Water chemistry controlled aggregation and photo-transformation of silver nanoparticles in environmental waters

The inevitable release of engineered silver nanoparticles (AgNPs) into aquatic environments has drawn great concerns about its environmental toxicity and safety. Although aggregation and transformation play crucial roles in the transport and toxicity of AgNPs, how the water chemistry of environmental waters influences the aggregation and transformation of engineered AgNPs is still not well understood. In this study, the aggregation of polyvinylpyrrolidone (PVP) coated AgNPs was investigated in eight typical environmental water samples (with different ionic strengths, hardness, and dissolved organic matter (DOM) concentrations) by using UV–visible spectroscopy and dynamic light scattering. Raman spectroscopy was applied to probe the interaction of DOM with the surface of AgNPs. Further, the photo-transformation and morphology changes of AgNPs in environmental waters were studied by UV–visible spectroscopy, inductively coupled plasma mass spectrometry, and transmission electron microscopy. The results suggested that both electrolytes (especially Ca^2 + and Mg^2 +) and DOM in the surface waters are key parameters for AgNP aggregation, and sunlight could accelerate the morphology change, aggregation, and further sedimentation of AgNPs. This water chemistry controlled aggregation and photo-transformation should have significant environmental impacts on the transport and toxicity of AgNPs in the aquatic environments.     

基于可拓理论与区间赋权的煤矿水害安全评价

煤矿水害是煤矿安全生产过程中的五大灾害之一。本文针对煤矿水害系统的复杂性,在建立科学合理的煤矿水害评价指标体系的基础上,将区间赋权法与可拓综合评价法相结合,建立了煤矿水害综合评价的物元模型,并以福建省龙岩市某煤矿为实例,运用该方法对该煤矿水害进行了安全评价。结果表明:该煤矿水害安全等级为安全,基于区间赋权的可拓综合评价方法在一定程度上克服了评价的主观性,不但可以准确地反映煤矿水害的安全等级,而且还能反映与相邻安全等级的距离。     

Analytical methods and environmental processes of nanoplastics

The degradation of plastic debris may result in the generation of nanoplastics(NPs). Their high specific surface area for the sorption of organic pollutions and toxic heavy metals and possible transfer between organisms at different nutrient levels make the study of NPs an urgent priority. However, there is very limited understanding on the occurrence, distribution, abundant, and fate of NPs in the environment, partially due to the lack of suitable techniques for the separation and identificatio...     

Geochemistry and health risk assessment of arsenic exposure to street dust in the zinc smelting district, Northeast China

The aim of this study was to investigate arsenic (As) accumulation in street dust and health risk of population. The investigation concentrated on: a. pollution levels of As in street dust; b. spatial distribution of As in street dust; c. physicochemical properties analysis of street dust; and d. assessment of population health risk due to As exposure to street dust. As concentration in street dust ranged from 3.33 to 185.1?mg?kg^?1, with a mean of 33.10?mg?kg^?1, which was higher than the background value of Liaoning soil. As contamination level of the area closing to Huludao Zinc Plant (HZP) was highest. Spatial variation showed that the pollution center was close to HZP, formed radial distribution pattern and extended to the northeast and southwest of HZP. The pH and organic matter of street dust were both higher than the background values of soil in Liaoning. There was significantly negative correlation between As concentration and the pH. The mass percentages of particles 180?C100,?<100?C75,?<75?C63, and?<63???m were 29.8, 3.7, 21.3, and 4.2?%, respectively. The highest of As concentration was found in the smallest particle size (<63???m). As loadings in the particles of grain size 180?C100 and?<75?C63???m were higher than other particle fractions. Results of the risk assessment indicated that the highest risk was associated with the ingestion of street dust particles. Health risk for different use scenarios to human decreased in the order of HZP?>?Industrial district?>?School?>?Commercial center?>?Residential area. Around HZP, Hazard Index (HI) for children and cancer risk of As by street dust exposure exceeded the acceptable values. It indicated that there was a potential adverse effect on children health by As exposure to the street dust of Huludao.     

基于二维和三维生态足迹的长三角城市群自然资本可持续性分析

城镇化和工业化进程的不断推进给城市群自然资本及其可持续利用带来较大的威胁。为明确城市群建设过程中自然资本可持续性变化特征,以长三角城市群为研究对象,采用二维和三维生态足迹评价模型,同时添加水资源账户对原模型进行改进以反映长三角地区水资源潜力与压力,研究分析了2005—2019年长三角城市群生态足迹、生态压力指数和生态协调指数变化、自然资本存量消耗和自然资本流量占用情况及其影响因素与作用机制。结果表明：1）研究期间,长三角城市群人均生态足迹和生态承载力分别为4.46和1.59 hm²/人,平均人均生态赤字为2.87 hm²/人,但万元GDP生态足迹不断下降,资源利用率不断上升;2）2005—2019年,长三角城市群生态压力指数由2.48升至3.25,生态协调指数由1.30变为1.25;3）基于改进三维生态足迹模型发现,长三角城市群资本存量利用程度越来越大,且对自然资本流量的更新起到较大抑制作用,2019年研究区自然资本存量的消耗量是资本流量占有量的2.26倍;4）影响因子分析表明,工业产值、能源消耗总量、建筑用地面积和城镇化率对生态足迹起到了正向促进作用,对自然资本的可持续性产生了较大压力。

