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1.
Ecotoxicol Environ Saf ; 212: 111992, 2021 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-33529922

RESUMO

Groundwater is an important water resource in arid and semi-arid regions. The impact of human activities on groundwater is increasing. After 60 years running, the groundwater quality and its formation mechanism are imperative questions needed to be answered in Jiaokou Irrigation District, Guanzhong Basin, China. In this study, the quality of groundwater in Jiaokou Irrigation District was assessed by a new integrated-weight water quality index (IWQI), and the groundwater chemistry is studied through integrated statistical, geostatistical and hydrogeochemical approaches. The patterns for the average anion and cation concentrations were HCO3- > SO42- > Cl- > NO3- > CO32- > NO2-, and Na+ > Mg2+ > Ca2+ > K+ > NH4+, respectively. Statistics showed that the major water chemistry types were HCO3-Na, SO4·Cl-Na, and Cl·SO4-Na. A new integrated-weight water quality index (IWQI) was proposed based on the entropy-weighted method and CRITIC method and showed excellent performance for explaining and evaluating the groundwater quality. The IWQI results show 65.33% of groundwater, mainly distributed in the central and western parts of this study area, was unsuitable for drinking. Furthermore, SO42-, HCO3-, Cl-, NO3-, and Na+ had more important effects on groundwater quality. The weathering process affecting groundwater quality in the study area is carbonate dissolution, followed by silicate weathering and evaporite dissolution, whereas the major geochemical processes include the dissolution and precipitation of calcite, as well as the dissolution of dolomite and gypsum (anhydrite). Cation exchange also plays an important role in the hydrogeochemical evolution of groundwater with a long residence time. Anthropogenic activities affecting groundwater quality included long-term irrigation infiltration and excessive use of fertilizers. The findings and the results of the study can improve understanding of the processes driving groundwater chemistry in Jiaokou Irrigation District, and can be used for reference to other similar regions in the world.


Assuntos
Monitoramento Ambiental , Poluentes Químicos da Água/análise , Ânions , Carbonato de Cálcio , Carbonatos/análise , China , Fertilizantes/análise , Água Subterrânea/análise , Água Subterrânea/química , Humanos , Magnésio , Qualidade da Água , Tempo (Meteorologia)
2.
Biol Bull ; 239(3): 183-188, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33347796

RESUMO

AbstractFor many historical and contemporary experimental studies in marine biology, seawater carbonate chemistry remains a ghost factor, an uncontrolled, unmeasured, and often dynamic variable affecting experimental organisms or the treatments to which investigators subject them. We highlight how environmental variability, such as seasonal upwelling and biological respiration, drive variation in seawater carbonate chemistry that can influence laboratory experiments in unintended ways and introduce a signal consistent with ocean acidification. As the impacts of carbonate chemistry on biochemical pathways that underlie growth, development, reproduction, and behavior become better understood, the hidden effects of this previously overlooked variable need to be acknowledged. Here we bring this emerging challenge to the attention of the wider community of experimental biologists who rely on access to organisms and water from marine and estuarine laboratories and who may benefit from explicit considerations of a growing literature on the pervasive effects of aquatic carbonate chemistry changes.


Assuntos
Laboratórios , Água do Mar , Dióxido de Carbono , Carbonatos/análise , Concentração de Íons de Hidrogênio , Oceanos e Mares
3.
Chemosphere ; 254: 126799, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957268

RESUMO

Enrichment of cadmium (Cd) during weathering and pedogenesis of carbonate rocks has resulted in large areas of lands with soil Cd concentrations exceeding the official guidelines in China and other countries. However, it is reported in many studies that the risk of soil contamination by Cd from this natural process can be neglected as most of the Cd is not bioavailable. Noticing that the previous studies focused only on eluvial areas but not on lowland alluvium, where Cd from the eluvial areas can be transported and accumulated, we selected the Qingyang county in Anhui province, where there are two small drainage basins developed wholly on carbonate bedrock, to compare the Cd speciation and activity between eluvium and alluvium, and to evaluate the risk of Cd pollution to the latter. By the application of systematic sampling and analysis of the bedrock, soil, and rice grain samples, and in comparison with the previously acknowledged "high background with low mobility" area in Guizhou, it was found that soil developed from alluvium has both higher total Cd and higher mobile Cd proportion than soil from the upland eluvium. A very high percentage of rice grain samples (51%) grown on the alluvial soil exceeded the food standard for Cd (0.2 mg kg-1). Therefore, the spatial division of alluvium and eluvium should be the first step in the assessment of the Cd risk in carbonate regions, and special attention should be given to soil developed from alluvium.


