Toxicity of the nerve agent tabun to Daphnia magna,a new experimental species in military toxicology

Daphnia magna, a freshwater microcrustacean, is currently tested as an alternative experimental species in research dealing with nerve agents poisonings treatment. Because of this, the toxicity of the nerve agent tabun (a cyanide-group containing organophosphate) to Daphnia had to be examined by estimating the EC₅₀ values. The immobilization of daphnids was chosen as the end-point. It was found that D. magna is sensitive to small amounts of tabun, even after 15 min exposure, and tabun toxicity increases with time. The estimated EC₅₀ values for 15, 30, 45, and 60 min exposure were as follows: 67.39, 38.10, 26.95, and 21.9 μg l^?1. In addition, the toxicity of media to which tabun was added 24 h before the start of experiments was examined. The results obtained indicate that daphnids can be used in experiments with nerve-agent intoxication treatment.     

Screening of textile finishing agents available on the Chinese market: An important source of per- and polyfluoroalkyl substances to the environment

Kendrick mass defect was used for PFASs screening in textile finishing agents (TFAs). Total oxidizable precursor assay provides insight into unknown precursors. Perfluorooctane sulfonate was found as impurity in short ECF technology based TFAs. Perfluorooctanoate was also detected in C6 telomerization based TFAs. Long chain precursors were also observed in both types of TFAs. Organofluorinated surfactants are widely employed in textile finishing agents (TFAs) to achieve oil, water, and stain repellency. This has been regarded as an important emission source of per-and polyfluoroalkyl substances (PFASs) to the environment. China is the biggest manufacturer of clothes, and thus TFA production is also a relevant industrial activity. Nevertheless, to date, no survey has been conducted on PFAS contents in commercially available TFAs. In the present study, TFA products were investigated by the Kendrick mass defect method. The quantification results demonstrated a significant presence of perfluorooctane sulfonate (0.37 mg/L) in TFAs manufactured by electrochemical fluorination technology. The products obtained by short-chain PFAS-based telomerization were dominated by perfluorooctanoic acid (mean concentration: 0.29 mg/L), whose values exceeded the limits stated in the European Chemical Agency guidelines (0.025 mg/L). Moreover, the total oxidizable precursor assay indicated high levels of indirectly quantified precursors with long alkyl chains (C7–C9). Together, these results suggest that there is currently a certain of environmental and health risks in China that originates from the utilization of TFAs, and a better manufacturing processes are required to reduce such risks.     

螯合剂对小麦幼苗吸收金属以及土壤金属形态的效应

本文通过盆栽试验研究三种螯合剂(EDTA、[S,S]-EDDS、DTPA)对小麦幼苗吸收土壤中重金属及其它微量元素的效应,并且通过改进的BCR连续提取法分析了种植后土壤样品中金属元素的形态。结果表明:EDTA、DTPA的添加导致小麦幼苗地上部分生物量以及叶片叶绿素a含量显著下降。螯合剂的存在明显增加了Pb和Mn在幼苗根部和茎叶的富集,并增加其由根部向茎叶的传输,但对Fe和Ni的作用比较小。小麦幼苗收获时,除Zn之外,其它元素酸溶/可交换态金属含量与对照组相比均有非常显著的增加,而各元素的可还原态由于EDTA等螯合剂的添加而有明显下降。添加螯合剂的情况下,富集量与酸溶/可交换态含量之间的相关系数大大提高,且各处理组茎叶富集量与酸溶/可交换态之间呈显著(P0.05)或极显著相关(P0.01)。因此,三种螯合剂的添加主要影响的是生物可利用形态以及潜在的生物可利用形态,并且可能导致可还原态以及可氧化态向酸溶/可交换态转变,增加金属的生物可利用性,从而也增加潜在生态风险。     

Pathways for the oxidation of sarin in urban atmospheres

The nerve agent sarin has recently been deployed by terrorists in a major city. The molecule is volatile and made its way to many victims by passing as vapor through a highly reactive medium. Here we estimate rates and pathways for the removal of gas phase sarin from a generalized urban atmosphere. Only information from the open scientific literature is used. By structure reactivity comparisons with the organophosphorus pesticides, hydroxyl radical hydrogen abstraction may occur in as little as one hour. Decomposition of side chains after hydroxyl attack leads to organic oxygenates which preserve the phosphonofluoridate and so toxicity. The aqueous aerosol surface is contacted in minutes and offers access to a range of dissolved nucleophiles. Substitution displaces the fluoride leaving group, giving safe phosphoric acid analogs. Because of uncertainties in the electron distribution and in aqueous decay mechanisms, the time constants must be viewed as lower limits.     

