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1.
Chemosphere ; 249: 126207, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32088458

RESUMO

The problem of sulfate pollution is becoming increasingly serious in freshwater and wetlands. Since paddy fields are the largest constructed wetland in Earth's surface, the increased sulfate input may have great effect on dissolved organic matter (DOM) in paddy soils. To understand these effects, a 24-day anaerobic incubation experiment was conducted with four Chinese paddy soils amended with high concentrations (0, 10, 25, 50, and 100 mmol L-1) of Na2SO4. Dissolved organic carbon (DOC) and chlorophyll a (Chl a) concentrations were determined after incubation. Parallel factor analysis (PARAFAC) of the excitation-emission matrix (EEM) spectra was used to analyze the DOM composition. In all four soils, DOC concentrations generally increased with increasing sulfate concentration, while the Chl a concentrations decreased. The EEM spectra of DOM were resolved into four components by PARAFAC. With increasing sulfate concentration, the proportion of the ultraviolet C humic acid-like compound decreased and the tyrosine-like compound increased in two algae-rich soils (Sichuan and Tianjin). No obvious variation was observed in the humification index (HIX) or the ratio of peak ß to peak α (ß:α) in any soils with added sulfate. Specific ultra-violet absorbance at 254 nm (SUVA254) decreased with increasing sulfate concentration in Jilin, Tianjin, and Ningxia soils, and the fluorescence index (FI) decreased in two algae-rich soils. In conclusion, although sulfate addition increased the DOC concentration, the DOM composition depended more strongly on soil type and physicochemical properties than sulfate. Sulfate addition only affected soil DOM origin and composition by inhibiting algal growth in algae-rich paddy soils.


Assuntos
Poluentes do Solo/química , Solo/química , Sulfatos/química , Clorofila A , Poluição Ambiental/análise , Substâncias Húmicas/análise , Modelos Químicos , Poluentes do Solo/análise , Espectrometria de Fluorescência , Sulfatos/análise , Áreas Alagadas
2.
Environ Monit Assess ; 192(2): 74, 2020 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-31897853

RESUMO

Most abundant form of sulphur in the geosphere has been sulphate. Sulphate, with sulphur in the plus six oxidation state is very stable. Sources of sulphate in groundwater include mineral dissolution, atmospheric deposition and other anthropogenic sources (mining, fertilizer, etc.). Gypsum is an important contributor to the high levels of sulphate in many aquifer of the world. Sulphate is not as much as toxic, but it can cause catharsis, dehydration and diarrhoea, and when ingested in higher amount through dietary absorption, the levels of methaemoglobin and sulphaemoglobin are changed in human and animal body. The role of sulphate in aqueous phase and sedimentary phase has been discussed. There is only limited work on sulphate pollution remediation in groundwater at national and international level; therefore, in the light of rising attention in sulphate as a contaminant, different sources of sulphate, its distribution and available different remediation techniques for groundwater system reported so far have been discussed in the present paper. Abiologic processes' thermochemical sulphate reduction (TSR) also plays significant role in reduction of sulphate.


Assuntos
Monitoramento Ambiental , Recuperação e Remediação Ambiental , Água Subterrânea/química , Sulfatos/análise , Poluentes Químicos da Água/análise , Animais , Humanos , Mineração
3.
Sci Total Environ ; 705: 135819, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-31972948

RESUMO

River damming is significant for hydropower production, but also alters the ecological conditions, and especially affects the microbial community. Sulfate-reducing prokaryotes (SRPs) make vital contributions to biogeochemical sulfur cycle, but the information on the effects of dam construction on the SRPs assemblage are unclear. Here, a comprehensive survey was conducted by collecting water and sediment samples along horizontal and vertical profiles from six sites at the Xiaowan Reservoir on the Lancang River, China. We used 16S rRNA gene amplicon sequencing and qPCR assay with dsrB gene to study the composition and activity of SRPs. The results indicated that river damming accumulated nutrients in the middle layer of the reservoir, and the impoundment provided an anaerobic and high nutrient available environment, which is beneficial for the survival of SRPs. The abundance and diversity of SRPs in water and sediments at the bottom of the reservoir were higher than those in the other sites. The network analyses revealed a synergistic effect between SRPs and other dominant bacteria in water column, which was more complex than in sediments. Moreover, a relatively higher sulfate reduction activity was found in the middle and lower layers of the water profile according to dsrB gene analysis.