Assuntos
Cádmio/análise , Poluentes do Solo/análise , Carbonatos/análise , China , Poluição Ambiental/análise , Poluição Ambiental/estatística & dados numéricos , Oryza , Solo , Tempo (Meteorologia)
4.
PLoS One ; 15(9): e0238432, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32881918

RESUMO

The carbonate system in two contrasting fjords, Rivers Inlet and Bute Inlet, on the coast of British Columbia, Canada, was evaluated to characterize the mechanisms driving carbonate chemistry dynamics and assess the impact of anthropogenic carbon. Differences in the character of deep water exchange between these fjords were inferred from their degree of exposure to continental shelf water and their salinity relationships with total alkalinity and total dissolved inorganic carbon, which determined seawater buffering capacity. Seawater buffering capacity differed between fjords and resulted in distinct carbonate system characteristics with implications on calcium carbonate saturation states and sensitivity to increasing anthropogenic carbon inputs. Saturation states of both aragonite and calcite mineral phases of calcium carbonate were seasonally at or below saturation throughout the entire water column in Bute Inlet, while only aragonite was seasonally under-saturated in portions of the water column in Rivers Inlet. The mean annual saturation states of aragonite in Rivers Inlet and calcite in Bute Inlet deep water layers have declined to below saturation within the last several decades due to anthropogenic carbon accumulation, and similar declines to undersaturation are projected in their surface layers as anthropogenic carbon continues to accumulate. This study demonstrates that the degree of fjord water exposure to open shelf water influences the uptake and sensitivity to anthropogenic carbon through processes affecting seawater buffering capacity, and that reduced uptake but greater sensitivity occurs where distance to ocean source waters and freshwater dilution are greater.


Assuntos
Carbonatos/análise , Monitoramento Ambiental/métodos , Água do Mar/química , Colúmbia Britânica , Carbonato de Cálcio/química , Carbono/química , Dióxido de Carbono/análise , Ecossistema , Estuários , Concentração de Íons de Hidrogênio , Salinidade , Água do Mar/análise
5.
Environ Geochem Health ; 42(11): 3819-3839, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32601907

RESUMO

Monitoring the groundwater chemical composition and identifying the presence of pollutants is an integral part of any comprehensive groundwater management strategy. The present study was conducted in a part of West Tripura, northeast India, to investigate the presence and sources of trace metals in groundwater and the risk to human health due to direct ingestion of groundwater. Samples were collected from 68 locations twice a year from 2016 to 2018. Mixed Ca-Mg-HCO3, Ca-Cl and Ca-Mg-Cl were the main groundwater types. Hydrogeochemical methods showed groundwater mineralization due to (1) carbonate dissolution, (2) silicate weathering, (3) cation exchange processes and (4) anthropogenic sources. Occurrence of faecal coliforms increased in groundwater after monsoons. Nitrate and microbial contamination from wastewater infiltration were apparent. Iron, manganese, lead, cadmium and arsenic were above the drinking water limits prescribed by the Bureau of Indian Standards. Water quality index indicated 1.5% had poor, 8.7% had marginal, 16.2% had fair, 66.2% had good and 7.4% had excellent water quality. Correlation and principal component analysis reiterated the sources of major ions and trace metals identified from hydrogeochemical methods. Human exposure assessment suggests health risk due to high iron in groundwater. The presence of unsafe levels of trace metals in groundwater requires proper treatment measures before domestic use.


