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1.
AAPS PharmSciTech ; 21(1): 9, 2019 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-31797083

RESUMO

Increased human-pet interactions have led to concerns related to the prevention and treatment of ectoparasite infestations. Fipronil (FIP) is a widely used ectoparasiticide in veterinary medicine available for topical administration; however, its use may cause damage to the owners and the environment. The aim of the study was to develop immediate-release tablets of FIP, as well as to determine its pharmacokinetic properties after oral administration in beagle dogs. The prepared FIP tablets were evaluated for pre-compression (angle of repose, speed flow, and Carr's index) and post-compression (weight variation, friability, thickness, hardness, disintegration time, and dissolution rate) parameters. Orally administered FIP at a dose of 2 mg/kg was rapidly absorbed with Cmáx of 3.13 ± 1.39 µg/mL at 1.83 ± 0.40 h post treatment (P.T.) and metabolized with 1.27 ± 1.04 µg/mL at 2.33 ± 0.82 h P.T. for fipronil sulfone (SULF) (the primary metabolite). The elimination of FIP and SULF occurred slowly and had maintained quantifiable plasma levels in the blood for up to 28 days P.T. The goal of the study is aligned with the concept of One Health, which aims to collaboratively achieve the best health for people, animals, and the environment. Therefore, the use of FIP tablets for the control of ectoparasites in dogs may be a safer alternative for owners and the environment.


Assuntos
Antiparasitários/química , Antiparasitários/farmacocinética , Pirazóis/química , Pirazóis/farmacocinética , Administração Oral , Animais , Antiparasitários/administração & dosagem , Cães , Dureza , Pirazóis/administração & dosagem , Comprimidos , Poluição da Água/prevenção & controle
2.
Georgian Med News ; (295): 171-177, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31804222

RESUMO

In modern conditions, the use and protection of water is an extremely complex problem. The environmental situation of water resources is relevant for all water basins in Ukraine, since most of the surface and groundwater in Ukraine are polluted. The aim of the research was to study the regulatory normatively-legal base of sanitary, ecolocal, water and urban planning legislation in the field of sanitary protection of water objects and establishing its compliance with the requirements of the European Union Directives with the development of measures to resolve issues of concern. Ukraine's international obligations are enshrined in more than 40 global and regional international acts relating to the sanitary protection and use of water resources.The main requirements of the EU Directive (2008/56/EC, 98/83/EC, 2008/105/EC, 2003/35/EC, 2003/4/EC, 2001/42/EC, 2011/92/EC) are already taken into account new laws in force and domestic regulatory documents. However, the regulatory framework of the legislation of Ukraine in the field of sanitary protection of water objects needs to be improved in terms of focusing on new mechanisms of economic regulation, decentralization of power, the introduction of effective monitoring of the ecological status of the Black and Azov Seas, and the implementation of the requirements of the EU Directives: 2006/7/ЄС, 2007/60/ЄС 91/271/ЄЕС, 91/676/ЄЕС and Regulation No648/2004. In order to improve the sanitary-epidemiological state of water resources in Ukraine, their rational use and protection, it is proposed to carry out: an effective state and legal policy in the field of sanitary protection of waters, focused on: the effective implementation of water, environmental, urban planning legislation of Ukraine; optimal coordination of architectural and planning, water-ecological, sanitary-epidemiological aspects and social interests; priority of drinking water supply and water protection measures; implementation of international treaties with a view to the proper legal, sanitary and epidemiological regime of transboundary water objects; implementation of European standards for the quantitative and qualitative status of waters; the formation of an ecological, sanitary and epidemiological worldview among the population.


