Combined toxicity of imidacloprid,acetochlor, and tebuconazole to zebrafish ( Danio rerio ): acute toxicity and hepatotoxicity assessment

Compound pollution refers to two or more kinds of pollutants with different properties, a pollutant from different sources, or the simultaneous existence of two or more different types of pollutants in the same environment. In this study, we aimed to investigate the individual and combined toxicity of the insecticide imidacloprid (IMI), the herbicide acetochlor (ACT), and the fungicide tebuconazole (TBZ) to zebrafish. The acute toxicity test results showed that the 96-h LC50 values of IMI, ACT, and TBZ were 276.84 (259.62–294.35) mg active ingredient (a.i.) L−1, 1.52 (1.34–1.74) mg a.i. L−1, and 8.16 (7.7–8.6) mg a.i. L−1, respectively. The combinations of IMI, ACT, and TBZ with toxicity ratios of 1:2:2, 1:4:4, 2:4:1, and 4:1:4 displayed synergistic toxic effects on zebrafish, while the toxicity ratios of 1:1:1, 1:1:2, 2:1:2, 2:2:1, and 4:2:1 of IMI, ACT, and TBZ, respectively, exhibited antagonistic toxic effects on zebrafish. The following experiments were performed with a toxicity ratio of 1:4:4 (IMI:ACT:TBZ). The activities of four enzyme biomarkers related to oxidative stress in the liver, catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), and malondialdehyde (MDA) content were evaluated in each exposure group on days 7, 14, 21, and 28. Compared with those of the control group, the activities of CAT, SOD, and GST and the MDA content were significantly altered at different time points in the individual and combined exposure groups. Additionally, the activities of CAT, SOD, and GST and the MDA content were significantly altered in the combined group compared with those of the individual group after 14 days or 21 days of exposure. Therefore, it was confirmed that combined toxicity studies are indispensable in risk assessment.     

Feasibility of nanoscale zerovalent iron-loaded sediment-based biochar (nZVI-SBC) for simultaneous removal of nitrate and phosphate: high selectivity toward dinitrogen and synergistic mechanism

Environmental Science and Pollution Research - In the process of water treatment, excessive nitrogen and phosphorus pollutants are of great concern. Therefore, we prepared nanoscale zerovalent iron...     

大伙房水源地环境风险评估与防控工程优化

大伙房水源地担负着辽宁省7个城市、2300多万人口的供水任务,战略地位十分重要。本文针对调整后保护区区划方案环境风险防控尚存的薄弱环节,全面排查保护区内环境风险源,采用"风险值定性评价"方法进行分类、评估、分级,确定最大风险源类型,进而提出"一堵、二封、三隔、四消"的隔离防控工程建设方案,为消除水源地环境风险隐患、确保水质安全提供工程保障。     

4种甲氧基丙烯酸酯类杀菌剂不同剂型对斑马鱼急性毒性效应

采用半静态法测定了4种甲氧基丙烯酸酯类杀菌剂原药及制剂对斑马鱼(Brachydonio rerio)急性毒性。结果表明,以实测浓度计,250 g·L~(-1)嘧菌酯悬浮剂对斑马鱼的96 h半数致死浓度(LC50)值为0.539 mg·L~(-1),急性毒性为高毒,95%嘧菌酯原药和50%嘧菌酯水分散粒剂对斑马鱼的LC50(96 h)值分别为1.09和1.21 mg·L~(-1),急性毒性均为中毒;98%啶氧菌酯原药和22.5%的啶氧菌酯悬浮剂对斑马鱼的LC50(96 h)值分别为0.0974和0.0972 mg·L~(-1),急性毒性均为剧毒;95%吡唑醚菌酯原药、15%吡唑醚菌酯悬浮剂和250 g·L~(-1)吡唑醚菌酯乳油对斑马鱼的LC50(96 h)值为0.0613、0.0549和0.0487 mg·L~(-1),急性毒性均为剧毒;95%醚菌酯原药和50%醚菌酯水分散粒剂对斑马鱼的LC50(96 h)值分别为0.468和0.702 mg·L~(-1),急性毒性均为高毒。这4种甲氧基丙烯酸酯类杀菌剂对斑马鱼均有较高风险,会对其他水生生物也存在潜在的风险。     

