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1.
Rev Environ Contam Toxicol ; 248: 111-189, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-30671689

RESUMO

Metal-rich sediments have the potential to impair life in freshwater streams and rivers and, thereby, to inhibit recovery of ecological conditions after any remediation of mine water discharges. Sediments remain metal-rich over long time periods and have long-term potential ecotoxicological interactions with local biota, unless the sediments themselves are physically removed or replaced by less metal-rich sediment. Laboratory-derived environmental quality standards are difficult to apply to the field situation, as many complicating factors exist in the real world. Therefore, there is a strong case to consider other, field-relevant, measures of toxic effects as alternatives to laboratory-derived standards and to seek better biological tools to detect, diagnose and ideally predict community-level ecotoxicological impairment. Hence, this review concentrated on field measures of toxic effects of metal-rich sediment in freshwater streams, with less emphasis on laboratory-based toxicity testing approaches. To this end, this review provides an overview of the impact of metal-rich sediments on freshwater stream life, focusing on biological impacts linked to metal contamination.


Assuntos
Monitoramento Ambiental , Metais/análise , Mineração , Rios , Poluentes Químicos da Água/análise , Água Doce , Sedimentos Geológicos/química
2.
Rev Environ Contam Toxicol ; 251: 1-24, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31011831

RESUMO

Heavy metal pollution in surface water is a global environmental problem. This study analyzed the trends, health risks, and sources of eight dissolved heavy metal species in river and lake water across five continents (Africa, Asia, Europe, North America, and South America; Oceania was excluded owing to a lack of data) for the period 1970-2017. We wanted to assess the effects of various implemented countermeasures to pollution and to determine those that could be adopted worldwide. Collectively, the water system showed increasing trends for Cd, Cr, Cu, Ni, Mn, and Fe and decreasing trends for Pb and Zn. The mean dissolved concentrations of most heavy metals were highest in Asia and lowest in Europe. Most heavy metals had low non-carcinogenic risks over this period. The cancer risks associated with Pb were lower than the hazardous level on all five continents over the five decades, whereas the cancer risks related to Cr exceeded the hazardous level in the 1970s, 2000s, and 2010s, and in Africa, Asia, and North America over the entire period. Mining and manufacturing were consistently found to be critical sources of metal pollution from 1970 to 2017. However, the heavy metal sources differed significantly by continent, with waste discharge and rock weathering dominant in Africa; mining and manufacturing, along with rock weathering, are dominant in Asia and South America; fertilizer and pesticide use, along with rock weathering, are dominant in North America; and mining and manufacturing, waste discharge, and rock weathering are dominant in Europe. Global trends in the metal loadings in water and in relevant pollution-control measures suggest that countermeasures in Europe have successfully controlled heavy metal pollution. The successful measures include implementing rigorous standards for metal emissions, limiting the metal concentrations in products, and rigorously treating metal-contaminated waste. Therefore, the measures implemented in Europe should be extended worldwide to treat heavy metal pollution in water.


Assuntos
Exposição Ambiental/análise , Metais Pesados/análise , Poluentes Químicos da Água/análise , Poluição Química da Água/estatística & dados numéricos , Exposição Ambiental/estatística & dados numéricos , Monitoramento Ambiental , Humanos , Lagos , Rios
3.
Water Sci Technol ; 80(3): 448-457, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31596256

RESUMO

In the present study, continuous-flow column experiments (using glass column, Tygon tubing, and peristaltic pump Manostat Carter) were conducted to investigate the performance of permeable sorption barriers for the removal of cadmium and zinc from synthetic groundwater. Zeolite, ion-exchange resin and granular activated carbon as reactive materials were used. The effectiveness and stability of reactive materials were studied by monitoring of changes of metal ions concentration and selected background anions and cations concentration in groundwater during its flow through columns. Results showed that ion exchange resin was the most effective material of permeable reactive barrier (PRB). Performance of resin barrier remained effective (>99.5% metal ions removal) for the time corresponding to on average of about 10,000 min. The high efficiency of ion-exchange resin in PRB for removal of heavy metals from groundwater was coupled with its reactivity and long barrier lifetime. The breakthroughs in the column tests on activated carbon and zeolite using synthetic groundwater occurred much earlier as compared to resin. Therefore, the system using resin requires smaller amount to treat a given volume of groundwater as compared to other materials. Moreover, the presence of other ions did not impact on activity and permeability of barrier filled with resin.


