Distribution and chemical speciation of arsenic in different sized atmospheric particulate matters

The distribution and chemical speciation of arsenic (As) in different sized atmospheric particulate matters (PMs), including total suspended particles (TSP), PM₁₀, and PM_2.5, collected from Baoding, China were analyzed. The average total mass concentrations of As in TSP, PM₁₀, and PM_2.5 were 31.5, 35.3, and 54.1 µg/g, respectively, with an order of PM_2.5 >PM ₁₀ > TSP, revealing that As is prone to accumulate on fine particles. Due to the divergent toxicities of different As species, speciation analysis of As in PMs is further conducted. Most of previous studies mainly focused on inorganic arsenite (iAs^III), inorganic arsenate (iAs^V), monomethylarsonate (MMA), and dimethylarsinate (DMA) in PMs, while the identification and sensitive quantification of trimethylarsine oxide (TMAO) were rarely reported. In this study, a high-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry system was optimized for As speciation including TMAO in PMs. An anion exchange column was used to separate MMA, DMA and iAs^V, while a cation exchange column to separate TMAO and iAs^III. Results showed that iAs^V was the dominate component in all the samples, corresponding to a portion of 79.2% ± 9.3% of the total extractable species, while iAs^III, TMAO and DMA made up the remaining 21%. Our study demonstrated that iAs^III accounted for about 14.4% ± 11.4% of the total extracted species, with an average concentration of 1.7 ± 1.6 ng/m³. It is worth noting that TMAO was widely present in the samples (84 out of 97 samples), which supported the assumption that TMAO was ubiquitous in atmospheric particles.     

Marine aquaculture regulates dissimilatory nitrate reduction processes in a typical semi-enclosed bay of southeastern China

Marine aquaculture in semi-enclosed bays can significantly influence nutrient cycling in coastal ecosystems. However, the impact of marine aquaculture on the dynamics of dissimilatory nitrate reduction processes (DNRPs) and the fate of reactive nitrogen remain poorly understood. In this study, the rates of DNRPs and the abundances of related functional genes were investigated in aquaculture and non-aquaculture areas. The results showed that marine aquaculture significantly increased the denitrification (DNF) and dissimilatory nitrate reduction to ammonium (DNRA) rates and decreased the rate of anaerobic ammonium oxidation (ANA), as compared with non-aquaculture sites. DNF was the dominant pathway contributing to the total nitrate reduction, and its contribution to the total nitrate reduction significantly increased from 66.72% at non-aquaculture sites to 78.50% at aquaculture sites. Marine aquaculture can significantly affect the physicochemical characteristics of sediment and the abundances of related functional genes, leading to variations in the nitrate reduction rates. Although nitrate removal rates increased in the marine aquaculture area, ammonification rates and the nitrogen retention index in the aquaculture areas were 2.19 and 1.24 times, respectively, higher than those at non-aquaculture sites. Net reactive nitrogen retention exceeded nitrogen removal in the aquaculture area, and the retained reactive nitrogen could diffuse with the tidal current to the entire bay, thereby aggravating N pollution in the entire study area. These results show that marine aquaculture is the dominant source of nitrogen pollution in semi-enclosed bays. This study can provide insights into nitrogen pollution control in semi-enclosed bays with well-developed marine aquaculture.     

MBR中膜孔堵塞控制方法的研究

简述了膜污染的过程，指出膜孔堵塞是膜污染中的重要一环，并对膜堵塞的形成过程和机理做了详细的阐述。在此基础上对引起膜孔堵塞的因素如膜、溶质、处理液、操作方式的影响进行了深入的研究，介绍和总结了目前在加MBR中为防治膜孔堵塞所采用的主要方法，提出了今后膜孔堵塞研究的重点。     

活性污泥中好氧反硝化菌的富集筛选及鉴别

采用SBR反应器,以硝基氮为底物,通过间歇曝气方式,DO保持5mg/L以上,对活性污泥进行强化驯化,实现好氧反硝化细菌的富集培养。利用琥珀酸钠作为碳源,溴百里酚蓝(BTB)作为pH指示剂,共筛选得到20株BTB琼脂平板阳性菌。通过反硝化性能测定,复筛得到4株好氧反硝化细菌。实验结果表明,琥珀酸盐为碳源、硝酸盐为惟一氮源、C/N<10的条件下,4株菌在4d内的TIN去除率均达到60%以上。通过16SrRNA序列同源性比较成功鉴定出3株菌,初步判断2株属于Pseudomonas菌属、1株属于Delftia菌属。     

废水中氨氮的去除与利用

化学沉淀剂可去除废水中的氨氮，并得到有用复合肥ＭｇＮＨ４ＰＯ４。探讨了诸反应对氨氮去除率的影响。     

环境中铅的化学循环

本文论述了环境中铅的背景值、来源、污染、质量标准，化学循环包括沉淀溶解、络合解离和吸附解吸以及环境中铅的烷基化，为铅污染治理提供理论依据．     

用二氧化氯降解废水中的苯胺类化合物（2）──降解机理的探讨

本文在上文（１）的基础上，进一步研究了经二氧化氯处理前后ＢＯＤ＿５／ＣＯＤ的变化规律，其比值大于或接近０．３．其降解产物有醌及醌的氧化产物和ＮＨＩ．对苯胺及二氧化氯来说其．反应级数为１，整个反应为二级反应．     

石油降解菌XD-1产表面活性剂的性能

从含油废水中筛选分离到1株原油降解菌XD-1,鉴定为假单胞菌（Pseuomonas sp.）.初步实验表明菌XD-1具有较强的产表面活性剂乳化原油的作用,对该菌的产表面活性剂性能进行了研究.实验证明,菌XD-1所产表面活性剂为脂肽类物质,菌在生长对数期产表面活性剂,表面活性剂的产生为生长相关型;充足的碳源是产表面活性剂的必需条件,菌利用原油为碳源时能持续大量地产表面活性剂;原油和尿素为产表面活性剂的最适碳源和氮源,菌XD-1产表面活性剂的最佳营养培养基组成为葡萄糖10 g,尿素4 g,磷酸二氢钾1 g,微量元素液4 mL,水1 L,pH 8.0.     

绍兴茶园小流域的3种农药生态风险评价

虫螨腈、联苯菊酯和溴氰菊酯是茶叶生产中较为常见的3种杀虫剂,但其对茶园小流域内生态环境影响的相关研究较少。为评价其生态风险,选取我国浙江绍兴茶园小流域内主要溪流及湖库采集水体样品,采用气相色谱-质谱法对样品中3种农药进行残留检测;基于美国生态毒理数据库(ECOTOX)收集了3种农药对我国常见水生生物的毒性数据,利用BITSSD软件平台构建了物种敏感度分布(species sensitivity distribution, SSD)曲线,结合研究区实测数据开展3种农药对绍兴茶园小流域的生态风险评价研究。结果表明：(1)无脊椎动物和节肢动物对3种农药的敏感度高于鱼类,营养级越高其敏感度越低;(2)根据SSD模拟结果,为保护该流域95%的物种,联苯菊酯和溴氰菊酯浓度需<0.001μg·L^(-1),虫螨腈为0.4μg·L(-1),虫螨腈为0.4μg·L^(-1);(3)农药喷施后,虫螨腈、溴氰菊酯和联苯菊酯在茶园溪流中的残留浓度最高分别影响22%、50%和66%的物种,联苯菊酯是生态风险的主要贡献者,但在喷施1个月后,茶园流域水溪及河湖水环境中的农药残留基本均未检出。这说明3种农药施用对茶园小流域物种的影响较小,所带来的生态风险尚在可控范围之内。