基于TOP-RICE模型嘧菌酯·噻呋酰胺4%展膜油剂稻田水溢出对水生生态系统风险评估研究

为评估嘧菌酯·噻呋酰胺4%展膜油剂在我国稻田水溢出对水生生态系统的风险,本研究依据中华人民共和国农业行业标准NY/T 2882.2—2016《农药登记环境风险评估指南第2部分:水生生态系统》,采用TOP-RICE暴露模型分别单独评估了嘧菌酯和噻呋酰胺2种有效成分稻田滴撒方式应用时水溢出对水生生态系统的风险。其中,TOP-RICE初级暴露模型中有我国连平和南昌2个水稻-地下水暴露场景,每个场景都对分蘖期和拔节期进行分别评估。分析结果显示,嘧菌酯·噻呋酰胺4%展膜油剂中的嘧菌酯按照申请的良好农业规范(GAP)使用,生物富集风险可接受,初级风险评估对无脊椎动物(急性)和无脊椎动物(慢性)风险不可接受,但经中宇宙研究后,在连平和南昌2个场景点,均为拔节期用药对无脊椎动物的风险可接受,但分蘖期用药对无脊椎动物的风险不可接受;嘧菌酯·噻呋酰胺4%展膜油剂中的噻呋酰胺按照申请的GAP使用,生物富集带来的风险可以接受,经初级风险评估风险均可接受。在忽略2种有效成分相互间作用时,初步认为嘧菌酯·噻呋酰胺4%展膜油剂在我国稻田拔节期按照GAP要求施用时水溢出对水生生态系统的风险可接受,但应避免在分蘖期用药,以免其中的有效成分嘧菌酯对水生无脊椎动物产生不良影响。     

4种甲氧基丙烯酸酯类杀菌剂对拟澳洲赤眼蜂成蜂的急性毒性及安全性评价

为甲氧基丙烯酸酯类杀菌剂合理使用提供科学依据,本研究采用试管药膜法测定了啶氧菌酯、吡唑醚菌酯、嘧菌酯和醚菌酯等4种药剂的原药及其制剂对拟澳洲赤眼蜂成蜂的急性毒性,并进行了安全性评价。对比原药结果发现,啶氧菌酯原药和醚菌酯原药毒性很高,LR50依次是2.66×10-4及7.32×10-4mg a.i.·cm~(-2),均属于高风险;而吡唑醚菌酯原药及嘧菌酯原药毒性较低,LR50分别为3.01×10-3和3.47×10-3mg a.i.·cm~(-2),均为中等风险药剂。对比制剂结果发现,啶氧菌酯悬浮剂毒性最高,LR50为5.02×10-5mg a.i.·cm~(-2),为极高风险药剂;其次是吡唑醚菌酯悬浮剂及乳油,LR50分别为3.78×10-3和5.80×10-3mg a.i.·cm~(-2),均为中等风险药剂;最低的是嘧菌酯水分散粒剂、悬浮剂和醚菌酯水分散粒剂,LR50均大于4.0×10-2mg a.i.·cm~(-2),均为低风险药剂。部分甲氧基丙烯酸酯类杀菌剂对天敌赤眼蜂存在较高风险,特别是啶氧菌酯,应避免田间使用,或通过避开赤眼蜂释放期来减少对赤眼蜂的伤害。     

提前支付劳动合同约定的工资应视合同解除

案情简介 申诉人梁某,于1996年7月1日入职被诉人深圳某公司,2005年2月1日,双方签订了劳动合同书,期限为2005年2月1日起至2005年7月31日止.2005年3月18日,被诉人发出《终止劳动合同通知书》,通知申诉人“合同期满后不再续签,从3月19日起不用上班,现准备提前于3月22日-23日发放3-7月份的工资给你”,“请你于3月1 8日下午16：00点钟办理有关手续”.