Assuntos
Água Subterrânea , Higiene , Poluição da Água , União Europeia , Controle Social Formal , Ucrânia , Poluição da Água/prevenção & controle , Abastecimento de Água
3.
Mar Pollut Bull ; 145: 316-324, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31590793

RESUMO

In 2020, the global cap of maximum allowable sulphur content in marine fuel will be reduced from the current 3.5% to 0.5%. Another way to reduce the sulphur emissions is to install a seawater scrubber that cleans exhausts but instead release acidic water containing nutrients and contaminants back to the marine environment. In the current study, scrubber washwater was tested on a Baltic Sea microplankton community. A significant increase in chlorophyll a, particulate organic phosphorus (POP), carbon (POC) and nitrogen (PON) were observed when the community was exposed to 10% scrubber washwater for 13 days as compared to the control. A laboratory experiment with the filamentous cyanobacteria Nodularia spumigena and the chain-forming diatom Melosira cf. arctica showed negative responses in photosynthetic activity (EC10 = 8.6% for N. spumigena) and increased primary productivity (EC10 = 5.5% for M. cf. arctica), implying species-specific responses to scrubber washwater discharge.


Assuntos
Plâncton/efeitos dos fármacos , Água do Mar/microbiologia , Emissões de Veículos/prevenção & controle , Poluição da Água/prevenção & controle , Países Bálticos , Clorofila A/análise , Cianobactérias/efeitos dos fármacos , Nitrogênio/análise , Nodularia/efeitos dos fármacos , Fósforo/análise , Fotossíntese/efeitos dos fármacos , Navios , Enxofre/toxicidade , Emissões de Veículos/toxicidade
4.
IET Nanobiotechnol ; 13(6): 553-559, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31432785

RESUMO

The various toxic contaminants such as dyes, heavy metals, pesticides, rare-earth elements, and hazardous chemicals are the major threats to all the flora and fauna. Owing to the harmful ill effects caused by the toxic contaminants, it is necessary to eliminate these compounds from the authors' ecosystem. The chitosan magnetic nanomaterials (CMNPs) are one of the superior materials used in the wastewater treatment through various conventional technologies. The chitosan is a natural source obtained from the crustacean shells of crabs, prawns etc. The magnetic nanomaterial prepared by the reinforcement of chitosan is highly effective in the removal of heavy metals, dyes, organic matter, and harmful chemicals. It is used in various technologies such as adsorption, flocculation, immobilisation, photocatalytic technology, and bioremediation. This possesses unique surface and magnetic characteristics, Moreover, it is simple, economically feasible, and eco-friendly material used efficiently in wastewater treatment. This review paper depicts the overview of CMNP in the industrial effluent treatment.


Assuntos
Quitosana/química , Nanoestruturas/química , Eliminação de Resíduos Líquidos/métodos , Poluição da Água/prevenção & controle , Purificação da Água/métodos , Animais , Humanos , Magnetismo/métodos , Nanopartículas de Magnetita/química , Poluentes Químicos da Água/isolamento & purificação
5.
Environ Sci Pollut Res Int ; 26(30): 30954-30966, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31452121

RESUMO

The study on the quantification of ecological compensation (eco-compensation) in a river basin can help to make environmental protection more compatible with ecological construction. In this paper, the upstream and downstream of the river basin were treated as the subjects and objects of eco-compensation, and the mechanism of eco-compensation was clarified. The emergy analysis theory (EMA) was used to calculate the values of water resources in sub-industries (agriculture, industry, life, and recreation). The pollution loss rate theory (PLR) was adopted to calculate the water pollution loss rate in sub-industries. According to the value of water resources and pollution loss rate in sub-industries, combined with the water consumption of sub-industries in the river basin, the Ecological Compensation Quantification Model of Sub-industries (ECQ-Is Model) was constructed. Under the guidance of the aforementioned theory and model, a comprehensive research was conducted on the Xiaohong River. The results showed that the eco-compensation values of the upstream area, industry, and agriculture in the river basin were higher. Therefore, it is essential that the water resources in the Xiaohong River basin be well conserved and managed. In addition, the research results point out the direction for water pollution control, which includes promoting the coordinated development of the upstream and downstream, and maximizing the ecological benefits of the river basin.