Assuntos
Sulfatos/análise , China , Sedimentos Geológicos , RNA Ribossômico 16S , Enxofre
4.
Artigo em Inglês | MEDLINE | ID: mdl-31971065

RESUMO

Development of an appropriate bioremediation strategy for acid mine drainage (AMD) impacted environment is imperative for sustainable mining but remained critically challenged due to the paucity of knowledge on desired microbiological factors and their nutrient requirements. The present study was conducted to utilize the potential of an anaerobic, acid-tolerant, Fe3+ and SO42- reducing microbial consortium for in situ remediation of highly acidic (pH 3.21), SO42- rich (6285 mg/L) mine drainage impacted soil (AIS). A microbial consortium enriched from AMD system and composed of Clostridiales and Bacillales members was characterized and tested for in situ application through microcosms. A combination of bioaugmentation (enriched consortium) and biostimulation (cellulose) allowed 97% reduction in dissolved sulfate and rise in pH up to 7.5. 16S rRNA gene-based amplicon sequencing confirmed that although the bioaugmented community could survive in AIS, availability of carbon source was necessary for superior iron- and sulfate- reduction. Quantitative PCR of dsrB gene confirmed the role of carbon source in boosting the SO42- reduction activities of sulfate reducers. This study demonstrated that native AIS harbored limited catabolic activities required for the remediation but addition of catabolically active microbial populations along with necessary carbon and energy source facilitate the bioremediation of AIS.


Assuntos
Ferro/análise , Consórcios Microbianos , Mineração , Poluentes do Solo/análise , Solo/química , Sulfatos/análise , Poluentes Químicos da Água/análise , Ácidos/química , Anaerobiose , Biodegradação Ambiental , Carbono/análise , Consórcios Microbianos/genética , RNA Ribossômico 16S/genética
5.
Chemosphere ; 241: 125033, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31610462

RESUMO

To evaluate light extinction contributions of aerosol chemical constituents and their impacts on atmospheric visibility, the PM2.5 and its chemical components, light scattering (bsp) and absorption (bap) were continuously measured in Wuhan from January to February 2018. The average of PM2.5 concentration, bsp and bap were 96.5 ±â€¯13.7 µg m-3, 564 ±â€¯124 Mm-1 and 44 ±â€¯8 Mm-1 during polluted days, respectively, which was about 2.0, 2.1 and 1.6 times higher than those of clean days, respectively. Compared with the clean days, the increase of the mass concentrations of SNA (SO42-, NO3-, NH4+) during polluted days was higher than those of organic (OC) and elemental (EC) carbon, indicated the increase of SNA was the main cause of air pollution. The PM2.5 concentration threshold was 66 µg m-3, corresponding to the visibility lower than 10 km. The revised Interagency Monitoring of Protected Visual Environments (IMPROVE) algorithm was used to reconstruct the light extinction coefficient (bext) in Wuhan. The sum of light extinction coefficients of (NH4)2SO4, NH4NO3 and organic matter (OM) accounted for 70.5% and 83.9% of bext during clean and polluted days, respectively. The backward trajectory and potential source contribution function (PSCF) analysis revealed that regional transport accounted for 55.6% of the total airflow, which originated from south, northwest and west of Wuhan. The increases of (NH4)2SO4 and NH4NO3 concentrations, emitted from local vehicle exhaust and coal combustion, and their hygroscopic growth in ambient were the major causes of pollution in Wuhan.


Assuntos
Aerossóis/química , Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Estações do Ano , Aerossóis/análise , Compostos de Amônio/análise , China , Carvão Mineral/análise , Nitratos/análise , Material Particulado/análise , Sulfatos/análise , Emissões de Veículos/análise
6.
Chemosphere ; 242: 125167, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31678854

RESUMO

This research developed a method of tracing major water chemical parameters (WCP) and soil heavy metals (HM) to identify the processes of mining pollution in topographically complex landscapes. Ninety-nine spatially distributed water samples were collected to characterise the hydrochemical characteristics of an alpine river in north-west China. Sixty river WCP and fifty-six soil HM samples from areas near mining sites were then used to analyse the mining pollution process. Geographical and mining activity characteristics were derived from topographic and mine site information. The occurrence of sulphates (SO42-) and nitrates (NO3-) in river water were highly correlated (up to 0.70), providing strong evidence of pollution from nearby mining activities. Levels of arsenic and cadmium were high in first and fifth order streams, where mining activities were most concentrated. The modelling results showed that geographical patterns and mining activity account for predicting HM distribution, and WCP can be reasonable predictors to trace soil mining pollution. This research can help improve the accuracy of predicting the mining pollution process.


