Evaluation of pesticides residues distribution in fresh and smoked body parts of Clarias gariepinus and assessment of possible health risks in Nigeria

Pesticides residues in fresh and smoked body parts of Clarias gariepinus were investigated to evaluate their contamination status and risks to human health. The results gave an overview of the contamination levels of these (head, body trunk and liver) fish parts. The pesticides [organochlorine (OC), organophosphorus (OP), pyrethroids (PY) and others like: guazatine, methoprene, metalaxyl and imidachloprid] concentration in the fresh and smoked body parts ranged from 0.002 to 0.221 µg/kg and 0.002 to 0.175 µg/kg, with mean concentration of 0.002–0.218 µg/kg and 0.002–0.126 µg/kg, respectively. Smoking was observed to reduce the overall pesticide concentration as follows: head (0.23 µg/kg or 17.3%), liver (0.34 µg/kg or 29.8%) and muscles (0.41 µg/kg or 27.2%). The pesticides contents were significantly lower than standard daily intake and the risk associated with consumption of the fish also showed that the fish posed no potential threat to consumers.     

Foliar damage to parental plants interacts to influence mating success of Ipomoea purpurea

Studies of how herbivory affects plant fitness often determine whether damage to one parent alters reproductive output (i.e., seed set or paternity) but ignore the possibility that the outcome may be different if both parents were damaged (i.e., the presence of maternal x paternal damage interactions). Using inbred lines of the common morning glory, Ipomoea purpurea, I conducted a series of greenhouse experiments to test whether foliar damage from a generalist insect herbivore, Trichoplusia ni, alters male and female fitness components when neither parent, one parent, or both I. purpurea parents had been damaged. In a single-donor experiment, flowers on both damaged and undamaged maternal plants received pollen from either damaged or undamaged paternal plants. I. purpurea flowers were more likely to be aborted when they received pollen from damaged paternal plants, or when maternal plants were both damaged and grown under low-resource conditions. Foliar damaged plants also produced less seed and pollen than undamaged plants, although seed mass and pollen viability were not affected by damage. In a multiple-donor experiment, flowers on damaged and undamaged maternal plants simultaneously received pollen from damaged and undamaged paternal plants, and F1 seeds were analyzed for paternity. Damaged paternal plants had reduced siring success compared to undamaged paternal plants, and this discrepancy was most pronounced when competition occurred on damaged maternal plants. Thus, damaged maternal plants were more "selective" than undamaged maternal plants. Although previous studies have demonstrated that herbivory can alter fruit and seed production and paternity patterns, this is the first study to show that the magnitude of herbivore damage experienced by both parents can interact to influence maternal and paternal mating success.     

交通源对西安夏季空气质量影响模拟研究

本文应用WRF-CHEM模式模拟分析了2016年6月西安市大气污染过程。模式准确地模拟了西安地区大气臭氧(O_3)、细颗粒物(PM_(2.5))以及二氧化氮(NO_2)的时空变化趋势,较好地再现了天气形势以及大气污染的演变过程。根据近年来西安市交通排放量的增加制定敏感性试验,结果表明:西安市20%交通排放量在研究时段内平均PM_(2.5)质量浓度贡献量为4.5μg?m~(-3),模拟时段内O_3平均贡献量为4.8μg?m~(-3),西安市20%交通排放量在研究时段内的平均NO_2贡献量为2.7μg?m~(-3),而且污染物浓度越高,交通源排放量的影响越显著。