Assuntos
Modelos Teóricos , Poluição da Água/análise , Poluição da Água/economia , Agricultura , China , Conservação dos Recursos Naturais/métodos , Indústrias , Rios , Poluição da Água/prevenção & controle , Recursos Hídricos
6.
Sci Total Environ ; 696: 134007, 2019 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-31465919

RESUMO

The "targeted ecopharmacovigilance (EPV)" strategy emphasizes the control of environmental pollution by high-priority hazardous pharmaceuticals from principal pollution sources especially in areas that are high risk as a result of drug administration. We conducted a prospective empirical study to explore the possibility of using a targeted EPV intervention as an optimized management tool for the control of aquatic pollution by antibiotics, a common type of pharmaceutical residue, in a rural area in China. Because of the notably high levels of ofloxacin in the studied aquatic environment and the well-accepted environmental risks posed by fluoroquinolone residues, ofloxacin was selected as the targeted high-priority antibiotic pollutant. Based on the main sources of antibiotic pollution in the studied rural aquatic environment, which had been traced previously, a five-step targeted EPV intervention was designed and conducted from Feb 2018 to Jan 2019. The results showed that the residual levels of ofloxacin in the studied Chinese rural aquatic environment significantly decreased during the targeted EPV intervention. Importantly, the EPV measures targeting ofloxacin were found to effectively reduce the environmental pollution by other non-targeted antibiotics. The data from a survey of 45 participants (42 residents and 3 clinicians) and 12 program committee members revealed that the targeted EPV intervention was acceptable to both participants and organizers and could be used as an economical and feasible solution for addressing antibiotic pollution in aquatic environments.


Assuntos
Antibacterianos/análise , Monitoramento Ambiental/métodos , Farmacovigilância , Poluentes Químicos da Água/análise , Poluição da Água/prevenção & controle
7.
Sci Total Environ ; 691: 1310-1319, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31466210

RESUMO

Microbial pollution in river networks is widespread, threatening human health and activities. Wastewater treatment plants are a major source of microbial pollution that affects downstream communities. We propose a simple modeling approach to identify possible hot-spots of microbial pollution in river networks receiving treated wastewater. We consider every reach in a river network as a potential site for the disposal of treated wastewater and we identify the corresponding section of the downstream river where the concentration of indicator bacteria exceeds a prescribed threshold value. In this paper, we introduce the methodology and demonstrate its application to a small river basin (Lockwitzbach, Germany). We computed the lengths of the polluted river sections for different scenarios in order to separately identify the impacts of hydrological boundary conditions and bacterial retention processes. Effective parameters describing bacterial retention were inferred from field samples. The proposed modeling approach can be used to generate dynamic maps of safe and vulnerable zones in a river network. Our approach helps disentangle the effects of network structure, hydrological variability and in-stream processes on the location and length of unsafe river sections. Our model can be used to identify optimal sites for the discharge of treated wastewater. For example, in the Lockwitzbach basin, we show that relocating the existing effluent discharge could reduce the stream length affected by severe microbial pollution by almost 30%.


Assuntos
Monitoramento Ambiental , Modelos Estatísticos , Rios , Eliminação de Resíduos Líquidos/métodos , Poluição da Água/prevenção & controle , Poluição da Água/estatística & dados numéricos
8.
Mar Pollut Bull ; 148: 3-4, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31422300

RESUMO

The strategic location of Malaysia along the world's busiest trade waterways underscores the need to cope ballast water issues for both domestic and international shipping. The adoption of Ballast Water Management Convention 2004 (BWMC) by the International Maritime Organization is suitable for management plans intended to prevent the introduction of invasive species through ballast water discharge. Malaysia has ratified the BWMC in September 2010 and the Convention has come into force in September 2017. However up to now, the BWMC has not been fully implemented by Malaysia for ships operating in its waters. This paper analyse the headway in implementing the provisions of the BWMC in Malaysia as well as the issues and challenges encountered for the implementation. The paper concludes that Malaysian government should promulgate laws and policies to clearly communicate on ballast water issues to the shipping industry communities.