Assuntos
Monitoramento Ambiental/métodos , Mineração , Rios/química , Poluentes do Solo/análise , Solo/química , Poluentes Químicos da Água/análise , Altitude , Arsênico/análise , Cádmio/análise , China , Nitratos/análise , Sulfatos/análise
7.
Chemosphere ; 245: 125603, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31855753

RESUMO

Elevated arsenic (As) in groundwater is an urgent environmental problem that has caused serious endemic diseases in Datong basin, China. The fate and toxicity of As are generally regulated by microbial As metabolic processes. However, little is known about the microbial community and As metabolism in Datong basin. Herein, the microbial community structure and As metabolism genes in four wells with different levels of As concentration in Shanyin county were investigated using metagenomics approach. The results showed that the presence of As influenced the microbial communities, and Rhodococcus genus was significantly enriched in elevated As wells. As resistance genes were dominant from low to high As containing wells, and As efflux genes such as arsB and acr3 were positively correlated with As concentrations, suggesting that microbes tend to pump As out of the cell as a strategy for As detoxification. Other environmental factors including oxidation-reduction potential (ORP), total organic carbon (TOC), sulfate, and temperature also played a role in shaping the microbial community structure and As metabolic processes.


Assuntos
Arsênico/metabolismo , Água Subterrânea/microbiologia , Metagenômica/métodos , Poluentes Químicos da Água/metabolismo , Carbono/análise , China , Metagenoma/genética , Microbiota/genética , Oxirredução , Sulfatos/análise , Temperatura
8.
Chemosphere ; 239: 124774, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31521937

RESUMO

Acid mine drainage represents an extreme type of water pollution. The environments develop especial hydrochemical and ecological characteristics, such as high concentrations of acidity and low biodiversity, with dominance of acidophilic organisms. Ecological criteria are assuming increasing relevance for assessing water quality, including in acid mine drainage-affected systems. Photosynthetic pigments, like chlorophyll, could be considered in this context as they are generally used to estimate phytoplankton biomass. The present work was focused on acid mine drainage and their relationships with chlorophyll a. It was developed in the historic mine of São Domingos (Iberian Pyrite Belt, SW Europe). The methodological approach comprised two sampling campaigns (October and February) to represent seasonal behaviour. The diversity of hydrological conditions was also considered through sampling sites established in the pit lake, acidic lagoons and affected stream. Hydrochemistry and chlorophyll a were analysed. The obtained results revealed very low pH values, with a minimum of 2.1. In general, hydrochemistry indicates higher concentrations of pollutants in summer. One of the sampling point, located in an acidic lagoon, stood out by highest concentrations, presenting maximum of sulfate (6564 mg/L), As (6.26 mg/L), and metals like Al (675 mg/L), Cd (1,30 mg/L), Zn (199 mg/L). These highest concentrations coincided with the maximum concentration of chlorophyll a (113 µg/L). The results suggested that the more contaminated the environment, more chlorophyll a was produced. Factor analyses emphasised the relationships between acid drainage properties and the photosynthetic activity, indicating a strong pH dependency of chlorophyll a production.


Assuntos
Clorofila A/análise , Mineração , Poluição da Água/análise , Biomassa , Monitoramento Ambiental , Europa (Continente) , Lagos/química , Metais/análise , Feofitinas/análise , Fotossíntese , Fitoplâncton , Rios/química , Estações do Ano , Sulfatos/análise , Poluentes Químicos da Água/análise , Qualidade da Água
9.
Anal Bioanal Chem ; 412(3): 533-537, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31853603

RESUMO

Glycosaminoglycans (GAGs) are a physio- and pharmacologically highly relevant class of complex saccharides, possessing a linear sequence and strongly acidic character. Their repetitive linear core makes them seem structurally simple at first glance, yet differences in sulfation and epimerization lead to an enormous structural diversity with only a few GAGs having been successfully characterized to date. Recent infrared action spectroscopic experiments on sulfated mono- and disaccharide ions show great promise. Here, we assess the potential of two types of gas-phase action spectroscopy approaches in the range from 1000 to 1800 cm-1 for the structural analysis of complex GAG oligosaccharides. Synthetic tetra- and pentasaccharides were chosen as model compounds for this benchmark study. Utilizing infrared multiple photon dissociation action spectroscopy at room temperature, diagnostic bands are largely unresolved. In contrast, cryogenic infrared action spectroscopy of ions trapped in helium nanodroplets yields resolved infrared spectra with diagnostic features for monosaccharide composition and sulfation pattern. The analysis of GAGs could therefore significantly benefit from expanding the conventional MS-based toolkit with gas-phase cryogenic IR spectroscopy. Graphical abstract.