Assuntos
Cádmio/análise , Água Subterrânea/química , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Zinco/análise , Íons
4.
Water Sci Technol ; 80(3): 487-498, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31596260

RESUMO

Methylparaben and triclosan are antimicrobial agents widely used as preservatives in a variety of personal care and pharmaceutical products. Wastewater is considered the main source of these compounds in the environment. Expanded granular sludge bed (EGSB) reactors are a high rate technology for wastewater treatment based on biological processes and have been shown to be efficient in removing different types of compounds; however, little is known about the effect of contaminants such as methylparaben and triclosan on their behavior and effectiveness. In this study, we evaluate and compare the microbial and physicochemical behavior of EGSB systems during methylparaben and triclosan removal. The presence of different concentrations of pollutants had an influence on the cluster organization of microbial communities, especially bacteria. However, this did not affect the stability and performance of the EGSB systems. The banding patterns of the denaturing gradient gel electrophoresis of archaea demonstrated the constant presence and abundance of Methanosaeta concilii throughout all stages of operation, showing that this microorganism played a fundamental role in the stability of the reactors for the production of methane. The type of compound and its concentration influenced the expression of the mcrA and ACAs genes; however, these changes did not alter the stability and performance of the EGSB systems.


Assuntos
Parabenos/análise , Triclosan/análise , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Reatores Biológicos , Esgotos
5.
Water Sci Technol ; 80(3): 507-516, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31596262

RESUMO

Adsorption characteristics of high-silica zeolites (HSZSM-5) for two selected sulfonamide antibiotics (SAs) (sulfamethoxazole and sulfadiazine) were investigated. The SAs were almost completely (>90%) removed from the water by HSZSM-5. Adsorption followed second-order kinetics with liquid-film diffusion as the dominant mechanism. SA adsorption capacity on high-silica zeolites was examined in terms of pH, temperature, and the presence of natural organic matter (NOM). HSZSM-5 had better adsorption performance in acidic conditions, and the apparent distribution coefficient indicated that SA0 species were the major contribution to the overall adsorption at pH of 2-10. Adsorption of SAs on HSZSM-5 was a spontaneous and exothermic physisorption process. SA removal by HSZSM-5 was a mixed mechanism through ion-exchange and hydrophobic interaction. HSZSM-5 has potential application prospects in removing SAs from wastewater.


Assuntos
Antibacterianos/análise , Sulfonamidas/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Cinética , Dióxido de Silício
6.
Water Sci Technol ; 80(3): 529-540, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31596264

RESUMO

A treatment and volume reduction process for a spent uranium-antimony catalyst has been developed. Targeted removal, immobilization and disposal of the uranium component has been confirmed, thus eliminating the radiological hazard. However, significant concentrations of antimony ([Sb] ≥ 25-50 mg L-1) remain in effluent from the process, which require removal in compliance with Korean wastewater regulations. Antimony(III/V) removal via co-precipitation with iron has been considered with optimal pH, dose and kinetics being determined. The effect of selected anions - Cl-, SO42- and PO43- - have also been considered, the latter present due to a prior uranium removal step. Removal of Sb(III) from both Cl- and SO42- media and Sb(V) removal from Cl- media to below release limits were found to be effective within 5 minutes at an iron dose of 8 mM (molar ratio, [FeIII]/[Sb] = 20) and a target pH of 5.0. However, Sb(V) removal from SO42- was significantly hampered requiring significantly higher iron dosages for the same removal performance. Phosphate poses significant challenges for the removal of Sb(V) due to competition between PO43- and Sb(OH)6- species for surface binding sites, attributed to similarities in chemistries and a shared preference for an inner vs outer binding mechanism.