Assuntos
Espécies Introduzidas , Navios , Poluição da Água/prevenção & controle , Purificação da Água/legislação & jurisprudência , Política Ambiental/legislação & jurisprudência , Malásia , Navios/legislação & jurisprudência , Poluição da Água/legislação & jurisprudência , Purificação da Água/normas
9.
Mar Pollut Bull ; 146: 598-607, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31426198

RESUMO

The Golden Horn (GH), as a consequence of heavy domestic and industrial discharges from Alibeykoy and Kagithane creeks, was heavily polluted for more than 50 years. As a result, the upstream area was filled with debris and organic solids, which produced unbearable odour in the past due to anaerobic decomposition of the organic matter in the sedimented zone. Istanbul Metropolitan Municipality (IBB) decided to develop new strategies of estuary management and pollution reduction. To this end, Golden Horn Environment Protection Project (GHEPP) was developed to transport 3m3/s of clean Black Sea water into GH through a diversion tunnel to keep circulation ongoing throughout the year. In this study, the performance of GHEPP is assessed by developing various scenarios. The relationship between Black Sea diversion flow (BSDF) and residence time is derived. The numerical tests highlight that BSDF is effective in reducing the residence time in the upstream, while in the downstream, exchange flows with the Bosphorus Strait (BS) is effective. Besides, the current patterns in the GH and exchange flow discharges with the BS are determined for three unique flow conditions occurring in the strait: (1) two-layer flow pattern, (2) one-layer flow patterns in the southern direction, and (3) one-layer flow pattern in the northern direction.


Assuntos
Conservação dos Recursos Naturais/métodos , Poluição da Água/prevenção & controle , Mar Negro , Cidades , Estuários , Modelos Teóricos , Turquia
10.
Mar Pollut Bull ; 144: 146-151, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31179981

RESUMO

Antifouling coatings are used to protect boat hulls from fouling organisms. The paints are designed to release biocides and by this prevent fouling organisms to attach. Until now the simultaneous release of the bulk plastic material has been over-looked. In this study the amount of antifouling paints on ships and leisure boats in Scandinavian countries and Germany has been compared and a calculation of the release of micro plastics has been performed. The result shows that use of a biocide-free hard coating will completely reduce outlet of biocides and the input of polymers will dramatically be reduced from at the most 5% in comparison to traditional paints where the release rate of plastics is estimated to be 70-85%. The advantage for the boat owners will be large since the hard maintenance work will be reduced, release of micro plastics will be low and thus lead to an improved environment.


Assuntos
Incrustação Biológica/prevenção & controle , Desinfetantes/análise , Pintura/análise , Polímeros/análise , Navios , Poluição da Água/prevenção & controle , Alemanha , Água do Mar/química
11.
Ecotoxicol Environ Saf ; 179: 182-187, 2019 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-31048214

RESUMO

Agricultural activities pose a significant risk of groundwater pollution. Indeed, fertilizers and treated wastewater used for irrigation are, in part, responsible for the deterioration of groundwater and surface water quality. In some cases, soil may provide a protective barrier against this pollution, but this depends on the nature of the soil and the contaminant. This work presents the effect of the soil clay content on the retention of four different pollutants in order to evaluate the risk they represent for the groundwater. These contaminants are generated by two main agricultural activities: 1/soil fertilization with phosphate and nitrate fertilizers and 2/irrigation with treated wastewater in which heavy metals such as nickel and lead are persistent. Firstly, the characterization of the sand and clay used in this work was performed and showed a cation exchange capacity of 1.24 and 25 meq/100 g, a specific surface area of 0.12 and 67.98 m2/g and a percentage of organic matter of 0.15 and 2% for sand and clay, respectively. The retention isotherms on all pollutants and the Langmuir, Freundlich, Freundlich-Langmuir, Hill and Koble-Corrigan models were applied. All experimental isotherms have been successfully adjusted using the Koble-Corrigan expression. The amounts of nitrates, phosphates, nickel and lead retained by the sandy soil, for an initial pollutant concentration equal to 1 meq/L, were evaluated at 0.29, 3.89, 5.97 and 8.56 µeq/g respectively. In contact with a soil containing 30% clay, the adsorbed amounts were estimated at 3.55, 15.00, 6.97 and 8.79 µeq/g for nitrates, phosphates, nickel and lead, respectively. These results mean that the pollutants that pose the greatest risk of groundwater contamination when carried by water through sandy soil are classified as follows lead < nickel < phosphate < nitrate while for a clayey soil, the classification becomes as follows: phosphates < lead < nickel < nitrate.