Assuntos
Glicosaminoglicanos/química , Oligossacarídeos/química , Espectrofotometria Infravermelho/métodos , Animais , Temperatura Baixa , Hélio/química , Humanos , Íons/química , Isomerismo , Espectrofotometria Infravermelho/instrumentação , Sulfatos/análise
10.
Environ Pollut ; 255(Pt 2): 113345, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31610508

RESUMO

Despite substantial mitigation of particulate matter (PM) pollution during the past decade in Beijing, the response of aerosol chemistry to clean air action and meteorology remains less understood. Here we characterized the changes in aerosol composition as responses to emission reductions by using two-year long-term measurements in 2011/2012 and 2017/2018, and WRF-Chem model. Our results showed substantial decreases for all aerosol species except nitrate from 2011/2012 to 2017/2018. Chloride exhibited the largest decrease by 65-89% followed by organics (37-70%), mainly due to reductions in coal combustion emissions in winter and agriculture burning in June. Primary and secondary organic aerosol (SOA) showed comparable decreases by 61-70% in fall and winter, and 34-63% in spring and summer, suggesting that reductions in primary emissions might also suppress SOA formation. The changes in nitrate were negligible and even showed increases due to less reductions in NOx emissions and increased formation potential from N2O5 heterogeneous reactions. As a result, nitrate exceeded sulfate and became the major secondary inorganic aerosol species in PM with the contribution increasing from 14-21% to 22-32%. Further analysis indicated that the reductions in aerosol species from 2011/2012 to 2017/2018 were mainly caused by the decreases of severely polluted events (PM1 > 100 µg m-3). WRF-Chem simulations suggested that the decreases in OA and sulfate in fall and winter were mainly resulted from emission reductions (27-36% and 25-43%) and favorable meteorology (4-10% and 19-30%), while they were dominantly contributed by emission changes in spring and summer. Comparatively, the changes in nitrate were mainly associated with meteorological variations while the contributions of emissions changes were relatively small. Our results highlight different chemical responses of aerosol species to emission changes and meteorology, suggesting that future mitigation of air pollution in China needs species-targeted control policy.


Assuntos
Aerossóis/análise , Poluentes Atmosféricos/análise , Poluição do Ar/estatística & dados numéricos , Monitoramento Ambiental , Material Particulado/análise , Poluição do Ar/análise , Pequim , China , Óxidos de Nitrogênio/análise , Estações do Ano , Sulfatos/análise
11.
Mar Pollut Bull ; 149: 110582, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31550573

RESUMO

Phosphorus (P) pollution can trigger severe marine eutrophication, which further leads to harmful algal blooms, and a deterioration of sea water quality. The P burial and regeneration in offshore sediments can directly affect the eutrophication levels of estuarine and coastal ecosystems. Although many researches on redox-dependent P burial and regeneration were studied, such process in the presence of silicate is still poorly understood, and the effects of pyrite formation on organic P (OP) burial and regeneration also remain unclear. In this study, a sulfidic sediment core was collected in the offshore of an estuary in the north Yellow Sea, China. Results indicated that indigenous biological input was found to be the primary source of organic matter in upper sediments. The regenerated P under reducing conditions was dominated by labile FeP and OP. The PO43- released from FeP and OP that could be captured by Al/Fe/Mn (oxyhydr) oxides in surface sediments and Ca minerals in deep sediments. CaP, AlP, unreactive Al/Fe-Si-P and some stable metal chelated OP were the main burial P fractions. Sulfate reduction and formation of insoluble metal sulfides including the pyrite promoted OP decomposition by anaerobic decomposition, removing metal ions from the "metal-OP" chelates and restoring the phosphatase activity.


