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Heavy metal contamination of minesoils is a widespread problem in China. In Pingle manganese mineland in Guangxi (south China), heavy metal concentrations in soils and dominant plants were determined, and soil contamination was assessed with pollution index (Pi) and index of geoaccumulation (I-geo). Pi showed the minesoil was heavily polluted by Cd and slightly polluted by Cr. I-geo showed a severer pollution for all metals (except for Mn) than Pi because I-geo tended to overestimate the real pollution effect of minesoil. Fresh tailings dam had both the highest Pi and I-geo among the four sites indicating a high metal contamination. All the “bio-available” fractions of the studied metals were below 5% of the totals. Dominant plants tended to accumulate higher Cd and Cr, and showed higher Mn translocation to aboveground parts. Besides the agricultural reclamation, more diverse restoration goals with lower environmental risks should be considered for the Mn mine wastelands in South China.
The biological community in activated sludge wastewater plants is organized within this ecosystem as bioaggregates or flocs, in which the biotic component is embedded in a complex matrix comprised of extracellular polymeric substances mainly of microbial origin. The aim of this work is to study the role of different floc-associated ciliates commonly reported in wastewater treatment plants-crawling Euplotes and sessile Vorticella- in the formation of aggregates. Flocs, in experiments with ciliates and latex beads, showed more compactation and cohesion among particles than those in the absence of ciliates. Ciliates have been shown to contribute to floc formation through different mechanisms such as the active secretion of polymeric substances (extrusomes), their biological activities (movement and feeding strategies), or the cysts formation capacity of some species. Staining with lectins coupled to fluorescein showed that carbohydrate of the matrix contained glucose, manose, N-acetyl-glucosamine and galactose. Protein fraction revealed over the latex beads surfaces could probably be of bacterial origin, but nucleic acids represented an important fraction of the extracellular polymeric substances of ciliate origin.
Total and organic mercury contents were determined from samples of surface soils (0-5 cm), sieved at ≤63 µm. collected from 10 different locations in the upper Manzanares River watershed, using cold vapor atomic absorption spectroscopy. Methylmercury was determined using a HPLC-UV detector. The mean total mercury concentration was 1.3 µg. g-1, a value permitted by the Canadian environment quality guidelines for farming soils, but high for European standards. Using certified reference materials, we verified that a modification of the method described by Qian et al. (2000) was effective for organic mercury extraction, with a recovery of 92.17% for DORM-2 and 92.11% for TORT-2. This modified method was applied to soil samples, obtaining concentrations of 0.5-1.0 µg.g-1 of organic mercury. The parameters for determining methylmercury using HPLC-UV were optimized; the best results were obtained with a 4.6 mm × 25 cm Zorbax CN– column, with a mobile phase of 70/30 V/V of methanol: ammonium acetate 0.05 mol.l-1, with a flow rate of 0.5 ml.min-1; the methylmercury was detected at 4.99 min retention time. Methylmercury was not found in the soil samples. Using the certified reference material we proved that the method used produced reliable results. The analysis confirmed the existence of mercury in this farming area.
Recreational water sites such as beaches along lakes, rivers, or oceans, are one of the most popular activities in many parts of the world. Recently rainfall and runoff due to rainfall events has been associated with increasing microbial levels in recreational water. This runoff can lead to beach closures and potentially unsanitary conditions at popular swimming beaches. The impact of stormwater on beach water quality has led to a myriad of option for controlling stormwater. Some of these include grass buffer partitions, stormwater detention basins, media filters, catch basin inserts, and infiltration units. Biofilters, or infiltration units are gaining popularity as a treatment option for stormwater around the Great Lakes basin, but we are aware of no studies that have looked at the indicator organism (i.e. Escherichia coli, or E.coli) removal potential of these infiltration units and the media used in them. The overall objective of this study was to evaluate the performance of a stormwater biofilter medium in removing the indicator organism E.coli in a laboratory system. When several laboratory biofilter system were challenged with E.coli concentrations of 2.82E3 and 2.85E5 E.coli/100mL of simulated stormwater in a 1.25 cm rain event, the systems were able to remove between 83 and 100% of the E.coli in this influent. During a subsequent 1.25 cm rain event with E.coli-free water, the biofilter was able to retain 68%-100% of the E.coli originally inoculated into the system. The results of this study indicate that these systems hold promise for mitigation of E.coli from storm water near recreational beaches. These findings will assist beach managers, engineers, and municipal stake holders evaluate the usefulness of biofilter infiltration as a storm water management tool in order to decrease E.coli input into beach areas.
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