Assuntos
Acrilonitrila/química , Antimônio/análise , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Adsorção , Compostos Férricos , Águas Residuárias
7.
Water Sci Technol ; 80(3): 575-586, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31596268

RESUMO

Preparation and characterization of activated carbons (ACs) from oily sludge by physical and chemical activation using steam, ZnCl2 and FeCl3 were investigated. The characteristics of produced adsorbents were determined by iodine number, Brunauer-Emmett-Teller (BET) equation, Fourier transform infrared spectrometry and scanning electron microscopy analyses. Batch adsorption experiments for phenol and phosphate were performed to evaluate the efficiency of adsorbents. The optimum porous structure of adsorbents with a BET surface area of 1,259 m2 g-1, total pore volume of 1.22 cm3 g-1 and iodine number of 994 mg g-1 was achieved by ZnCl2 activation at 500 °C and impregnation ratio of 1:1. The adsorption data were well fitted to the pseudo-second-order kinetic model (R2>0.99) and Freundlich isotherm (R2>0.99). The maximum adsorption capacity of phenol (238 mg g-1) and phosphate (102 mg g-1) based on the Langmuir model was achieved at pH of 6.0 and adsorbent dose of 1 g L-1. Thermodynamic parameters were negative and showed that adsorption of phenol and phosphate onto the AC was feasible, spontaneous and exothermic. The results suggested that prepared AC was an effective adsorbent for removal of phenol and phosphate ions from the polluted water.


Assuntos
Carvão Vegetal , Fenol/análise , Fosfatos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Cinética , Esgotos , Soluções
8.
Water Sci Technol ; 80(3): 587-596, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31596269

RESUMO

The aim of this study was to determine the removal of ciprofloxacin (CIP) by the electro-persulfate (EC-PS) process using aluminum (Al) electrodes. The effects of variables including pH, contact time, PS concentration, initial CIP concentration and current density on the removal efficiency of CIP were studied. In order to determine the mechanisms of the EC-PS process, the radical scavenger tests, as well as energy dispersive spectroscopy (EDS) and Fourier transform infrared spectroscopy (FT-IR) were performed on the sludge. The results showed that the PS process alone had no effect on the CIP removal, and the EC process alone could remove 25% of CIP after 160 min. However, the EC-PS process under the optimum conditions: pH of 7, time of 40 min, current density of 2.75 mA/cm2, CIP concentration of 20 mg/L, and PS concentration of 0.84 mM removed 90% of CIP. The effect of the EC-PS process on the actual hospital wastewater was 81% in optimal conditions. The kinetic study also showed that the second-order kinetic model was the most consistent. The oxidation process during the initial contact was dominant in the EC-PS process and, over time, the EC process was dominant for CIP removal.


Assuntos
Ciprofloxacino/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Alumínio/química , Eletrodos , Espectroscopia de Infravermelho com Transformada de Fourier
9.
J Water Health ; 17(5): 728-736, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31638024

RESUMO

Drinking water is an important source of lead exposure, and definitively characterizing the sources of lead in drinking water, particularly in large institutional settings, can be time-consuming and costly. This study examined lead concentrations in drinking water at a large university, focusing on variability in first-draw samples and variability with dispensed volume. Over 350 sources were sampled twice by independent groups, and while 78% of these samples were within 2.5 µg/L, almost 10% differed by >10 µg/L. In both sampling events, approximately 50% of sources had lead concentrations >1 µg/L, 6% were >15 µg/L, and 30% were between 1 and 15 µg/L. The highest lead concentration detected was 400 µg/L, with five sources >100 µg/L. Nine sources were sampled more intensively and six had first-draw sample ranges >5 µg/L. Lead concentration versus dispensed volume profiles indicated that while most sources had decreasing lead concentrations after the first draw, others had maximum lead concentrations at higher dispensed volumes. The variability observed suggests that assessments using only one or two samples per source may not identify all sources with elevated lead concentrations, and management strategies should account for this possibility.


Assuntos
Água Potável/química , Chumbo/análise , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Poluição da Água
10.
J Water Health ; 17(5): 749-761, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31638026

RESUMO

Riparian communities in the Amazon suffer from water-borne diseases due to the lack of adequate water treatment capabilities. Therefore, small local water treatment plants are necessary, but the selection of treatment procedures depends largely on the physico-chemical characteristics of the water. The aim of the present research was to evaluate the physico-chemical characteristics of the water in the Amazon River and its tributaries, in order to determine customized processes for water treatment. Data from 54 fluviometric monitoring stations were organized and used to construct distribution maps. The parameters such as pH, electrical conductivity, and the concentration of suspended matter, turbidity and flow rates were evaluated. Results showed that pH was very acidic (4-5) in the northwestern portion of the region while conductivity was quite low in the entire Amazonian region (<140 µS cm-1). Both parameters were strongly influenced by geological settings and sources of organic matter. Suspended matter and turbidity were affected by weathering processes. It was concluded that considering the acidity of the waters, mechanical procedures like filtration or slow settling should be applied to remove suspended matter rather than chemical procedures. For disinfection, instead of chemicals, solar energy should be applied.