Assuntos
Água Subterrânea/análise , Chumbo/análise , Níquel/análise , Nitratos/análise , Fosfatos/análise , Poluentes do Solo/análise , Adsorção , Irrigação Agrícola , Fertilizantes/análise , Água Subterrânea/normas , Risco , Solo/química , Águas Residuárias/química , Poluição da Água/prevenção & controle
12.
Integr Environ Assess Manag ; 15(5): 703-713, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31021523

RESUMO

To address stormwater management, China initiated the construction of sponge cities (SPCs) in 2014. Sponge city construction in China has previously been evaluated using subjective expert methods. Based on China's SPC evaluation regulations, the evaluation criteria system was divided into 6 categories and 22 indicators. This study presents a multicriteria approach to evaluating SPC construction through multicriteria attributes value theory (MAVT). Coupled with the entropy method, this approach can reduce errors caused by individual methods. This work improved the evaluation method from a subjective to an objective method. Additionally, the sensitivity of an alternative to these criteria was conducted. The analysis reveals the inner relationship between the SPC alternative and the criteria. The city of Hebi, an actual SPC project, was selected as a case study. The findings indicate that the proposed approach is efficient and simple. It can help decision makers better understand SPC performance, and it is a pilot SPC evaluation method using relatively objective means. Integr Environ Assess Manag 2019;15:703-713. © 2019 SETAC.


Assuntos
Conservação dos Recursos Naturais/métodos , Técnicas de Apoio para a Decisão , Poluição da Água/prevenção & controle , China , Cidades , Entropia
13.
J Environ Qual ; 48(2): 280-288, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30951105

RESUMO

Vegetated buffer strips (VBS) are recognized as a cost-effective way to reduce agricultural nonpoint-source pollution. In agroecosystems with high field fragmentation, only narrow VBS that partially compromise farmers' revenue are accepted. This study aimed to identify some ecosystem services as provided by VBS in terms of soil and water quality, and VBS performance in terms of wood for energy purposes. Buffer strip design (3 vs. 6 m wide) and composition were considered to define best practices for wood use at the farm level and for the local firewood market. Results showed that yearly wood pole production was 0.5 t 100 m, on average, ranging between a minimum of 0.22 t 100 m and a maximum of 0.72 t 100 m per row. Wood production had negligible effects on farmers' revenue. By contrast, water quality was enhanced, especially with 6-m-wide VBS. Specific subsidies for the maintenance of VBS increased total income despite a reduction in crop production (-17.5% in 6-m VBS with two rows). Subsidies might be better quantified at a site-specific level by taking into account all ecosystem services that are provided by VBS. Promising solutions to increase farmers' income are related to the wood seasoning process for firewood production; reducing the moisture content to <25% before the start of the winter season increases its market value.