Bioaccessibility of metals in soils and dusts contaminated by marine antifouling paint particles

Fragments of antifouling paint and environmental geosolids have been sampled from the island of Malta and analysed for total and bioaccessible metals. Total concentrations of Ba, Cd, Cu, Pb, Sn and Zn were two to three orders of magnitude higher in spent antifouling composites relative to respective values in background soils and road dusts. Paint fragments were visible in geosolids taken from the immediate vicinity of boat maintenance facilities and mass balance calculations, based on Ba as a paint tracer, suggested that the most contaminated soils, road dusts and boatyard dusts contained about 1%, 7% and 9%, respectively, of antifouling particles. Human bioaccessibilities of metals were evaluated in selected samples using a physiologically based extraction technique. Accessibilities of Cd, Cu, Pb and Zn in the most contaminated solids were sufficient to be cause for concern for individuals working in the boat repair industry and to the wider, local community.     

冷原子吸收法测汞用干燥剂

试验了几种常用的干燥剂在冷原子吸收法测定水中汞时,对汞蒸气的干燥性能及对测定灵敏度的影响。结果表明,以无水氯化钙和无水高氯酸镁效果最好     

不同交联剂制备的环氧氯丙烷-二甲胺聚合物的结构及脱色性能

以环氧氯丙烷和二甲胺为原料,加入不同的胺类交联剂(乙二胺、二乙烯三胺和三乙烯四胺)合成出一系列环氧氯丙烷-二甲胺聚合物(EPI-DMA).研究了交联剂及用量对产品特性的影响;利用红外光谱(IR)和电子透射电镜(TEM)等现代分析仪器研究了EPI-DMA的结构及在水中的聚集形态;并通过烧杯实验研究了EPI-DMA对染料模拟废水和实际印染废水的处理效果.结果表明,交联剂的加入使EPI-DMA的粘度和阳离子度发生变化;不同交联剂制备的EPI-DMA的IR谱图相差不大,但在水溶液中的结构形貌不相同;EPI-DMA处理模拟活性艳红废水时以电中和和吸附架桥为作用机理,在处理还原大红废水时以电中和作用为主;在用EPI-DMA处理实际废水时脱色率和COD的去除率分别可达80%和60%.     

有木几热载休锅炉请洗剂的性能试验研究

通过对目前市场上常见的几种有机热载体清洗剂,尤其是在线清洗剂进行模拟清洗试验,同时试验研究了在线清洗对有机热载体的影响,评估其清洗效果和对锅炉及传热系统安全性影响。     

堆肥过程多阶段强化接种对细菌群落多样性的影响

以生活垃圾为原料进行好氧堆肥,采用多阶段的方式强化接种功能微生物菌剂,利用PCR-DGGE方法并结合聚类分析和Shannon-Weaver指数变化来研究堆肥过程中多阶段强化接种对细菌群落多样性的影响,同时监测木质纤维素降解率的变化.结果表明,多阶段接种堆肥能有效提高堆体降温期和二次发酵期的温度;和普通接种堆肥相比可使半...     

利用微生物菌剂净化城市河道水质试验研究

在无外加碳源的静态试验条件下,用4种微生物菌剂进行水质净化效果研究。结果表明：4种微生物菌剂对水中氮磷的降解效果明显,但对COD的降解效果不甚理想;对TN及NH3-N的去除效果,脱氮菌显著大于复合芽孢杆菌和硝化细菌;4种微生物茵剂投至水体中其微生物菌群均在7d左右开始进入衰亡期。