Delineating landfill leachate discharge to an arsenic contaminated waterway

Discharge of contaminated ground water may serve as a primary and on-going source of contamination to surface water. A field investigation was conducted at a Superfund site in Massachusetts, USA to define the locus of contaminant flux and support source identification for arsenic contamination in a pond abutting a closed landfill. Subsurface hydrology and ground-water chemistry were evaluated in the aquifer between the landfill and the pond during the period 2005-2009 employing a network of wells to delineate the spatial and temporal variability in subsurface conditions. These observations were compared with concurrent measures of ground-water seepage and surface water chemistry within a shallow cove that had a historical visual record of hydrous ferric oxide precipitation along with elevated arsenic concentrations in shallow sediments. Barium, presumably derived from materials disposed in the landfill, served as an indicator of leachate-impacted ground water discharging into the cove. Evaluation of the spatial distributions of seepage flux and the concentrations of barium, calcium, and ammonium-nitrogen indicated that the identified plume primarily discharged into the central portion of the cove. Comparison of the spatial distribution of chemical signatures at depth within the water column demonstrated that direct discharge of leachate-impacted ground water was the source of highest arsenic concentrations observed within the cove. These observations demonstrate that restoration of the impacted surface water body will necessitate control of leachate-impacted ground water that continues to discharge into the cove.     

Effectiveness of electrocoagulation process in removing organic compounds from slaughterhouse wastewater using monopolar and bipolar electrolytic cells

Slaughterhouse wastewaters contain varied and high amounts of organic matter (e.g., proteins, blood, fat). In order to produce an effluent suitable for stream discharge, electrochemical techniques have been particularly explored at the laboratory pilot scale for organic compounds removal from poultry slaughterhouse (PS) effluent. Electrocoagulation (EC) process was tested using either mild steel or aluminium electrodes arranged in bipolar (BP) or monopolar configuration system. Results showed that the best performance was obtained using mild steel BP electrode system operated at a current intensity of 0.3A, through 60 or 90 min of treatment. Under these conditions, removals of 86+/-1% and 99+/-1% were measured for BOD and oil and grease, respectively, whereas soluble COD and total COD were removed by 50+/-4% and 82+/-2%, respectively. EC is also efficient for decolorization (red-color) and clarification of the PS effluent. Removals of 89+/-4% and 90+/-4% have been measured for total suspended solids and turbidity, respectively. Electrochemical coagulation operated under the optimal conditions involves a total cost of 0.71 USD $ per cubic meter of treated PS effluent. This cost includes energy and electrode consumptions, chemicals, and sludge disposal.     

Allocation plasticity and plant-metal partitioning: meta-analytical perspectives in phytoremediation

In this meta-analysis of plant growth and metal uptake parameters, we selected 19 studies of heavy metal (HM) phytoremediation to evaluate trends of allocation plasticity and plant-metal partitioning in roots relative to shoots. We calculated indexes of biomass allocation and metal distribution for numerous metals and plant species among four families of interest for phytoremediation purposes (e.g. Brassicaceae, Fabaceae, Poaceae, and Solanaceae). We determined that plants shift their biomass and distribute metals more to roots than shoots possibly to circumvent the challenges of increasing soil-HM conditions. Although this shift is viewed as a stress-avoidance strategy complementing intrinsic stress-tolerance, our findings indicate that plants express different levels of allocation plasticity and metal partitioning depending on their overall growth strategy and status as ‘fast-grower’ or ‘slow-grower’ species. Accordingly, we propose a conceptual model of allocation plasticity and plant-metal partitioning comparing ‘fast-grower’ and ‘slow-grower’ strategies and outlining applications for remediation practices.     

Critical Sampling Points Methodology: Case Studies of Geographically Diverse Watersheds

Only with a properly designed water quality monitoring network can data be collected that can lead to accurate information extraction. One of the main components of water quality monitoring network design is the allocation of sampling locations. For this purpose, a design methodology, called critical sampling points (CSP), has been developed for the determination of the critical sampling locations in small, rural watersheds with regard to total phosphorus (TP) load pollution. It considers hydrologic, topographic, soil, vegetative, and land use factors. The objective of the monitoring network design in this methodology is to identify the stream locations which receive the greatest TP loads from the upstream portions of a watershed. The CSP methodology has been translated into a model, called water quality monitoring station analysis (WQMSA), which integrates a geographic information system (GIS) for the handling of the spatial aspect of the data, a hydrologic/water quality simulation model for TP load estimation, and fuzzy logic for improved input data representation. In addition, the methodology was purposely designed to be useful in diverse rural watersheds, independent of geographic location. Three watershed case studies in Pennsylvania, Amazonian Ecuador, and central Chile were examined. Each case study offered a different degree of data availability. It was demonstrated that the developed methodology could be successfully used in all three case studies. The case studies suggest that the CSP methodology, in form of the WQMSA model, has potential in applications world-wide.     

Preliminary results of modeled ozone uptake for Fagus sylvatica L. trees at selected EU/UN-ECE intensive monitoring plots

The objective of this study was to establish whether EU and UN-ECE/ICP-Forests monitoring data (i) provide the variables necessary to apply the flux-based modeling methods and (ii) meet the quality criteria necessary to apply the flux-based critical level concept. Application of this model has been possible using environmental data collected from the EU and UN-ECE/ICP-Forests monitoring network in Switzerland and Italy for 2000-2002. The test for data completeness and plausibility resulted in 6 out of a possible total of 20 Fagus sylvatica L. plots being identified as suitable from Switzerland, Italy, Spain, and France. The results show that the collected data allow the identification of different spatial and temporal areas and periods as having higher risk to ozone than those identified using the AOT40 approach. However, it was also apparent that the quality and completeness of the available data may severely limit a complete risk assessment across Europe.     

How environment and vole behaviour may impact rodenticide bromadiolone persistence in wheat baits after field controls of Arvicola terrestris?

We aimed to evaluate whether environmental factors affect the persistence of bromadiolone in baits in field treatment. Baits were distributed in three soils according to two types of distribution: (1) artificial galleries conform to agricultural practices; (2) storage cavities to mimic bait storage by voles. Persistence was evaluated for 30 days in galleries and 80 days in storage cavities in autumn and spring. The decrease of bromadiolone concentrations was described by a first-order kinetic model. In galleries, the half-lives ranged from 3.0 to 5.1 days in autumn and from 5.4 to 6.2 days in spring. The half-lives were similar between soils and seasons but the pattern of persistence differed lightly for two soils between seasons. Half-lives in storage cavities, 42.7 and 24.6 days in autumn and spring respectively, were longer than in galleries. To conclude, both soil characteristics and climatic conditions weakly influence persistence, while bait storage lengthens it dramatically.     

Potential of agro-industrial produced laccase to remove ciprofloxacin

Environmental Science and Pollution Research - Ciprofloxacin (CIP), a widely used antibiotic, is frequently detected in the environment due to insufficient wastewater and water treatment. Hence,...     

Methods for selenium removal from contaminated waters: a review

Environmental Chemistry Letters - Worldwide contamination of waters by metals, metalloids, and organometallic pollutants is a major health issue. In particular, the occurrence of the selenium...