     

Cell wall surface layer (S-layer) promotes colony formation in Microcystis: comparison of S-layer characteristics between colonial and unicellular forms of Microcystis and function conformation

Colony is a key to Microcystis becoming a dominant population and forming blooms. To find the mechanism of colony formation, we investigated cell wall structures of colonial and unicellular strains. Results showed that colonial strains had significant surface layer protein (S-layer) on the surface of cells than unicellular strains by transmission electron microscopy. Western blot showed colonial strains had more S-layer than the unicellular strains. When the S-layer gene (GenBank accession number CAO89090.1) of Microcystis aeruginosa PCC7806 was expressed in Synechocystis sp. PCC6803, PCC6803 aggregated into colonial morphology. The results indicated that the S-layer could promote colony formation in Microcystis. Based on the S-layer sequences of PCC6803 and PCC7806, nine S-layer genes in other Microcystis strains were screened from the GenBank. Sequence comparing showed that the S-layers conserved regions were all located in N-terminal. The S-layers contain repeats-in-toxin (RTX) sequences with Ca²⁺-binding site, and their amino acid composition, hydrophobicity, isoelectric point, etc. were consistent with the characteristics of RTX-type S-layer in bacteria.

     

Response of extracellular and intracellular alkaline phosphatase in Microcystis aeruginosa to organic phosphorus

Environmental Science and Pollution Research - Cyanobacterial blooms caused by Microcystis have become a menace to public health and water quality in the global freshwater ecosystem. Alkaline...     

UV光降解有机砷废水

阿散酸（4-氨基苯胂酸,PAA）作为饲料添加剂被广泛地应用于家禽养殖业,但是大部分PAA的化学结构不会改变。采用UV光降解水中PAA,并研究了PAA初始浓度、溶液pH、叔丁醇和腐殖酸对其降解效果的影响。结果表明：PAA能被UV高效完全降解,且光解过程受溶液pH、腐殖酸和叔丁醇显著影响。UV辐射20 min,PAA降解率为100%,且NH4+和无机砷（As（Ⅴ）/As（Ⅲ））是其主要的最终的降解产物。此外,根据自由基捕获实验和ESR检测分析,提出了PAA的光降解机理。在UV光照中,PAA的氧化降解一方面是由于直接的光解,另一方面归因于光敏化产生的氧化性自由基（·OH/1O2）参与的光氧化降解。研究结果有助于评价环境风险和PAA的去除。     

土壤对煤矸石填充时地下水中F-、SO42-的吸附规律

通过室内静态模拟浸泡试验,文章探讨了平煤集团十二矿附近的土壤对该矿煤矸石井下填充过程中地下水溶出的F-和SO42-的吸附性能.研究发现:土壤对F-吸附效果较好,而对SP42-较差;改性土壤对F-和SO42-的吸附效果均较好,均能使其在地下水中的含量达到地下水Ⅲ类标准;F-和SO42-在改性土壤上的吸附等温模型分别符合Freundlich、Temkin等温式;改性土壤对F-和SO42-的解吸过程分为快速和慢速两个反应阶段.通过试验数据分析得出:井下填充时煤矸石和改性土壤的最佳配比为1∶0.26.     

活化处理活性炭纤维的表面特性及其汞吸附性能

选用了3种比表面积不同的粘胶基活性炭纤维(ACF-1、ACF-2和ACF-3),并对样品ACF-1进行了浓硝酸和氨水活化处理,获得样品ACF-N和ACF-NH3,最后对这5种ACF样品进行表面特性表征和单质汞的吸附实验.氮分子吸附(77.4K)实验结果表明,ACF-N和ACF-NH3的微孔容积与ACF-1相比有所减小,各样品的微孔(d2nm)分布有一定差异.ACF含有许多不规则的表面微结构,其X射线光电子能谱(XPS)分析表明,ACF-N的含氧官能团(CO、COOH)和ACF-NH3的含氮官能团含量与ACF-1相比均有明显增加.X射线衍射(XRD)分析结果表明,ACF-2和ACF-3的石墨化程度和晶体化程度较ACF-1有所提高.汞吸附实验表明,由于受到ACF表面微结构的影响,微孔容积与吸附能力之间并非简单的依附关系,增加含氧、含氮基团含量在一定程度上能提高ACF的汞吸附容量.