Assuntos
Água Potável , Purificação da Água/métodos , Brasil , Condutividade Elétrica , Monitoramento Ambiental , Rios , Poluentes Químicos da Água/análise , Qualidade da Água
11.
J Water Health ; 17(5): 801-812, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31638030

RESUMO

Well water around the world can be contaminated with arsenic, a naturally occurring geological element that has been associated with myriad adverse health effects. Persons obtaining their drinking water from private wells are often responsible for well testing and water treatment. High levels of arsenic have been reported in well water-supplied areas of the United States. We quantified - in cases and dollars - the potential burden of disease associated with the ingestion of arsenic through private well drinking water supplies in the United States. To estimate cancer and cardiovascular disease burden, we developed a Monte Carlo model integrating three input streams: (1) regional concentrations of arsenic in drinking water wells across the United States; (2) dose-response relationships in the form of cancer slope factors and hazard ratios; and (3) economic cost estimates developed for morbidity endpoints using 'cost-of-illness' methods and for mortality using 'value per statistical life' estimates. Exposure to arsenic in drinking water from U.S. domestic wells is modeled to contribute 500 annual premature deaths from ischemic heart disease and 1,000 annual cancer cases (half of them fatal), monetized at $10.9 billion (2017 USD) annually. These considerable public health burden estimates can be compared with the burdens of other priority public health issues to assist in decision-making.


Assuntos
Arsênico/análise , Efeitos Psicossociais da Doença , Água Potável/química , Poluentes Químicos da Água/análise , Purificação da Água , Poços de Água , Estados Unidos , Abastecimento de Água
12.
J Environ Sci (China) ; 85: 17-34, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31471024

RESUMO

Is our food safe and free of the crisis of antibiotics and antibiotic resistance (AR)? And will the derived food waste (FW) impose AR risk to the environment after biological treatment? This study used restaurant FW leachates flowing through a 200 tons-waste/day biological treatment plant as a window to investigate the fate of antibiotics and antibiotic-resistance genes (ARGs) during the acceptance and treatment of FW. Sulfonamides (sulfamethazine, sulfamethoxazole) and quinolones (ciprofloxacin, enrofloxacin, ofloxacin) were detected during FW treatment, while tetracyclines, macrolides and chloramphenicols were not observable. ARGs encoding resistance to sulfonamides, tetracyclines and macrolides emerged in FW leachates. Material flow analysis illustrated that the total amount of antibiotics (except sulfamethazine) and ARGs were constant during FW treatment processes. Both the concentration and total amount of most antibiotics and ARGs fluctuated during treatment, physical processes (screening, centrifugation, solid-liquid and oil-water separation) did not decrease antibiotic or ARGs concentrations or total levels permanently; the affiliated wastewater treatment plant appeared to remove sulfonamides and most ARGs concentrations and total amount. Heavy metals Ni, Co and Cu were important for disseminating antibiotics concentrations and MGEs for distributing ARGs concentrations. Humic substances (fulvic acids, hydrophilic fractions), C-associated and N-associated contents were essential for the distribution of the total amounts of antibiotics and ARGs. Overall, this study implied that human food might not be free of antibiotics and ARGs, and FW was an underestimated AR pool with various determinants. Nonetheless, derived hazards of FW could be mitigated through biological treatment with well-planned daily operations.


