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141.

The presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA in wastewater has been reported as a result of fecal shedding of infected individuals. In this study, the occurrence of SARS-CoV-2 RNA was explored in primary-treated wastewater from two municipal wastewater treatment plants in Quintana Roo, Mexico, along with groundwater from sinkholes, a household well, and submarine groundwater discharges. Physicochemical variables were obtained in situ, and coliphage densities were determined. Three virus concentration methods based on adsorption-elution and sequential filtration were used followed by RNA isolation. Quantification of SARS-CoV-2 was done by RT-qPCR using the CDC 2020 assay, 2019-nCoV_N1 and 2019-nCoV_N2. The Pepper mild mottle virus, one of the most abundant RNA viruses in wastewater was quantified by RT-qPCR and compared to SARS-CoV-2 concentrations. The use of three combined virus concentration methods together with two qPCR assays allowed the detection of SARS-CoV-2 RNA in 58% of the wastewater samples analyzed, whereas none of the groundwater samples were positive for SARS-CoV-2 RNA. Concentrations of SARS-CoV-2 in wastewater were from 1.8 × 103 to 7.5 × 103 genome copies per liter (GC l−1), using the N1 RT-qPCR assay, and from 2.4 × 102 to 5.9 × 103 GC l−1 using the N2 RT-qPCR assay. Based on PMMoV prevalence detected in all wastewater and groundwater samples tested, the three viral concentration methods used could be successfully applied for SARS-CoV-2 RNA detection in further studies. This study represents the first detection of SARS-CoV-2 RNA in wastewater in southeast Mexico and provides a baseline for developing a wastewater-based epidemiology approach in the area.

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142.
Groundwater dependent ecosystems. Part I: Hydroecological status and trends   总被引:3,自引:0,他引:3  
Groundwater dependent ecosystems (GDEs) include valuable ecosystems such as springs, wetlands, rivers, lakes and lagoons. The protection of these systems and services they provide is highlighted by international agreements, i.e. Ramsar convention on wetlands, and regional legislation, i.e. the European Water Framework Directive. Groundwater provides water, nutrients and a relatively stable temperature. However, the role of groundwater in surface ecosystems is not fully understood. The ecosystem can depend on groundwater directly or indirectly, and the reliance can be continuous, seasonal or occasional. This has implications for the vulnerability of ecosystems, as some may be easily affected by external pressure. Conceptual models and quantitative assessments of how groundwater interacts with the environment are needed. GDEs are also threatened by different land use activities and climate change. Hence, we need to understand how GDEs are affected by changes in groundwater quantity and quality, as severe groundwater changes have been observed in many regions. This study examines key aspects of GDEs (hydrogeology, geochemistry and biodiversity) in order to improve conceptual understanding of the role of groundwater in such ecosystems. The status and baseline of different types of GDEs are discussed, with particular emphasis on past evidence of environmental change and potential thresholds and threats in GDEs in various parts of Europe with different land use, climate and geology.  相似文献   
143.
Groundwater in sufficient amounts and of suitable quality is essential for potable water supplies, crop irrigation and healthy habitats for plant and animal biocenoses. The groundwater resource is currently under severe pressure from land use and pollution and there is evidence of dramatic changes in aquifer resources in Europe and elsewhere, despite numerous policy measures on sustainable use and protection of groundwater. Little is known about how such changes affect groundwater dependent ecosystems (GDEs), which include various aquatic and terrestrial ecosystems above ground and inside the aquifer. Future management must take this uncertainty into account. This paper focuses on multiple aspects of groundwater science, policy and sustainable management. Examples of current management methods and practices are presented for selected aquifers in Europe and an assessment is made of the effectiveness of existing policies such as the European Water Framework Directive and the Habitat Directive in practice and of how groundwaters and GDEs are managed in various conditions. The paper highlights a number of issues that should be considered in an integrated and holistic approach to future management of groundwater and its dependent ecosystems.  相似文献   
144.
145.
Hybrid materials represent the family of compounds comprising mixtures of natural and synthetic materials. The study of this field is in a marked expansion since their preparation represents a valid methodology for optimizing the insufficient properties exhibited by materials integrally formed from naturally-occurring sources. In the present work, we describe soy protein modification by grafting reaction with methyl methacrylate. The reaction was confirmed by Fourier Transform Infrared Analysis and Carbon Nuclear Magnetic Resonance. In addition, films were prepared with the material by heat compression. Films were physically and mechanically characterized by determining contact angle with water, total soluble matter, moisture content, swelling in water, water vapor permeability, tensile strength, elongation at break and Young’s modulus. These measurements suggest that the material increased its hydrophobic character as compared with that of the control film since marked reductions in water vapor permeability, swelling and water solubility were determined. Moreover, their mechanical properties were improved by obtaining a more rigid material. These results represent an interesting advance in the preparation of hybrid biocomposites.  相似文献   
146.