Assuntos
Agricultura , Poluição Difusa/prevenção & controle , Rios , Madeira , Ecossistema , Solo , Poluição da Água/prevenção & controle
14.
J Environ Qual ; 48(2): 289-296, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30951131

RESUMO

Nitrate from artificial drainage pipes (tiles) underlying agricultural fields is a major source of reactive N, especially NO, in surface waters. A novel approach for reducing NO loss is to intercept a field tile where it crosses a riparian buffer and divert a fraction of the flow as shallow groundwater within the buffer. This practice is called a saturated riparian buffer (SRB), and although it is promising, little data on the performance of the practice is available. This research investigated the effectiveness of SRBs in removing NO at six sites installed across Iowa, resulting in a total of 17 site-years. Water flow and NO in the tile outlets, diverted into the buffers, and NO concentration changes within the buffers were monitored throughout the year at each site. Results showed that all the SRBs were effective in removing NO from the tile outlet, with the average annual NO load removal ranging from 13 to 179 kg N for drainage areas ranging from 3.4 to 40.5 ha. This is NO that would have otherwise discharged directly into the adjoining streams. The annual removal effectiveness, which is the total NO removed in the SRB divided by the total NO draining from the field, ranged from 8 to 84%. This corresponds to an average removal rate of 0.040 g N m d with a range of 0.004 to 0.164 g N m d. Assuming a 40-yr life expectancy for the structure and a 4% discount rate, we computed a mean equal annual cost for SRBs of US$213.83. Given the average annual removal of 73 kg for all site-years, this cost equates to $2.94 kg N removed, which is very competitive with other field-edge practices such as denitrification bioreactors and constructed wetlands. Thus, SRBs continue to be a promising practice for NO removal in tile-drained landscapes.


Assuntos
Monitoramento Ambiental , Óxido Nítrico/análise , Poluição Difusa/prevenção & controle , Rios , Iowa , Poluição Difusa/estatística & dados numéricos , Poluição da Água/prevenção & controle
15.
J Environ Qual ; 48(2): 297-304, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30951134

RESUMO

Nitrogen runoff from pastures fertilized with animal manure, such as poultry litter, can result in accelerated eutrophication. The objective of this study was to evaluate the long-term effects of grazing management and buffer strips on N runoff from pastures fertilized with poultry litter. A 12-yr study was conducted on 15 small watersheds in Booneville, AR, using five management practices: continuous grazing, haying, rotational grazing, rotational grazing with an unfertilized buffer strip, and rotational grazing with a fenced unfertilized riparian buffer. Poultry litter was applied annually at a rate of 5.6 Mg ha. Concentrations and loads of total N, NO-N, NH-N, organic N, and total organic C in runoff varied intra- and interannually and coincided with precipitation trends. Overall, the greatest component of total N in runoff was organic N. Rotational grazing resulted in the highest concentrations and loads of all forms of N in runoff compared with other treatments, including the continuously grazed paddocks, which were grazed almost twice as much. Total organic C concentrations and loads in runoff were also higher from rotationally grazed watersheds than other treatments. Rotational grazing is considered a best management practice that typically reduces soil erosion; hence, the mechanism by which it caused higher N and C runoff is unclear. Nitrogen runoff losses from rotationally grazed pastures were reduced by 44% with unfertilized buffer strips, by 54% with fenced unfertilized riparian buffers, and by 52% by converting pastures to hayfields.


Assuntos
Criação de Animais Domésticos/métodos , Nitrogênio/análise , Poluentes da Água/análise , Poluição da Água/prevenção & controle , Agricultura , Animais , Monitoramento Ambiental , Fertilizantes , Esterco , Aves Domésticas
16.
Environ Sci Pollut Res Int ; 26(15): 14904-14919, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30977005

RESUMO

Bioretention systems have been implemented as stormwater best management practices (BMPs) worldwide to treat non-point sources pollution. Due to insufficient research, the design guidelines for bioretention systems in tropical countries are modeled after those of temperate countries. However, climatic factors and stormwater runoff characteristics are the two key factors affecting the capacity of bioretention system. This paper reviews and compares the stormwater runoff characteristics, bioretention components, pollutant removal requirements, and applications of bioretention systems in temperate and tropical countries. Suggestions are given for bioretention components in the tropics, including elimination of mulch layer and submerged zone. More research is required to identify suitable additives for filter media, study tropical shrubs application while avoiding using grass and sedges, explore function of soil faunas, and adopt final discharged pollutants concentration (mg/L) on top of percentage removal (%) in bioretention design guidelines.


