Contamination status of arsenic,lead, and cadmium of different wetland waters

The present investigation was conducted to determine the contamination status of arsenic (As), cadmium (Cd), and lead (Pb) in the wetland waters of Bhaluka in Bangladesh. Water samples were collected from 15 selected wetlands of Bhaluka region and analyzed using an atomic absorption spectrophotometer. Estimated results of three metals detected were As (7–80?µg?L^?1), Pb (0–86?µg?L^?1) and Cd (0–70?µg?L^?1) in water samples in all wetlands. The level of As in all investigated wetlands (93%) was higher than that of WHO recommended permissible limit of drinking water except Alanga wetland. However, As levels were higher than that recommended for livestock water quality levels. Eighty-seven percent of the investigated wetlands showed lower content of Pb than WHO recommended permissible limit of drinking water, but two wetland waters (Dohuria-1 and Chowdhuri) were polluted with higher Pb levels. Sixty-seven percent of the investigated wetlands displayed higher levels of Cd than WHO recommended permissible limit in drinking water. Dissolved organic material showed no significant difference among the 15 investigated wetlands water, but total dissolved solids was significantly greater. The condition of the water of all wetlands was basic pH. All water samples were applied to linear regression equation and correlation coefficients where values showed no significant differences. Data demonstrate that the estimated high metal concentrations of these ponds may contribute to bioaccumulation within plants, food grains and shrimp.     

Sustainability and the measurement of future paths in genuine savings: case studies

This paper extrapolates future paths of genuine savings (GS) by using our integrated assessment model. The results with the base case (BC) indicate that both GS without population change (GS) and GS with population change (GSn) are almost positive in OECD countries in the twenty-first century (satisfying the necessary but insufficient condition for sustainability); those numbers are projected to be negative in 2100. Asia (ASIA), the Middle East and Africa (MEAF), the former Soviet Union and Eastern Europe (FSEE), and the world show upward trends for both values, showing negative signs in 2010 and positive signs after 2050 (in ASIA, MEAF, and the world) and in 2100 (in FSEE). The values in Latin America (LAMR) remain negative throughout. We examine additional following three cases: demand reduction (DR), carbon dioxide (CO₂) emissions reduction (CR), and population reduction (PR). The GSn results compared to the BC indicate that (1) GSn in DR is similar to that of BC, (2) GSn in PR is slightly higher than that of BC, and (3) GSn in CR is unexpectedly lower than that of BC. This GSn reduction in the CR case derives from the fact that the term for calculating resource depletion (especially resource rent, which equals the difference between price and cost) in GS and GSn increased, leading to a greater term being subtracted from gross savings. The resource price increases with the marginal price of natural gas, given the energy-source shift in reducing CO₂ emissions, from cheap coal to expensive natural gas.     

Fostering food and energy security through by-product valorization within agricultural and agro-industrial networks: study of the province of Santiago de Cuba

ABSTRACT

The aim of this study is to investigate of how the concept of ‘integrated food and energy systems’ or IFES production networks could be applied – within the specific context of Eastern Cuba’s agricultural and agro-industrial sectors – as an innovative approach to improve food and energy security. The Province of Santiago de Cuba in southeast Cuba was the focus of this study; its existing operations, infrastructure, resource flows and scarcities, and actor relationships provide the basis of the data used for the evaluation.

The authors investigated the regional context, identify potential members of an agricultural and agro-industrial network in three municipalities of the province, and identify the main residuals and by-products of key facilities. Potential avenues for by-product valorization are investigated along with the possible influence/impacts on the sustainability of the surrounding systems and actors. A conceptual model for a regional network for integrated food and energy production is then provided based upon the development of three agricultural/agro-industrial scenarios: influence at the farm level, regional agro-industrial networks, and ‘anchor tenant’ eco-industrial systems. The main challenges and opportunities for the development of the networks are described with recommendations for addressing such where possible.     

