Termites build their habitat in the form of anthills or termitaria or termite mounds which are characterised by soil of clayey texture. This paper investigated the relative grain size from the base, middle and near the peak of three anthills located 20 km west of Winneba near the Apam-Winneba highway in Ghana and also correlated their elemental compositions. The results showed significant grain size gradation of soils which range from <0.075 mm to 2 mm such that coarse grains occurred at the base while finer fractions were at higher parts of the anthills. Major oxides (wt. %) showed that SiO2 (51.70 - 60.24) was positively correlated with total FeO (12.22 - 15.24), Al 2O 3 (22.18 - 28.88), MnO (0.08 - 0.09), and K 2O (0.4 - 0.61). However, as K 2O decreased with height on anthill, SiO2, total FeO and Al 2O 3 increased. Probably soils used to construct these anthills were derived from different rock types and/or the termites were selective in the use of soils rich in silica or iron oxide.
Anthill (termitaria) is a habitat of termites constructed with soils of modified texture, increased content of organic matter, phosphorus (P), nitrogen (N), and potassium (K) due to biological activities of the ants [
Anthills were used in geochemical mineral exploration by West [
The study area is located at about 20 km west of Winneba junction in Gomoa East district, located in the south-eastern part of the Central Region of Ghana. The district experiences two rainfall seasons―the major rainy season is from March/April-June/July while the minor season is from September-November. The main dry season is from November to March and a minor one from mid-July to mid-August [
The area of study is underlain by the Birimian Supergroup composed of metavolcanic rocks with isolated amphibolite due partly to contact metamorphism from granitoid intrusives; generally foliations dip at 5˚ to 20˚ towards the north-northwest (
Of the many anthills which occur on either side of the highway from Apam junction to Winneba junction in Ghana, three of them which were used for the study, were located at about 20 km west of Wnneba junction. Their positions were picked using GPS and sampled at the surface from three spot heights after their circumferences were measured at the base at 5 cm from the ground, middle, and at the top. To avoid contamination of samples, mount surfaces were cleaned by scrapping with a metal chisel, bagged and labelled. Samples from the field were dried in the open sun, coned and quartered to obtain a representative sample. A quarter of the sample was taken, weighed to 500 g, soaked in water and passed through 0.075 mm sieve to separate the upper size (sand fraction) and under size (fine fraction). Grain size distribution for the sand fraction was obtained through sieving and under size dried and weighed. These analyses were done in the Geotechnical Laboratory of the University of Mines and Technology at Tarkwa in Ghana. Elemental composition was determined on two batches of samples by X-Ray fluorescence analysis at the Geological Survey Department (GSD) in Accra, Ghana.
At GSD, each sample with a labelled tag was put in a crucible, oven dried at a temperature of about 105 degrees Celsius for 20 minutes after which samples were removed and put into glass desiccators to prevent moisture entry whilst cooling. Then 4 g of each sample was then mixed with about 0.9 g of wax powder,
homogenised by milling for about 5 minutes and then compressed under a load of 15 tonnes to obtain a 32 mm diameter pellet. X-ray florescence analysis was conducted using SPECTRO X-LAB 2000 multi element analyser to obtain major oxides (wt. %) and trace elements (ppm).
The land surface of the study area was gently undulating, occupied by poorly drained, dark olive brown clay or yellowish red silt clay with scarce iron oxide and manganese oxide nodules. Anthills used for the study were wider at the base (6.0 - 6.8 m), reduced near the middle by about 1.0 m and smaller at the top by a third. These structures were up to 2 m high (
Sieve size (mm) | Anthill 1 (g) | Anthill 2 (g) | Anthill 3 (g) | |||||||
---|---|---|---|---|---|---|---|---|---|---|
A | B | C | A | B | C | A | B | C | ||
2.000 | 8.6 | 11.4 | 4.1 | 2.2 | 1.1 | 0.5 | 1.7 | 1.3 | 1.0 | |
1.180 | 33.6 | 37.3 | 31.3 | 15.5 | 13.6 | 11.5 | 11.1 | 11.8 | 11.5 | |
0.600 | 24.0 | 29.6 | 26.7 | 17.5 | 18.1 | 18.7 | 50.2 | 61.4 | 65.2 | |
0.425 | 15.6 | 16.7 | 17.5 | 10.8 | 11.8 | 11.4 | 74.9 | 77.5 | 84.8 | |
0.300 | 13.8 | 15.4 | 16.0 | 10.4 | 10.0 | 11.1 | 25.4 | 15.6 | 17.2 | |
