from naturally
occurring processes [2]. Bioavailable P could be defined
as the total of readily available P (NaHCO3-P) and mod-
erately available P (NaOH-P) [2,5]. Different P sources
have different potential ecological impact on river sys-
tems [5]. Input of P to surface waters should be reduced
in order to control eutrophication and algal growth [5].
Phosphorus bioavailablility is dependent on P input
source; reducing P inputs could reduce algal biomass in
river systems [5]. The BAP analysis could help to mini-
mize eutrophication in rivers [5].
Orthophosphate (,, or
2
24
HPO2
4
HPO 3
4
PO

) is the
major available P source for plant uptake [2]. Total dis-
solved phosphorus (TDP) includes dissolved reactive P
(DRP) and dissolved unreactive P (DUP) is filterable
through a 0.45 µm membrane filter [2]. The soluble P is
retained, transformed and assimilated within the river
channel, resulting in the spatial variations along the river
[4]. Particulate P (PP) could be mobilized to orthophos-
phate from physical, chemical and biochemical processes,
such as desorption, dissolution and enzyme hydrolysis;
these processes are affected by pH, temp, and redox et al.
[2,6]. Potential bioavailable PP may have higher bio-
availability than immediately available P or DRP (<10
µg·l–1) [2]. Enzymatic hydrolysis is a powerful technique
to characterize hydrolysable OP in waters and sediments
[7-12]; and enzymatic hydrolysis estimates hydrolysable
(bioavailable) OP in sediments and water [7,12-14].
Enzymatically hydrolysable phosphorus (EHP) was
composed of labile monoester phosphates, diester phos-
phoates and a phytase-hydrolysable fraction that includes
myo-inositol hexakisphosphate (phytic acid); EHP is an
important portion of DOP, represented a significant and
potential BAP fraction [15]. Dissolved organic phospho-
rus (DOP) plays an important role in natural water eco-
systems [16]. Hydrolyzable OP could be classified by
using phosphatase enzymes to simple monoester P,
polynucleotide P, phytate-like P, and non-hydrolyzable P
[7]. Quantifying BAP can predict EHP and potential
BAP, which could be achieved by enzyme hydrolysis,
sequential extraction, 31P-NMR (Nuclear Magnetic Reso-
nance) and other methods [7]. Enzymatically hyrolyzable
P (EHP), the monoesters of orthophosphoric acid, is the
major organo-P in natural waters. It is important to know
that EHP portion in DOP, to predict the bioavailability of
P in water systems [16-17]. Kobori and Taga [18] found
that EHP proportation relative to DOP was between 18%
- 50% in water systems where biological activity was
high.
Effective regulation of P supply could help manage-
ment ecosystem and achieve good water quality [4].
Phosphorus retention in rivers includes biogeochemical
and physical processes associated with biotic and abiotic
assimilation, which remove or transport P downstream; P
retention in rivers is varied temporally and spatially [4].
Anthropogenic P inputs impact downstream communities
[4]. Phosphorus cycling and transport in the river were
controlled by physico-chemical factors (such as sorp-
tion/desorption, mineral precipitation and dissolution,
advection and diffusion) and biological factors (such as
microorganism activities) [4]. P cycling in the Bronx
River was controlled by these physico-chemical and bio-
logical factors (Figure 1).
This study was conducted to predict potential BAP in
the water columns and sediments and their relations to
enzymatic hydrolysis; as well as estimate impacts of land
use and anthropogenic activities on P bioavailability, P
transport and water quality in the Bronx River, NY. Spa-
tial variations along the river and the temporal variations
between the two years were studied, which showed that
sediment texture, land use changes, oil spill, raw sewer
discharge, fertilizer application and management, animal
manure management, constructions, WWTP sewer over-
flows, pollutants from the East River resulted in spatial
P sorption/desorption
Fe/Al-P
SRP
(BAP) Uptake of P by
algae,
microorganism
/Enzymatic
hydrolysis of
OP
Diffusion of P across
sediment-water
interface
Co-precipitation
P-Ca/Mg
Deposition of P-rich
particles to bed
sediment (contain OM)
Biological
activity/storm
events e.g.Via
food chain to
fish
Resuspension of
P-rich particles
Mineralizationof OM
Uptake/release
by invertebrate
grazers
P sources -storm water runoff, sewer overflow
from HP WWTP, fertilizer, animal manure etc.
Adsorption
River flow downstream
P sorption/desorption
Fe/Al-P
SRP
(BAP) Uptake of P by
algae,
microorganism
/Enzymatic
hydrolysis of
OP
Diffusion of P across
sediment-water
interface
Co-precipitation
P-Ca/Mg
Deposition of P-rich
particles to bed
sediment (contain OM)
Biological
activity/storm
events e.g.Via
food chain to
fish
Resuspension of
P-rich particles
Mineralizationof OM
Uptake/release
by invertebrate
grazers
P sources -storm water runoff, sewer overflow
from HP WWTP, fertilizer, animal manure etc.
Adsorption
River flow downstream
Figure 1. P cycling process in the Bronx River (modified
from Withers and Jarvie, 2008).

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York 344
and temporal variations.
2. Material and Methods
2.1. Study Area
The Bronx River, approximately 20 miles (32 km) long
from its headwaters at Davis Brook and Kinsico Dam in
Westchester County (WC) though the Bronx, flows into
East River [19]. Davis Brook became the new headwater
of the Bronx River after the construction of Kensico Dam.
Kensico Dam was built in 1915 reduced a quarter of the
water flowing into the Bronx river, and the reservoir
covers 13 square miles (33.67 km2) and holds 30 billion
gallons of water for several Westchester townships and
New York City (NYC) [20]. Watershed of the Bronx
River in WC is 23,020 acres (93 km2), and in NYC is
5110 acres. There are over 100 stormwater and CSOs
and other discharges to the river from WC to East River;
Hunts Point Wastewater Treatment Plant (HP WWTP)
services this area [19]. Fresh and saline water in the
Bronx River does not meet dissolved oxygen and coli-
form standards [19]. The pollutants in the tidal portion
are floatables, pathogens and oxygen demand, and this
portion was affected uses as being aesthetics, aquatic life
and reaction. The main pollutants sources in freshwater
section of the Bronx River are floatables, debris, oxygen
demand and pathogens [19]. Pathogen was the main pol-
lutant in the Bronx River, with urban storm runoff and
CSO as the main pollution source [21]. NYCDEP con-
structed a four million gallon triple barrel CSO storage
conduit with downstream outfall relocation in 2005 [19].
New York City Department of City Planning (DCP) de-
signed the old industrial area such as western river bank
at the mouth and the mouth including Sound View Park
as a Special Natural Waterfront area [19].
2.2. Water and Sediment Sample Collection
Representative sediment samples were collected in the
Bronx River from the origin at Davis Brook to the Sound
View Park estuary at 15 sites (Figure 1-2) in July/August
2006 and 2007. Each site was located with a Global Po-
sition System (GPS) unit, and the coordinates are pro-
vided (Table 1). A Core Sampler (diameter 8 cm; length
17 cm) was used to obtain the bed sediments. The sedi-
ment samples were sealed in gallon zipper bags. Water
samples were also collected in the Bronx River from
Davis Brook to estuary at 14 sites (not including 7B Pax-
ton Ave Southwest because the water is at site 7B was
considered the same as site 7 Paxton Ave South) using 1-
gallon DDI pre-washed water bottles. Both the sediment
and water samples were transported to Environmental
Laboratory of Department of Environmental, Geographic
and Geological Sciences at Lehman College of The City
University of New York at the end of each sampling day,
and stored at 4ºC in a Fisher Scientific Isotemp Labora-
tory Refrigerator until further experimentation. The
sediment samples were immediately homogenized and
Figure 2. The Bronx River study area and 14 sampling sites along the river.

