Pesticide Contamination Monitored by Passive Sampling in Environmental Water of Japanese Coral Island

Abstract

The pesticide contaminations in the water of rivers and an estuary of a Japanese coral island with unique ecosystems in enclosed moats and on fringing reefs were analyzed by means of passive sampling. Samplers were deployed in the rivers and estuary for each 2 weeks of August through December of 2013 and of February of 2014. One to 12 kinds of pesticides were detected from all the samplers at the river sites with the maximum amount of 260 ng day -1 per sampler for EPN. The detected compounds and their amounts fluctuated widely at each sampling occasion. The analyses of the grab water samples detected much less compounds in comparison with the passive samples from the same sites. The time weighted average (TWA) concentrations of these pesticides are estimated as several micrograms per litter in the river waters. Further, 0.1 ng day -1 of procymidone was also detected from a sampler in the middle of the estuary where the river water is largely diluted with seawater. This amount of pesticide corresponds to a TWA concentration in the estuary water with the order of several ng L -1 . Considerable discharges of chemicals into coastal water by intensive agricultural practices such as flower cultivations on the island is concerned.