Enteric viruses are a cause of waterborne disease worldwide, and low numbers in drinking water can present a significant risk
of infection. Because the numbers are often quite low, large volumes (100–1,000 L) of water are usually processed. The VIRADEL
method using microporous filters is most commonly used today for this purpose. Negatively charged filters require the addition
of multivalent salts and acidification of the water sample to effect virus adsorption, which can make large-volume sampling
difficult. Positively charged filters require no preconditioning of samples, and are able to concentrate viruses from water
over a greater pH range than electronegative filters. The most widely used electropositive filter is the Virosorb 1MDS; however,
the Environmental Protection Agency has added the positively charged NanoCeram filters to their proposed Method 1615. Ultrafilters
concentrate viruses based on size exclusion rather than electrokinetics, but are impractical for field sampling or processing
of turbid water. Elution (recovery) of viruses from filters following concentration is performed with organic (e.g., beef
extract) or inorganic solutions (e.g., sodium polyphosphates). Eluates are then reconcentrated to decrease the sample volume
to enhance detection methods (e.g., cell culture infectivity assays and molecular detection techniques). While the majority
of available filters have demonstrated high virus retention efficiencies, the methods to elute and reconcentrate viruses have
met with varying degrees of success due to the biological variability of viruses present in water. 相似文献
Environmental Science and Pollution Research - The anionic surfactant SLES (sodium lauryl ether sulfate) is an emerging contaminant, being the main component of foaming agents that are increasingly... 相似文献
During the last 50 years, the Common Agricultural Policy (CAP) has impacted the evolution of European agricultural landscapes by driving changes in land use and farming practices. We propose a typology characterising the scales relevant for agricultural landscapes management and argue that action is required on three scales: (1) a landscape oriented management at the farm level; (2) the coordination of land managers’ actions at the landscape level; and (3) the conservation of the diversity of agricultural landscapes in the EU. We provide evidence that until now the CAP has mainly focused on the first scale. We also illustrate how agricultural policy could encourage coordinated actions at the landscape- and EU-scales. In particular, we propose policy instruments to coordinate actions of individual land owners (e.g. collective bonus in agro-environmental contracts or support to environmental cooperatives (scale 2)). We also analyse how the recognition and transposition of the European Landscape Convention could promote trans-frontier landscape cooperation in order, not only to conserve high-quality rural landscapes, but also to ensure the conservation of the diversity of EU landscapes (scale 3). This paper provides a knowledge base to support an integrated CAP design in the direction of improved landscape management, as an important component of the EU project towards more sustainable agriculture. 相似文献
The present work aims at evaluating the ability of the River Tiber natural microbial community to degrade naproxen in water samples collected downstream from a wastewater treatment plant. For this purpose, different water microcosms were set up (microbiologically active vs sterile ones) and treated with naproxen (100 μg/L) alone or in the co-presence of gemfibrozil in order to evaluate if the co-presence of the latter had an influence on naproxen degradation. The experiment was performed in the autumn and was compared with the same experimental set performed in spring of the same year to highlight if seasonal differences in the river water influenced the naproxen degradation. Pharmaceutical concentrations and microbial analysis (total cell number, viability, and microbial community composition) were performed at different times in the degradation experiments. The overall results show that the natural microbial community in the river water had a key role in the naproxen degradation. In fact, although there was a transient negative effect on the natural microbial community in all the experiments (3 h after adding the pharmaceutical), the latter was able to degrade naproxen within about 40 days. On the contrary, no decrease in the pharmaceutical concentration was observed in the sterile river water. Moreover, the co-presence of the two drugs lengthened the naproxen lag phase. As regards the natural microbial community composition detected by Fluorescence in situ Hybridization, Alpha and Gamma-Proteobacteria increased when the pharmaceutical halved, suggesting their role in the degradation. This study shows that with the concentration studied, naproxen was degraded by the natural microbial populations collected from a river chronically contaminated by this pharmaceutical. 相似文献
In order to study the bioaccumulation of Pb, Cr, Ni, and Zn and the stress response, the floating aquatic plant Limnobium laevigatum was exposed to increasing concentrations of a mixture of these metals for 28 days, and its potential use in the treatment of wastewater was evaluated. The metal concentrations of the treatment 1 (T1) were Pb 1 μg L−1, Cr 4 μg L−1, Ni 25 μg L−1, and Zn 30 μg L−1; of treatment 2 (T2) were Pb 70 μg L−1, Cr 70 μg L−1, Ni 70 μg L−1, and Zn 70 μg L−1; and of treatment 3 (T3) were Pb 1000 μg L−1, Cr 1000 μg L−1, Ni 500 μg L−1, and Zn 100 μg L−1, and there was also a control group (without added metal). The accumulation of Pb, Cr, Ni, and Zn in roots was higher than in leaves of L. laevigatum, and the bioconcentration factor revealed that the concentrations of Ni and Zn in the leaf and root exceeded by over a thousand times the concentrations of those in the culture medium (2000 in leaf and 6800 in root for Ni; 3300 in leaf and 11,500 in root for Zn). Thus, this species can be considered as a hyperaccumulator of these metals. In general, the changes observed in the morphological and physiological parameters and the formation of products of lipid peroxidation of membranes during the exposure to moderate concentrations (T2) of the mixture of metals did not cause harmful effects to the survival of the species within the first 14 days of exposure. Taking into account the accumulation capacity and tolerance to heavy metals, L. laevigatum is suitable for phytoremediation in aquatic environments contaminated with moderated concentrations of Cr, Ni, Pb, and Zn in the early stages of exposure.