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York345
Table 1. Bronx River sampling sites locations and geographic coordinates.
Site# Location Latitude(North) Longitude(West)
1 Davis Brook, Valhalla 41º04'23.63"N 73º46'20.04"W
2 Station A (Virginia Rd) 41º03'43.40"N 73º46'24.80"W
3 North of Troublesome Brook 41º02'15.58"N 73º46'37.99"W
4 South of Troublesome Brook 41º02'15.40"N 73º46'38.39"W
5 Troublesome Brook 41º02'16.24"N 73º46'39.58"W
6 Paxton Ave North 40º56'19.20"N 73º50'15.11"W
7 Paxton Ave South 40º56'19.20"N 73º50'15.11"W
7B Paxton Ave Southwest 40º56'19.20"N 73º50'15.11"W
8 Sprain Brook 40º56'19.20"N 73º50'15.11"W
9 233rd St City Line (between Westchester and Bronx) 40º53'42.74"N 73º51'43.77"W
10 New York Botanical Garden (old snuff mill) 40º51'34.42"N 73º52'33.70"W
11 Bronx Zoo (south of Mitsubishi waterfall, north of Gate B, Bronxdale Parking lot) 40º51'10.20"N 73º52'27.45"W
12 East Tremont Ave Bridge (East Tremont Ave& Boston Rd) 40º50'26.47"N 73º52'40.95"W
13 Bronx River Estuary (old Sound View Park water testing station, facing meat and
fish wholesale markets) 40º48'42.89"N 73º52'07.30"W
14 Sound View Park Station 40º48'28.89"N 73º51'33.67"W
saved in waterproof double-track zipper bags (10.2 ×
15.2 cm; made by Fisher Scientific Co., USA), and
stored at 4˚C until they were used for further analysis. A
portion of each homogenized sediment sample was dried
at 70˚C for 72 h, thereafter, finely ground and used for
selected physico-chemical analysis (17, 22). The fresh
water samples were analyzed of EC, pH, SRP, OP and
TP in 28 days after sampling. The water samples were
also put in 25 ml vials and frozen for future analysis.
2.3. Assessment of Potential BAP
Sediment samples were analyzed for EC, pH, total or-
ganic matter (OM), TP, SRP or (total IP = Pi) and OP.
Sediments were sequential extracted by NaHCO3, NaOH,
and HCl, and TP was sum of NaHCO3-P, NaOH-P,
HCl-P and residue-P. The sum of NaHCO3-P and NaOH-P
was considered as BAP here [6,23-25]. Sediments were
hydrolyzed by commercial PDEase and NPase at 37˚C
[12]. Phosphorus sorption characteristics were deter-
mined from batch incubation experiments under aerobic
conditions [26-27]. Water samples were analyzed for EC,
pH, for SRP using ascorbic color metric method [28]; ash
TP was determined by persulfate digestion block method
[29] for comparison with sum TP, and OP was calculated
from the difference between sum TP and SRP [25]. P
compounds in sediments were identified by 31P-NMR.
NPase hydrolyzed water sample at 37˚C (modified meth-
ods from [11,15,30]). Enzymatic method together with
sequential extraction provides a tool to understand sedi-
ment P and water P [7].
3. Results and Discussion
3.1. Headwater
Site 1, headwater of the Bronx River is located at Davis
Brook, Valhalla, beside the railway station. Sediments
collected in this site during summer 2006 were sandy
texture. The only major P compound in sediments is
GlyP [17]. Bioavailable P (sum of NaHCO3-P and
NaOH-P, 146 mg·kg-1), sediment total IP (Pi) (393
mg· k g –1), sediment total organic P (Po) (99 mg·kg–1) and
sediment TP (sum of P fractionation of NaHCO3-P,
NaOH-P, HCl-P and residue-P, 492 mg·kg–1), plus
PDEase-P (42 mg·kg–1) and NPase-P (41 mg·kg–1) [12]
were blow average (BAP-246 mg·kg–1, TP-580 mg·kg–1,
PDEase-P-80 mg·kg–1, and NPase-P-59 mg·kg–1) but
around median level concentrations (BAP-185 mg·kg–1,
TP-479 mg·kg–1, PDEase-P-54 mg·kg–1, and NPase-P-44
mg· k g –1) among the 15 sample sites (Table 2 and 3, Fig-
ure 3)). Total Pi was 80%, and Po was 20% of TP, which
were around average percentages. River water is quite
clear in this site; SRP in water (SRPwater), OP in water
(OPwater) and TP in water (TPwater) (Table 5 , Figure 4) in
were the lowest at headwater [43]. NPasewater concentra-
ion was the second lowest. t

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York 346
Table 2. Selected physico-chemical characteristics of sediments collected in 2006 and 2007.
# BAP Pi Po TP Pi% Po%
2006 2007 2006 2007 2006 2007 2006 2007 2006 2007 2006 2007
mg·kg–1 %
1 146 cde 45 f 393 cdef 300 b 99 cd 7 a 492 cdef306 b 80 abc 98 a 20 abc2 a
2 315 bc 39 f 538 c 209 b 165 bc 15 a 703 c 219 b 77 abc 95 a 24 abc6 a
3 145 cde 77 ef 445 cde 381 b 61 d 15 a 506 cde 396 b 88 ab 97 a 12 bc 3 a
4 919 a 66 ef 1205 a 296 b 358 a 22 a 1563 a 311 b 77 abc 96 a 23 abc6 a
5 95 e 41 f 353 cdef 313 b 46 d 6 a 398 ef 318 b 88 ab 98 a 12 bc 2 a
6 122 de 76 ef 231 f 387 b 58 d 8 a 288 f 393 b 80 abc 98 a 20 abc2 a
7 86 e 317 c 251 ef 732 b 61 d 4 a 312 ef 735 b 81 abc 99 a 19 abc1 a
7b 245 cde 69 ef 379 cdef 332 b 145 bc 2 a 523 cde 335 b 72 bc 99 a 28 ab 1 a
8 246 cde 62 ef 324 def 237 b 154 bc 2 a 479 def 239 b 68 c 99 a 32 a 1 a
9 186 cde 44 f 363 cdef 254 b 114 cd 4 a 477 def257 b 76 abc 98 a 24 abc2 a
10 185 cde 41 f 373 cdef 252 b 97 cd 4 a 470 def 255 b 80 abc 98 a 20 abc2 a
11 109 e 601 a 314 ef 1049 b 63 d 3 a 376 ef 1051 b 83 abc 99.7 a 17 abc0.3 a
12 160 cde 137 de 423 cdef 5360 a 50 d 0 a 473 def 5360 a 89 a 100 a 11 c 0 a
13 289 bcd 171 d 522 cd 604 b 142 bc 17 a 663 cd 621 b 79 abc 97 a 21 abc3 a
14 435 b 491 b 774 b 1092 b 200 b 21 a 974 b 1106 b 79 abc 98 a 21 abc2 a
Ave 246 152 459 787 121 9 580 793 80 98 20 2
median 185 69 379 332 99 6 479 335 79 99 21 2
Table 3. Enzymatic hydrolysis and microbial activity of sediments collected in 2006 and 2007 (Wang and Pant, 2010b and
2011a).