Assuntos
Antibacterianos/análise , Resistência Microbiana a Medicamentos/genética , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/análise , Genes Bacterianos , Metais Pesados/análise , Restaurantes , Águas Residuárias/química , Águas Residuárias/microbiologia
13.
Water Sci Technol ; 80(2): 300-307, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31537766

RESUMO

The aim of this work is to study the performances of isomeric α-, ß-, and γ-FeOOH (goethite, akaganéite and lepidocrocite, including five samples named as Gth1 and Gth2, Aka1 and Aka2, and Lep, respectively) for removing hexavalent chromium (Cr(VI)) from aqueous solutions. The adsorption mechanisms were explored by kinetic and isothermal experiments. Adsorption efficiencies under the different pH values, anions, and the levels of adsorbate and adsorbent were also measured. Results showed that the Cr(VI) adsorption by isomeric FeOOH could be best described by pseudo-second-order kinetic model. The processes of Cr(VI) isothermal adsorption could be greatly fitted by the Langmuir and Freundlich equations with the high correlation coefficients of R2 (>0.92). Also, there were the optimum pH values of 3.0-8.0 for FeOOH to adsorb Cr(VI), and their adsorption capacities were tightly related with the active sites of adsorbents. Cr(VI) adsorptions by these adsorbents were easily influenced by H2PO4-, and then SO42-, while there were little effects by Cl-, CO32- and NO3-. These obtained results could provide a potentially theoretical evidence for isomeric FeOOH materials applied in the engineering treatment of the polluted chromate-rich waters.


Assuntos
Cromo/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Cromo/análise , Concentração de Íons de Hidrogênio , Cinética , Poluentes Químicos da Água/análise
14.
Water Sci Technol ; 80(2): 308-316, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31537767

RESUMO

In this study, a novel composite of modified diatomite supported nanoscale zero-valent iron (mD-NZVI) was synthesized and characterized. The effects of four factors (mD-NZVI dose, temperature, contact time and initial pH) on the removal of Cr(VI) by mD-NZVI were studied by experimental work and analyzed by response surface methodology (RSM). A second-order polynomial equation fitted by Box-Behnken design was used as a statistical model and proved to be precise in describing the significance of four factors. The analysis results show that the effects of four factors on the removal efficiency of Cr(VI) were significant (F value is 19.83), initial pH was found to be the key factor. In addition, the effect of initial pH was further studied and the maximum removal efficiency of 89.34% was obtained at pH of 3, the decrease in removal efficiency with the increase in pH is a synergistic effect of Cr(VI) species, surface charge of mD-NZVI and OH- amount at different pH.


Assuntos
Cromo/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Cromo/análise , Terra de Diatomáceas , Concentração de Íons de Hidrogênio , Poluentes Químicos da Água/análise
15.
Water Sci Technol ; 80(2): 329-338, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31537769

RESUMO

In this study, biochar was prepared from Alternanthera philoxeroides (AP) under O2-limited condition at 350 °C (LB) and 650 °C (HB) and treated with aging by HNO3/H2SO4 oxidation. Structural changes of the biochar after aging treatment and the treatment's effect on Pb(II) absorption were explored. The results showed that oxygen-containing functional groups, aromatic structure and surface area of the biochar increased after the aging treatment. However, the integrity of the tubular structure was broken into fragments. The adsorption process of Pb(II) was in accordance with the pseudo-second-order kinetic model and fitted by the Langmuir model. With the increase of pH, the adsorption capacities of Pb(II) increased gradually, and the adsorption effect was best at pH 5. The aged HB presented a decrease of the carboxyl group, which caused less adsorption capacity of Pb(II) than that of aged LB. The maximum adsorption capacities of Pb(II) on fresh biochar at 350 °C and 650 °C were 279.85 and 286.07 mg·g-1 and on aged biochar were 242.57 and 159.82 mg·g-1, respectively. The adsorption capacity of HB for Pb(II) was higher than that of LB, and the adsorption capacity of aged biochar for Pb(II) decreased obviously, which might be attributable to changes in physicochemical properties of biochar after the aging treatment.


Assuntos
Carvão Vegetal/química , Chumbo/química , Poluentes Químicos da Água/química , Adsorção , Cinética , Chumbo/análise , Poluentes Químicos da Água/análise
16.
Sci Total Environ ; 690: 1068-1088, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31470472