Assuntos
Água Subterrânea/análise , Metais/análise , Oligoelementos/análise , Poluentes Químicos da Água/análise , Qualidade da Água , Carbonatos/análise , Carbonatos/química , Exposição Dietética/efeitos adversos , Exposição Dietética/análise , Água Potável/análise , Monitoramento Ambiental/métodos , Fezes/microbiologia , Água Subterrânea/química , Água Subterrânea/microbiologia , Humanos , Hidrologia/métodos , Índia , Nitratos/análise , Medição de Risco/métodos , Águas Residuárias/análise , Águas Residuárias/microbiologia , Microbiologia da Água
6.
Ecotoxicol Environ Saf ; 196: 110529, 2020 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-32247240

RESUMO

Cadmium (Cd) is a highly toxic element and non-essential to human. Herein, the source and fate of Cd were examined in a typical sediment profile from the North River, South China, which was affected by the massive Pb-Zn smelting activities for decades. An exceptionally high enrichment of Cd, 107-441 mg/kg, was observed across the whole profile. Approximately 50-75% of Cd was retained in the weak acid soluble fraction. Risk assessment based on geoaccumulation index (Igeo), potential ecological risk index (Eri), bioavailable metal index (BMI) and toxic risk index (TRI) further indicated an extremely strong degree of potential ecological pollution and high toxic risks. The mineralogical composition of particles from the sediment profile exhibited the presence of pyrite, magnetite, wurtzite and greenockite. This further confirmed that Cd was migrated from smelting slags to the North River basin and enriched in sediment profile. Sediment Cd speciation analysis also implied a possible transformation of Cd from metal oxides in smelting slags to adsorbed phases and carbonates, which enhances the bioavailability of Cd. The findings indicate proper countermeasures or remediation approaches should be promptly taken towards high ecological risks of Cd arising from the depth profile extending nearly 1 m, due to lead-zinc smelting related activities.


Assuntos
Cádmio/análise , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Chumbo/análise , Rios/química , Poluentes Químicos da Água/análise , Zinco/análise , Carbonatos/análise , China , Ecologia , Humanos , Medição de Risco
7.
Isotopes Environ Health Stud ; 56(3): 297-313, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32138548

RESUMO

Selenium and oxygen isotope systematics can be useful tools for tracing sources and fate of Se oxyanions in water. In order to measure δ18O values of selenate, SeO4 2- must first be sequestered from water by precipitation as BaSeO4(s). However, other dissolved oxyanions insoluble with Ba2+ require removal. Dissolved selenate was separated from dissolved selenite, carbonate, phosphate, and arsenate by addition of Ce3+ cations that quantitatively removed these oxyanions by precipitation as insoluble Ce2(SeO3)3(s), Ce2(CO3)3(s), CePO4(s), and CeAsO4(s), respectively. δ18O-selenate (-8.19 ± 0.17 ‰) did not change after four replicates of selenite removal by Ce2(SeO3)3(s) precipitation and Ce3+ removal by cation exchange (-8.20 ± 0.14, -8.32 ± 0.09, -8.17 ± 0.13, and -8.29 ± 0.13 ‰). δ18O-selenate values (-10.86 ± 0.45 ‰) were preserved also when selenate was pre-concentrated on anion exchange resin, quantitatively retrieved by elution, and processed with Ce3+ to remove interfering oxyanions (-10.77 ± 0.07 ‰). The extraction and purification steps developed here successfully isolated dissolved selenate from interfering oxyanions while preserving δ18O-selenate values. This method should be useful for characterizing δ18O-selenate when present with the co-occurring oxyanions above in laboratory experiments and field sites with high Se concentrations, although further research is required for methods to eliminate any co-occurring sulphate.


Assuntos
Arseniatos/análise , Carbonatos/análise , Isótopos de Oxigênio/análise , Fosfatos/análise , Ácido Selênico/análise , Ácido Selenioso/análise , Poluentes Químicos da Água/análise , Selênio/análise , Soluções , Sulfatos/análise
8.
Cancer Res ; 80(8): 1762-1772, 2020 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-32094303