# PDEase-P NPase-P Microbial P OM pH EC
2006 2007 2006 2007 2006 2007 200620072006 2007 2006 2007
mg·kg–1 % µs·cm–1
1 42 cde 14 d 41 bc 83 b –72 ab 1 d 0.7 1 7.1 7.2 66 17
2 68 bcde 73 abcd0 c 21 b –56 ab 3 d 3.3 0.5 6.8 7.5 298 9
3 13 e 33 cd 0 c 39 b –27 ab 8 d 1.9 1.2 6.7 7.4 133 12
4 352 a 76 abcd170 a 67 b –154 c 13 d 10.7 1.1 6.5 7.3 342 14
5 25 de 13 d 21 bc 24 b –15 a –3 d 0.1 0.3 7.4 7.9 220 34
6 54 cde 26 d 44 abc 41 b –32 ab 14 cd 0.1 0.8 7.5 7.7 158 60
7 70 bcde 237 a 56 abc 95 b –13 a 34 bcd0.3 3.5 7.0 7.1 167 62
7b 137 b 53 bcd 84 abc 37 b –81 b 7 d 1.7 1 6.7 7.4 160 14
8 101 bcd 45 bcd 49 bc 34 b –78 b 4 d 1 1.1 7.0 7.8 103 10
9 40 cde 83 abcd34 bc 30 b –56 ab 5 d 1.7 0.6 6.8 7.7 209 10
10 118 bc 89 abcd91 abc 32 b –84 b 5 d 3.7 0.3 7.0 8.2 108 12
11 33 de 216 abc44 bc 495 a–39 ab 82 a 3.2 6.7 6.8 7.1 133 23
12 26 de 15 d 13 bc 13 b –33 ab 51 abc3.8 1.1 7.8 7.1 254 13
13 35 de 226 ab 110 abc 46 b –79 b 6 d 4.9 16.7 7.8 8.2 1917 277
14 91 bcde 63 abcd122 ab 32 b –162 c 63 ab 3.6 3.4 7.8 8.3 4290 363
Ave 80 84 59 73 –67 18 2.7 3
median 54 63 44 37 –56 7.4 1.9 1.1

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York347
0
200
400
600
800
1000
1200
1400
1600
1800
Davis Brook,
Valhalla
Station A
N of TB S of TB
TB
Paxton Ave N
Paxton Ave S
Paxton Ave SW
SB
City line
NYBG
Bronx Zoo
East Tremont
Ave Bridge
Bronx River
Es tu ary
Sound View
Park Station
1 23 4 5677B8 91011121314
mg kg-1
0
200
400
600
800
1000
1200
1400
1600
1800
Davis Brook,
Valhalla
Station A
N of TB S of TB
TB
Paxton Ave N
Paxton Ave S
Paxton Ave SW
SB
City line
NYBG
Bronx Zoo
East Tremont
Ave Bridge
Bronx River
Es tu ary
Sound View
Park Station
1 23 4 5677B8 91011121314
mg kg-1
bioavailable P
TP
PDEase-P
N
Pase-P
Pi
Po
558729 30 63
367
1069
1019
785
143
414 460
1113
501
53 82 115 49
333
1030964
714
51
193
360
979
379
2518 2513 34 40 55 71 92
221
100 135
122
0
200
400
600
800
1000
1200
Davis Brook,
Valhalla Station A North of
Troublesome
South of
Troublesome Troublesome
Brook
Paxton Ave
(North)
Paxton Ave
(South)
Sprain Brook 233rd Street City line
NYBG
Bronx Zoo
East Tremont
Ave Bridge Bronx River
Estuary
Sound View Park Station
1234567891011121314
sites
µg l-1
558729 30 63
367
1069
1019
785
143
414 460
1113
501
53 82 115 49
333
1030964
714
51
193
360
979
379
2518 2513 34 40 55 71 92
221
100 135
122
0
200
400
600
800
1000
1200
Davis Brook,
Valhalla Station A North of
Troublesome
South of
Troublesome Troublesome
Brook
Paxton Ave
(North)
Paxton Ave
(South)
Sprain Brook 233rd Street City line
NYBG
Bronx Zoo
East Tremont
Ave Bridge Bronx River
Estuary
Sound View Park Station
1234567891011121314
sites
µg l-1
water TP
water OP
water SRP
μg l
–1
mg
·
kg
–1
Figure 3. BAP and EHP analysis of sediments collected in 2006.
5587 29 30 63
367
1069
1019
785
143
414 460
1113
501
53 82 11 5 49
333
1030 964
714
51
193
360
979
379
2518 25 13
34 4055 71 92
221
100 135
122
0
200
400
600
800
1000
1200
Davis Brook,
Valhalla
Station A
Nort h of
Troubles ome
Sout h of
Troub lesome
Troublesome
Brook
Paxton Ave
(North)
Paxton Ave
(South)
Sprain Brook
233r d S treet
City line
NY B G
Bronx Zoo
East Tremont
Ave Bridg e
Bronx River
Estuary
S ound V i e w Park Stat ion
1234567891011121314
sites
µg l-1
5587 29 30 63
367
1069
1019
785
143
414 460
1113
501
53 82 11 5 49
333
1030 964
714
51
193
360
979
379
2518 25 13
34 4055 71 92
221
100 135
122
0
200
400
600
800
1000
1200
Davis Brook,
Valhalla
Station A
Nort h of
Troubles ome
Sout h of
Troub lesome
Troublesome
Brook
Paxton Ave
(North)
Paxton Ave
(South)
Sprain Brook
233r d S treet
City line
NY B G
Bronx Zoo
East Tremont
Ave Bridg e
Bronx River
Estuary
S ound V i e w Park Stat ion
1234567891011121314
sites
µg l-1
water TP
water OP
water SRP
μg·l–1
Figure 4. 2006 Water SRP, OP and TP.
Sediments collected in 2007 were also sandy sediments.
P compound is GlyP remained the same as 2006 sample
[17]. Total P, BAP, and Pi were all lower than median
and average concentrations; Po was slightly higher than
median and lower than average; and all of these concen-
trations were decreased from 2006 significantly. Micro-
bial P was lowest (other than site 5) in positive concen-
trations. PDEase-P in 2007 was less than median and
average, and also lower than 2006; NPase-P in 2007 was
the third highest (Table 3), which was higher than aver-
age and median and around twice as in 2006. SRPwater
increased from 2 in 2006 to 28 µg·l–1 (lower than median

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York 348
and average) in 2007; OPwater (much higher than median
and average, third highest) in 2007 was similar as in 2006;
TPwater increased 1.5 times from 55 to 83 µg·l–1 (lower than
median and average) (Table 5 , Figure 5). NPasewater was
the fourth lowest (below average and median), and also
decreased from 2006. There is not significant difference
between 2006 and 2007 in sediment and water samples at
Headwater-Davis Brook, Valhalla.
3.2. Bronx River Valley
Site 2, Station A located at Virginia Road in Bronx River
Valley, East of Bronx River Parkway (Pkwy) North (N),
beside a bike path in Town of Mt Pleasant. There is a gas
station on west of Virginia road. Bronx River Valley has
been the major transportation corridor of the region, and
people commute with cars, bicycles, and trains [20].
Sediment collected in 2006 was mostly fine sand (33%),
silt (19%) and clay (19%) and total fine sediments were
up to 71% from granulometric fraction analysis. Bioavail-
able P (315 mg·kg–1), Pi (538 mg·kg–1, 76% of TP), Po
(165 mg·kg–1, 24% of TP), and TP (703 mg·kg–1) (Table
2, Figure 3) were the third highest concentrations among
the 15 sites. NPase-P was nearly zero in concentration,
and PDEase-P (68 mg·kg–1) was higher than median (54
mg· k g –1) and lower than average (80 mg·kg–1) (Table 3)
values of the 15 sites [12]. Major P compound was GlyP,
minor P compounds are NMP, PolyN, and IMP [17]. Smax
was the third highest and Ox-Al was the second highest,
Ox-Al associated with OM affected P sorption process
[27]. Clay-sized particles and sediments usually have
higher sorption of nutrients and pollutants [31]. Both
PDEase and NPase-P were strongly correlated with OM
with correlation coefficients of 0.745 and 0.683 respec-
tively), correlated TP (r = 0.814, 0.719; p < 0.01), Po (r =
0.872, 0.755; p < 0.01) and BAP (r = 0.887, 0.751; p <
0.01) (Table 6), indicating enzyme hydrolysis was re-
lated with OM associated BAP [12]. Water samples col-
lected in 2006 showed that SRPwater was higher than site
1 but lower than most other sites; TPwater and OPwater were
the highest in the first five sites. SRPwater OPwater and
TPwater were higher than in headwater (Table 5, Figure
4), while much lower than average and median [14].
