Long-term fate of the herbicide cinosulfuron in lysimeters planted with rice over four consecutive years

In order to elucidate the long-term fate of the sulfonylurea herbicide cinosulfuron, the 14C-labelled chemical was applied to a clay loam soil, encased in two lysimeters, 22 days after rice (Oryza sativa L.) transplanting, and rice plants were grown for four consecutive years. Throughout the experimental period, leaching through soil profiles, absorption and translocation by rice plants, and distribution of 14C by downward movement in the soil layers were clarified. The total volume of leachates collected through the lysimeter soil over the four years amounted to 168 and 146 L in lysimeters I and II, respectively. The leachates contained 2.43% and 2.99% of the originally applied 14C-radioactivity, corresponding to an average concentration of 0.29 and 0.41 microg/L as the cinosulfuron equivalent in lysimeters I and II, respectively. The total 14C-radioactivity translocated to rice plants in the third and fourth year was 0.69% and 0.60% (lysimeter I), and 1.02% and 0.84% (lysimeter II) of the 14C applied, respectively. Larger amounts of cinosulfuron equivalents (0.54-0.75%) remained in the straw in the fourth year than in any other parts. The 14C-radioactivities distributed down to a depth of 70 cm after four years were 56.71-57.52% of the 14C applied, indicating the continuous downward movement and degradation of cinosulfuron in soil. The non-extractable residues were more than 88% of the soil radioactivity and some 45-48% of them was incorporated into the humin fraction. The 14C-radioactivity partitioned into the aqueous phase was nearly 30% of the extractable 14C, suggesting strongly that cinosulfuron was degraded into some polar products during the experimental period. It was found out in a supplemental investigation that flooding and constant higher temperature enhanced mineralization of [14C]cinosulfuron to 14CO2 in soil, indicating the possibility of chemical hydrolysis and microbial degradation of the compound in the flooded lysimeter soil.     

Monitoring for Lead Pollution using Feathers of Feral Pigeons (Columba livia) from Korea

We investigated lead exposure conditions using unwashed feathers of feral pigeons as a monitor for lead pollution from rural, central urban, and four industrial complex areas in Korea with different ambient lead concentrations. Overall, the lead levels in the feathers increased when the atmospheric lead levels increased, so that the lead levels in the feathers from urban and industrial areas were two to four times greater than those in the rural area. However, there are no significant differences in the liver lead concentrations between rural and the other areas, suggesting that the lead originated from ingestion are not differences in locations. A positive correlation was found between the concentration of lead in livers and feathers from rural, indicating that the feather lead concentrations in this area seem to mainly reflect the internal tissue lead through the metabolic process. However, there are no significant correlations in the other areas, and we observed a relatively higher lead accumulation ratio of feathers to livers. It, therefore, indicates that external contamination onto the feather surface may be an important source for lead levels in feathers rather than transfer from internal tissue lead.     

Factors Causing Variations of Lead and Cadmium Accumulation of Feral Pigeons (Columba livia)

In order to understand the factors causing variation of lead and cadmium accumulation in tissues of feral pigeons in Seoul and Ansan, Korea, we investigated their age, food items (crop and gizzard contents) as well as environmental factors such as soil, atmosphere, and local traffic density. The results indicate that concentrations of Pb and Cd were highly increased in the order of eggs < chicks < adults. In food analysis, supplementary foods (rice, small stones, domestic scraps, cements, hairs, Styrofoam, etc.) could be considered as factors considering the Pb concentration differences. Concentrations of Cd in foodstuffs, the proportion of crop contents as their major foods could have an influence on the difference of Cd levels from a nutritional viewpoint. The Pb levels in gizzard contents and soil had an effect on the tissue accumulations, these were associated with the volume of vehicular traffic. However, we could not find any differences of Cd concentrations in gizzard contents and soil, although there were significantly different Cd accumulations in target organs of adult pigeons between the study areas. The Pb and Cd levels in tissues did not correspond to atmospheric metal levels.