0.212 | 16.3 | 18.2 | 19.2 | 12.5 | 12.4 | 13.5 | 33.5 | 22.6 | 34.0 | |
0.150 | 13.7 | 15.7 | 16.7 | 10.9 | 10.3 | 11.5 | 14.8 | 15.4 | 18.8 | |
>0.075 | 151.5 | 179.1 | 168.1 | 107.7 | 109.6 | 118.0 | 241.1 | 231.4 | 276.6 | |
<0.075 | 348.5 | 320.9 | 331.9 | 392.3 | 390.4 | 382.0 | 258.9 | 268.6 | 223.4 |
sieve size (8.6 g) followed by anthill 2 (2.2 g) and then anthill 3 (1.7 g); total mass above 0.075 mm sieve size was higher in anthill 3 (231.4 - 276.6 g), followed by anthill 1 (151.5 - 179.1 g) and then anthill 2 (107.7 g - 118.0 g); fines were higher in anthill 2 (392.3 - 382.0 g), followed by anthill 1 (320.9 - 348.5 g) and least in anthill 3 (223.4 - 268.6 g) (
Percentage of soil grain size from anthills which passed through sieve size 0.075 mm was more than the retained (
SiO2 (wt. %) decreased higher up of anthill 1 but increased with increasing height in anthill 2 (
Major Oxide (wt. %) | 1A | 1B | 1C | 2A | 2B | 2C |
---|---|---|---|---|---|---|
SiO2 | 56.08 | 51.70 | 51.88 | 54.30 | 56.65 | 60.24 |
TiO2 | 1.22 | 1.20 | 1.18 | 1.30 | 1.38 | 1.38 |
Al2O3 | 27.29 | 27.79 | 28.88 | 22.18 | 23.18 | 23.72 |
FeOT | 14.35 | 14.92 | 15.24 | 12.42 | 12.24 | 12.22 |
MnO | 0.09 | 0.09 | 0.09 | 0.09 | 0.08 | 0.08 |
MgO | 1.58 | 1.50 | 1.50 | 1.20 | 1.90 | 1.78 |
CaO | 0.34 | 0.25 | 0.20 | 0.25 | 0.24 | 0.23 |
Na2O | 1.27 | 0.92 | 1.06 | 0.95 | 1.17 | 1.19 |
K2O | 0.61 | 0.40 | 0.34 | 0.34 | 0.38 | 0.39 |
P2O5 | 0.09 | 0.09 | 0.08 | 0.07 | 0.06 | 0.07 |
SO3 | 0.08 | 0.08 | 0.07 | 0.08 | 0.08 | 0.07 |
Total | 103.00 | 98.93 | 100.52 | 93.17 | 97.37 | 101.38 |
Trace Elements (ppm) | ||||||
Ti | 0.73 | 0.72 | 0.71 | 0.78 | 0.83 | 0.82 |
V | 0.02 | 0.02 | 0.02 | 0.02 | 0.02 | 0.02 |
Cr | 0.03 | 0.04 | 0.03 | 0.04 | 0.03 | 0.02 |
Co | 63.00 | 44.00 | 70.00 | 72.00 | 102.00 | 63.00 |
Ni | 40.80 | 40.10 | 41.80 | 33.80 | 30.20 | 33.90 |
Cu | 46.00 | 42.00 | 45.40 | 34.70 | 33.70 | 34.40 |
Zn | 45.00 | 42.50 | 45.70 | 43.40 | 42.20 | 38.90 |
Ga | 22.30 | 22.10 | 24.00 | 20.70 | 20.30 | 20.30 |
Ge | 2.10 | 2.10 | 2.20 | 0.70 | 1.70 | 1.40 |
As | 10.40 | 11.40 | 11.20 | 9.50 | 11.60 | 10.20 |
Br | 0.90 | <0.3 | <0.3 | <0.4 | <0.3 | <0.3 |
Rb | 18.00 | 12.50 | 12.30 | 13.30 | 11.20 | 12.10 |
Sr | 41.10 | 29.80 | 23.30 | 26.80 | 22.90 | 22.70 |
Y | 0.90 | 1.20 | 0.90 | 0.90 | 1.60 | 0.80 |
Zr | 343.00 | 304.00 | 272.00 | 346.00 | 366.00 | 342.00 |
Nb | 18.00 | 18.60 | 14.60 | 23.50 | 21.60 | 21.60 |
Mo | 5.60 | <4.4 | <6.0 | 3.80 | 10.50 | <4.7 |
I | 53.00 | 54.30 | 54.50 | 44.70 | 36.90 | 37.00 |
Cs | 9.50 | <9.30 | <9.40 | <9.90 | <9.70 | 15.50 |
Ba | 263.50 | 177.70 | 146.20 | 176.00 | 183.80 | 168.20 |
La | <19 | 39.80 | 34.90 | 25.90 | <20 | <19 |
Ce | 80.00 | 56.00 | 48.00 | 68.00 | 65.00 | 56.00 |
steadily to the top of anthill 2. MnO was fairly constant in both anthills and almost homogeneous with height. K2O decreased with height in anthill 1 and
increased with height in anthill 2. The variations in the concentration of the major oxides suggest that soils used to construct the anthills were possibly derived
from different rock types or there were differences in termite preference for clay richer in selective SiO2 or total FeO.
The anthills showed that the termites had similar building techniques. Soils for construction of anthills were mainly sand and clay of varied proportions. The variation in grain size differed from one locality to another and height on the anthill as more fines (<0.075 mm) were used in the construction of the upper parts.
SiO2 was positively correlated with total FeO, Al2O3, MnO, and K2O. Whilst SiO2, total FeO and Al2O3 increased with height; there was a decrease in K2O with height of anthill. Major oxides were different in anthill 1 and 2 possibly due to differences in rock types from which these soils were derived. There could also be different types of termites involved in the construction process as different anthills exhibited clay richer in silica or total iron oxide. Hence during mineral prospecting, geochemical sampling and analysis of upper portions of anthills (where fine fractions usually occur) are recommended as these portions may yield valuable information of the geology of the area. Care should, however, be taken for uniformity of sample material in terms of colour, type and size of anthills.
Tetteh, G.M. and Zuyeri, J.K.A. (2017) Grain Size and Major Oxide Analyses of Selected Anthill Soils from Winneba Area, Ghana. Journal of Geoscience and Environment Protection, 5, 264-274. https://doi.org/10.4236/gep.2017.59018