Riverine fluxes of the persistent organochlorine pesticides hexachlorcyclohexane and DDT in the Russian Federation.

The contribution of gross riverine organochlorine pesticide (OCP) transport to estuaries of Russian seas and Lake Baikal was determined to help understand OCP transboundary transfer and to provide a basis for estimating Russia's contribution to global pollution by these pesticides. The official OGSNK/GSN data ranks sea/ocean/lake basins in the following order based upon the amounts of total OCPs received from agricultural use: Eastern Arctic>Western Arctic>Pacific>Baltic>Caspian>Azov/Black>Baikal. A similar ranking was obtained using an independent set of data: Eastern Arctic>Pacific>Caspian>Western Arctic>Baltic>Azov/Black. In terms of riverine flow-associated discharge of HCH isomers (i.e., sum of alpha-, beta- and gamma-HCH) estuaries of the Kara, Okhotsk and Beloye (White)/Barents seas received more pesticides than other seas. No HCH was discharged to estuaries of the Eastern Siberian and Bering seas. For DDT and its derivative (DDE), estuaries of the Kara, Caspian, Okhotsk and Baltic seas received the greatest amounts. During our study period (1988-1996), HCH transport was more prevalent in the majority of rivers reflecting both the official ban on the use of DDT in the former Soviet Union and the greater popularity of HCH as a pesticide. In general, it appears that Russian rivers play a significant role in OCP contamination of some estuaries of regional seas, especially those of the eastern Arctic basin, such as the Kara Sea.

In vitro effects of cadmium and DDVP (dichlorvos) on intestinal carbohydrase and protease activities in freshwater teleosts.

In vitro effects of cadmium (0.5-50 mg/l) and DDVP (0.2-100 mg/l) on the total amylolytic, sucrase and protease activities of intestinal mucosa have been studied for the first time in 11 freshwater teleosts. Total amylolytic activity in burbot, crucian carp and common carp, sucrase activity in blue bream and total proteolytic activity in burbot and pike were significantly decreased by cadmium at 50 mg/l. DDVP (at 0.2 mg/l) caused a significant decrease in total proteolytic activity in pike but had no effect on either protease or carbohydrase activities in other fish species.

[The effect of cadmium on the gill structure in Tilapia]. / Vliianie kadmiia na strukturu zhabr tiliapii.

The effect of a long-term (2 months) exposure to cadmium (5 mg/l), with a subsequent recovery in clean water, upon gill structural organization of Mozambique tilapia was studied using scanning and light microscopy. Some of nonspecific components of the gill response on cadmium action were revealed: hypertrophy and fusion of respiratory lamellae, swelling and lifting of the epithelium from capillaries, vascular stasis. In addition, heavy metal-specific components of this reaction were found, which are involved in the development of epithelial necrosis and leucocyte infiltration into the tissue. The gill ultrastructure recovery was not achieved completely even after a 1.5 month exposure of fishes in clean water.