Turkey’s inland water ecosystem consists of 33 rivers (177.714 miles), 200 natural lakes (906.118 ha), 159 reservoirs (342.377 ha) and 750 ponds (15.500 ha). Sedimentological studies conducted on inland water ecosystems during the last 15 years in Turkey can be categorized into two main topics. The first group of studies is concerned with heavy metal levels in sediment, with especial reference to the interaction between water, sediment and aquatic organisms. Additionally, the studies in question deal with the potential impacts of heavy metal concentrations on the ecosystem. The second group of studies is concerned with the role of eutrophication in the sediment as a result of serious contamination of inland water ecosystems. It is known that the sediment can directly influence the nutrient level in standing inland waters such as lakes and ponds by way of internal nutrient loading. In this context, studies regarding sediment, overlying water, sediment pore water and nutrient release from the sediment should be emphasized as these are important steps with respect to the eutrophication process. By keeping these studies in mind, the researcher in this study compiled and analyzed studies dealing with inland water ecosystems with differing nutrient levels and uses, including for drinking water, in Turkey’s drainage basins. In addition, field and laboratory studies regarding nutrient release from sediment into Turkey’s inland water ecosystems were evaluated in light of lake management practices.
The concentrations of heavy metals in receiving environments have both natural causes, such as sea-bed volcanic activity, atmospheric convection, rivers or erosion, and man-made causes, such as mining, the rapid increase of treatment and refining systems, the excessive use of fossil fuels, and the use of metallic products in agriculture (like arsenic pesticides). Of the heavy metals that are transported into the water, one portion is diffused in the water and the other portion forms solid compounds with carbonate, sulfate and sulfur, sinks to the bottom, and is accumulated in the sediment [
Fish can take in heavy metals through respiration (through the gills or the skin), adsorption to body surfaces or feeding. The intake of heavy metals and their accumulation in the organisms in aquatic ecosystems are affected by several factors, such as differences in the amount of metals entering the environment, the condition of the organism and the physical and chemical properties (temperature, salinity, pH and dissolved oxygen) of the aquatic environment in which the organisms are found.
Quantitative sediment quality guidelines (SQG) exist for freshwater ecosystems, and these provide a reliable benchmark for assessing sediment quality in freshwater ecosystems. The threshold effect level (TEL) and the probable effect concentrations (PEC) for different sediment contaminants in freshwater ecosystems were determined by [
For this review, studies on the interaction between water, sediment and aquatic organisms conducted over the past 15 years in five different types of aquatic ecosystem in Turkey (lakes, reservoirs, wetlands, rivers and streams) were compiled, and the surface sediment concentrations of arsenic, cadmium, chromium, copper, lead, mercury, nickel and zinc reported by these studies were compared with [
Some heavy metal concentrations in sediment from different lakes in Turkey are shown in