Assuntos
Poluentes Químicos da Água/análise , Poluição da Água/prevenção & controle , Cidades , Nitrogênio/análise , Nitrogênio/isolamento & purificação , Fósforo/análise , Fósforo/isolamento & purificação , Plantas , Chuva , Solo , Clima Tropical
17.
Environ Monit Assess ; 191(5): 265, 2019 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-30953208

RESUMO

The Anacostia River, a Chesapeake Bay tributary running through Washington, D.C., is small but highly polluted with nutrients and contaminants. There is currently a multi-billion dollar tunnel project underway, being built in several phases, aimed at diverting effluent to sewage treatment, especially during high flow periods, and improving water quality of the Anacostia and the river into which it flows, the Potomac. Here, 4 years of biweekly to monthly nutrient and phytoplankton data are analyzed to assess pre-tunnel eutrophication status and relationships to flow conditions. Under all flow conditions, nutrients prior to tunnel implementation were well in excess of values normally taken to be limiting for growth, and hypoxia was apparent during summer. Chlorophyll a was higher in summer (averaging 26.9 µg L-1) than in spring (averaging 14.8 µg L-1), and based on pigment composition, summer communities had proportionately more cyanobacteria (> 2-fold higher zeaxanthin to chlorophyll a ratios) compared to spring, which had proportionately more diatoms (> 2-fold higher fucoxanthin to chlorophyll a ratios). When all data from all years and sites were considered, there was a decrease in diatoms and increase in cyanobacteria with decreasing NO3- and increasing NH4+ concentrations, increasing ratios of NH4+ to NO3-, and increasing temperature. Tunnel implementation and associated nutrient reductions may reduce the severity of summer blooms but reductions of spring assemblages may be even greater because river flows are typically higher at that time of year.


Assuntos
Monitoramento Ambiental , Política Ambiental , Poluição da Água/prevenção & controle , Baías , Clorofila/análise , Clorofila A , Cianobactérias , District of Columbia , Eutrofização , Maryland , Nitrogênio/análise , Fósforo/análise , Fitoplâncton/crescimento & desenvolvimento , Rios/química , Estações do Ano , Poluição da Água/estatística & dados numéricos
18.
Chemosphere ; 224: 247-255, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30825850

RESUMO

The objective of the present study was firstly acute toxicity bioassay of arsenic on common carp (Cyprinus carpio) and then the development of natural sorbent beds (clinoptilolite and pumice) to reduce bioconcentration of arsenic in muscle tissue were considered in comparative evaluation. In this regard, the acute toxicity of arsenic on juvenile fish was assessed according to the OECD guideline (No. 203). Moreover, the efficacy of clinoptilolite and pumice as natural sorbents was assessed to reduce bioconcentration of arsenic in the fish muscle tissue during a 21 day by response surface methodology (RSM) under central composite design (CCD). The most important point of this study was to evaluate the interactions between independent variables (clinoptilolite and pumice as sorbents and arsenic as pollutant) and arsenic bioconcentration in fish muscle tissue as a dependent variable (response). In these regards, a total of 24 sets of experiments (12 sets for clinoptilolite and pumice separately) were designed by the software to achieve the best adsorption conditions. According to the arsenic toxicity test, results as estimated by Probit method, the 96 h LC50 was 9.48 ±â€¯1.01 mg/L. Analysis of variance (ANOVA) which was applied to modeling and optimization of response revealed that the predicted values were in relatively good agreement with the experimental data. Additionally, the obtained value for model desirability by clinoptilolite and pumice were 0.932 and 0.958, respectively. Overall, the obtained results indicate that both adsorbents reduced the bioconcentration of As (V) in the muscle tissue of common carp, but clinoptilolite was more effective.


