Environmental Fluid Mechanics - In plunging jets and at hydraulic jumps, large amounts of air bubbles are entrained at the impingement of the liquid jet into the receiving body. Air is entrapped... 相似文献
Polychlorinated biphenyls (PCBs) contaminate 19% of US Superfund sites and represent a serious risk to human and environmental health. One promising strategy to remediate PCB-contaminated sediments utilizes organohalide-respiring bacteria (OHRB) that dechlorinate PCBs.
However, functional genes that act as biomarkers for PCB dechlorination processes (i.e., reductive dehalogenase genes) are poorly understood. Here, we developed anaerobic sediment microcosms that harbor an OHRB community dominated by the genus Dehalococcoides. During the 430-day microcosm incubation, Dehalococcoides 16S rRNA sequences increased two orders of magnitude to 107 copies/g of sediment, and at the same time, PCB118 decreased by as much as 70%. In addition, the OHRB community dechlorinated a range of penta- and tetra-chlorinated PCB congeners including PCBs 66, 70?+?74?+?76, 95, 90?+?101, and PCB110 without exogenous electron donor. We quantified candidate reductive dehalogenase (RDase) genes over a 430-day incubation period and found rd14, a reductive dehalogenase that belongs to Dehalococcoides mccartyi strain CG5, was enriched to 107 copies/g of sediment. At the same time, pcbA5 was enriched to only 105 copies/g of sediment. A survey for additional RDase genes revealed sequences similar to strain CG5’s rd4 and rd8. In addition to demonstrating the PCB dechlorination potential of native microbial communities in contaminated freshwater sediments, our results suggest candidate functional genes with previously unexplored potential could serve as biomarkers of PCB dechlorination processes.
Ambio - The choice of tree species used in production forests matters for biodiversity and ecosystem services. In Sweden, damage to young production forests by large browsing herbivores is helping... 相似文献
Ambio - In the original published article, the sentence “Nevertheless, semi-natural forest remnants continue to be harvested and fragmented (Svensson et al. 2018; Jonsson et al. 2019), and... 相似文献
Environmental Science and Pollution Research - Acrylamide (AA), an industrial monomer, may cause multi-organ toxicity through induction of oxidative stress and inflammation. The antioxidant... 相似文献
Environmental Science and Pollution Research - Dengue fever (DF) is one of the world’s most important vector-borne illnesses. In 2017, Egypt experienced a dengue outbreak. This study aimed to... 相似文献
Environmental Science and Pollution Research - Malaria is a dangerous disease affecting millions around the globe. Biosynthesized nanoparticles are used against a variety of diseases including... 相似文献
This paper mainly aims to study the linear element influence on the estimation of vascular plant species diversity in five Mediterranean landscapes modeled as land cover patch mosaics. These landscapes have several core habitats and a different set of linear elements -habitat edges or ecotones, roads or railways, rivers, streams and hedgerows on farm land- whose plant composition were examined. Secondly, it aims to check plant diversity estimation in Mediterranean landscapes using parametric and non-parametric procedures, with two indices: Species richness and Shannon index.Land cover types and landscape linear elements were identified from aerial photographs. Their spatial information was processed using GIS techniques. Field plots were selected using a stratified sampling design according to relieve and tree density of each habitat type. A 50×20 m2 multi-scale sampling plot was designed for the core habitats and across the main landscape linear elements. Richness and diversity of plant species were estimated by comparing the observed field data to ICE (Incidence-based Coverage Estimator) and ACE (Abundance-based Coverage Estimator) non-parametric estimators.The species density, percentage of unique species, and alpha diversity per plot were significantly higher (p < 0.05) in linear elements than in core habitats. ICE estimate of number of species was 32% higher than of ACE estimate, which did not differ significantly from the observed values. Accumulated species richness in core habitats together with linear elements, were significantly higher than those recorded only in the core habitats in all the landscapes. Conversely, Shannon diversity index did not show significant differences. 相似文献
The rapidly developing Asian countries may face threatening environmental contamination, that however remains largely unassessed.
We studied persistent trace elements in three wetlands, Poyang Lake, relatively unpolluted, and Tai Lake, and Pearl River
Delta, selected as hotspots of pollution in Central China. We adopted as indicator the Little Egret, a widespread colonial
waterbird, and during 1999 and 2000 we collected and analysed the same samples as for a parallel study we conducted in Pakistan,
e.g. eggs, body feathers of chicks, prey spontaneously regurgitated by the chicks, and sediments at the areas most used by
foraging egrets. The levels of trace-metals at our three study areas were similar, or within the range, of those found in
the few other studies for East Asia, with few exceptions. The concentrations of the various elements were below the threshold
that may affect the survival or reproduction of the birds, and even the highest concentrations relative to background, i.e.
Se in eggs, and Hg in feathers at Pearl Delta, do not pose toxic hazards. In sediments, the levels of trace elements were
lower than the critical levels assumed for contaminated soil, except for alarming high levels of As at Poyang. These results
do not confirm our expectation, that Poyang was relatively uncontaminated, while Tai and Pearl were polluted. Although trace
metal concentration differed significantly among the three study areas, these differences were minor and were not consistent
among elements and samples. The bioaccumulation ratios from sediments through prey, feather and egg, were consistent with
our previous findings for Pakistan. Only Hg exhibited high bioaccumulation, while Se and Zn had low accumulation, and the
other elements no accumulation. This reasserts that feathers of predators such as egrets, may be more sensitive indicators
of environmental contamination for the elements subject to bioaccumulation, whereas the sediments or the organisms low in
the food chain are better indicators for the other elements. 相似文献
Anthropogenic compounds that are able to disrupt the endocrine system of wildlife species are a major cause for concern and
have led to a demand for new screening methods. The identification and quantification of endocrine disruptor compounds at
wastewater treatment plant is of major interest to assess the endocrine activity of wastewater treatment plant discharges
into the environment. This study consists of a preliminary survey of concentrations of previously selected endocrine disruptor
compounds, undertaken to establish environmental concentrations and to support a biological program assay exposing freshwater
fish to them. Selected endocrine disrupting chemicals (APEs, bisphenol A and 17 β-estradiol) were measured in samples from a wastewater treatment plant located in Lisbon (Portugal), using recent commercial
enzyme-linked immunosorbent assay kits and also LC-MS/MS. The results show that the wastewater treatment plant treatment process
is efficient on the removal of target endocrine disruptor compounds. However, environmentally significant concentrations are
still present in the treated effluent. The results also show that enzyme-linked immunosorbent assay kit is suitable for routine
analysis of the selected compounds. The results are also useful since the wastewater treatment plant is located in a Mediterranean
region, which results in an effluent with its own characteristics. 相似文献