Beyşehir Lake is a conservation area located in southwestern Turkey used for irrigation and drinking water. The main factors contributing to its contamination are industrialization and urbanization. During the spring of 2001, water, sediment, plankton and fish samples were collected from three different stations in the lake. The order of heavy metals accumulation in the food chain was determined as water > plankton > sediment > fish tissues, except for Cr. The highest concentration in sediment samples was recorded for Pb and the lowest for Hg. Concentrations of Cd, Pb, Hg and Cr in the lake were recorded as 13.05, 32.65, 0.24 and 10.63 µg・g−1, respectively. According to the research, there were high concentrations of heavy metals in the water, sediment, plankton and fish. Direct contamination of the water by metals or the geochemical structure of the region was cited as possible reasons for this situation [
Kovada Lake is located in the Lakes Region, Turkey’s most visited wetland, which is extremely rich in terms of flora and fauna. The lake gained importance due to its surrounding forest and its natural beauty, and was given national park status and protection in 1970. In an analysis of heavy metals in the sediment of the lake, which has a maximum depth of five m, Cr, Cu, Fe, Mn, Pb, Zn, Al and Ni were present in all seasons, but Cd remained under the ICP-OES analytic limit in the summer and fall of 2005 [
Heavy metal concentrations from several fish species (Cyprinus carpio, Capoeta tinca, Leiciscus cephalus, Carassius gibelio and Silurus glanis) and sediment samples from six different lakes in Tokat province (Bedirkale, Boztepe, Belpınarı, Avara, Ataköy and Akın) were determined by [
Heavy metal conc. Lakes | As | Cd | Cr | Cu | Pb | Hg | Ni | Zn | References |
---|---|---|---|---|---|---|---|---|---|
Beyşehir Lake | - | 13.051,2 | 10.63 | - | 32.65 | 0.241 | - | - | [ |
Kovada Lake | - | nd-0.27 | 6.63 - 17.59 | 4.65 - 13.77 | 1.96 - 4.42 | - | 9.13 - 25.931 | 12.82 - 33.42 | [ |
(Tokat Lakes) Bedirkale | - | - | 4.5 - 6.1 | 5.1 - 8.2 | 2.9 - 3.4 | - | 51.1 - 53.61,2 | 33.7 - 38.9 | [ |
Boztepe | - | - | 6.4 - 7.8 | 4.7 - 6.1 | 6.7 - 7.0 | - | 51.6 - 55.41,2 | 23.3 - 23.9 | |
Belpınarı | - | - | 9.4 - 10.7 | 5.8 - 6.3 | 3.9 - 4.0 | - | 37.8 - 38.01 | 26.5 - 29.7 | |
Avara | - | - | 5.1 - 5.6 | 3.4 - 3.7 | 3.8 - 5.1 | - | 42.1 - 42.71 | 30.4 - 32.3 | |
Ataköy | - | - | 4.7 - 4.9 | 6.3 - 6.8 | 2.7 - 3.1 | - | 50.6 - 55.01,2 | 24.7 - 25.0 | |
Akın | - | - | 4.4 - 4.6 | 4.6 - 5.0 | 2.9 - 3.5 | - | 40.7 - 43.11 | 23.3 - 26.5 | |
Hazar Lake | - | 29.0 - 35.0 | 24.0 - 51.01(H) | nd | 41.01 | 49.0 - 70.0 | [ | ||
- | nd | 87.70 ± 43.341 | 46.32 ± 9.141 | 1.14 ± 3.49 | 49.50 ± 28.611,2 | 27.09 ± 10.26 | [ | ||
Terkos Lake | 0.56 - 1.161 | 91.88 - 123.921,2(H) | 5.94 - 33.09 | 22.61 - 62.511(H) | 25.07 - 39.411 | 76.22 - 137.551 | [ | ||
Uluabat Lake | - | 0.02 - 0.12 | 0.83 - 4.88 | 0.25 - 1.03 | 0.42 - 2.39 | - | 1.84 - 8.93 | 0.74 - 8.36 | [ |
- | 2.01 | 9.0 | 12.0 | 13.0 | - | 8.0 | 1.0 | [ | |
- | 0.691 | 57.91 | 119.21 | 110.71 | - | 209.41,2 | 171.01 | [ | |
Işıklı Lake | 1.14 - 16.331 | 0.09 - 3.061 | 11.60 - 269.552(H) | 2.68 - 38.841(H) | 11.23 - 211.161,2(H) | 16.34 - 159.561(H) | [ | ||
Yeniçağa Lake | - | 0.81 | 92.81 | - | 16 | - | - | - | [ |
Mogan Lake | - | - | 28.55 | 15.13 | 0.82 | - | - | 13.79 | [ |
Karataş Lake | - | 0.11 - 0.25 | 13.82 - 53.131(H) | 1388 - 32.27 | 0.54 - 1.13 | - | 47.16 - 203.921,2 | 12.92 - 45.00 | [ |
SQGs | As | Cd | Cr | Cu | Pb | Hg | Ni | Zn | Reference |
TEL1 | 5.9 | 0.596 | 37.3 | 35.7 | 35.0 | 0.174 | 18.0 | 123 | [ |
PEC2 | 33.0 | 4.98 | 111.0 | 149.0 | 128.0 | 1.06 | 48.6 | 459.0 |
1Every superscript with 1 for heavy metal concentrations mean the concentration exceeds the TEL value; 2Every superscript with 2 for heavy metal concentrations mean the concentration exceeds the PEC value.