RESUMO

Breast microcalcifications are a common mammographic finding. Microcalcifications are considered suspicious signs of breast cancer and a breast biopsy is required, however, cancer is diagnosed in only a few patients. Reducing unnecessary biopsies and rapid characterization of breast microcalcifications are unmet clinical needs. In this study, 473 microcalcifications detected on breast biopsy specimens from 56 patients were characterized entirely by Raman mapping and confirmed by X-ray scattering. Microcalcifications from malignant samples were generally more homogeneous, more crystalline, and characterized by a less substituted crystal lattice compared with benign samples. There were significant differences in Raman features corresponding to the phosphate and carbonate bands between the benign and malignant groups. In addition to the heterogeneous composition, the presence of whitlockite specifically emerged as marker of benignity in benign microcalcifications. The whole Raman signature of each microcalcification was then used to build a classification model that distinguishes microcalcifications according to their overall biochemical composition. After validation, microcalcifications found in benign and malignant samples were correctly recognized with 93.5% sensitivity and 80.6% specificity. Finally, microcalcifications identified in malignant biopsies, but located outside the lesion, reported malignant features in 65% of in situ and 98% of invasive cancer cases, respectively, suggesting that the local microenvironment influences microcalcification features. This study confirms that the composition and structural features of microcalcifications correlate with breast pathology and indicates new diagnostic potentialities based on microcalcifications assessment. SIGNIFICANCE: Raman spectroscopy could be a quick and accurate diagnostic tool to precisely characterize and distinguish benign from malignant breast microcalcifications detected on mammography.


Assuntos
Doenças Mamárias/metabolismo , Doenças Mamárias/patologia , Mama/patologia , Calcinose/metabolismo , Calcinose/patologia , Análise Espectral Raman/métodos , Biomarcadores/análise , Biópsia , Mama/química , Carcinoma de Mama in situ/química , Carcinoma de Mama in situ/diagnóstico , Carcinoma de Mama in situ/patologia , Doenças Mamárias/diagnóstico , Neoplasias da Mama/química , Neoplasias da Mama/diagnóstico , Neoplasias da Mama/patologia , Calcinose/diagnóstico , Fosfatos de Cálcio/análise , Carbonatos/análise , Feminino , Humanos , Fosfatos/análise , Sensibilidade e Especificidade
9.
Environ Sci Pollut Res Int ; 27(12): 13142-13154, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32016871

RESUMO

The coupled carbonate weathering represents a significant carbon sink and can be controlled by the riverine hydrochemical variations. However, magnitudes, variations, and mechanisms responsible for the carbon sink produced by coupled carbonate weathering are unclear. In view of this, temperature, pH, dissolved oxygen, turbidity, electrical conductivity, and discharge of the Xijiang River at Wuzhou Hydrologic Gauging Station was recorded during October 2013 to September 2015 to elucidate the temporal variations in riverine hydrochemistry and their controlling mechanisms. To obtain the complete carbon sink flux (CSF) produced by coupled carbonate weathering with terrestrial aquatic photosynthesis in the river basin, the fluxes of dissolved inorganic carbon (DIC), autochthonous organic carbon (AOC, sourced from the transformation of DIC via aquatic photosynthesis), and sedimentary AOC were all considered. The results show that seasonal hydrochemical variations in the Xijiang River were related not only to dilution effects but also aquatic primary production. These results demonstrate that the variations in discharge caused by rainfall played a dominant role in controlling the variations in the CSF due to the chemostatic behavior of DIC and dissolved organic carbon (DOC). The CSF of the Xijiang River produced by coupled carbonate weathering was calculated as 11.06 t C km-2 a-1, including DIC carbon sink flux of 6.56 t C km-2 a-1, AOC flux (FAOC) of 2.25 t C km-2 a-1, and sedimentary AOC flux (FSAOC) of 2.25 t C km-2 a-1. The FAOC and FSAOC together accounted for approximately 69% of DIC carbon sink flux, or approximately 41% of the CSF, indicating that the riverine AOC flux may be high and must be considered in the estimation of rock weathering-related carbon sinks.


Assuntos
Sequestro de Carbono , Rios , Carbono/análise , Carbonatos/análise , China , Monitoramento Ambiental , Fotossíntese
10.
Sci Adv ; 6(7): eaax9361, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-32110726

RESUMO

Studying the origin of avian thermoregulation is complicated by a lack of reliable methods for measuring body temperatures in extinct dinosaurs. Evidence from bone histology and stableisotopes often relies on uncertain assumptions about the relationship between growth rate and body temperature, or the isotopic composition (δ18O) of body water. Clumped isotope (Δ47) paleothermometry, based on binding of 13C to 18O, provides a more robust tool, but has yet to be applied across a broad phylogenetic range of dinosaurs while accounting for paleoenvironmental conditions. Applying this method to well-preserved fossil eggshells demonstrates that the three major clades of dinosaurs, Ornithischia, Sauropodomorpha, and Theropoda, were characterized by warm body temperatures. Dwarf titanosaurs may have exhibited similar body temperatures to larger sauropods, although this conclusion isprovisional, given current uncertainties in taxonomic assignment of dwarf titanosaur eggshell. Our results nevertheless reveal that metabolically controlled thermoregulation was the ancestral condition for Dinosauria.


