503种储运过程常见化学品的安全管控浓度的计算——基于化学品对藻类的环境风险评价

化学品在提高人们生活水平的同时会对生态环境,对化学品进行环境风险评价可有效地避免这一不利影响.本文通过对商值法进行逆向推导的方法,根据化学品对藻类的急性毒性EC_(50),通过相关公式计算出了两个评价指标,即慢性无可见有害作用水平NOAEL和预测无效应浓度PNEC,最终推导出503种化学品的安全管控浓度C_控.系列化学品的C_控不仅能够直接为企业提供可参照的化学品环境暴露管控标准,还能为企业的化学品科学管理工作提供数据支撑和决策支持.     

Effects of operating parameters on in situ NH3 emission control during kitchen waste composting and correlation analysis of the related microbial communities

Ammonia emission during composting results in anthropogenic odor nuisance and reduces the agronomic value of the compost due to the loss of nitrogen. Adjusting the operating parameters during composting is an emerging in situ odor control technique that is cheap and highly efficient. The effects of in situ NH₃ emission control were investigated in this study by simultaneously adjusting key operating parameters (such as C/N ratio, aeration rate, and moisture content) during the composting processes (C1–C9). Results showed that the average NH₃ emission concentrations for different treatments were in the order of C1 > C4 > C2 > C5 > C3 > C6 > C7 > C8 > C9. The total content of NH₃ emission (21.02 g/kg) in C9 (C/N ratio = 35, aeration rate = 15 L/min, and moisture content = 60%) was much lower than that (65.95 g/kg) in C1 (C/N ratio = 15, aeration rate = 5 L/min, and moisture content = 60%). The nitrogen loss ratio was 27.36% for C1, while 16.15% for C9. The microbial diversity and abundance in C9 and C1 were compared using high-throughput sequencing. The relationship between NH₃ emission, operating parameters, and the related functional microbial communities was also investigated. Results revealed that Nitrosospira, Nitrosomonas, Nitrobacter, Pseudomonas, Methanosaeta, Rhodobacter, Paracoccus, and Sphingobacterium were negatively related to NH₃ emission. According to the above results, the optimal values for different operating parameters for the in situ NH₃ control during kitchen waste composting were, respectively, moisture content of 70%, C/N ratio of 35, and aeration rate of 15 L/min, with the order of effectiveness from high to low being aeration rate > C/N > moisture. This information could be used as a valuable reference for the in situ NH₃ emission control during kitchen waste composting.

     

Feasibility of iron scraps for enhancing nitrification of domestic wastewater at low temperatures

Environmental Science and Pollution Research - The development of an effective approach to improve low-temperature nitrification of domestic wastewater remains an important issue that needs to be...     

Phase transformation of Cr(VI)-adsorbed ferrihydrite in the presence of Mn(II): Fate of Mn(II) and Cr(VI)

Ferrihydrite is an important sink for the toxic heavy metal ions, such as Cr(VI). As ferrihydrite is thermodynamically unstable and gradually transforms into hematite and goethite, the stability of Cr(VI)-adsorbed ferrihydrite is environmentally significant. This study investigated the phase transformation of Cr(VI)-adsorbed ferrihydrite at different pH in the presence of aqueous Mn(II), as well as the fate of Mn(II) and Cr(VI) in the transformation process of ferrihydrite. Among the ferrihydrite transformation products, hematite was dominant, and goethite was minor. The pre-adsorbed Cr(VI) inhibited the conversion of ferrihydrite to goethite at initial pH 3.0, whereas little amount of adsorbed Mn(II) favored the formation of goethite at initial pH 7.0. After the aging process, Cr species in solid phase existed primarily as Cr(III) in the presence of Mn(II) at initial pH 7.0 and 11.0. The aqueous Mn concentration was predominantly unchanged at initial pH 3.0, whereas the aqueous Mn(II) was adsorbed onto ferrihydrite or form Mn(OH)₂ precipitates at initial pH 7.0 and 11.0, promoting the immobilization of Cr(VI). Moreover, the oxidation of Mn(II) occurred at initial pH 7.0 and 11.0, forming Mn(III/IV) (hydr)oxides.     

天津某住宅区降雨径流颗粒粒径分布及污染物赋存形态

为考察城市不同下垫面降雨径流中颗粒粒径分布及与污染物的关系,2020年7—8月在相同降雨条件下对天津市某居民区油毡屋面、塑钢屋面、水泥瓦屋面和沥青路面的6场降雨事件进行采样,分析降雨径流污染特征及颗粒物分布. 结果表明:①沥青路面降雨径流中悬浮颗粒物（suspended solids, SS）浓度最高,与油毡屋面、塑钢屋面和水泥瓦屋面径流SS浓度在统计上有显著差异(P<0.05);②不同下垫面降雨径流中颗粒物粒径主要分布在10~200 μm之间,4种下垫面中值粒径（D₅₀）浓度在计量上均有显著差异(P<0.05);③粒径在10~50 μm的颗粒物占比最大,在油毡屋面、塑钢屋面、水泥瓦屋面和沥青路面径流中占比分别为30.95%、25.53%、30.41%和50.47%,粒径大于300 μm的颗粒物体积分数占比最小;④降雨径流中颗粒物是污染物的主要载体,径流中化学需氧量（COD）和总磷（TP）主要以颗粒态形式存在,而总氮（TN）主要以溶解态形式存在. 通过对降雨径流中颗粒物粒径分布和污染物赋存形态的研究,以期为城市径流污染控制及雨水净化方法的选取提供数据支撑.      

