南京冬季典型霾天气过程多元对比分析

选取2017～2020南京地区冬季3个典型霾天气过程,综合分析了霾天气过程中污染物、气象要素以及边界层条件等影响机制与特征变化.结果表明,3次过程中,AQI指数峰值分别为304(严重污染)、227(重度污染)与176(中度污染),且与PM2.5、PM10浓度变化基本趋于一致,PM25与PM10比值基本都大于0.7;污染...     

2016~2020年山东省空气质量时空分布特征及影响因素分析

基于2016～2020年山东省城市空气质量监测结果,结合人口密度和城镇化率等社会经济数据以及风速、气温和相对湿度等气象要素,综合应用地理加权回归模型（GWR）、多尺度地理加权回归模型（MGWR）和小波分析等方法,探究山东省空气污染物的时空分布特征及其与社会经济和气象要素的关系.结果表明：（1）近5年来山东省空气质量整体呈好转趋势,除O₃外,SO₂、 NO₂、 PM_2.5和PM₁₀等污染物浓度逐年降低.空气污染物分布存在明显的空间差异,沿海地区污染物浓度更低.（2）山东省PM_2.5与人口密度和第二产业占比具有极显著的正相关关系（P<0.01）,而与城镇化率呈极显著负相关关系（P<0.01）.同时,这种相关关系在空间上存在尺度差异,人口密度、民用汽车量和工业用电量与PM_2.5空间关系较平稳,而城镇化率和第二产业占比对PM_2.5的影响的空间异质性较高.（3）气象要素对菏泽和威海两市PM_2.5     

南水北调丹江口库区土壤中微塑料分布特征及风险评估

为探究丹江口库区土壤中微塑料赋存特征及影响因素,通过对果园、旱地、水田和湿地进行土壤样品采集,利用密度分选、显微镜观察和拉曼光谱仪测定等方法对土壤中微塑料进行鉴定.结果表明,研究区采集的64个样本均有微塑料检出,丰度范围为645~15161 n·kg^-1.空间分布上,库尾高于库中和库首,且表层土壤（0~20 cm）中微塑料的丰度明显低于下层土壤（20~40 cm）.微塑料主要类型为聚丙烯（26.4%）和聚酰胺（20.2%）,粒径主要集中在50~500 μm之间（75%）,常见形状为碎片状（66.2%）.相关性分析显示,土壤微塑料丰度与土地利用、距水面和住宅的距离、人口密度和土壤性状密切相关.从微塑料污染风险来看,72.1%区域微塑料聚合物污染指数处于Ⅲ级和Ⅳ级,丹江口库区存在一定的微塑料污染风险.研究结果可为微塑料风险评估提供支撑.     

改良剂调控下水稻镉累积和土壤溶解性有机质光谱特征的响应

研究土壤中溶解性有机质(DOM)的化学组成和特征差异对理解改良剂对Cd的稳定机制具有重要意义.土壤改良剂被广泛应用于受污染农田以缓解重金属在农作物中的累积,但改良剂调控下土壤DOM的光谱特征却鲜见报道.采集南方典型Cd污染水稻土为研究对象,通过投加三大类改良剂(有机类、无机类和石灰类,共11种)进行水稻种植盆栽试验,研究了不同改良剂对土壤DOM的影响.利用紫外-可见光谱、三维荧光光谱和平行因子分析法(PARAFAC)对比分析了不同改良剂调控下根际土壤DOM的光谱特征.结果表明,石灰类改良剂提高土壤pH,促进土壤固相中有机质的溶解,从而显著提高了土壤DOM的质量分数.与对照相比,有机类改良剂提高了土壤DOM的相对分子量和新生自生源贡献率,无机类改良剂提高了土壤DOM的芳香性和疏水性组分,石灰类改良剂提高了土壤DOM的显色组分和腐殖化程度.通过PARAFAC分析和OpenFluor数据库验证,解析出了4个荧光组分C1(255/465)、 C2(325/400)、 C3(275/390)和C4(240/460),均为类腐殖质.两种光谱相互印证,表明土壤DOM来源以陆源输入的类腐殖质为主.相关...     

稻田土壤砷、镉复合污染阻控技术研究进展

砷（As）和镉（Cd）是稻田土壤中最常见的有毒有害重金属元素,且易从土壤迁移到水稻籽粒中.目前,我国稻田土壤中As和Cd及其复合污染现象普遍,对粮食安全和人体健康均构成了严重威胁.As和Cd在土壤中的环境行为相反,对As-Cd复合污染的同步治理是当前水稻安全生产的关键技术难点.通过综述近年来同步阻控水稻对As和Cd吸收以及转运的若干实用技术,包括水分管理、钝化技术、淋洗技术、电动修复技术、植物修复技术、低累积水稻品种的选取以及叶面阻控技术,归纳并分析了各种技术的处理效果、作用机制和制约因素,提出了主要阻控技术的发展方向,指出构建区域高适配性综合技术模式的重要性,以期为稻田As-Cd复合污染治理和水稻安全生产提供参考.     

淡水环境沉积物中微塑料的密度分离方法研究

微塑料污染已广泛覆盖了全球海洋和淡水环境的表层水体、深层水体以及沉积物,沉积物中的泥沙和其他杂质颗粒会严重影响对沉积物中微塑料的实验分析.因此,将微塑料从沉积物中分离出来至关重要,而目前我国微塑料分离方法暂无统一的系统程序和检测标准.该研究在岷江成都段选取4个采样点采集沉积物样品,通过对比研究基于密度分离法的3种分离方...     