Assuntos
Sedimentos Geológicos/química , Fósforo/metabolismo , China , Monitoramento Ambiental/métodos , Estuários , Eutrofização , Sedimentos Geológicos/análise , Ferro/análise , Ferro/química , Minerais/química , Oxirredução , Óxidos/análise , Óxidos/química , Oceano Pacífico , Fosfatos/análise , Fosfatos/química , Fósforo/análise , Sulfatos/análise , Sulfatos/química , Sulfetos/análise , Sulfetos/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/metabolismo
12.
Analyst ; 144(19): 5724-5737, 2019 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-31486453

RESUMO

In order to explore the properties of any species in solution, the actual, i.e. equilibrium concentration of the free species should be taken into account. Researchers have not paid attention to the deprotonation equilibrium between HSO4- and SO42- while probing bisulfate ion. In this study, we have addressed this concern and developed two zwitterions, CG (coumarin-integrated glycine) and CA (coumarin-integrated alanine), for the selective detection of HSO4- at a picomolar level (50 to 325 pM) with very high binding affinity (∼108 M-1) in pure water at physiological pH. The principle of HSO4- recognition was established via UV-vis and fluorescence techniques. DFT calculations suggested that the H-bonding interactions between the probes and HSO4- are the driving force for this unforeseen selectivity. The membrane penetration ability and nontoxicity of CG/CA enable them to function as staining agents in living brine shrimps and bacteria. The use of these probes for the estimation of HSO4- in various day-to-day edible foods and drugs along with urine samples is unprecedented. The significance and novelty of this study lies in the application and development of assays for estimating bisulfate in several real-world samples that are predominantly aqueous in nature, which are the first of their kind.


Assuntos
Cumarínicos/química , Corantes Fluorescentes/química , Imagem Óptica/métodos , Plantas Comestíveis/química , Sulfatos/análise , Alanina/química , Animais , Artemia/química , Bactérias/química , Cães , Análise de Alimentos , Glicina/química , Humanos , Concentração de Íons de Hidrogênio , Limite de Detecção , Permeabilidade , Sensibilidade e Especificidade , Sulfatos/urina , Água/química
13.
J Trace Elem Med Biol ; 56: 207-212, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31541895

RESUMO

Traceability of metal-glycinate-sulphate complexes (Metal-GLY) in feed requires specific analysis to differentiate complexes from inorganic forms. A previously described method focused on the quantification of Metal-GLY at one single concentration but not on the quantification of free metal ion forms. The objective of this work was to extend the method to quantify both Metal-GLY and free metal ion forms of various metals at low inclusion levels. A 50/50 w/w mix of corn flour and soybean meal was used as feed. Copper-glycinate(Cu-GLY), Manganese-glycinate (Mn-GLY) and Zinc-glycinate (Zn-GLY) complexes (provided by Pancosma SA) were used for in-feed inclusions. The feed metal background concentrations and species repartitions were assessed. Cu-GLY was spiked on feed at levels matching 5, 15 and 45 mg/kg, corresponding to metal concentrations of 1.2, 3.6 and 10.8 mg/kg. Mn-GLY and Zn-GLY were spiked at 15, 45 and 100 mg/kg, corresponding to 3.3, 9.9, 22 mg/kg Mn and 3.9, 11.7, 26mg/kg Zn, respectively. The water soluble fraction of un-supplemented feed contained 0.06 mg/kg Cu, 0.05 mg/kg Mn and 0.12 mg/kg Zn, with 69.5% of Cu, 33.2% of Mn and 24.3% of Zn being present under free metal ions but 30.4% of Cu being present under Cu-GLY, 66.82% of Mn and 75.7% of Zn being present under Mn-GLY and Zn-GLY, respectively. The supplemented feeds at the 3 tested doses, from the lowest to the highest inclusion levels, contained in total respectively: 1.1, 3.05 and 9.06 mg/kg Cu; 2.99, 8.9 and 18.2 mg/kg Mn; 3.72, 10.9 and 23.4 mg/kg Zn. The M-GLY species recovered by analysis within the different supplemented feeds ranged from 76.26 to 89.32% for Cu-GLY, form 94.5 to 98.51% for Mn-GLY and from 76.05 to 98.96% for Zn-GLY. These results showed that CE-ICP-MS technique can be used to quantify low doses and to measure metal-species repartition between Metal-GLY and free metal ions, when included in feeds. For the first time, this study highlighted that the raw materials used contain Metal-GLY compounds. This raises the question of the occurrence of these compounds within the different raw materials used in feed production that could dramatically affect the way to supplement minerals in animal feed.