铸造起重机多单元装配与耦合建模分析

结构建模分析是工程应用领域中应用较为普遍的一种分析设计方法,对于简单的几何模型实体单元不仅能够得到较高的精度而且能够很好地再现结构受力特性,应力云图具有较高的展示度,而对于复杂的几何模型,实体模型不仅消耗大量的建模时间,而且求解时间也相对较长.文中分析了Solid-Shell-Beam(S-S-B)多单元建模及耦合技术原理,建立了铸造起重机S-S-B多单元装配模型,通过S-S-B多单元模型与实体模型的对比分析,验证了S-S-B单元装配模型计算准确性,最后利用S-S-B单元耦合分析方法计算了铸造起重机在空载、满载、偏载等典型工况下的结构受力情况,为铸造起重机的设计、校核及使用维护提供技术支撑.     

The dispersion,stability, and resuspension of C60 in environmental water matrices

Environmental Science and Pollution Research - Environmental waters cover a range of water quality characteristics which could greatly affect the behavior and fate of C60 in the aquatic...     

Perfluoroalkyl substances in the Lingang hybrid constructed wetland,Tianjin, China: occurrence,distribution characteristics,and ecological risks

Environmental Science and Pollution Research - In this study, the occurrence, spatial distribution, sources, and ecological risks of perfluoroalkyl substances (PFASs) in the surface waters of the...     

Binding and detoxification of chlorpyrifos by lactic acid bacteria on rice straw silage fermentation

This investigation examined the reduction of pesticide residues on straw inoculated with lactic acid bacteria (LAB) during ensiling. Lactobacillus casei WYS3 was isolated from rice straw that contained pesticide residues. Non-sterilized rice straw, which was inoculated with L. casei WYS3, showed increased removal of chlorpyrifos after ensiling, compared with rice straw that was not inoculated with L. casei WYS3 or sterilized rice straw. In pure culture, these strains can bind chlorpyrifos as indicated by high-performance liquid chromatography analysis. Viable L. casei WYS3 was shown to bind 33.3–42% of exogenously added chlorpyrifos. These results are similar to those of acid-treated cells but less than those of heat-treated cells, which were found to bind 32.0% and 77.2% of the added chlorpyrifos respectively. Furthermore, gas chromatography–mass spectrometry analysis determined that L. casei WYS3 detoxified chlorpyrifos via P-O-C cleavage. Real-time polymerized chain reaction analysis determined that organophosphorus hydrolase gene expression tripled after the addition of chlorpyrifos to LAB cultures, compared with the control group (without chlorpyrifos). This paper highlights the potential use of LAB starter cultures for the detoxification and removal of chlorpyrifos residues in the environment.     

Fabrication of electrochemically-modified BiVO4-MoS2-Co3O4composite film for bisphenol A degradation

A new electrochemically-modified BiVO₄-MoS₂-Co₃O₄ (represented as E-BiVO₄-MoS₂-Co₃O₄) thin film electrode was successfully synthesized for environmental application. MoS₂ and Co₃O₄ were grown on the surface of BiVO₄ to obtain BiVO₄-MoS₂-Co₃O₄. E-BiVO₄-MoS₂-Co₃O₄ film was achieved by further electrochemical treatment of BiVO₄-MoS₂-Co₃O₄. The as-prepared E-BiVO₄-MoS₂-Co₃O₄ exhibited significantly enhanced photoelectrocatalytic activity. The photocurrent density of E-BiVO₄-MoS₂-Co₃O₄ thin film is 6.6 times that of BiVO₄ under visible light irradiation. The degradation efficiency of E-BiVO₄-MoS₂-Co₃O₄ for bisphenol A pollutant was 81.56% in photoelectrochemical process. The pseudo-first order reaction rate constant of E-BiVO₄-MoS₂-Co₃O₄ film is 3.22 times higher than that of BiVO₄. And its reaction rate constant in photoelectrocatalytic process is 14.5 times or 2 times that in photocatalytic or electrocatalytic process, respectively. The improved performance of E-BiVO₄-MoS₂-Co₃O₄ was attributed to the synergetic effects of the reduction of interfacial charge transfer resistance, the formation of oxygen vacancies and sub-stoichiometric metal oxides and higher separation efficiency of photogenerated electron-hole pairs. E-BiVO₄-MoS₂-Co₃O₄ is a promising composite material for pollutants removal.