Comprehensive Analysis of Pesticide Pollution across the Yangtze River Basin: Spatiotemporal Distribution, Socio-Economic Correlations, and Ecological Risk Assessment

As an important grain-producing region in China, the
Yangtze River
Basin is potentially threatened by pesticide contamination. In this
study, occurrence, spatiotemporal distribution, possible drivers,
and ecological risks of 40 pesticides including 23 herbicides, 8 insecticides,
and 9 bactericides were investigated from Panzhihua to Nanjing of
the Yangtze River. Atrazine historical data in the past two decades
were used to analyze the impact of socio-economic development on pesticide
residues. Results showed higher pesticide concentrations during wet
and normal seasons than dry season, with mean concentrations ordered
as normal season (182.18 ng/L) > wet season (157.20 ng/L) >
dry season
(69.65 ng/L). Several pesticides, such as atrazine, gestomine, isoprocarb,
dichlorvos, diethyltoluamide, triadimenol, and isoprothiolane were
the dominant pesticides with high detection frequency and concentration
proportion. In addition, a decline trend of pesticides abundance was
found from the Three Gorges to the subsequent section, indicating
that the reservoir is likely to act as a sink for pesticide residues.
Atrazine historical trends indicated pesticide pollution correlated
with urbanization, per capita gross domestic product, and pesticide
usage rather than wastewater discharge. Ecological risk assessment
using the species sensitivity distribution (SSD) method exhibited
that pesticides have no significant risks on aquatic organisms.