Abundance,spatial distribution,and physical characteristics of microplastics in stormwater detention ponds

Despite extensive research on microplastics (MP) in marine environments, little is known about MP abundance and transport in terrestrial systems. There is, therefore, still little understanding of the main mechanisms driving the substantial transport of MP across different environmental compartments. Storm events can transport MP beyond boundaries, such as from the land to groundwater or the ocean, as has already been discovered for organic carbon transport. Urban stormwater detention ponds are suitable environments to study the impact of stormwater on the environmental fate and transport of MP. Herein, we investigate the longitudinal and vertical distribution of MP within two detention ponds with different physical characteristics. Soil samples were collected at various locations and from multiple depths (surface and subsurface layers) for measuring MP concentrations using fluorescence microscopy. Our findings show that MP are retained more near the inlet of the ponds, and MP of larger sizes were found more abundantly near inlets than outlets. We also found that MP mass and sizes decrease from surface soil to subsurface soil. In the pond, where vegetation (grass root network) was more considerable, MP were found more evenly distributed along the depth. In terms of shape, the fragments were the most abundant MP shape.     

电子废弃物拆解园区重金属排放特征和周边土壤重金属污染来源解析及风险评价

对某典型电子废弃物拆解园区排放的废气以及周边土壤中的重金属进行监测分析。结果显示,拆解过程中排放的重金属总量由高到低依次为：锡（Sn）、铬（Cr）、镍（Ni）、铅（Pb）、铜（Cu）、锑（Sb）、锰（Mn）、砷（As）、镉（Cd）、汞（Hg）;从处理工艺来看,几个主要拆解工序均有重金属排放,排放量由高到低依次为：加热烤板、火法冶炼、塑料造粒和湿法冶炼工序。园区周边土壤中的Hg、Cd、Cu、Pb平均质量分数超过珠三角土壤污染风险筛选值。相关性和主成分分析结果表明,Pb、Cu、Cd、Ni、Zn等重金属来源于电子废弃物拆解过程,包括废水排放、大气干湿沉降和固体废弃物随意堆放等途径,Cr可能主要来源于成土母质,Hg有电子废弃物之外的其他来源。土壤生态风险评价结果表明,该区域属于很强生态风险,其中Cd和Hg对生态危害的贡献率达到91.6%。土壤环境容量评价结果表明,该区域仅有As和Cr的土壤现存容量较大,Zn和Ni的土壤现存环境容量较小,已达到警戒值,其余重金属均处于超载状态。该地区土壤重金属污染状况须引起足够重视,应尽快制定管控治理措施。     

有机垃圾的处理和资源化技术进展

有机垃圾具有易腐烂、热值低、有机质含量丰富等特点,常规的填埋和焚烧难以妥善处理。文章在分析各类有机垃圾组成和特性的基础上,认为堆肥化处理、厌氧发酵和综合利用应是有机垃圾处理和处置的发展趋势,这不仅有利于消除污染、保护环境,还能最大程度地实现物质和能量的自然循环。     

水溶剂加速萃取-超高效液相色谱串联质谱测定土壤中全氟羧酸

采用水溶剂加速萃取-超高效液相色谱串联质谱法（UPLC-MS/MS）建立了土壤中6种全氟羧酸（PFCs）的分析方法,并对色谱分析条件、水溶剂萃取条件、固相萃取柱净化条件及实验材料选择等进行了优化。结果表明,以ACQUITY UPLC BEH C18色谱柱为分离柱,2.0 mmol/L乙酸铵水溶液为流动相A,甲醇为流动相B,梯度洗脱下可在9 min内完成6种PFCs的测试,检出限为0.03~0.4 μg/kg。对实际土壤样品进行测定,加标回收率为90.7%~118%,相对标准偏差为5.6%~18.0%,精密度和准确度均较好。该方法前处理过程简单、易操作,仪器检测效率高、结果准确,能够满足土壤中PFCs的检测要求。     

自然水体中主要有毒有机物的研究进展

介绍了主要有毒有机物多环芳烃(PAHs)、多氯联苯(PCBs)、有机氯农药(OCPs)在环境中的危害及其来源,着重评述了近年来中国自然水体中和沉积物中该类污染物的研究进展,指出新的检测技术的开发、有毒有机物的生殖毒性和生态环境风险影响方法学的研究及污染区域污染控制、消减及修复是今后该领域的工作重点.     

加压活性污泥法处理有机中间体废水的研究

对加压活性污泥法处理有机中间体废水进行了研究,主要考察了停留时间(HRT)、污泥浓度(MLSS)和反应压力等条件对COD去除率的影响.有机中间体废水经铁炭预处理后,COD从原来的8 000 mg/L降到5 000 mg/L左右,BOD5/COD由原来的0.20升高到0.40左右.当反应器内废水混合后COD 2 000 mg/L时,在反应压力0.10 MPa、污泥质量浓度3～5 g/L、停留时间8～10 h条件下,出水COD小于600 mg/L,COD去除率大于70%;出水经混凝沉淀处理后COD小于400 mg/L,可以达到<污水综合排放标准>(GB 8978-1996)三级标准.与常规的活性污泥处理方法相比,加压活性污泥法具有处理速度快、降解效率高和容积负荷大等优点.     

