RESUMEN
Bioconcentration factors (BCF) for pentachlorophenol (PCP) and 2,4-dichlorophenol (2,4-DCP) in Japanese medaka (Oryzias latipes) were determined at five different concentrations of the chemicals, between 0.1 and 10 microg/l (PCP), 0.3 and 30 microg/l (2,4-DCP), in the ambient water. Medaka were exposed to each chemicals in a continuous-flow system during the embryonic development period and 60 days after hatching from eggs collected in the laboratory. Both the exposure time and the aqueous concentrations are much more realistic and closer to natural aquatic environments than those used in conventional BCF studies. The BCF values of PCP were from (4.9+/-2.8)x10(3) at the aqueous concentration of 0.074+/-0.028 microg/l to (2.1+/-1.4)x10(3) at 9.70+/-0.56 microg/l. The BCF value of 2,4-DCP were from (3.4+/-3.0)x10(2) at 0.235+/-0.060 microg/l to 92+/-27 at 27.3+/-1.6 microg/l. Generally, BCF values increased as the aqueous concentrations of PCP or 2,4-DCP decreased. This finding suggests that a relatively low and realistic aqueous concentration of these compounds is necessary to more accurately determine their BCF values in natural aquatic environments. Conventional BCF experiments at higher aqueous concentrations may underestimate the BCF values.
Asunto(s)
Clorofenoles/farmacocinética , Oryzias , Pentaclorofenol/farmacocinética , Contaminantes Químicos del Agua/farmacocinética , Animales , Clorofenoles/análisis , Monitoreo del Ambiente , Japón , Pentaclorofenol/análisis , Distribución Tisular , Contaminantes Químicos del Agua/análisisRESUMEN
Sinotaia quadrata histrica is a fresh water viviparous snail distributing from the Kanto region to Kyushu Island, Japan. About 7000 snails were collected in Lake Kasumigaura (L. Nishiura and L. Kitaura) in 2001 and 2002, and the sex ratio, maturity in terms of the gonad-somatic index (GSI) and operculum diameter were determined. The total female proportion was 55.2% in 2001, 53.0% in 2002 in L. Nishiura, and that of L. Kitaura was 60.4% in 2002. Comparing the season, the female proportion was the highest during early summer in both 2001 (59.6%, July in L. Nishiura) and 2002 (61.6%, June in L. Nishiura, 65.8%, July in L. Kitaura). The GSI of females in L. Nishiura significantly increased from April to May and significantly decreased from June to August. The GSI of males was higher in spring, but significantly lower from June to August. The mean female operculum diameter was consistently larger than that of males for each month and year, and a particularly significant difference was found between females and males from April to August 2001, and from April to September 2002. The number of resting zones on the operculum correlates with the operculum diameter and the female proportion was larger in the snails, which have a high number of resting zones, suggesting a sex-dependent difference in age composition. This study estimated that the sex ratio and seasonal maturation of S. quadrata histrica and the sex-dependent difference in age composition might contribute to the population structure in L. Kasumigaura.