去除预处理生活污水的潜流人工湿地中试除氮性能

为研究人工湿地除氮机制,构建并考察了中试潜流人工湿地对不同形态氮的去除效果,并通过分析出水各种形态氮的分布和湿地系统内部不同形态氮的二维分布特征研究了人工湿地的除氮机制. 结果表明,进水ρ(TN)为30～115 mg/L,ρ(NH₄+-N)为25～60 mg/L,ρ(COD_Cr)为90～190 mg/L,水力停留时间为4 d条件下,氮素被有效去除,TN去除率为32%～70%,NH₄+-N去除率为33%～73%;试验系统脱氮的主要方式为硝化/反硝化作用;湿地上部主要进行硝化反应,中下部主要进行反硝化反应;湿地下半部对NH₄+-N去除贡献有限,硝化作用受限;欲提高系统除氮效率,需提高溶解氧水平并改善有机氮矿化条件.      

Relationships of nitrous oxide fluxes with water quality parameters in free water surface constructed wetlands

The effects of chemical oxygen demand (COD) concentration in the influent on nitrous oxide (N₂O) emissions, together with the relationships between N₂O and water quality parameters in free water surface constructed wetlands, were investigated with laboratoryscale systems. N₂O emission and purification performance of wastewater were very strongly dependent on COD concentration in the influent, and the total N₂O emission in the system with middle COD influent concentration was the least. The relationships between N₂O and the chemical and physical water quality variables were studied by using principal component scores in multiple linear regression analysis to predict N₂O flux. The multiple linear regression model against principal components indicated that different water parameters affected N₂O flux with different COD concentrations in the influent, but nitrate nitrogen affected N₂O flux in all systems.     

Estimating rate constants of contaminant removal in constructed wetlands treating winery effluent: A comparison of three different methods

In this paper we investigated the use of three different methods for determining the rate constants for degradation of winery effluent within a sub-surface flow constructed wetland (CW). These methods comprised of using a dispersed plug flow (the Peclet) equation; a tanks-in-series (TIS) equation; and analysing the residence time distribution (RTD) directly. The last of these is described by the convolution integral (CI). We demonstrated self-similarity of the RTDs, which meant that the system's hydraulics were similar throughout the CW. We therefore extrapolated the RTD data to develop a more complete understanding of the hydraulic properties of the CW and examine how they affected the kinetics of degradation. We found that whilst both the Peclet and the TIS equation were able to predict concentration within the CW, this required the optimisation of more than one variable at the same time rendering a result that was more of a modelling exercise than a useful design tool. The CI method could be applied to predict system parameters effectively. We used it to measure rate constants of removal for both ethanol and potassium (key species for tracking the degradation/treatment of the effluent). Acetic acid, however, did not degrade implying that the CW operated aerobically. The concentration of sodium increased very slightly, indicating that it is not bioremediated/removed and that there are some minor evapotranspirative effects. The rate constant found for the biodegradation of COD was found to have significantly more uncertainty associated with it than the measurement of the rate of degradation individual components and we therefore posit that it is better to describe the processes of degradation by tracking individual components rather than lumped parameters.     

海滨湿地景观过程模型与模拟研究——以江苏盐城保护区核心区为例

景观过程模型已经成为深化景观变化研究的重要手段并日益受到重视。海滨湿地是一种高度复杂和动态变化的景观系统,构建景观过程模型能够从机理上解释湿地景观时空动态演变过程。研究中,将盐城国家级自然保护区核心区划分为人工管理区和自然湿地区两种模式,根据2000、2006、2011 年3 个时相的景观资料以及野外生态监测数据,构建海滨湿地景观过程模型,结果如下：①利用空间代替时间并结合灰色关联分析,确定了海滨湿地景观演变的关键影响因素为土壤盐度和水分;②运用人工神经网络的方法,分析了土壤盐度和水分的空间分异,并通过图层叠加和分级统计,得出了土壤盐度和水分的阈值范围以及变化规律;③运用GIS-Matlab-CA技术构建了基于关键生态过程的海滨湿地景观过程模型,模型总体精度都在80%以上,Kappa 系数都在0.7 以上,一致性检验结果表明空间位置一致率决定了整个景观模拟的精度;④运用已构建好的模型对研究区2012-2020、2025 年的结果进行了模拟预测,预测结果表明,盐城海滨湿地芦苇沼泽和米草沼泽扩张、碱蓬沼泽面积减少的趋势将愈加明显。     

人工湿地污水处理系统春季空气微生物群落结构分析?