地下水曝气理论模型研究进展

地下水曝气(Air Sparging,AS)是修复饱和土壤及地下水有机污染的有效技术.AS多相流动过程中气液流动以及污染物传质过程的模型研究是AS技术的关键因素,详细介绍了近年来AS系统的理论模型方法及研究进展,并对其效果进行评价.     

Identifying hydrologically sensitive areas: bridging the gap between science and application

Researchers have noted that current water quality protection strategies, like nutrient management plans, lack a sound hydrological underpinning for pollutant transport processes. This is especially true for areas like the northeastern U.S. where copious research has shown that variable source area hydrology largely governs runoff generation. The goal of this study was to develop a scientifically justified method to identify the locations that generate overland flow. Furthermore, this methodology must be computationally simple enough that it can be utilized or incorporated into nutrient management plans and other established water quality tools. We specifically tested the reliability of the 'distance from a stream,'D(s), and the 'topographic index,'lambda, to predict areas with a high propensity for generating overland flow, i.e. hydrologically sensitive areas (HSA). HSAs were defined by their probability of generating runoff, P(sat), based on 30 year simulations using a physically based hydrological model. Using GIS, each location's P(sat) was correlated with D(s) and lambda. We used three Delaware Co., NY watersheds in the New York City watershed system with areas varying in size from 1.6 to 37 km2 and with forested and agricultural land uses. The topographic index gave stronger, more regionally consistent correlations with P(sat) than did D(s). Equations correlating lambda and P(sat) for each month are presented and can be used to estimate hydrological sensitivity in the region surrounding our study watersheds, i.e. in Delaware Co. This work is currently being incorporated into an Internet Mapping System to facilitate user-friendly, on-line identification of HSAs.     

Socioeconomic Factors Affecting Farmers’ Perceptions of Land Degradation and Stonewall Terraces in Central Palestine

Land degradation by soil erosion is a socioeconomic and environmental problem facing many developing countries. Application of stonewall terraces for soil moisture conservation is vital to reducing the environmental impacts of this phenomenon. To this end, a field plot experiment was conducted in the study area along with the use of a closed-ended questionnaire. The object of the experiment was to study the socioeconomic impacts of soil erosion on local farmers and their adoption of the stonewall terrace technique. The study showed a higher net profit in areas that had implemented terrace conservation practices than in areas that had not (i.e., 3.5 to 6 times higher net profit). Correlation analysis indicated that the farmers’ perceptions, land ownership, and geomorphology were significantly related to the farmers’ incentives and willingness to adopt terraces as soil conservation measures (P < 0.05), although the correlations were negative. Smallholder farmers (52% of the interviewed farmers) were involved in the sale of the agricultural land for urban uses, largely because of the high price and immediate returns offered. However, the associated land use changes warrant greater involvement of both the private and public sectors. This cooperation may be accomplished through the introduction of a long-term agricultural loan system and the development of proper legislation accompanied by a comprehensive and durable infrastructure and service system with the goal of reducing the negative impact of land use changes and encouraging sustainable use of resources.     

A numerical study of soil cover performance

In the investigation of soil cover design options for final decommissioning of reactive mine waste, it is often necessary to analyze or predict the anticipated cover performance as a function of the cost of implementation, which is governed by the type, number and thickness of the layers in the cover system. An example of such investigation is presented in this study where one-dimensional evaporation from hypothetical moisture-retaining cover systems is simulated to assess the influence of several cover properties and hydrogeologic parameters on performance. The commercially available transient flow model, SoilCover, was used to compute suction and water content profiles for different cover design scenarios. The predicted water content profile and porosity of layers were then used to estimate the oxygen diffusion coefficients of the various layers. The oxygen diffusion coefficients were used to estimate oxygen flux through the cover systems. The oxygen flux was, in turn, related to the maximum acid flux. The studied cover and hydrogeologic parameters included soil type, thickness of barriers, and water table elevation. Two types of infiltration and oxygen barrier and two types of capillary layer with different thicknesses were studied. The water table was either kept constant at the base of the waste (tailings) or dropped by 0.5, 1, 2, and 3m over 120 days. The results showed that the relationship between water table depression and the thickness of capillary layers, on one hand, and desaturation of the infiltration and oxygen barrier, on the other, is not linear. Relationships between oxygen flux and barrier thickness and between cost increase and performance improvement of the studied cover systems are presented. Finally, a method that outlines steps for site-specific and economically feasible design of multi-layer cover systems is introduced.