2003-2004. In the fish samples, the maximum Fe, Zn, Cu, Pb, Cr, Mn and Ni concentrations were 167, 48.6, 3.6, 2.8, 1.6, 64.3 and 5.6 µg・g−1, respectively. As for the sediment samples, the maximum Fe, Mn, Zn, Cu, Pb, Cr and Ni concentrations of were 2138, 232, 38.9, 8.2, 7.0, 10.7 and 55.4 µg・g−1, respectively. The nickel values of three of the six lakes (Bedirkale, Boztepe ve Ataköy) exceeded both the TEL and the PEC values for nickel outlined by [
Lake Hazar (Elazığ, Turkey) is one of the largest and deepest lakes in Eastern Anatolia. Alburnus heckeli and Aphanius asquamatus are native fish species of the lake. [
In an additional study of the same lake conducted by [
A study performed by [
Uluabat Lake, home to Turkey’s largest water lily beds and declared a Ramsar protected wetland in 1998, is located south of the Marmara Sea in Bursa province and lake has an area of between 120 and 240 km2. The Lake Uluabat drainage is located in one of the most productive agricultural regions of Turkey. There are 16 urban settlements on the lake shores, and the main human activity on the lake is fishing. In addition to fisheries and agriculture, livestock breeding is also an important activity near the lake [
In another study conducted in the same lake by [
A third study done on the same lake by [
Işıklı Lake is located in the southwest of Turkey and is used for irrigation. With a depth of approximately seven m. and an area of 9.749 ha, it is fed by the Büyük Menderes, Karanlık and Kuti Rivers. There are small rush islands in the lake, and the surrounding shores are home to apple, cherry and peach orchards, grains fields, restaurants and hotels. The most common fish species in the lake are Cyprinus carpio, Esox lucius, Tinca tinca and two local fish species (Aphanius anatoliae and Chondrostoma meandrense). The lake is polluted by agricultural runoff and domestic effluents. Several heavy metals (Ba, As, Co, Cd, Cr, Cu, Fe, Mn, Ni and Zn) were detected in water, sediment and a total of 144 fish samples from Işıklı Lake between March 2009 and February 2010. Among the metals observed, Fe had the highest concentrations in both the water and the sediment, while Cd had the lowest value in the sediment, ranging between 0.19 - 3.06 mg・kg−1. The results of this study point to a potential risk developing in the future depending on agricultural development [
Yeniçağa Lakein Bolu province is an extremely important aquatic ecosystem due to its position on the migration route of birds coming over the straits of Istanbul and Çanakkale, the peat beds on its perimeter, and the fishing that is practiced in the lake. It is also used for irrigation and recreational purposes. In a study conducted by [
Mogan Lake, located 20 km to the south of Turkey’s capital city, Ankara, is near the town of Gölbaşı, which has undergone considerable development in recent years due to population increase and urban settlement. In a study of the lake conducted by [
Karataş Lake, in the southwest of Burdur province, is used primarily for irrigation. It also hosts migrating birds and seven fish species, one of which is endemic. A study of the water, sediment and the gills of the Sander lucioperca in the lake done by [
Some heavy metal concentrations of sediment samples from different wetlands and dam lakes in Turkey are presented in
Akyatanis the biggest fishery lagoon in Iskenderun Bay on Turkey’s Mediterranean coast. Akyatan Lagoon is a multipurpose wetland ecosystem that has important contributions to the local economy, such as aquaculture and touristic activities [
Yedigöller is the nearest wetland to the Kütahya city center and provides irrigation water to some of the farmland surrounding it. Yedigöller is eutrophic, and has been used as a waste disposal area (landfill) since 1977. Of the seven lakes in the wetlands, two are now dry. [
Heavy metal cons. Wetlands and Dam Lakes | As | Cd | Cr | Cu | Pb | Hg | Ni | Zn | References |