NPasewater concentration was the highest, indicating po-
tential threat on river water quality when temperature
increases [8,9,11,12]. This site is around 1 mi from
headwater, however the P characteristics were much dif-
ferent from site 1. Residential in Town of Pleasant com-
mute to the city by automobiles and the gas station activ-
ity could affect on P transport and deposit here [1].
Sediment collected in 2007 was sandy sediment, and
83
34 33 30 39
178
54
90
74 56
112
91
197
17
3
56
000 2
115
0
63
0000
35
22
28 3433 30 37
63
54
27
74 56
112
91
162
151
0
50
100
150
200
250
David B r ook ,
Valhalla
S t ation A
N of TB S of TB
TB
N of S B
S of SB
SB
Cit y Linebt
WC and BX
NYBG
B ronx Z oo
E Tremont Ave
Bridge
B ronx River
estuary
S ound V i ew
Park Station
1234567891011121314
sites
µg l
-1
83
34 33 30 39
178
54
90
74 56
112
91
197
17
3
56
000 2
115
0
63
0000
35
22
28 3433 30 37
63
54
27
74 56
112
91
162
151
0
50
100
150
200
250
David B r ook ,
Valhalla
S t ation A
N of TB S of TB
TB
N of S B
S of SB
SB
Cit y Linebt
WC and BX
NYBG
B ronx Z oo
E Tremont Ave
Bridge
B ronx River
estuary
S ound V i ew
Park Station
1234567891011121314
sites
µg l
-1
water TP
wat e r OP
wat e r SRP
water TP
wat e r OP
wat e r SRP
μg·l
–1
Figure 5. 2007 Water SRP, OP and TP.

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York349
its texture was different from that of 2006. GlyP is the
only P compound in 2007, and trace amounts of NMP,
PolyN, IMP in 2006 not showing up here [17]. Bioavail-
able P, Pi, and TP concentrations were the lowest among
the 15 sites; TP, BAP, OM, Pi and Po were all decreased
significantly from 2006 (Table 2), and other than Po
were all lower than median and average concentrations.
PDEase-P and NPase-P were increased from 2006 and
both lower than median and average. TPwater in 2007 was
the third lowest (lower than median and average concen-
trations), lower than background concentration in natural
waters, also lower than water samples collected in 2006.
SRPwater increased from 2006, which was still lower than
median and average; OPwater in 2007 is 0, and only
SRPwater in this site. NPasewater (Table 5, Fig.5) was
higher than median but lower than average, and much
lower than that of in 2006. Perhaps the decreased OPwater
was the reason of decreased EHP and consequently de-
creased NPase hydrolysis activity in water column [7,
15,16].
3.3. Troublesome Brook Tributary
Site 3, 4, and 5 were located at Troublesome Brook
tributary (TB), east of Westchester County Center and
Bronx River Parkway (Pkwy) North (N). Westchester
County Center was built in 1930, adjacent to the Pkwy
[20]. Sediment textures were different among these three
sites. Fine sandy sediments (coarse dand 19%, medium
sand 26%, and fine sand 41%) collected in 2006 at site 3
N of TB, silty clay (fine sand 38%, silt 30%, and clay
17% from Granulometric fraction analysis) in site 4, S of
TB, and sandy sediments in site 5 (coarse sand 42% and
medium sand 16%), TB. Site 4 is a very representative
tributary site, and it had highest TP, Pi (1205 mg·kg–1,
77%), Po (358 mg·kg–1, 23%), BAP (919 mg·kg–1) (Table
2), PDEase-P, NPase-P, OM, Ox-Al, S0; the third highest
Ox-Fe, HCl-Ca and HCl-Mg, and the lowest Smax. Major
P compound was DHAP, and GlyP, NMP, and IMP were
in trace amounts [17]. BAP% was also the highest of
59%, which was higher than BAP% in Great Lake tribu-
taries (25% - 50%) [31]. Al, Fe, Mg, Ca associated with
OM affected P sorption. Original sorbed P-S0, P absorp-
tion energy Kf and bonding strength (k) were highest
among 15 sites [27]; Smax was the lowest among the 15
sites, relative high EPC0 values (more than average 0.36
mg· l –1), indicating there was high original sorbed P-S0 in
sediments that was correlated with P absorption en-
ergy-Kf (0.883), constant relates to bonding strength-k
(0.569), and sorption coefficient Kd (0.796) meanwhile
there was low sorption capacity in sediments [27]. Site 4
had the second most negative value of microbial P. Wang
and Pant [25] mentioned that the negative values of mi-
crobial P were possibly caused by different microorgan-
isms or bacteria which were resistant to cell ly-
sis/inhibition, and they could not be paralyzed by chlo-
roform. Those resistant microorganisms and bacteria con-
tinue to proliferate and uptake the SRP/BAP resulting in
negative values. The more negative the value, the more
resistant microorganism/bacteria biological activities
occurred and uptake more P [4,25]. The high negative
microbial P at site 4 indicated there were more P micro-
bial available, and enzyme could hydrolyzed those mi-
crobial P to SRP for plants use. PDEase-P was strongly
correlated with BAP, TP, Pi, Po, k, Kf , and OM at p <
0.01, S0 and Ox-Al at p < 0.05. NPase-P was correlated
with BAP, TP, Pi, Po, OM at p < 0.01, with EPC0, S0, k,
and Kf at p < 0.05 (Tabl e 6), indicating enzyme hydroly-
sis, microbial activity, BAP, potential BAP, and P sorp-
tion processes were correlated and impacted each other.
PDEase-P and NPase-P were strongly correlated with S0
(r = 0.589, 0.556; p < 0.05), NPase-P was negatively
correlated with microbial P (r = –0.677; p < 0.01) (be-
cause microbial-P concentrations were in negative val-
ues), and indicating P sorption is connected with micro-
bial activity and enzyme hydrolysis process [4]. Micro-
bial P was negatively correlated (because microbial P
were in negative values) with BAP, TP, Po, Pi and NP,
indicating that the highest TP, Po, Pi values could proba-
bly resulting in a second most negative microbial P, and
the more negative value, the more microbial activity
could have occurred that might have provided more in-
herent EHP resulting in highest NPase-P. However, the
negative values of microbial P were still need further
exploration in the future. It is known that physico- chemi-
cal activity such as sorption/desorption and biological
activity such as microbial activity/enzyme hydrolysis
were interaction each other and controlled P cycling and
transport in rivers [4]. Site 4 TB was a narrow small low
flow rate tributary that could result in OM and other
metal associated P deposition [17]. Clay-sized particles
and sediments usually have higher sorption of nutrients
and pollutants [31]. Clay-sized sediments are easily sus-
pended and settle slowly, and usually have high sorption
rates of OM and cation (Al, Fe, Ca, Mg) associated P
[33,39]; and P content increased as sediment size de-
creased [25, 32]. SRPwater was 25 µg·l–1, TPwater was 30
µg·l–1, OPwater was 5 µg·l–1 (Table 5), and all of them
were lower than average and median concentrations. Al-
gal growth is linear correlated with P concentration
ranged from 10 to 200 µg·l–1 [5], indicating that there
was potential possibility of algal growth at this site.