RESUMO

Existence of anthropogenic contaminants (ACs) in different environmental matrices is a serious and unresolved concern. For instance, ACs from different sectors, such as industrial, agricultural, and pharmaceutical, are found in water bodies with considerable endocrine disruptors potency and can damage the biotic components of the environment. The continuous ACs exposure can cause cellular toxicity, apoptosis, genotoxicity, and alterations in sex ratios in human beings. Whereas, aquatic organisms show bioaccumulation, trophic chains, and biomagnification of ACs through different entry route. These problems have been found in many countries around the globe, making them a worldwide concern. ACs have been found in different environmental matrices, such as water reservoirs for human consumption, wastewater treatment plants (WWTPs), drinking water treatment plants (DWTPs), groundwaters, surface waters, rivers, and seas, which demonstrate their free movement within the environment in an uncontrolled manner. This work provides a detailed overview of ACs occurrence in water bodies along with their toxicological effect on living organisms. The literature data reported between 2017 and 2018 is compiled following inclusion-exclusion criteria, and the obtained information was mapped as per type and source of ACs. The most important ACs are pharmaceuticals (diclofenac, ibuprofen, naproxen, ofloxacin, acetaminophen, progesterone ranitidine, and testosterone), agricultural products or pesticides (atrazine, carbendazim, fipronil), narcotics and illegal drugs (amphetamines, cocaine, and benzoylecgonine), food industry derivatives (bisphenol A, and caffeine), and personal care products (triclosan, and other related surfactants). Considering this threatening issue, robust detection and removal strategies must be considered in the design of WWTPs and DWTPs.


Assuntos
Monitoramento Ambiental , Poluentes Químicos da Água/análise , Abastecimento de Água/estatística & dados numéricos , Organismos Aquáticos , Compostos Benzidrílicos , Diclofenaco , Disruptores Endócrinos , Praguicidas , Preparações Farmacêuticas , Fenóis , Poluentes Químicos da Água/toxicidade , Recursos Hídricos
17.
Sci Total Environ ; 690: 1110-1119, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31470474

RESUMO

This study investigated the occurrence and fate of 19 biocides in 8 wastewater treatment plants and receiving aquatic environments (both freshwater and estuarine systems) in Thailand. The predominant compound in wastewater and surface water was methylparaben with the maximum concentration of 15.2 µg/L detected in the receiving river, while in sludge and sediment was triclocarban with the maximum concentration of 8.47 µg/g in sludge. Triclosan was the main contaminants in the fish samples with the maximum concentration of 1.20 µg/g. Similar results of biocides were found in the estuarine system in Pattaya city, with the maximum concentration of 185 ng/L in sea water for methylparaben, and 242 ng/g in estuarine sediment for triclocarban. The aqueous removal rates for the biocides ranged from 15% to 95% in average. The back estimated-usage and total estimated emission of Æ©19 biocides in Thailand was 279 and 202 tons/year, respectively. Preliminary ecological risk assessment showed that clotrimazole and triclosan could pose high risks to aquatic organisms in the receiving aquatic environments.


Assuntos
Desinfetantes/análise , Monitoramento Ambiental , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/análise , Carbanilidas/análise , Rios/química , Tailândia , Triclosan/análise , Águas Residuárias/química
18.
Sci Total Environ ; 690: 1342-1354, 2019 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-31470496

RESUMO

Oil and gas development can result in natural gas migration into shallow groundwater. Methane (CH4), the primary component of natural gas, can subsequently react with solutes and minerals in the aquifer to create byproducts that affect groundwater chemistry. Hydro-biogeochemical processes induced by fugitive gas from leaky oil and gas wells are currently not well understood. We monitored the hydro-biogeochemical responses of a controlled natural gas release into a well-studied Pleistocene beach sand aquifer (Canadian Forces Base Borden, Ontario, Canada). Groundwater samples were collected before, during, and up to 700 days after gas injection and analyzed for pH, major and minor ions, alkalinity, dissolved gases, stable carbon isotope ratios of CO2 and CH4, and microbial community composition. Gas injection resulted in a dispersed plume of free and dissolved phase natural gas, affecting groundwater chemistry in two distinct temporal phases. Initially (i.e. during and immediately after gas injection), pH declined and major ions and trace elements fluctuated; at times increasing above baseline concentrations. Changes in the short-term were due to invasion of deep groundwater with elevated total dissolved solids entrained with the upward migration of free phase gas and, reactions that were instigated through the introduction of constituents other than CH4 present in the injected gas (e.g. CO2). At later times, more pronounced aerobic and anaerobic CH4 oxidation led to subtle increases in major ions (e.g. Ca2+, H4SiO4) and trace elements (e.g. As, Cr). Microbial community profiling indicated a persistent perturbation to community composition with a conspicuous ingrowth of taxa implicated in aerobic CH4 oxidation as well anaerobic S, N and Fe species metabolism.