---|---|---|---|---|---|---|---|---|---|
Akyatan Lagoon | - | 1.41 - 1.611 | - | 15.87 - 22.81 | 35.14 - 58.401 | - | - | 27.90 - 52.46 | [ |
Yedi Göller | - | nd | 43.20 - 43.931 | 67.80 - 68.531 | 30.67 - 32.67 | nd | 59.87 - 60.331,2 | 68.47 - 104.13 | [ |
Seyhan Dam Lake | - | 2.15 ± 0.381 | 118.95 ± 21.71,2 | 19.80 ± 4.57 | - | - | - | 39.09 ± 6.50 | [ |
Porsuk Dam Lake | - | 3.36 ± 0.131 | 78.40 ± 4.571 | 26.08 ± 1.20 | 90.00 ± 40.661 | nd | 159.12 ± 5.651,2 | 656.40 ± 32.391,2 | [ |
Enne Dam Lake | - | 5.04 ± 0.151,2 | 59.08 ± 1.791 | 27.84 ± 0.68 | 88.96 ± 3.221 | nd | 136.82 ± 5.101,2 | 272.00 ± 11.471 | |
Atatürk Dam Lake Bozyazı (Bozova) | - | nd | - | 14.57 | nd | nd | 43.691 | 60.79 | [ |
Akpınar (Adıyaman) | - | nd | - | 22.70 | nd | nd | 139.691,2 | 59.14 | |
Atatürk Dam Lake | - | nd | - | 35.05 ± 5.02 | - | nd | 72.50 ± 28.421,2 | 35.15 ± 3.32 | [ |
Demirköprü Dam Lake | - | 0.70 - 0.821 | 3.58 - 6.75 | 9.3 - 15.1 | 2.66 - 6.50 | 7.41 - 14.30 | - | [ | |
Avşar Dam Lake | - | 0.761 | 13.33 - 14.48 | 23.47 - 29.98 | 2.44 - 4.04 | - | 28.25 - 29.991 | - | [ |
Geyik Dam Lake | - | nd - 2.0 | - | 11.0 - 120.01(H) | 28.0 - 31.3 | - | 104.0 - 320.01,2 | 32.0 - 104.0 | [ |
Çatören Dam Lake | - | 12.41,2 | - | - | - | - | - | 32.0 | [ |
SQGs | As | Cd | Cr | Cu | Pb | Hg | Ni | Zn | Reference |
TEL1 | 5.9 | 0.596 | 37.3 | 35.7 | 35.0 | 0.174 | 18.0 | 123 | [ |
PEC2 | 33.0 | 4.98 | 111.0 | 149.0 | 128.0 | 1.06 | 48.6 | 459.0 |
1Every superscript with 1 for heavy metal concentrations mean the concentration exceeds the TEL value; 2Every superscript with 2 for heavy metal concentrations mean the concentration exceeds the PEC value.
sediment are below measurable values, the wetland is under the pressure of extreme pollution due to its use as a landfill. Therefore, the authors of the study maintain that several measures should be taken in the area: first and foremost, leachates from the landfill should be prevented from contaminating the underground and surface water, aerobic and anaerobic bacteria should be used to break down organic matter, waste should be sorted at its source for recycling, a proper solid waste disposal facility should be built, and water quality parameters should be periodically measured and recorded. The sediment chromium and copper concentrations recorded in the study exceeded the TEL values reported by [
Seyhan Dam Lake, built across the Seyhan River, has been in operation since 1956. It is an important dam lake in the Mediterranean Region, and was built for the purposes of flood control, irrigation and energy production. It also serves as an important recreation area for the city of Adana. [
Porsuk and Enne Dam Lakes, located in Kütahya, are freshwater reservoirs that are highly polluted because of nearby industrialization and urbanization. There are also many boron deposits and thermal springs in the region surrounding these dam lakes. A study conducted by [
Atatürk Dam Lake, on the Euphrates River, is the largest reservoir in Turkey. It is used for irrigation and electrical energy production purposes. It has a surface area of about 81,700 ha and a volume of 48,700,000,000 m3, and 28 fish species are known to inhabit its waters. Industrial development and anthropogenic waste affect this reservoir, and the population in this region has recently increased [
A later study conducted by [
Demirköprü Dam Lake, located in Manisa province on the Gediz River in western Anatolia, has a maximum capacity of 1,320,000,000 m3 and an area of 47.66 km2. Contamination studies must be performed on the reservoir at regular intervals as the reservoir is used for agricultural irrigation purposes and has a significant impact on both the environment and public health. In a 2005 study undertaken by [