Bioavailable P and TP in sites 3 and 5 were much
lower, and significantly lower PDEase-P and NPase-P
concentrations than most of other sites (lower than me-
dian and average concentrations). Microbial P was in
lower negative concentrations, much less negative than

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York 350
concentration in site 4. Phosphorus compounds in sites 3
and 5 were controlled by GlyP, and minor P compounds
in site 3 is Poly-N and Pyro-P; and the Pyro-P was possi-
bly related with P fertilizer application from lawn and
golf course along Bronx River Pkwy near city of White
Plains [5,17]. SRPwater, OPwater, and TPwater were quite low
in TB estuary sites [43], and TPwater was higher in site 5
than sites 3 and 4 that might be caused by the down
stream P accumulation in the water column. NPasewater
concentrations in these three TB sites were distinguished
higher than other freshwater sites, indicating that OP
could become bioavailable during increased temperature
and changed hydro-climatic conditions [8-12].
In 2007, sandy sediments were collected in sites 3, 4
and 5; texture in site 4 showed different pattern. Total P,
BAP and Pi were higher at site 3 (slightly higher than
median concentration and lower than average) than sites
4 and 5 (both lower than median and average). Overall,
Pi, Po, TP, and BAP of these three TB sites were much
lower than values in 2006 (Tabl e 2). P compounds in site
4 showed difference that main compound was GlyP in
2007 instead of DHAP in 2006 [17]. PDEase-P, NPase-P,
and microbial P all had higher concentration at site 4
than sites 3 and 5 in 2007 (Table 3). NPase-P was sig-
nificantly correlated with microbial P (r = 0.718, p <
0.01), meaning that microbial activity was associated
with enzyme hydrolysis [12]. Compared with PDEase-P
and NPase-P in 2006 at site 4, both values decreased in
2007; sediment texture changed from silty clay domi-
nated to sandy sediments. It was known that small-
grained sediments adsorb more OM and OP; therefore
increase phosphatase activity in sediments [33]. NPasewa-
ter concentrations of these three TB sites in 2007 were
much lower than in 2006 (Table 5), NPasewater at site 3 in
2007 was higher than median lower than average,
NPasewater of site 4 and 5 in 2007 were all much lower
both median and average; SRPwater increased slightly in
2007, OPwater decreased significantly in 2007 and so did
TPwater, other than OPwater at site 5 (slightly higher than
median but much lower than average), all other concen-
trations in 2007 were much lower than median and aver-
age.
3.4. Sprain Brook Tributary
Sites 6, 7, 7b, and 8 were represented Sprain Brook
tributary (SB) sites, located beside Sprain Brook Pkwy
East of Bronx River Pkwy in Village of Bronxville, south
to City of Yonkers. Sandy sediments were found in SB
estuary (site 7b: coarse sand 42%, medium sand 34%,
total around 76%). Other than site 7B, GlyP was the ma-
jor compounds at sites 6 (PolyN and IMP were in trace
amounts other than GlyP), 7 and 8. NMP was the major P
compound at site 7b, PolyN, NMP, and Pyro-P were mi-
nor P compounds in trace amounts. The raw sewer dis-
charge from city of Yonkers since 2002 could possibly
result in the various OP and IP compounds in SB sedi-
ments [17,34]. Site 7b had the highest TP, Pi, PDEase-P,
NPase-P, Ox-Al, Ox-Fe, OM, EPC0 and the most nega-
tive microbial P values among these four SB sites. Site 8
had the highest Po and BAP among SB sites. Strong cor-
relations between PDEase and BAP, TP, Pi and Po, be-
tween NPase-P and BAP, TP, Pi and Po mean that if
more P bioavailable, predicted there was more enzy-
matically hydrolysable OP [7,13]. Sites 6, 7 and 8 had
comparatively higher NPase-P and PDEase-P (Table 3)
than most of other sites (PDEase: Site 6-close to median
value, site 7, between median and average, site 8-higher
than average; NPase-site 6, 7, and 8 all close to median
value); and sites 6 and 7 had comparatively lower values
of BAP and TP (all lower than median, and Site 7 had the
lowest BAP and site 6 had the lowest TP). Site 7b is lo-
cated at SW of SB; a sandy bar formed here and water
flowed very slowly, therefore P accumulation in site 7b
could be the reason of more intense enzymatic hydrolysis
and microbial activity [12,17,25,27]. TPwater of sites 7
and 8 were much higher than other freshwater sites:
TPwater in site 7 was the second highest and site 8 was the
third highest, OPwater of site 7 was the highest in and site
8 was the second highest [14]. SRPwater at site 7 was 40
µg·l–1, and it was close to background concentration in
natural water (42 µg·l–1) (Table 5); SRPwater at site 8 was
55 µg·l-1 that was higher than background concentration
and still lower than national median concentration (250
µg·l–1) [1]; however the TPwater at SB tributary sites 6, 7
and 8 were way higher than national median concentration
(site 6 - 1.5 times, site 7 and 8 both around 4 times) and
background concentration in natural water (site 6 - 9 times,
site 7 - 26 times, site 8 - 24 times). Both TPwater and OPwater
in sites 7 and 8 were first and second highest among fresh
water sites; water P levels could possibly associated with
the raw sewer spill from City of Yonkers since 2002,
possibly the raw sewer accelerating nutrient accumula-
tion [7]; and it could also associated with runoff from
golf course and residential activity along the river [1].
In 2007, SB tributary sites showed some different
characteristics especially at site 7 compared with 2006
data. Sediments were silty clay sticky type of finer sedi-
ments at site 7 in 2007. Site 7 had significantly higher TP,
Pi, BAP, PDEase-P, NPase-P, OM and microbial P in
2007 among the 15 sites; other than TP and Pi (around
2.2 times of median but slightly lower than average) all
these parameters were much higher than average and
medians, higher than all other SB sites 6, 7b and 8.
Meanwhile, these concentrations were higher in 2007
than those in 2006. SB sites other than site 7 have lower
BAP, TP concentrations in 2007 than in 2006. Po con-

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York351
centrations were much lower in 2007 than 2006 on four
SB sites (sites 7, 7b and 8 were lower than median and
average; site 6 between median and average). P com-
pounds showed difference, that PolyN, NMP showed up
trace amounts in 2007 at site 7, main P compound in
2007 was GlyP instead of DHAP [17]. SRPwater (other
than site 11) and TPwater were highest at site 6 among the
first 12 fresh water sites; OPwater and NPasewater were
highest among all sites. OPwater and SRPwater were lower
than concentrations in 2006; however NPasewater was
much higher than that of 2006 (nearly 22 times) (Table
5); indicating that the high P content and NPase hydroly-
sis activity in the water column at SB tributary [14]. Wa-
ter P levels and NPasewater in site 7 were decreased from
2006.
3.5. City Line-Boundary between Westchester
and the Bronx
Site 9, City Line at 233rd St and Nereid Ave, boundary
between WC and the Bronx, east of Woodlawn cemetery,
close to Metro-North Woodlawn station. River had been
straightened to accommodate the parkway in the border
of Bronx/WC [20]. There was sandy sediment (coarse
sand 32%, medium sand 22%, fine sand 21%) in this site.
BAP and TP were quite close to median, but lower than
average (Table 2). PDEase and NPase-P were lower than
median and average (Table 3). Po is 114 mg·kg–1, be-
tween median and average; Pi is 363 mg·kg–1, lower than
average and median concentrations. Microbial P was
close to median negative concentration, but less negative
than average negative concentration. Microbial P was
negatively correlated with NPase-P, BAP, TP, Po and Pi,
indicating that less bioavailable P and less EHP could
possibly explain the less negative value of microbial P.