Assuntos
Regulação da Temperatura Corporal , Dinossauros/metabolismo , Casca de Ovo/química , Animais , Peso Corporal , Calibragem , Carbonatos/análise , Fósseis , Isótopos , Moluscos/química , Filogenia , Temperatura , Oligoelementos/análise
11.
Environ Sci Pollut Res Int ; 27(10): 11375-11386, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31965499

RESUMO

Understanding the mechanisms that lead various hydrological conditions to influence solute and carbon dynamics in karst rivers is a crucial issue. In this study, high-frequency sampling and analyses of water chemistry and ẟ13CDIC were conducted from October 2013 to September 2014 in a typical karst river, the Beipan River in southwestern China. The major ions (such as Ca2+, Mg2+, HCO3-, K+, SO42-, Na+, and Cl-) in the river are mainly from the weathering of carbonates and silicates and present temporal hydrological variabilities. Sr and U are mainly derived from carbonate weathering and show chemostatic behaviors responding to increasing discharge, similar to carbonate-sourced ions Ca2+, Mg2+, and HCO3-. Silicate weathering is the primary source of Al and Li, which show significant dilution effects similar to those of Na+ responding to high discharge. Meanwhile, most dissolved trace elements (such as Zn, Cu, Ba, Sb, Mn, Mo, and Pb) are strongly impacted by anthropogenic overprints and also exhibit a significant seasonal variability, which may be related with mining activities in the investigated area. A simultaneous increase of ẟ13CDIC and decrease in ∆DIC contents and pCO2 values suggests that photosynthesis is the primary control on riverine DIC variability during the high-flow season. Besides, the pCO2 values display significant chemostatic behaviors owing to the influx of biological CO2, which is produced by microbiological activities and ecological processes, and enhanced by monsoonal climatic conditions. A two-dimensional endmember mixing model demonstrates that carbonate weathering (averaging 62%) along with biological carbon (averaging 38%) are main sources to the riverine DIC, with temporal variability. Consequently, these results show that carbonate weathering and involved plant photosynthesis are the dominant processes controlling the riverine DIC contents under high discharge and temperature conditions. This work provides insight into the crucial influence of hydrological variability on solute sources and carbon dynamics under monsoonal climate for the karst rivers.


Assuntos
Carbono/análise , Rios , Carbonatos/análise , China , Monitoramento Ambiental , Hidrologia
12.
Chemosphere ; 245: 125620, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31869671

RESUMO

The geographical distributions of Cd and several other metals (Cu, Ni, Pb, Zn, and Cr) were characterized in 308 terra rossa samples across the Guangxi karst region. We found significant enrichments of heavy metals in the saprolites and terra rossa developed in 30 profiles, which is mainly caused by the weathering of Cd-enriched carbonate rocks, while the subsequent pedogenic processes were the dominant factor of the enrichments for Cu, Ni, Pb, Zn, and Cr. Sequential extraction analysis indicated that geogenic Cd and Pb in terra rossa mostly distributed in the residual fractions and exhibited low mobility, whereas the amorphous Fe/Mn oxide fraction was the principal Cd-bearing phase in Cambisols. The good correlation of Fe, Al, and Ti in related bedrocks, saprolites, and terra rossa suggested that in-situ pedogenetic processes provided most of the parent materials for terra rossa. The residual accumulation during the special pedogenesis in the karst region, caused elevated Cd and Pb concentrations with increasing weathering intensity, which was indicated by chemical index of alternation (CIA). In addition, results of Pb isotopic fingerprinting confirmed that terra rossa mainly derived from insoluble residues of underlying carbonate rocks. The allochthonous input of Pb also occurred during pedogenesis, whereas the transport and deposition of non-carbonate materials (clasolite/granite derived soils) was only a minor source to Pb input in terra rossa and the anthropogenic impact seemed to be negligible.


