Pesticide residues in water and an aquatic plant, Nelumbo nucifera, in a river mouth at Lake Kasumigaura, Japan

Pesticide residues in water and an aquatic plant, Nelumbo nucifera, were investigated near a river mouth in Edosakiiri Bay, Lake Kasumigaura, from April to December, 1986. The maximum concentrations of fenobucarb, diazinon, iprobenfos and simetryn in the water were 1.6, 1.1, 24, and 2.4 μg 1−1, respectively. We detected simetryn with peak width at half height for one month, and diazinon with that for two months. The seasonal changes in simetryn concentration in N. nucifera were similar to those in the water. The simetryn residue concentration was highest in the lamina (300 μg kg−1) among the various plant organs. The residue and bioconcentration factor 6.0 in June for simetryn were lower than the reported values for aquatic plants.