Gly P is the only P compound in sediment at site 9 [17].
All SRPwater, OPwater and TPwater were higher than average
and median concentrations (Table 5). TPwater was the
fourth highest among 14 water sampling sites, and is the
third highest among fresh water sites (sites 1-11); SRPwa-
ter is the highest in the first nine sampling sites around 1.7
times of background concentration, and still much lower
than lower river fresh and saline water sites, OPwater is the
fourth highest among total sites and the third highest
among fresh water sites [14]. NPasewater is 5 µg·l–1, the
lowest among 14 sites, showing that limited amount EHP
and fair amount of non-hydrolyzable OP in river at this
location [7].
In 2007, sediment collected in the City Line had de-
creased BAP, TP, Pi, Po, OM, and NPase compared with
sediment collected in 2006; and all these parameters
were also lower than median and average concentrations
of 2007 data. Only PDEase-P in 2007 was greater and
around twice of 2006 concentration, which was higher
than median and close to average. P compounds showed
up pyro-P in trace amounts other than major compound
in GlyP [17]. TPwater, OPwater, NPasewater (Table 5) were
also lower in 2007 than in 2006. There was construction
near Woodlawn Metro-North train station near the city
line during sample collection in July 2007, which was
one of the P source in urban area and could possibly ex-
plain the temporal variations [1].
3.6. Bronx Park-New York Botanical Garden
and the Bronx Zoo
Bronx Park includes New York Botanical Garden
(NYBG) and the Bronx Zoo, which was covered by
dense trees and vegetation. Bronx River runs through a
50-acre native forest in NYBG, which was home to trees
nearing 300 years old [35]. Site 10, NYBG, at Old Snuff
Mill; Site 11, Bronx Zoo, south of Mitstubish waterfall,
entered from Gate B, Bronxdale Parking lot. Both sites
had fine sandy sediments (Site 10: coarse sand 31%, me-
dium sand 41%, fine sand 18%; site 11: coarse sand 14%,
medium sand 45%, fine sand 34%). Both sites TP, Pi, Po
and BAP were lower than median and average. Site 10
had the third highest PDEase-P concentration, fourth
highest NPase-P, and third most negative microbial P; it
had higher BAP, TP, Po, Pi, OM, Ox-Fe, HCl-Mg, Kd,
Smax, and Kf than site 11. The larger BAP, Po values and
more negative microbial P could possibly explain the
higher values of EHP in site 10 than site 11[7], and it
might be associated with the fertilizer management in
NYBG and animal manure management and runoff from
the Wildlife Conservation Society’s (WCS) Bronx Zoo
[5,17,19]. GlyP was the major P compound for both sites,
but site 10 also had PolyN, IMP and Pyro-P in trace
amounts [17]. P levels in water samples were higher in
site 11 than 10. P levels increased from upper river down
stream to lower river, sites 10 and 11 had higher SRPwater
values than upstream sites, and site 11 had highest
SRPwater among 14 sampling sites, and its TPwater, SRPwa-
ter, and OPwater were higher than site 10. EPC0 was sig-
nificantly correlated with SRPwater (r = 0.749, p < 0.01),
which could possibly explain the higher water P levels in
site 11 and site 10. NPasewater concentration is the second
highest in Bronx Zoo, that again indicates a potential
threat to water quality in an increased temperature [12,14].
In 2007, Site 10 had decreased BAP, TP, Po, Pi,
PDEase-P, NPase-P and OM compared with sediments in
2006. Other than PDEase-P, all these concentrations
were lower than median and average. P compound is
GlyP only; other trace amounts compounds not show up
in 2007. It could relate with P fertilizer management in
NYBG [17]. In contrast, it had much lower P content
than that of Bronx Zoo. Site 11 had the highest BAP,
microbial P, and NPase-P; third highest TP, Pi, and

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York 352
PDEase-P, second highest OM. Other than Po, all these
parameters were increased from 2006 to 2007. Sediment
texture in 2007 at site 11 was silty clay fine sediments,
and OM associated P, microbial and enzymatic activities,
EHP, BAP and overall P content increased as sediment
size decreased [25,32,33]; which might be also related to
animal manure management from Wildlife Conservation
Society (WCS) in the Bronx Zoo [17]. In 2007, P com-
pounds were DHAP 10% and GlyP 90% instead of 100%
GlyP in 2006 [17]. In 2007, NPasewater is higher in site 10
(higher than median and average) than site 11(lower than
median and average), however, SRPwater and TPwater were
higher in site 11 (higher than median and average concen-
trations). Compared with 2006, SRPwater, OPwater and TPwater
concentrations all decreased for both sties, NPasewate r in-
creased at site 10 and decreased at site 11.
3.7. East Tremont Avenue Bridge-Boundary
between Fresh and Saline Water
Site 12, East Tremont Avenue (Ave) Bridge is the
boundary of fresh and saline water in the Bronx River.
Sediment and water samples were collected at the East
Tremont Bridge between East Tremont Ave and Boston
Road, east of West Farm, and west of Bronx Art Center.
There were many abandoned tires on east bank of the
river, and there was busy traffic on East Tremont Ave.
Bridge with buses, automobiles. Sediments were mixed
with shell and pebbles collected at this site, below E
Tremont Bridge. Bioavailable P, Po, TP were lower than
median and average, Pi was in between median and av-
erage; and microbial P was in lower negative value less
negative than median and average. PDEase-P and
NPase-P were in third lowest values compared with other
sites, below median and average. Ox-Fe, HCl-Ca, HCl-
Mg and Smax were highest here, and Ox-Al is the third
highest; indicating large sorption capacity [17,25,27]. P
compounds were GlyP (major), PolyN and IMP (trace
amounts). During sample collection, there was oil spill
found on the river (might either from CSOs or runoff
from the bridge), and it might have inhibited microbial
activity and enzymatic hydrolysis, resulting compara-
tively lower EHP (PDEase and NPase-P) and less nega-
tive microbial P values [25]. SRPwater, OPwater and TPwater
in this fresh and saline water mixed site were higher than
most of the freshwater sites, much higher than average
and median (other than OPwater is higher than median but
slightly lower than average concentrations). Sediment
EPC0 was less than TPwater, and sediment could adsorb P
from water column whenever P is available, plus it had
the highest Ox-Fe, HCl-Ca, HCl-Mg, and third highest
Ox-Al and those cations binds P in a stable form (under
aerobic conditions) [27]; resulting in the highest P sorp-
tion capacity-Sma x [17,25,27,36]. NPasewater was the
fourth highest, indicating potential threat on water qual-
ity in this fresh and saline water boundary site [12,14].
Sediments collect in 2007 at East Tremont Ave Bridge
was sandy sediments. It had distinguished highest TP,
third highest microbial P, highest Pi but lowest Po, OM
was the same as median but lower than average; showing
that IP composed of the largest amount of TP due to
highest HCl-P [25]. Oil spill was not found during sam-
pling in 2007, this could enhance microbial activity.
Sediments in 2006 had largest Smax, and they could ad-
sorb P whenever it was available; those P was HCl ex-
tractable, and which was why highest HCl-P, Pi, and TP
[25-27]. Phosphorus compound is GlyP only; trace
amounts of PolyN and IMP in 2006 were not showing in
2007. In 2007, PDEase-P and NPase-P were both lower
than median and average; PDEase-P decreased from
2006, NPase-P was similar as 2006, and OM was also
decreased from 2006. In 2007, NPasewater was slightly
lower than median but only 27% of average concentra-
tion; SRPwater was higher than average and median (Table
5); OPwater was 0; TPwater was higher than median and
slightly higher than average, which was composed of
SRPwater only and it was 2.2 times of background concen-
tration 42 µg·l–1 but only 37% of median concentration
250 µg·l–1 of national streams. Overall, SRPwater, OPwater,
TPwater and NPasewater were much lower in 2007 than
2006.
