Abstract:
Narok and Bomet are agricultural counties in Kenya which depend on flowing surface waters
for farming activities. Agrochemicals have frequently
been used to increase agricultural produce in this
region. Occasionally, appropriate pesticide utilization
measures are not followed. These surface waters are
also consumed domestically by humans, livestock,
and wild animals thus posing safety concerns to them.
The current study sought to evaluate the levels and
nature of pesticide residues found in surface waters
in the dry and wet seasons of these counties. Eight
water samples were collected in July (dry season) and
October (wet season) at four different river sites in
each of the two counties predetermined by the agricultural activity of its proximate environs. Pesticides
extracted by solid phase extraction were analyzed by
gas chromatography-mass spectrometry. At least 38
different pesticides were detected in the two counties with the highest concentration being recorded
for chlorpyrifos and piperidine in Narok and Bomet
counties, respectively. The pesticides chlorpyrifos,
cypermethrin, cyfluthrin, and cyhalothrin were more
prevalent in Narok County while triazine, semicarbazone, and epinephrine were more prevalent in Bomet
County. There were significantly more pesticides
detected during the wet season (P≤0.05). Out of the
nine prevalent pesticides detected, four of them posed
serious ecotoxicology concerns with risk quotients
above 1.0 (high risk); thus, there is a need for more
government policy interventions in deterring farming
near riparian lands and in training of famers regarding best practice for pesticide applications.
Keywords Pesticides · Seasons · Agrochemicals ·
Pollution · Ecotoxicological