Type 0092丝状菌污泥微膨胀在短程硝化中的实现

利用Type 0092丝状菌不易引发污泥恶性膨胀的特点,本实验采用实际生活污水,以SBR反应器接种短程硝化污泥,考察了短程硝化状态下启动Type 0092丝状菌污泥微膨胀的特性,研究了系统启动与维持期间的污泥沉降性能、亚硝酸盐积累率(NAR)、污染物去除特性以及污泥菌群结构变化情况.结果表明控制DO为0. 3～0. 8 mg·L~(-1),F/M(以COD/MLSS计)=0. 24 kg·(kg·d)~(-1),按照交替缺氧/好氧模式运行(单周期3次,缺氧∶好氧=20 min∶60 min),能够启动Type 0092丝状菌污泥微膨胀与短程硝化耦合,系统SVI值维持在180 m L·g~(-1)左右,NAR一直维持在99%左右,COD和TN去除率能够分别提高约13%和5%,相较于传统全程硝化非微膨胀状态曝气量能节省约62. 5%.当交替缺氧/好氧模式变为单周期交替6次,缺氧∶好氧=10 min∶30 min,亚硝酸盐氧化菌(NOB)的活性会恢复,使短程硝化被破坏;低溶解氧、交替缺氧/好氧、低负荷是实现Type 0092丝状菌污泥微膨胀的关键因素,当负荷(以COD/MLSS计)大于0. 25 kg·(kg·d)~(-1)时,仅靠低溶解氧和间歇曝气无法维持污泥微膨胀状态.     

Real-time quantification of mcrA, pmoA for methanogen, methanotroph estimations during composting

Composting is the controlled biological decomposition of organic matter by microorganisms during predominantly aerobic conditions. It is being increasingly adopted due to its benefits in nutrient recycling, soil reclamation, and urban land use. However, it poses an environmental concern related to its contribution to greenhouse gas production. During composting, activities of methanogenic and methanotrophic communities influence the net methane (CH4) release into the atmosphere. Using quantitative polymerase chain reaction (qPCR), this study was aimed at assessing the changes in the methyl-coenzyme M reductase (mcrA) and particulate methane monooxygenase (pmoA) copy numbers for estimation of methanogenic and methanotrophic communities, respectively. Open-windrow composting of beef cattle (Bos Taurus L.) manure with temperatures reaching > 55 degrees C was effective indegrading commensal Escherichia coli within the first week. Quantification of community DNA revealed significant differences in mcrA and pmoA copy numbers between top and middle sections. Consistent mcrA copy numbers (7.07 to 8.69 log copy number g(-1)) were detected throughout the 15-wk composting period. However, pmoA copy number varied significantly over time, with higher values during Week 0 and 1 (6.31 and 5.41 log copy number g(-1), respectively) and the lowest at Week 11 (1.6 log copy number g(-1)). Net surface CH4 emissions over the 15-wk period were correlated with higher mcrA copy number. Higher net ratio of mrA: pmoA copy numbers was observed when surface CH4 flux was high. Our results indicate that mcrA and pmoA copy numbers vary during composting and that methanogen and methanotroph populations need to be examined in conjunction with net CH4 emissions from open-windrow composting of cattle feedlot manure.     

Responses of community to the possible use of recycled water for washing machines: A case study in Sydney, Australia

Recycled water is a valuable resource that has potential to free up potable water supplies and recharge systems while improving the environment. Recycled water for washing machine could be one of the options as new end use of recycled water to alleviate the demand on existing and limited water supplies. This paper summarizes the findings of a research survey in Sydney, Australia to explore the attitudes and opinions of community towards the use of recycled water for different purposes, especially for the washing machine. The survey showed that 97% of the respondents were aware of the persisting water shortage problem while more than 60% of the respondents supported the use of recycled water for washing clothes. This paper exposes the basic concern of participants for using recycled water in washing machine. Health issue was found as the most concerns of the community. The survey also presents the further conditions to be considered for using recycled water for washing machine according to the participants’ opinions. Correlation between knowledge and attitudes of respondents was also found in this survey.     

上游式筑坝法尾矿坝的安全系数随堆筑坝高变化分析

对于投资较少的上游式尾矿筑坝法而言,在实际的堆积施工过程中,由于很难严格按照设计的坡比进行每一级子坝的堆筑,导致矿方无法及时、真正掌握当前尾矿坝的受力性能和稳定状态。因此,针对某典型尾矿坝剖面,采用迈达斯商业软件试用版对尾矿坝的堆积过程进行了模拟分析,利用强度折减有限元方法对施工当前状态的尾矿坝进行了边坡稳定分析,得到了当前状态尾矿坝的塑性剪应变云图和相对应的抗滑稳定安全系数。比较了尾矿坝安全系数随着子坝堆筑的变化情况,结果发现：随着堆积子坝的进行,尾矿坝的整体抗滑稳定系数逐渐减小,此外在初期坝和一级子坝的下游坡脚处容易出现相对较大的变形。此研究结果为矿部管理部门及时了解尾矿坝的稳定程度和实际生产提供了技术支持。