3.8. Bronx River Estuary
Bronx River estuary, along Sound View Park, connected
to the East River. Site 13, located at old Sound View
Park water testing station, facing meat market, close to
river channel marker 7 and 8. Currently local businesses
are working with the city to create new parks, walking
trails and boating launching sites on Hunts Point and
between the Cross Bronx and Bruckner Expressways
[20]. Sediments were fine sandy (coarse sand-27%, me-
dium sand-21%, and fine sand-15%,) at Site 13. Sedi-
ments were fine sandy but a little sticky at site 14 (coarse
sand 0.5 - 1 mm: 28%, medium sand 0.25 - 0.5 mm: 17%,
and fine sand 0.125 - 0.25 mm: 12%), sediment depth
was very shallow at mouth of the river and stream bed
was rocky [4,41]. Wholesale fish market moved to Hunts
Point from Fulton Street in lower Manhattan in 2005;
wholesale meat market is also close by, besides HP
WWTP. Sound View Park is along the east of river estu-
ary, rounding off the southern end of the Bronx River,
was built on a former landfill, 158-acre, becoming sport
fields, fishing spots with beautiful views across Hunts
Point to Manhattan [20]. Mixture of fresh and saline wa-
ters in the river provides diverse plants, fisheries, benthic
mcaroinvertebrates and migratory birds such as herons
and egrets [19]. Many people were fishing in summer

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York 353
during sample collection time. Fishes in Bronx Estuary
includes striped bass, American eel, blue fish, summer
flounder etc.
Electrical Conductivity (EC) in water and sediments
were much higher than fresh water sites. Site 14 sedi-
ments had second highest BAP, TP, Po, Pi and NPase-P,
the most negative microbial P, the fifth highest PDEase-P
(all of these values were above average and median con-
centrations), indicating intense microbial activity pro-
vided more available P for enzyme hydrolysis activities
[26]. The most negative microbial P could represent a
significant amount of TP [25,26,37]. Site 13 had the
fourth highest TP, BAP, and Pi, sixth highest Po. Site 14
had higher Smax than site 13, even though Ox-Al, Ox-Fe,
HCl-Ca, and HCl-Mg were not as high as site 13, be-
cause there were higher P levels (BAP, Pi, Po and TP in
sediments) and higher P retained (92% in site 14 vs. 88%
in site 13) [25,27]. Bioavailable P was the second highest
(435 µg–1) (Table 1), and BAP% (BAP/TP%) was the
fifth highest (45%) in site 14; BAP was the fourth high-
est (289 µg–1) (Table 1) and BAP% (44%) was sixth
highest in site 13; both BAP and BAP% were higher than
average and median levels in both sites; showing the lar-
ger amount BAP in estuary because discharges from HP
WWTP sewer overflow during summer storms
[12,17,27]. Similarly, other studies found that BAP%
was higher in effluents from WWTP (average 72%) than
other urban drainage discharges with BAP of 53% [5].
Furthermore, Smax was correlated with BAP (r = 0.641, p
< 0.05), TP (r = 0.613, p < 0.05) and Pi (r = 0.623, p <
0.05), site 14 had significant higher BAP, TP and Pi than
site 13 and other 12 sites, therefore, it had second highest
Smax. Major P compound in estuary was GlyP; trace
amounts of polyN in site 13 and NMP in site 14 [17].
Sewer overflow from HP WWTP during summer storm,
CSOs from fish and meat wholesale markets, potential
pollutants from East River could result in higher P in
river water [38] and substantial microbial activity and
enzyme hydrolysis process in estuary [1,12]. In site 13,
TPwater (1113 µg·l–1) was the highest and OPwater (979
µg·l-1) was the second highest among the 14 water sam-
pling sites (Table 4), showing a second peak of P con-
centrations in estuary other than the first peak at SB (sites
7 and 8). In the water column, SRPwater, OPwater and TPwater
in site 13 were all higher than those of site 14; TPwater and
OPwater concentrations in both estuary sites were above
median and average values and greater than national me-
dian P concentration (250 µg·l–1) in waters, showing the
highest nutrient concentrations in urban rivers were down-
stream of WWTP facilities [1]. NPasewater of these two
estuary sties were lower than median and average, mean-
while, NPasewater in site 14 was slightly higher than that of
site 13 (Table 4). Fishing is popular in summer at
Table 4. Sorption characteristics of sediments collected in
2006 (Wang and Pant, 2010c).
# EPC0 S
0 S max
mg·kg–1
1 0.15 9 120
2 0.04 4 333
3 0.28 20 244
4 0.45 66 81
5 0.15 2 167
6 0.15 3 175
7 0.02 0 192
7b 0.73 29 179
8 0.44 53 370
9 0.42 24 169
10 0.41 13 208
11 0.58 13 120
12 0.33 46 476
13 0.54 31 333
14 0.67 42 435
Ave 0.36 24 240
median 0.41 24 192
Bronx River estuary. P levels in water and sediments
could be a potential threat to water quality and fish con-
sumption safety in estuary area.
In 2007, sediments collected at site 13 were silty clay
sticky sediments, and at site 14 were mixed sandy and
silty sediments. Total P, Pi, Po, BAP and microbial P
were second highest in site 14 (Table 2); Site 13 had the
fifth highest TP and Pi, third highest Po, fourth highest
BAP, and highest OM (16.7%, around 6 times of aver-
age). Similar as data showed in 2006, it was indicating
higher P levels in estuary sediments. PDEase-P was sec-
ond highest in site 13, which was higher than site 14
(Table 3); NPase was also higher in site 13 than 14. As
had mentioned earlier, it was showing that fine-grained
silty clay type of sediments tends to adsorb more OM
consequently increased enzymatic hydrolysis activities
[33]. Microbial P was significantly correlated with BAP
(r = 0.879, p < 0.01), Pi (r = 0.547, p < 0.05), and TP (r
= 0.547, p < 0.05); therefore similar as 2006, site 14 had
both second highest microbial P and P concentrations,
further proved higher P levels and intense microbial ac-
tivity in estuary [1,12]. Compared with data in 2006,
BAP, TP, Po, NPase-P decreased, PDEase-P and OM

Current Distortion Evaluation in Traction 4Q Constant Switching Frequency Converters 354
Table 5. physico-chemical characteristics and native enzyme hydrolysis of OP of water samples collected in 2006 and 2007
(Wang and Pant, 2011b).
# NPase-Pwater SRPwater TPwater OPwater pH EC
2006 2007 2006 20072006 20072006 20072006 2007 2006 2007
µg·l–1 µs·cm
-1
1 28 10 2 28 55 83 53 56 7.9 7.9 530 540
2 1818 79 5 34 87 34 82 0 7.8 7.8 396 621
3 154 135 18 33 29 33 11 0 7.9 7.9 651 739
4 286 17 25 30 30 30 5 0 8.0 7.9 674 786
5 428 22 13 37 63 39 49 2 7.9 7.7 1257 1415
6 80 1731 34 63 367 178 333 115 7.9 7.9 853 770
7 208 60 40 54 1069 54 1030 0 7.9 7.9 846 777
8 55 61 55 27 1019 90 964 63 7.9 8.0 806 701
9 5 0 71 74 785 74 714 0 8.0 7.9 766 678
10 42 507 92 56 143 56 51 0 8.0 7.9 820 727
11 1165 40 221 112 414 112 193 0 8.0 7.9 685 569
12 404 47 100 91 460 91 360 0 7.9 7.9 786 569
13 88 145 135 162 1113 197 979 35 7.4 7.5 34500 25400
14 109 0 122 151 501 173 379 22 7.3 7.5 35300 37800
ave 348 204 67 68 438 89 372 21 7.9 7.8
median 132 54 47 55 391 79 263 0
Table 6. Pearson correlation coefficient and significance of sediment and water data in 2006.