Avsar Dam Lake, constructed in western Turkey to help ease water problems in the Gediz Basin, is actively fished by local inhabitants. The ecosystem’s quality has been compromised as a result of agricultural and human activities. In a study conducted by [
Geyik Dam Lake, which was constructed on the Sarıçay River in 1988 to provide irrigation and industrial water, supplies 38 hm3 of domestic water to the town of Milas. In a study conducted on the reservoir, new information was obtained on the accumulation of heavy metals (Cd, Co, Cu, Fe, Mn, Ni, Pb, and Zn) in fish tissue (Cyprinus carpio and Carassius carassius), sediment, and water from the reservoir. Sediment samples from the study showed high Fe concentrations in winter and summer, but low concentrations of Cd and Pb in summer, and likewise, low Co and Cu in winter [
Çatören Dam Lake is in Seydisuyu Basin in the Kırka district of Eskişehir province. This is one of Turkey’s most important boron mining regions. In the reservoir some limnological parameters as well as macro-micro accumulations of certain elements in the water, the sediment, and some tissues of Cyprinus carpio, Cyprinus carpio var. specularis and Tinca tinca, which are important fish for regional trade [
Some heavy metal concentrations in different rivers and sediment samples (Turkey) are presented in
The Gediz and Buyuk Menderes (BM) Rivers, which have great economic importance for Turkey, in order to determine the extent of environmental contamination [
In a separate study undertaken on the Sakarya River, [
The Yesilirmak River has a total basin area of 2352.8 km2, and the river is 519 km long. A large part of the river flows through the city of Tokat. Concentrations of trace metals in sediment samples from the river were as follows: Cu 37.9 mg・kg−1, Mn 392.2 mg・kg−1, Zn 126.2 mg・kg−1, Fe 3726 mg・kg−1, and Pb 29.6 mg・kg−1 [
The Tigris River has its start in the mountains of Eastern Anatolia and flows southeastwards from Turkey into Iraq. Samples taken by [
The Dipsiz Stream is 88 km long and yields about 1000 L/s−1. It flows into the Buyuk Menderes River in southwestern Turkey. In three surveys carried out on the stream in April, July and October 2004 [
Heavy metal cons. Rivers and Streams | As | Cd | Cr | Cu | Pb | Hg | Ni | Zn | References |
---|---|---|---|---|---|---|---|---|---|
Büyük Menderes River | - | - | 165.0 ± 7.01,2 | 137.0 ± 5.01 | 54.0 ± 8.01 | - | 315.0 ± 25.01,2 | 120.0 ± 10.0 | [ |
Gediz River | - | - | 200.0 ± 6.01,2 | 140.0 ± 3.01 | 128.0 ± 15.01 | - | 106.0 ± 10.01,2 | 160.0 ± 15.01 | |
Kızılırmak River | - | 0.92 ± 0.031 | - | 9.95 ± 2.65 | 0.62 ± 0.04 | - | 47.91 ± 6.431 | 34.62 ± 6.46 | [ |
Sakarya River (in the lower part) | - | nd | 9.47 ± 2.7 | 5.63 ± 1.70 | 4.31 ± 0.40 | - | 18.17 ± 2.101 | 10.55 ± 2.20 | [ |
TigrisRiver | - | nd | - | 25.39 - 194.531,2(H) | nd | - | 36.68 - 170.831,2(H) | 17.09 - 66.26 | [ |
Yeşilırmak River | 0.55 | 38.71 | 17.3 | 79.21,2 | 45.5 | [ | |||
37.91 | 29.6 | 126.21 | [ | ||||||
Dipsiz Stream | - | 0.80 ± 0.601 | 19.70 ± 15.60 | 13.00 ± 9.00 | 83.60 ± 56.201 | - | - | 37.00 ± 26.00 | [ |
Delice Stream (Kızılırmak Basin) | - | - | 74.4 - 237.41,2 | 7.11 - 57.31(H) | 27.99 - 39.71(H) | 4.16 - 14.811,2 | - | 86.2 - 170.61(H) | [ |
Felent Stream | [ | ||||||||
Upstream | 15.56 - 119.901,2(H) | - | 48.38 - 62.691 | 9.62 - 19.53 | 11.73 - 230.751,2(H) | - | - | 39.31 - 343.251(H) | |
Lentic | 27.121 | - | 53.471 | 22.29 | 11.29 | - | - | 54.69 | |
Downstream | 14.84 - 18.531 | - | 33.42 - 46.291(H) | 15.47 - 163.481,2(H) | 8.52.123.661(H) | - | - | 56.13 - 138.001(H) | |
SQGs | As | Cd | Cr | Cu | Pb | Hg | Ni | Zn | Reference |
TEL1 | 5.9 | 0.596 | 37.3 | 35.7 | 35.0 | 0.174 | 18.0 | 123 | [ |
PEC2 | 33.0 | 4.98 | 111.0 | 149.0 | 128.0 | 1.06 | 48.6 | 459.0 |
1Every superscript with 1 for heavy metal concentrations mean the concentration exceeds the TEL value; 2Every superscript with 2 for heavy metal concentrations mean the concentration exceeds the PEC value.