Assuntos
Ração Animal/análise , Complexos de Coordenação/análise , Eletroforese Capilar/métodos , Glicina/análise , Metais/análise , Espectrofotometria Atômica/métodos , Sulfatos/análise , Animais
14.
Environ Sci Pollut Res Int ; 26(30): 31354-31367, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31473924

RESUMO

Springs are an important source of drinking water supply in mountainous karst areas of SW China. However, the quality of many spring waters has deteriorated greatly in recent years, which leads to a significant problem of drinking water scarcity. In this study, hydrochemistry and stable sulfur and oxygen isotopic compositions of SO42- (δ34S and δ18OSO4) of 38 representative samples of waters (incl. spring water, surface water, rainwater, and sewage) from the Hongjiadu Basin, Guizhou province, SW China, were investigated in order to identify the sources of contaminates in spring waters and trace the processes affecting the karst groundwater quality. Approximately 28% of the total investigated springs has been suffered from serious contamination and the concentrations of NO3-, SO42-, and total iron (TFe) in many spring waters have exceeded the standards for drinking water. The springs that have NO3- concentrations of > 30 mg/L are concentrated in residential and agricultural areas, suggesting that NO3- in spring water are mainly derived from chemical fertilizers, manure, and sewage. δ34S and δ18OSO4 data indicate that SO42- in spring water mainly originates from sulfide oxidation, acid rain, and sewage. Furthermore, the high δ34S and δ18OSO4 values of SO42- in some spring waters may be related to the occurrence of bacterial sulfate reduction. Some springs that are discharged from abandoned coal mines have SO42- concentrations of > 250 mg/L, demonstrating that mining activities have accelerated the deterioration of spring water quality. Also, springs with TFe concentrations of > 0.3 mg/L are discharged from coal-bearing strata, revealing that iron in spring waters is mainly derived from the oxidation of pyrite. Our results show that the karst spring waters are highly vulnerable to anthropogenic contaminations and human activities, such as agricultural fertilizing and sewage and waste disposal as well as mining activities, which exert a great impact on the quality of groundwater in karst areas.


Assuntos
Nascentes Naturais/análise , Poluentes Químicos da Água/análise , Qualidade da Água , Agricultura , China , Carvão Mineral , Monitoramento Ambiental/métodos , Fertilizantes , Ferro , Mineração , Isótopos de Oxigênio/análise , Esgotos , Sulfatos/análise , Sulfatos/química , Sulfetos , Isótopos de Enxofre/análise
15.
Environ Sci Pollut Res Int ; 26(29): 30055-30068, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31414390

RESUMO

Long-term mining activities reshape the hydraulic and hydrochemical field, and threaten the safe use of groundwater and ecosystem balance. Here, we concluded the evolution characteristics and processes of karst groundwater system based on the water level and hydrochemistry data of the Carboniferous and Devonian aquifer in Maoping lead-zinc deposit, a representative in southwestern China. After concentrated mining lasting for nearly three decades, this mining area has generated a huge depression cone coupled with decreased level, changed flowpath, massive drainage, and direct hydraulic connection across the aquiclude. However, these two sets of karst aquifers exhibited distinct hydrochemical evolution patterns in particular with respect to sulfate. SO42- and the total dissolved solids (TDS) increased slightly in the Carboniferous aquifer and maintained the hydrochemical type of HCO3 and HCO3·SO4. While, SO42- and TDS in the Devonian aquifer decreased drastically, and the hydrochemical type was converted from SO4 and SO4·HCO3 to HCO3 and HCO3·SO4. Before concentrated mining, pyrite oxidation and dissolution of carbonate minerals mutually promoted each other in sluggish groundwater flow, then generated abnormally high concentrations of SO42-, Ca2+, and Mg2+ in Devonian karst aquifer, causing an illusion of saturation state of gypsum dissolution. At present, SO42- is mainly derived from pyrite oxidation indicated by sulfur isotope except deep groundwater contributed by gypsum dissolution. Groundwater quality in the Devonian aquifer was improved together by the dilution of northern shallow groundwater from the external Carboniferous aquifer and upward recharge of southern deep groundwater itself. Results of principal component analysis (PCA) verified the different recharge resources and mixing process resulted from continuous mining activities, which were the driving forces of hydrochemical evolution. Qualitatively speaking, the disturbing degree of the hydrodynamic field was consistent with the variation degree of hydrochemical filed. This research shed light upon the groundwater system and its evolution induced by intensive mining, which will benefit the future mining project.


Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Água Subterrânea , Mineração , Poluentes Químicos da Água/análise , China , Ecossistema , Água Subterrânea/análise , Água Subterrânea/química , Hidrodinâmica , Ferro/análise , Sulfatos/análise , Sulfetos/análise
16.
Artigo em Inglês | MEDLINE | ID: mdl-31364465

RESUMO

This paper presents the results of laboratory investigations conducted on gold mine tailings (GMT) to assess their chemical, mineralogical and geotechnical characteristics in view of assessing its suitability as an alternative backfilling solution in mine reclamation. Chemical characterization revealed that GMT is dominated by Si, Al, and Fe with notable amounts of Cr, Zr, Zn, Pb, Ce, As, Ba, Ni, V, Sr, Nd, Cu, U, and Co. Mineralogical characterization revealed a composition of silicate minerals with secondary minerals such as jarosite, goethite and hematite. GMT composites showed improved strength characteristics. The particle sizes of the tailings are capable of producing a good paste fill that will require lower water-cement ratio. Moreover, the plasticity of the tailings provide for a likelihood for shear resistance to sliding in fluvial conditions. Curing and addition of cement showed positive effects on the compressive strength and shear strength of the tailings. However, the effect of curing and cement addition on the compaction characteristics and permeability of the tailings were negligible. GMT showed favorable characteristics for use in mine backfilling; it would be interesting to evaluate higher cement ratios to improve the characteristics of the tailings.


Assuntos
Ouro/análise , Ácidos/análise , Monitoramento Ambiental/métodos , Compostos Férricos/análise , Compostos de Ferro/análise , Minerais/análise , Mineração , África do Sul , Sulfatos/análise
17.
Environ Pollut ; 254(Pt A): 112864, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31369912

RESUMO

To better understand the mechanism of PM2.5 explosive growth (EG), we conducted concurrent measurements of gaseous pollutants, PM2.5 and its chemical composition (inorganic ions, organic carbon, and element carbon) with a time resolution of 1 h in Shanghai in late autumn and winter from 2014 to 2017. In this study, the EG events, which are defined as the net increase in the mass concentration of PM2.5 by more than 100 µg m-3 within hours, are separately discussed for 3, 6, or 9 h. The number of EG events decreased from 19 cases in 2014 to 6 cases in 2017 and the corresponding PM2.5 concentration on average decreased from 183.6 µg m-3 to 128.8 µg m-3. Both regional transport and stagnant weather (windspeed < 2.0 m s-1) could lead to EG events. The potential source contribution function (PSCF) shows that the major high-pollution region is in East China (including Zhejiang, Jiangsu, Shandong, and Anhui Province) and the North China Plain. The contribution of stagnant conditions to EG episode hours of 55% (198 h, 156.9 µg m-3) is higher than that of regional transport (45%, 230 h, 163.0 µg m-3). To study the impact of local emission, chemical characteristics and driving factors of EG were discussed under stagnant conditions. The major components contributing to PM2.5 are NO3- (17.9%), organics (14.1%), SO42- (13.1%), and NH4+ (13.1%). The driving factors of EG events are the secondary aerosol formation of sulfate and nitrate and primary emissions (vehicle emissions, fireworks, and biomass burning), but the secondary transformation contributes more to EG events. The formation of sulfate and nitrate is dominated by gas-phase oxidation and heterogeneous reactions, which are enhanced by a high relative humidity. The current study helps to understand the chemical mechanism of haze and provides a scientific basis for air pollution control in Shanghai.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Material Particulado/análise , Aerossóis/análise , Carbono/análise , China , Poluentes Ambientais , Poluição Ambiental , Gases , Nitratos/análise , Óxidos de Nitrogênio , Estações do Ano , Sulfatos/análise , Emissões de Veículos/análise , Tempo (Meteorologia)
18.
J Microbiol ; 57(10): 852-864, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31376109

RESUMO

Recent work suggests that microbial community composition in high-elevation lakes is significantly influenced by microbes entering from upstream terrestrial and aquatic habitats. To test this idea, we conducted 18S and 16S rDNA surveys of microbial communities in a high-alpine lake in the Colorado Rocky Mountains. We compared the microbial community of the lake to water entering the lake and to uphill soils that drain into the lake. Utilizing hydrological and abiotic data, we identified potential factors controlling microbial diversity and community composition. Results show a diverse community entering the lake at the inlet with a strong resemblance to uphill terrestrial and aquatic communities. In contrast, the lake communities (water column and outlet) showed significantly lower diversity and were significantly different from the inlet communities. Assumptions of neutral community assembly poorly predicted community differences between the inlet and lake, whereas "variable selection" and "dispersal limitation" were predicted to dominate. Similarly, the lake communities were correlated with discharge rate, indicating that longer hydraulic residence times limit dispersal, allowing selective pressures within the lake to structure communities. Sulfate and inorganic nitrogen and phosphorus concentrations correlated with community composition, indicating "bottom up" controls on lake community assembly. Furthermore, bacterial community composition was correlated with both zooplankton density and eukaryotic community composition, indicating biotic controls such as "top-down" interactions also contribute to community assembly in the lake. Taken together, these community analyses suggest that deterministic biotic and abiotic selection within the lake coupled with dispersal limitation structures the microbial communities in Green Lake 4.