Variables PDEase-P Npease-P S0 SRPwater TPwater
BAP 0.887** 0.751** 0.705**
TP 0.814** 0.719** 0.677**
Po 0.872** 0.755** 0.683**
Pi 0.773** 0.690** 0.658**
OM 0.745** 0.683** 0.660**
Kf 0.785** 0.588** 0.883**
k 0.895** 0.630** 0.569*
Kd 0.796**
EPC0 - 0.565* 0.602* 0.749**
Ox-Al 0.608* - 0.534*
S0 0.589* 0.556*
Smax 0.720**
Microbial P - –0.677**
OPwater 0.989**
**correlation is significant at the 0.01 level (2-tailed). *correlation is significant at the 0.05 level (2-tailed).

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York 355
Table 7. Pearson correlation coefficient and significance of
sediment and water data in 2007.
PDEase-P NPase-P TPwater
BAP 0.582* 0.717**
Microbial P - 0.718*
OM 0.724* -
NPasewater 0.563*
SRPwater 0.789**
**correlation is significant at the 0.01 level (2-tailed). *correlation is sig-
nificant at the 0.05 level (2-tailed).
significantly increased and Pi slightly increased in site 13
(Table 2); in site 14 Pi, TP, and BAP increased (Table 1);
and Po, PDEase and NPase-P decreased (Table 1 & 2).
SRPwater, OPwater and TPwater in both estuary sites were
higher than median and average concentrations (Table 5).
TPwater of estuary sites was higher than national back-
ground concentration (5 times in site 13 and 4 times in
site 14); but lower than national median concentration.
TPwater and SRPwater were highest in site 13, TPwater was
third highest and SRPwater was second highest in site 14
(Table 4), indicating increased P concentrations in waters
downstream [1]. However, TPwater and OPwater were much
lower than concentrations in 2006. In 2007, NPasewater in
site 13 was the third highest (higher than in 2006), indi-
cating P levels and enzymatic hydrolysis increased in
estuary site downstream where close to HP WWTP [1,
14]. But there was no native enzyme activity showed at
site 14 (lower than in 2006) indicating that substantial
portion of the P pool was inaccessible to phosphata-
ses/enzymes to be hydrolyzed at this site [12].
Overall, in 2006 sites 2, 4, 7b and 14 had finer sedi-
ments, and highest BAP, Pi, Po and TP. Sites 4 and 14
had most negative microbial P. Sites 4, 14, 7b and 10 had
higher NPase and PDEase-P. Estuary and TB had higher
TP in water samples. Station A at Bronx River Valley
upstream in Westchester, S of TB, SW of SB, NYBG,
and the mouth of the river in estuary showed more in-
tense microbial activity and more EHP, BAP and poten-
tial BAP. The TP, BAP, Pi, and Po content variations
are related to land use and other characteristics of the
Bronx River [12,39]. TPwater showed peaks at sites 7, 8
and 13, NPasewater showed peaks at sites 2 and 11.
In 2007, sediments collected in sites 7, 11, 13 and 14
had finer texture, silty/clay type of sediments, and these
sites had high TP, BAP, Pi and Po (other than site 7). Site
12 had the distinguished highest TP and Pi. Sites 7, 11,
12, and 14 also had higher microbial P values. Sites 7, 11
and 13 had significantly higher PDEase-P, and site 11
had highest NPease-P, followed by site 7. TPwater showed
peaks at site 6, 11 and 13. NPasewater showed peaks at
sites 3, 7, 10 and 13. Overall, SB, Bronx Zoo, fresh and
saline water boundary and estuary showed distinguished
P characteristics in 2007. TPwater peaks showed in SB and
estuary for both years, indicating the raw sewer discharge
in Yonkers since was affected P levels and microorgan-
ism and enzyme hydrolysis at SB, and downstream HP
WWTP facility probably affect Bronx River estuary wa-
ter P and enzymatic activity as well.
4. Bronx River Ecosystems Improvement
and Future Research Perspective
It would be very interesting to continuously survey on P
levels in water and sediments under changing hy-
dro-climatic conditions in near future. For instance, this
summer is the hottest summer in NYC history; the in-
herent EHP could increase under increased temperature,
threatening freshwater quality. Bronx EcoAdventure or-
ganized canoe trip along the Bronx River through NYBG
and the Bronx Zoo currently, and canoes were launched
at the Concrete Plant Park between Westchester Avenue
and Bruckner Boulevard, near the nexus of the Sheridan
and Bruckner Expressways (Expy) [40,41]. With effort
from Bronx River Alliance, Concrete Park, a waterfront
park along the Bronx River, was built up from aban-
doned site used to contain trash and tries through
re-establishing salt marshes on riverbank, completed in
Sep 2009, and currently open to public for canoe/kayak
trips [40]. It was showing the ecosystem improvement
with effort from Bronx River Alliance (migratory birds,
shoots along the banks and shell of a small crab discov-
ered). [41].
New York City Parks Department, the Hudson River
Foundation, and the Bronx River Alliance are working
together on an oyster project that laid about 50,000 oys-
ters into Bronx River on Thursday (10/28/10) morning
[42]. High school students placed live oysters onto an
experimental oyster reef in the shallow waters off of
Sound View Park near the mouth of Bronx River on Oct
28, 2010 [43]. Students from Harbor School, a public
school on Governors Island raised the oysters. The reefs
located in the Bronx River, Jamaica Bay, off the shores
of Governors Island, Staten Island, Bay Ridge, and
Hasting in Westchester will be monitored for the next
two years [24]. NYC harbor were once flourished oysters
in mid-19th century before over-harvesting and pollution
nearly wiped out entire population. If oysters are able to
survive, the reef will provide shelter for fish and crabs
and improve the biodiversity of New York harbor. Water
quality could be improved as a result of the oyster’s abil-
ity to filter contaminants out of the water and improve
water clarity [42]. Those oysters are not safe to eat be-
cause they grow in water that is contaminated when raw

Land Use Impact on Bioavailable Phosphorus in the Bronx River, New York 356
sewage discharges into the river estuary during heavy
rain [43]. Ecologists hope to restore New York harbor’s
oysters, plan 500 acres of oyster beds by 2015, and 5000
acres of oyster beds by 2050 [43].
5. Conclusions
Phosphorus transport varied spatially along the Bronx
River. Distinguished characteristics appeared at Bronx
River Valley upstream in Westchester, TB, SB, NYBG
and estuary in 2006; in SB, Bronx Zoo, fresh and saline
water boundary at East Tremont Ave Bridge, and estuary
in water and sediments samples collected in 2007. Two
years data showed temporal variations as well. Sediment
texture, transport, deposition, assimilation, P adsorption
and desorption, land use and anthropogenic activities
including raw sewer discharge, oil spill, urban construc-
tion, fertilizer application and manure management along
the Bronx River as well as local hydro-climate changes
(such as temperature and precipitations) affected BAP,
potential BAP, potential EHP, microbial activity and
enzyme hydrolysis; resulting in spatial and temporal
variations. Analyses of land use impacts on P transport in
the Bronx River, help regulate P in river’s watershed and
restore river ecosystems. Efforts to restore Bronx River
ecosystems and wildlife habitat have been made by
community, NY Dept of Park and Recreations, showing
improvement and future research perspective. How to
coordinate P application, land use and recreation is a key
to improve water quality of the Bronx River.
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