The Kızılırmak River the longest river within the borders of Turkey (1355 km) is currently used as a source of drinking water for Ankara, the capital of Turkey. The study carried out in Kızılırmak River (in April and October 2005) has been conducted to determine cadmium, cobalt, copper, chromium, iron, manganese, nickel, lead and zinc concentrations in the five different tissues of carp (gills, muscle, liver, kidney and gonads), and in the surface water, sediment samples, and aquatic plant from the study area. The highest sediment heavy metal concentration was recorded for Fe, and the lowest for Cd and Pb. The origin of the elements could be attributed to the geological environment surrounding the river, and some industrial facilities near the river. Results of correlation coefficient analysis gained from the study suggested that metal concentrations in the sediment and aquatic plant are the most curucial factors governing the metal body concentration of fish [
Felent Stream is one of the most important branches of Porsuk Stream in the Sakarya River Basin. It is used for irrigation, industrial water supply, domestic waste disposal and fishing [
According to water quality regulations [
Although the geochemical structure of the region does play a role in the increase of heavy metal levels in lake sediment, the main cause has been shown to be terrestrial inputs originating from anthropogenic (domestic and industrial) sources which are delivered via rivers and rainfall. Especially harmful are effluents from urban settlements on the lake’s shores and agricultural development in the drainage basin. Studies done in different years on the same aquatic systems have shown that heavy metal concentrations in the water and sediment have been on the increase. This result points to the fact that contamination is continuing and the measures that have been taken are not effective enough. When the heavy metal concentrations in the lake sediment mentioned in this review are examined in light of the TEL and PEC levels for sediment reported by [
The contamination sources that lead to high heavy metal concentrations in wetland and reservoir sediment are no different from those that affect other aquatic systems. For many reservoirs, for example Demirköprü, Avşar, Seyhan and Geyik reservoirs, it has been suggested that the heavy metal levels in the sediment result from agricultural and domestic waste discharges. For others, primarily Atatürk Reservoir, geological sources are thought to play a role as the main contaminating element. For example, for Seyhan Reservoir, chrome mining, and for Çatören Reservoir, boron processing were found to contribute to the increase of some sediment heavy metal concentrations. In highly polluted reservoirs like Porsuk and Enne Reservoirs, on the other hand, industrialization and urbanization activities are the primary culprit. Among the reservoirs discussed (Demirköprü and Avşar Reservoirs) concentrations of especially Cd, Cr, Ni and Pb in the fish that are caught for food exceed tolerable values delineated by international institutions. When the heavy metal concentrations in the sediment of the wetlands and reservoirs investigated in this review are examined according to the threshold effect level (TEL) and probable effect concentrations (PEC) for sediment levels reported by [
When examining heavy metal levels in the sediment of rivers and streams, it has been noted that limited studies have been done on this topic. Of the areas that are included in such studies, it has been reported that especially for the Büyük Menderes, Gediz and Yeşilırmak river basins, industrial plants, agricultural lands and sites are responsible for heavy metal contamination. When the sediment heavy metal concentrations for the rivers and streams discussed in this study were evaluated in light of the TEL and PEC for sediment levels indicated by [
In conclusion, there has been considerable attention given to sediment heavy metal contamination in Turkey’s freshwater ecosystems over the past 15 years. Terrestrially derived wastewater discharge, agricultural and industrial run-off and regional geological characteristics are known to be the most common sources of heavy metals in the sediments of these freshwater ecosystems. All five types of freshwater aquatic systems in Turkey are contaminated with heavy metals according to the TEL and PEC values. Moreover, the tissues of aquatic biota in the study areas have been reported as having high levels of heavy metals in them. For this reason, site-specific information should be collected to supplement the use of SQGs for evaluating sediment quality on a regional and national basis.
