Masters Thesis
Oestrogens are hormones, naturally produced by mammals or synthetically produced as drugs used in hormone therapy or as contraceptives. In the recent past years, oestrogens have gained much recognition due to their detrimental effect to aquatic life, which ranges from induction of intersexuality to complete reproductive failure of fish. Their main source in the aquatic environment is attributed to human and livestock waste and residues of oestrogens are found in water downstream of waste water treatment plants (WWTP). As such, this research sought to investigate the presence of these hormones in Lake Kariba as well as identify the anthropogenic activities leading to their introduction. A structured questionnaire, was administered in order to identify anthropogenic activities that would lead to oestrogen introduction in Lake Kariba. Siavonga’s harsh terrain precludes its involvement in intensive animal husbandry activities thereby leaving only human wastewater as the main source of oestrogens in the lake. The synthetic hormone 17α-ethinyl estradiol (EE2) was undetected in all of the samples collected evidently due to low usage of oestrogen containing contraceptives and high usage of pit latrines in the area. On the contrary, natural oestrogens were detected in all sites in the range of 0.38 ng/L to 6.68ng/L in water samples and 0.01 ng/g to 2.74 ng/g in sediment samples. Source of the detected oestrogens could be a result of waste water discharge into the lake as well from terrestrial and aquatic animals. Further investigations are required to identify other sources of oestrogen introductions in sparsely populated areas that recorded oestrogen levels as high as sites receiving waste water as well as the biological effects in aquatic animals.
TRAHESA project (TAN-13/0017)