Assuntos
Monitoramento Ambiental , Água Subterrânea/química , Metano/análise , Campos de Petróleo e Gás , Poluentes Químicos da Água/análise , Gás Natural , Ontário
19.
J Agric Food Chem ; 67(40): 11244-11255, 2019 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-31532667

RESUMO

Evaluation of acetylcholinesterase (AChE) activity and determination of organophosphorus pesticides (OPs) are of great importance for the clinical diagnosis of several serious diseases correlated with their variations in human blood serum. In this study, a highly selective and sensitive ratiometric fluorescent probe was innovatively fabricated for the evaluation of AChE activity and the determination of OPs in tap water and food on the basis of the inner filter effect (IFE) between nitrogen-doped carbon dots (N-CDs) and 2,3-diaminophenazine (DAP). N-CDs were synthesized via a one-pot hydrothermal method by using pancreatin and 1,2-ethanediamine as precursors. N-CDs showed excellent fluorescence properties and negligible cytotoxicity on human cervical carcinoma HeLa cells and human embryonic kidney 293T cells, suggesting their further biological applications. Upon the addition of AChE and choline oxidase, acetylcholine was catalyzed to produce choline that was further oxidized to produce H2O2. In the presence of horseradish peroxidase, o-phenylenediamine reacted with H2O2 to produce fluorescent DAP. Therefore, a ratiometric fluorescent probing platform existed via IFE between N-CDs with a fluorescence signal at 450 nm and DAP with a fluorescence signal at 574 nm. OPs irreversibly impeded the catalytic activity of AChE, finally leading to the decrease of DAP amount and the variation of ratiometric fluorescent signal. Under optimal conditions, such a fluorescent probe showed relatively low detection limits of 0.38 U/L for AChE, 3.2 ppb for dichlorvos, and 13 ppb for methyl-parathion. Practical application of this ratiometric fluorescent probe to detect OPs was further verified in tap water and food samples with satisfying results that were highly consisted with the results obtained by GC-MS.


Assuntos
Acetilcolinesterase/química , Técnicas Biossensoriais/métodos , Carbono/química , Corantes Fluorescentes/química , Contaminação de Alimentos/análise , Compostos Organofosforados/análise , Praguicidas/análise , Poluentes Químicos da Água/análise , Fluorescência , Água Doce/análise , Células HeLa , Humanos , Limite de Detecção , Pontos Quânticos/química
20.
Environ Monit Assess ; 191(10): 601, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31478100

RESUMO

The presence of organic compounds in drinking water is well recognized in many developing countries; however, the occurrence of organic contaminants in the groundwater of Saudi Arabia, which is the main source of drinking water in the country, is not well documented. A national comprehensive study was carried out to assess the occurrence of organic compounds in groundwater wells used for drinking water purpose, in different regions of Saudi Arabia. A total of 993 well water samples were collected from all 13 administrative regions of the kingdom. Samples were analyzed for a total of 131 organic compounds using the standard methods. The results indicated that total organic carbon values were in the range of 0.01 to 84.13 mg/L with an average weighted value of 12.61 mg/L. Organic compounds were detected in only 9 regions, with 19.84% of the samples containing organic compounds. Only 96 wells (9.67%) showed contents of organic compounds above the safe limits. Pesticides were not detected in any of the well water samples. Overall, organic compounds were found in only 197 out of 993 wells (19.84%) in the whole country. Most of the wells containing organic compounds were located in residential, industrial, and agriculture areas. Riyadh region and Eastern Province were found to have the most affected wells as compared to other regions. Several regions did not show any organic compounds in the well waters.It can be said that the problem of groundwater contamination with organic compounds in Saudi Arabia is not acute and is manageable at present. It is, however, recommended that a regular monitoring of drinking water wells of all regions should be carried out by the competent authorities for organic compounds to know any contamination if and when it happens. Preventing such contaminants from reaching drinking water sources and protecting drinking water well heads from such contaminants remains a priority.


Assuntos
Monitoramento Ambiental , Água Subterrânea/química , Compostos Orgânicos/análise , Poluentes Químicos da Água/análise , Água Potável/normas , Praguicidas/análise , Arábia Saudita
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