In aquatic environments, phosphorus transfer occurs between water and sediment as a result of several physical, chemical and biological events. Transfer of phosphorus from the sediment to the water is known as internal phosphorus loading. Sediment is very important for the nutrient dynamics of shallow lakes. Even in lakes where the external loading has been reduced, internal phosphorus loading from the sediment has in some cases been seen to prevent improvements in lake water quality [
Phosphorus release amounts are estimated by comparing total filterable orthophosphate concentrations to the sediment porewater as well as overlying waters, with the water content of the sediment and the diffusion coefficient depending on the temperature. Physical, chemical and biological measures must be taken in aquatic systems in order to control eutrophication by reducing internal phosphorus load. Phosphorus release from the sediment to the lake water through molecular diffusion can generally be estimated using Fick’s First Law. Accordingly, the formula specified by [
The number of studies conducted in the last 15 years regarding the release of nutrients from the sediment to the water of some lakes and ponds in Turkey is extremely low. The first study of this type was done at Kırkgız Pond (West Pond), one of the five Sakaryabaşı Karst Springs. These Karst Springs in Central Anatolia are part of a confined/semi-confined karst aquifer, which also has a thermal component. Kırkgız Pond was naturally converted to a pond due to the presence of macrophytes in the spring. The pond supplies water to the Rainbow Trout Culture and Research Station, which produces approximately 40 tons of fish per year. The above-men- tioned study on Kırkgız Pond was conducted by [
Mogan Lake, an important recreational area for metropolitan Ankara, is designated with environmental protection status as “Gölbaşı Specially Protected Area.” The chief source of phosphorus in the region is waste-water, which contains detergents and fertilizers used in the nearby agricultural areas. A study was undertaken between July 2004 and June 2005 to examine the seasonal and spatial patterns of Mogan Lake’s littoral sediment phosphorus and the potential for its release into the water. Sediment phosphorus release fluctuated between 0.002 and 0.062 μg・m−2・d−1 within the research period, and reached minimum and maximum values in November and June, respectively. By examining the estimated values of phosphorus release into the lake, the study has quantitatively shown that the sediment had only a minimal effect of on the trophic level of the lake. Organically-bound phosphorus fractions were estimated to make up the largest proportion of fractions preventing phosphorus release into the lake (Org ≈ P: 36%), followed by calcium-bound (Ca ≈ P: 35%), iron + aluminium-bound (Fe + Al ≈ P: 16%) and carbonate-bound (CO3 ≈ P: 13%) phosphorus fractions. Internal phosphorus load was estimated to be very low, and thus, it is suggested that sediment dredging of the lake would not affect its trophic level, and would only deepen the lake [
From these three studies involving sediment phosphorus release in Mogan Lake, it can be concluded that the sediments of this lake must be monitored over time, taking management measures and continued external phosphorus loading into account, to improve its management and promote the continuation of a clear water state. Consequently, two steps should be taken in order to control the eutrophication process in Lake Mogan: first, the sediment should be examined to determine its adsorption capacity, and second, a program should be implemented which monitors the lake’s trophic level by recording variations in the lake water’s total filterable orthophosphate concentrations.
Küçük Çekmece Lagoon, located in the Marmara Region 15 km to the west of Turkey’s largest metropolis, Istanbul, is a shallow sea-level wetland water source used for various purposes. It has gained widespread international importance due to its biological diversity. In a study comparing sediment nutrient release in the lagoon under field and laboratory conditions, sediment samples were taken monthly between October 2006 and February 2008. The highest readings for nitrate (NO3-N) and orthophosphate (o-PO4) obtained under field conditions were 3.39 mg/L−1 and 6.62 mg/L−1, respectively. However, under laboratory conditions, the highest value of NO3-N was measured as 3.41 mg/L−1, while the highest value of o-PO4 was 2.95 mg・L−1. Using these results, the highest values for nitrate and orthophosphate flux were calculated as 3035 and 1487 mg・m−2・day−1, respectively. Under field conditions, significant variation was seen in the measured nutrient values between the deepest and costal stations. Under laboratory conditions, however, the measured values did not generally show such a difference. The data from the study point toward a nutrient load in the lagoon characteristic of highly eutrophic lakes. According to the study, sediment fluxes account for 45% of the nitrogen load and 85% of the phosphorus load entering the Küçük Çekmece Lagoon annually. This result shows that sediment flux plays an important role in the lagoon’s eutrophication process [
Sediment has been shown to have a significant effect on nutrient transfer in lakes, especially shallow ones. When phosphorus enters the sediment of a lake, it is employed in the chemical and biological processes of the sediment. Later, it either becomes permanently deposited in the sediment or is released by various processes and returns to the water column in dissolved form through the porewater. It should be emphazised, however, that sediment can differ drastically from one lake to another, and even within the same lake, may have highly variable chemical composition. Factors such as dry weight, organic content, and the presence of iron, aluminum, manganese, calcium, clay and other elements with the capacity to bind and release phosphorus may affect interactions between the water and the sediment. It can be understood from this review that there have been an extremely limited number of studies on this topic conducted in Turkey. Due to their significant effect on lake water concentrations, awareness of sediment-water interaction and the processes behind phosphorus retention and release in the sediment is crucial in order to understand shallow lakes’ functioning and determine effective management strategies.