Assuntos
Arseniatos/toxicidade , Carpas/metabolismo , Poluentes Químicos da Água/toxicidade , Poluição da Água/prevenção & controle , Zeolitas/química , Adsorção , Animais , Arseniatos/metabolismo , Dose Letal Mediana , Músculos/metabolismo , Testes de Toxicidade , Poluentes Químicos da Água/metabolismo
19.
Sci Total Environ ; 669: 431-447, 2019 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-30889442

RESUMO

Increasing interest in urban drainage green infrastructure brings attention to grass swales and filter strips (GS&GFS) and their role in stormwater management. While the understanding of the hydrology and hydraulics of these stormwater control measures is adequate for current needs, there are knowledge gaps in understanding the water quality processes in GS&GFS and such a finding motivated preparation of the review paper that follows. The review revealed that most of the empirical studies of GS&GFS flow quality focused on the removal of pollutants associated with road runoff, and particularly solids, with relatively few studies addressing nutrients, traffic associated hydrocarbons, oxygen demanding substances, chloride, and faecal indicator bacteria. The reported results suffer from limitations caused by experimental conditions often representing a steady flow used to irrigate GS&GFS and generate runoff, non-submerged flows, no lateral inflows along swale side slopes, constant dosing of solids, emphasis on larger-than-typical solids, incomplete descriptions of experimental conditions, and limited attention to experimental uncertainties. Besides settling, other treatment processes, like adsorption/desorption, plant uptake, chemical precipitation and microbial degradation are often acknowledged, but without attempting to quantify their effects on flow quality. The modelling of GS&GFS flow quality would be beneficial for an improved understanding of green urban drainage infrastructure, but currently it is infeasible without a better knowledge of stormwater quality processes in GS&GFS facilities.


Assuntos
Recuperação e Remediação Ambiental/métodos , Chuva , Poluição da Água/prevenção & controle , Monitoramento Ambiental , Poaceae , Movimentos da Água , Poluentes Químicos da Água/análise , Qualidade da Água
20.
Environ Sci Pollut Res Int ; 26(15): 15314-15323, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30927225

RESUMO

In the context of improving permeable reactive barrier (PRB) filters, axial and a centripetal column tests were performed to compare their evolution in terms of chemical and hydraulic performances. For both tests, the MgO reactive media, made of crushed (< 10 mm) spent MgO-C refractory bricks was used to treat water contaminated with Co and Ni by raising the pH and promoting hydroxide precipitation. As opposed to the traditional cylindrical axial configuration, the centripetal column consists of an annulus of reactive media through which the water flows from the outer radius towards the inner radius. Under similar conditions (total reactive mass, porosity), the centripetal column is expected to delay the breakthrough of contaminants because of its higher cross-section and lower flow speeds at the entrance of the media. However, as we found in this study, the design of a granular radial filter poses several technical problems. Indeed, a breakthrough of the contaminants, accompanied by a decline in pH, was observed much sooner in the centripetal (100 pv) than in the axial (375 pv) filter. This lower performance was deemed to be due to a hydraulic shortcut and was supported by the results of a tracer test (average renewal volume much lower (199 ml) than the theoretical one (7530 ml)) as well as the observation of preferential clogging upon dismounting the radial filter. While the design of a filter that induces a purely radial flow still poses a technical challenge, this study contributes to advance the knowledge for centripetal radial filtration of groundwater in PRBs.


Assuntos
Filtração/instrumentação , Filtração/métodos , Água Subterrânea/química , Óxido de Magnésio , Purificação da Água/métodos , Concentração de Íons de Hidrogênio , Hidróxidos/química , Porosidade , Reciclagem , Poluição da Água/prevenção & controle , Purificação da Água/instrumentação
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