The purpose of the present study was to investigate the biodegradation kinetics in aerobic and anaerobic soil of the following brominated flame retardants: 2,4,4′-tribromodiphenyl ether (BDE 28), decabromodiphenyl ether (BDE 209), tetrabromobisphenol A (TBBPA), 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH), 2,4,6-tribromophenol (246BrPh), and hexabromobenzene (HxBrBz). For comparison, the biodegradation of the chlorinated compounds 2,4,4′-trichlorodiphenyl ether (CDE 28), 2,4,6-trichlorophenol (246ClPh), hexachlorobenzene (HxClBz), and 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB 153) was also assessed. In aerobic soil, BDE 209 showed no significant degradation during the test period, but concentrations of the other BFRs declined, with half-lives decreasing in the following order: BDE 28 > TBBPA > TBECH > HxBrBz > 246BrPh. Declines in almost the same order were observed in anaerobic soil: BDE 28, BDE 209 > TBBPA > HxBrBz > TBECH >246BrPh.  相似文献   
147.
Nitrogen leaching from boreal and temporal forests, where normally most of the nitrogen is retained, has the potential to increase acidification of soil and water and eutrophication of the Baltic Sea. In parts of Sweden, where the nitrogen deposition has been intermediate to high during recent decades, there are indications that the soils are close to nitrogen saturation. In this study, four different approaches were used to assess the risk of nitrogen leaching from forest soils in different parts of Sweden. Nitrate concentrations in soil water and C:N ratios in the humus layer where interpreted, together with model results from mass balance calculations and detailed dynamic modelling. All four approaches pointed at a risk of nitrogen leaching from forest soils in southern Sweden. However, there was a substantial variation on a local scale. Basing the assessment on four different approaches makes the assessment robust.  相似文献   
148.
The muscle tissue total mercury (THg) and organomercury (OrHg) concentrations of eel (Anguilla anguilla) and roach (Rutilus rutilis) from the Hg-contaminated River Yare and the uncontaminated Ormesby Broad were compared to their respective bed sediment THg and OrHg concentrations in order to determine if fish in the River Yare had begun to approach 'background' levels. While eel from the Yare had higher flesh concentrations (260 g kg-1) than those from Ormesby Broad (102 g kg- 1), roach were found to have similar concentrations regardless of location (55 and 54 g kg-1 for Yare and Ormesby respectively). However, roach in the Yare had significantly higher body burdens of Hg and organomercury, which when analysed over time (1985–95) showed a decreasing trend approaching the levels observed in fish from Ormesby Broad, suggesting that roach are an overall better biomonitor of contamination then eel. This said, the elevated levels of Hg found in fish from Ormesby Broad indicate the existence of a diffuse source such as atmospheric deposition to the surface waters of East Anglia.  相似文献   
149.
Changes in sulphur and nitrogen pollution in Swedish forests have been assessed in relation to European emission reductions, based on measurements in the Swedish Throughfall Monitoring Network. Measurements were analysed over 20 years with a focus on the 12-year period 1996 to 2008. Air concentrations of SO2 and NO2, have decreased. The SO4-deposition has decreased in parallel with the European emission reductions. Soil water SO4-concentrations have decreased at most sites but the pH, ANC and inorganic Al-concentrations indicated acidification recovery only at some of the sites. No changes in the bulk deposition of inorganic nitrogen could be demonstrated. Elevated NO3-concentrations in the soil water occurred at irregular occasions at some southern sites. Despite considerable air pollution emission reductions in Europe, acidification recovery in Swedish forests soils is slow. Nitrogen deposition to Swedish forests continues at elevated levels that may lead to leaching of nitrate to surface waters.  相似文献   
150.
The creation of protected conservation areas may result in protracted conflicts between stakeholders. In this study we examine the drivers of anthropogenic wildfire ignitions in the National Park of “los Alerces” (NPA) in Patagonia, Argentina. The NPA was established in 1937 to protect the native “andino-patagónico” forests from wildfires as well as preserving its scenic beauty and native flora and fauna. At the time of its creation state authorities prohibited all extractive human activities in the “intangible”—fully protected—“National Park” section, while other regulated extractive and ecotourism activities were allowed to continue in the “Natural Reserve” section in an effort to accommodate the historical entitlements of the displaced populations of “pobladores” (settlers) that had been living in the NPA for over a century. Here we interviewed the main stakeholder groups—“pobladores”, forest rangers and administrators, ecolodge owners and angler club members—to identify the drivers of wildfire ignitions in the park. Wildfires have been singled out by state authorities as the main threat to the NPA though considerable scientific uncertainty exists regarding their complex ecological effects. This study argues, based on the human and biophysical system data collected, that two conflicting cultural frames exist within the NPA that provide the necessary backdrop for understanding the drivers of wildfire ignitions. In turn, these findings raise puzzling dilemmas for the main theoretical approaches that have been used to inform and design conflict management strategies in protected conservation areas.  相似文献   
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