Assuntos
Cádmio/análise , Metais Pesados/análise , Poluentes do Solo/análise , Solo/química , Carbonatos/análise , China , Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Tempo (Meteorologia)
13.
Chemosphere ; 240: 124938, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31574444

RESUMO

Clearwater Mesa (James Ross Island, northeast Antarctic Peninsula) provides a unique opportunity to study solute dynamics and geochemical weathering in the pristine lacustrine systems of a high latitude environment. In order to determine major controls on the solute composition of these habitats, a geochemical survey was conducted on 35 lakes. Differences between lakes were observed based on measured physico-chemical parameters, revealing neutral to alkaline waters with total dissolved solids (TDS) < 2500 mg L-1. Katerina and Trinidad-Tatana systems showed an increase in their respective TDS, total organic carbon values, and finner sediments from external to internal lakes, indicating an accumulation of solutes due to weathering. Norma and Florencia systems exhibited the most diluted and circumneutral waters, likely from the influence of glacier and snow melt. Finally, isolated lakes presented large variability in TDS values, indicating weathering and meltwater contributions at different proportions. Trace metal abundances revealed a volcanic mineral weathering source, except for Pb and Zn, which could potentially indicate atmospheric inputs. Geochemical modelling was also conducted on a subset of connected lakes to gain greater insight into processes determining solute composition, resulting in the weathering of salts, carbonates and silicates with the corresponding generation of clays. We found CO2 consumption accounted for 20-30% of the total species involved in weathering reactions. These observations allow insights into naturally occurring geochemical processes in a pristine environment, while also providing baseline data for future research assessing the impacts of anthropogenic pollution and the effects of climate change.


Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Lagos/química , Minerais/análise , Compostos Orgânicos/análise , Oligoelementos/análise , Regiões Antárticas , Carbonatos/análise , Mudança Climática , Ecossistema , Camada de Gelo/química , Chumbo/análise , Trinidad e Tobago , Tempo (Meteorologia) , Zinco/análise
14.
Environ Geochem Health ; 42(9): 2609-2626, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31673916

RESUMO

Karst groundwater, an important water source, is often highly influenced by human impacts, causing environmental damage and threats to human health. However, studies on the anthropogenic influences on the hydrogeochemical evolution of karst groundwater are relatively rare. To assess hydrogeochemical formation and evolution, we focused on a typical karst groundwater system (Jinan, China) which is composed of cold groundwater (av. temperature 13-17 °C), springs and geothermal water (av. temperature > 30 °C) and is significantly affected by human activities. The study was performed by means of water samples collecting and analyzing and isotope analysis (2H, 18O and 14C). The statistical analysis and inverse models were also applied to further understand geochemical processes and anthropogenic influences. The 2H, 18O and 14C results indicate that the cold karst groundwater is easily influenced and contaminated by the local environment, while geothermal water is relatively old with a slow rate of recharge. The hydrochemical types of cold karst groundwater are mainly HCO3-Ca and HCO3·SO4-Ca, while geothermal water hydrochemical types are SO4-Ca·Na and SO4-Ca. Groundwater Ca2+, Mg2+, HCO3- and SO42- are mainly controlled by carbonate equilibrium, gypsum dissolution and dedolomitization. Groundwater Na+, K+ and Cl- are mainly derived from halite dissolution, and in geothermal water, they are also affected by incongruent dissolution of albite and K-feldspar. Anthropogenic nitrogen produces ammonium resulting in nitrification and reduction in CO2(g) consumption and HCO3- release from carbonate dissolution. Principal component analysis and inverse models also indicate that nitrification and denitrification have significantly affected water-rock interactions. Our study suggests that karst groundwater quality is dominated by water-rock interactions and elucidates the influence of anthropogenic nitrogen. We believe that this paper will be a good reference point to study anthropogenic influences on the groundwater environment and to protect karst groundwater globally.


