基于非本地物种毒性数据推导出的水质基准可为本地物种提供适当保护吗？

基于非本地物种的毒性数据推导出的水质基准一直存在争议,质疑者提出应有针对不同生物区系的水质基准。而这个问题在中国尤为突出。本文作者搜集了38种污染物对本地物种和非本地物种的毒性数据,比较了这些生物的HC₅和物种敏感度分布,结果显示,基于非本地物种推导的水质基准有74%的确定性可以有效保护中国的水生态系统。如果采用评价因子(AF=5)来校正基准,那么可以获得90%的确定性。
精选自Xiaowei Jin, Zijian Wang, Yeyao Wang, Yibing Lv, Kaifeng Rao, Wei Jin, John P. Giesy and Kenneth M. Y. Leung. Do water quality criteria based on nonnative species provide appropriate protection for native species? Environmental Toxicology and Chemistry: Volume 34, Issue 8, pages 1744–1750, August 2015. DOI: 10.1002/etc.2985
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.2985/full     

Effect of adjuvants on rainfastness and herbicidal activity of glyphosate deposits on trembling aspen foliage

Abstract

Radiolabelled end‐use mixtures of glyphosate with and without a cationic surfactant (Ethomeen® T/25) and an organosilicone surfactant (Silwet® L‐77) were applied onto trembling aspen (Populus tremuloids Michx.) leaves at the rate of 1.0 kg of AE (acid equivalent) in 35 L/ha area of foliage. A 5‐mm rainfall with an intensity of 10 mm/h was applied at intervals of 0.5, 8, 24, 36, 48, 72, and 96 h after treatment. Glyphosate washoff was determined by liquid scintillation counting of radioactivity in the rain‐washing. At 36 h post‐treatment, both the adjuvants significantly reduced glyphosate washoff (Ethomeen by 69.6% and Silwet by 59.7%) from foliage, compared to the washoff (82.6%) when Vision alone was applied without the adjuvants. Results on the rate of plant growth indicated that with a rain‐free period of 8 h or more, the growth of most seedlings was stunted within 1 or 2 d. Percentage of foliar browning 20 d after treatment with rain‐free period of 8 to 48 h ranged from 8 to 80% for Vision alone, 75 to 100% for Vision with Ethomeen, and 85 to 100% for Vision with Silwet, respectively. Physical properties of the end‐use mixtures were measured with and without the two adjuvants to examine droplet spreading and drying rates in relation glyphosate rainfastness. The Silwet adjuvant lowered the surface tension of the end‐use mixture, but Ethomeen did not. Droplets containing Silwet were spread more than those containing Ethomeen. However, the greater area of contact caused by Silwet did not contribute to a significant increase in the translocation rate of glyphosate into untreated parts of the seedlings, and showed no relationship with rainfastness of glyphosate deposits on trembling aspen.     

Physical properties,droplet spectra and deposits of oils used in pesticide sprays

Abstract

The influence of liquid properties on spray atomization and deposition characteristics was studied using two oils of different viscosities and volatilities. For a given volume of oil sprayed, insecticide diluent 585 (ID 585), a petroleum distillate of low viscosity and high volatility, provided numerous small droplets on Kromekote^® cards. However, volume of oil deposited was low. For the same volume of oil sprayed, Sun‐spray® 6N, a non‐volatile paraffinic oil of high viscosity provided fewer but larger droplets, and consequently, the volume of oil deposited was much higher on the cards. These observations are explained on the basis of viscosities and volatilities of the two oils.