Insecticides in sediment cores from a rural and a suburban area in South China: A reflection of shift in application patterns.
A shift in pesticide application pattern has occurred in recent decades, yet little information is available in the consequence of this shift. To better understand how the shift is reflected in aquatic environment, two sediment cores were collected from a rural (RLY) and a suburban (SGZ) river in South China. A variety of legacy organochlorine pesticides (OCPs) and current-use pesticides (CUPs), including organophosphate, pyrethroid and phenylpyrazole insecticides were quantified at distinct increments of the sediment cores. Total insecticide concentrations were in the ranges of 67.6-1671 and 99.2-231ng/g dry weight in RLY and SGZ with pyrethroids and organochlorines being the dominant components, respectively. In general, the shifting profile of sediment-bound insecticides from legacy OCPs to CUPs over time followed their historical application pattern, but significant differences were noted between the temporal profiles of the rural and suburban cores in regards to concentrations and composition of insecticides. The observed difference between the suburban and rural cores was synchronous with land use pattern and local economic changes. A steep increased occurrence of CUPs in the 1990s was observed in the RLY core, which is consistent with the onset of economic growth in this area. In contrast, the suburban SGZ area has been historically contaminated by legacy OCPs, with fresh input of OCPs in SGZ believed to be caused by soil erosion, caused by land reclamation activities associated with urban expansion. The current study shows the shift in insecticide application pattern from legacy OCPs to CUPs leading to an elevated CUP occurrence in the environment. It also suggests a stronger need for understanding not only environmental fate and risk, but also how their use pattern and land use changes impact the occurrence of pesticides.
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; College of Horticulture and Landscape Architecture, Southwest University, Chongqing 400716, China.
Dali
D
Sun
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Yanli
Y
Wei
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
Huizhen
H
Li
State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Xiaoyi
X
Yi
School of Environment, Guangzhou Key Laboratory of Environmental Exposure and Health, and Guangdong Key Laboratory of Environmental Pollution and Health, Jinan University, Guangzhou 510632, China. Electronic address: youjing@jnu.edu.cn.
Jing
J
You
Current-use pesticides; Historical profile; Legacy organochlorine pesticides; Pesticide application pattern; Sediment core