Assuntos
Água Subterrânea/análise , Água Subterrânea/química , Radioisótopos de Carbono/análise , Carbonatos/análise , China , Cloretos/análise , Monitoramento Ambiental/métodos , Humanos , Hidrologia/métodos , Hidrologia/estatística & dados numéricos , Modelos Teóricos , Nascentes Naturais , Isótopos de Oxigênio/análise , Potássio/análise , Análise de Componente Principal , Sódio/análise , Temperatura , Poluentes Químicos da Água/análise , Qualidade da Água
15.
Geobiology ; 18(1): 14-30, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31496070

RESUMO

The formation of carbonate concretions is a cementation process which passively infills the pore spaces within sediments. They record the original environments of deposition and diagenetic conditions of the host rocks. Little is known about the precise mechanisms responsible for the precipitation of carbonate concretions. The most common host rocks are mudstones/shales, sandstones, and limestones. This study presents an example of large carbonate concretions from an unusual host rock, the black bedded cherts of the Gufeng Formation (Guadalupian) at Enshi on the northern Yangtze Platform, South China. Petrographic observations (X-ray diffraction, optical microscopy, scanning electron microscopy) and multiple geochemical analyses (pyrite- and carbonate-associated-sulfate (CAS)-sulfur isotopes, carbon isotopes) indicate that (a) the studied carbonate concretion are mainly composed of micritic calcite with subordinate dolomite; (b) the concretions may have been mainly formed in the bacterial sulfate reduction (BSR) zone during very early diagenesis near the sediment-water surface; (c) the paleo-bottom water overlying the sediments during formation of the concretions was mainly euxinic; and (d) the growth of the studied concretions proceeded via a pervasive model, where later cementation phase initiated in the lower part of the concretions and progressed upward.


Assuntos
Carbonatos/análise , Isótopos de Carbono , China , Sedimentos Geológicos , Isótopos de Enxofre
16.
Environ Geochem Health ; 42(2): 579-599, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31444588

RESUMO

The present study region comprises granite and granite gneisses aquifer system constituted by Precambrian rocks. Groundwater is the primary source for drinking and other domestic purposes. Many developing regions in the world suffer from lack of safe drinking water. A rural part of Wanaparthy District in Telangana State, India, is one of them. For this reason, the groundwater samples collected from the study region were analyzed for pH, TDS, Ca2+, Mg2+, Na+, K+, HCO3-, Cl-, SO42-, NO3- and F- and evaluated groundwater quality criteria, using ionic spatial distribution (ISD), entropy water quality index (EWQI) and principal component analysis (PCA). The ISD maps show that some locations are not suitable for drinking purpose due to exceeding concentrations of TDS, Mg2+, Na+, K+, HCO3-, Cl-, NO3-and F-, compared to those with national drinking water quality standards. According to the EWQI, about 3%, 47%, 43% and 7% of the total area come under the excellent, good, medium and extremely poor water quality types for drinking purpose, respectively. Chadha's diagram classified the area as carbonate hardness (63%), non-carbonate alkali (17%), carbonates alkali (13%) and non-carbonate hardness (7%) zones. The binary diagrams (Na+ + K+ vs TC, Na+ vs Ca2+ and HCO3- vs TC) indicate that the quality of groundwater is controlled by influences of water-rock interactions, mineral weathering and dissolution, ion exchange and evaporation as well as the impact of anthropogenic sources. The PCA transferred the chemical variables into three principal components accounts for about 81% of the total variance. The high positive loadings of PC1 (Cl-, TDS, SO42-, Na+, NO3-, Mg2+ and HCO3-) stand for processes of silicate weathering and dissolution, ion exchange and evaporation, and the influence of domestic waste waters, irrigation return flows and chemical fertilizers on the groundwater system, the PC2 (F- and pH) signifies the alkaline nature of groundwater, which causes fluorosis, and the PC3 (K+) is a result of potassium fertilizers. The study helps to take remediate measures at a specific site and hence suggests the treatment of water before its drinking and also the recharge of the aquifer artificially to improve the groundwater quality.


