Abstract:
The extensive use of pesticides considered as a global threat to the ecological integrity of aquatic
ecosystems. Most developing countries including Ethiopia are burdened with these toxic and persistent
pesticides due to their wider used for agricultural pest and malaria control. The present study was aimed
to investigate the concentration and risk of pesticides in Lakes of Tana and Hayqe. The composite eight,
eight, and five water, sediment and fish samples were collected, respectively. A laboratory based cross
sectional study was conducted from Dec, 2020 to March 2021 in Lake Tana and Lake Hayqe. A
sensitive method for the determination of 36 pesticides in water, sediments, and fish were adopted using
QuEChERS and GC-MS. Percent of recovery ranged from 85.0-107.6%. From the result lindane
(1.11µg/L) was recorded the lowest concentration of OCPs in water samples and total endosulfan was
the highest (14.97 µg/L). In OPPs, Malathion (1.19 µg/L) was the lowest and chloropyrifos (1.65 µg/L)
was the highest concentration. In sediment samples, lindane (10.96 µg/kg) was the lowest and endrin
(70.42 µg/kg) was the highest OCPs. Whereas ethion (11.15 µg/kg) was the lowest and Diazinon
(30µg/kg) was the highest. From fish samples, lindane (12.63 µg/kg) was the lowest and total
endosulfan (68.78 µg/kg) was the highest detected OCPs. Moreover, Malathion (11.31 µg/kg) was the
lowest and diazinon (30 µg/kg) was the highest detected OPPs in fish samples. The ANOVA test also
depicted that the levels of most pesticides were significantly varied with different sampling sites. The
health and ecological risks were evaluated through a calculated hazard quotient (HQ) and risk quotient
(RQ) models, respectively. Eleven and thirteen pesticides were detected in the water and sediment
samples in Lakes Tana and Hayqe, respectively. From the ecological risks of fish, daphnia, and algae,
the RQ values ranged from 0.167 to 28.438). In the result most of the studied OCPs and OPPs have a
high-level of ecological risk except for lindane, dieldrin and Malathion in water sample. The highlevels of ecological risk of most OCPs and OPPs indicates there is a potential adverse effects of
pesticides to aquatic organisms. The HQ values of all detected pesticides for fish samples ranged from
0.0003-0.0766 and 0.00019-0.075 in Lake Tana and Lake Hayqe, respectively. The HQ values for fish
samples were <1, indicating that the consumption of fish from these two Lakes found in ANRS was
safe for human health. However, the ecological risks of pesticides in the ANRS Lakes could not be
ignored.