通过构建16S/18S rDNA基因文库,分析自由表面流人工湿地污水处理系统春季空气细菌和空气真菌群落结构特征.结果表明,空气细菌分布在变形菌门(Proteobacteria)、放线菌门(Actinobacteria)、浮霉菌门(Planctomycetes)、蓝藻门(Cyanophyta)、绿弯菌门(Chloroflexi)、拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes),主要为β-变形菌纲(71.04%)、γ-变形菌纲(12.03%)、α-变形菌纲(3.83%)、蓝藻纲(4.38%)、芽孢杆菌纲(3.28%)和鞘脂杆菌纲(2.19%),优势菌属是马赛菌属(Massilia 66.66%)、假单胞菌属(Pseudomonas 4.37%)、蓝丝细菌属(Cyanothece 3.83%)和沙雷氏菌属(Serratia 3.28%).空气真菌主要类群为座囊菌纲(Dothideomycetes 61.18%),其次是接合菌纲(Zygomycetes 16.47%)、盘菌纲(Discomycetes 14.12%),优势菌属是核腔菌属(Pyrenophora 48.31%)、被孢霉属(Mortierella 15.7%)、缘刺盘菌属(Cheilymenia 12.4%)、Boothiomyces (4.5%).人工湿地空气微生物中未检测出大肠杆菌(Escherichia coli)、沙门氏菌(Salmonella spp.)和产气荚膜梭菌(Clostridium perfringens),但存在粘质沙雷氏菌(S. marcescens)、恶臭假单胞菌(P. putida)、表皮葡萄球菌(Staphylococcus epidermidis)等致病菌或条件致病菌.     

Heavy metals of natural and reclaimed tidal riparian wetlands in south estuary, China

The concentrations of Cd, Cr, Cu, Ni, Pb, and Zn in two plant species (Scirpus tripueter Linn. and Cyperus malaccensis Lam.), water, and soils sampled from the reclaimed tidal riparian wetlands (RTRWs) and the natural riparian wetlands (NRWs) in the Pearl River estuary (PRE), were analyzed to investigate and compare their distribution and accumulation. The results show that the concentrations of the six studied heavy metals in soils exceed the eco-toxic threshold recommended by USEPA. The concentrations of Cd, Cr, and Zn in plants may lead to toxic effects compared to others.The hydraulic conditions and the degree of human disturbances can affect the heavy metal accumulation in RTRWs and NRWs. The heavy metal concentrations in water are higher whereas they are lower in soils of RTRWs Compared with that in the NRWs. The accumulation of heavy metals in the roots of plants is higher in NRWs than those in RTRWs while the opposite result is found for heavy metal accumulation in shoots. Based on the bioaccumulation and translocation factors, the plants in NRWs have the higher capacity to accumulate heavy metals, while higher abilities to transport heavy metals from roots to shoots are observed in RTRWs. Heavy metal contaminations in RTRWs are dominated by anthropogenic sources from both side uplands and river water, whereas in NRWs, the metal accumulations are simultaneously affected by anthropogenic and natural factors.     

好氧/厌氧潜流湿地微生物多样性与净化能力的关系

好氧/厌氧多级串联潜流人工湿地对COD和NH4＋-N具有较高的去除率.为了探究该类型湿地高效去除污染物的具体机制,采用荧光素双醋酸酯（FDA）法、4,6-联脒—2-苯基吲哚（DAPI）法和BIOLOG法测定了人工湿地基质中微生物的活性、数量和代谢功能多样性,并分析其与水质净化能力之间的相关性.结果表明,沿水流方向,OA...