Assuntos
Bactérias/isolamento & purificação , Eucariotos/isolamento & purificação , Lagos/microbiologia , Lagos/parasitologia , Bactérias/classificação , Bactérias/genética , Biodiversidade , Colorado , Eucariotos/classificação , Eucariotos/genética , Lagos/química , Microbiota , Nitrogênio/análise , Nitrogênio/metabolismo , Sulfatos/análise , Sulfatos/metabolismo
19.
Environ Pollut ; 253: 377-383, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31325882

RESUMO

Changzhou, an industrial city in the Yangtze River Delta, has been experiencing serious haze pollution, particularly in winter. However, studies pertaining to the haze in Changzhou are very limited, which makes it difficult to understand the characteristics and formation of winter haze in this area, and develop effective control measures. In this study, we carried out continuous online observation of particulate matter, chemical components, and meteorology in Changzhou in February 2017. Our results showed that haze pollution occurred frequently in Changzhou winter and exhibited two patterns: dry haze with low relative humidity (RH) and wet haze with high RH. Water-soluble inorganic ions (SO42-, NO3-, and NH4+) accounted for ∼52.2% of the PM2.5 mass, of which sulfate was dominant in wet haze periods while nitrate was dominant in other periods. With the deterioration of haze pollution, the proportion of nitrate in PM2.5 increased, while sulfate proportion increased under wet haze and decreased under dry haze. Dry haze and wet haze appeared under slow north wind and south wind, respectively, and strong north wind or sea breeze scavenged pollution. We found that formation of nitrate occurred rapidly in daytime with high concentrations of odd oxygen (Ox = O3 + NO2), whereas formation of sulfate occurred rapidly during nighttime with high RH, indicating that photochemistry and heterogeneous reaction were the major formation mechanisms for nitrate and sulfate, respectively. Through the cluster analysis of 36-h backward trajectories, five sources of air masses from three directions were identified. High PM2.5 concentrations (84.1 µg m-3 on average) usually occurred under the influence of two clusters (46%) from the northwest, indicating that regional transport from northern China aggravated the winter haze pollution in Changzhou. Emission reduction, particularly the mobile sources, and regional joint prevention and control can help to mitigate the winter haze in Changzhou.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental , Material Particulado/análise , Aerossóis/análise , China , Cidades , Umidade , Meteorologia , Nitratos/análise , Óxidos de Nitrogênio/análise , Rios , Estações do Ano , Sulfatos/análise , Vento
20.
Res Microbiol ; 170(6-7): 288-295, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31279086

RESUMO

Due to land uplift after the last ice age, previously stable Baltic Sea sulfidic sediments are becoming dry land. When these sediments are drained, the sulfide minerals are exposed to air and can release large amounts of metals and acid into the environment. This can cause severe ecological damage such as fish kills in rivers feeding the northern Baltic Sea. In this study, five sites were investigated for the occurrence of acid sulfate soils and their geochemistry and microbiology was identified. The pH and soil chemistry identified three of the areas as having classical acid sulfate soil characteristics and culture independent identification of 16S rRNA genes identified populations related to acidophilic bacteria capable of catalyzing sulfidic mineral dissolution, including species likely adapted to low temperature. These results were compared to an acid sulfate soil area that had been flooded for ten years and showed that the previously oxidized sulfidic materials had an increased pH compared to the unremediated oxidized layers. In addition, the microbiology of the flooded soil had changed such that alkalinity producing ferric and sulfate reducing reactions had likely occurred. This suggested that flooding of acid sulfate soils mitigates their environmental impact.


Assuntos
Bactérias/metabolismo , Sedimentos Geológicos/química , Sedimentos Geológicos/microbiologia , Microbiota/efeitos dos fármacos , Poluentes do Solo/análise , Solo/química , Ácidos/análise , Bactérias/genética , Ferro/análise , Metais/análise , Microbiologia do Solo , Sulfatos/análise , Sulfetos/análise
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