Assuntos
Água Subterrânea/análise , Água Subterrânea/química , Qualidade da Água , Irrigação Agrícola , Carbonatos/análise , Água Potável , Entropia , Monitoramento Ambiental/estatística & dados numéricos , Fertilizantes , Hidrologia/estatística & dados numéricos , Índia , Análise de Componente Principal , Águas Residuárias , Poluentes Químicos da Água/análise , Qualidade da Água/normas
17.
Ann Rev Mar Sci ; 12: 499-523, 2020 01 03.
Artigo em Inglês | MEDLINE | ID: mdl-31451083

RESUMO

In the last few decades, numerous studies have investigated the impacts of simulated ocean acidification on marine species and communities, particularly those inhabiting dynamic coastal systems. Despite these research efforts, there are many gaps in our understanding, particularly with respect to physiological mechanisms that lead to pathologies. In this review, we trace how carbonate system disturbances propagate from the coastal environment into marine invertebrates and highlight mechanistic links between these disturbances and organism function. We also point toward several processes related to basic invertebrate biology that are severely understudied and prevent an accurate understanding of how carbonate system dynamics influence organismic homeostasis and fitness-related traits. We recommend that significant research effort be directed to studying cellular phenotypes of invertebrates acclimated or adapted to elevated seawater pCO2 using biochemical and physiological methods.


Assuntos
Organismos Aquáticos/efeitos dos fármacos , Dióxido de Carbono/análise , Carbonatos/toxicidade , Monitoramento Ambiental/métodos , Invertebrados/efeitos dos fármacos , Água do Mar/química , Poluentes Químicos da Água/toxicidade , Animais , Organismos Aquáticos/crescimento & desenvolvimento , Carbonatos/análise , Homeostase , Concentração de Íons de Hidrogênio , Invertebrados/crescimento & desenvolvimento , Modelos Teóricos , Poluentes Químicos da Água/análise
18.
Environ Geochem Health ; 42(1): 95-108, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31011941

RESUMO

Soils formed after the desiccation of Lake Atamanskoe, which has served as a reservoir for liquid industrial waste from the city of Kamensk-Shakhtinsky during a long time, were studied. These soils differ from zonal soils by a strong contamination with zinc and sulfur. Preliminary studies showed that Fe compounds fix a significant part of zinc. This requires to study S, Zn, and Fe minerals. In this work, Mössbauer spectroscopy was used for the identification of iron compounds and scanning electron microscopy was used for the microanalysis of these and other minerals. To facilitate the identification of Fe minerals, brown iron ocher was removed from a contaminated soil sample and analyzed. From electron microscopy and Mössbauer spectroscopy data, ocher contained hydrogoethite with a high content of sorption water and schwertmannite (a rare mineral, probably found in Russia for the first time). The chemical composition of this schwertmannite better corresponds to the Cashion-Murad model than to the Bigham model. Particles of partially oxidized magnetite and wustite enriched with zinc were revealed under electron microscope. Siderite with partial substitution of Fe2+ by Zn2+ was detected. Thus, contaminated hydromorphic soil contains both common minerals (illite, goethite, hematite, gypsum) and rare minerals (schwertmannite, Zn siderite, partially oxidized magnetite and wustite enriched with zinc).


Assuntos
Ferro/análise , Minerais/análise , Poluentes do Solo/análise , Enxofre/análise , Zinco/análise , Carbonatos/análise , Compostos Férricos/análise , Compostos Ferrosos/análise , Compostos de Ferro/análise , Minerais/química , Federação Russa , Solo/química
19.
Int J Legal Med ; 134(2): 811-821, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31172274

RESUMO

ATR-FTIR spectroscopy is a fast and accessible, minimally or non-destructive technique which provides information on physiochemical characteristics of analyzed materials. In forensic and archaeological sciences, it is commonly used for answering numerous questions, including the archaeological or forensic context of the human skeletal remains. In this research, the accuracy of ATR-FTIR-obtained spectra for separation between forensic, WWII, and archaeological human skeletal remains was investigated. Building from the previously proposed methodological procedures, various ratio-based and whole spectra separation procedures were applied, carefully analyzed, and evaluated. Results showed that employing whole spectral domains works best for the separation of archaeological, WWII, and forensic samples, even with samples of highly variable origin. Principal component analysis (PCA) further highlighted the necessity of acknowledging all the major components in the remains: amides, phosphates, and carbonates for the separation. Most influential proved to be amide I, namely its secondary structure, which presented well-preserved and organized collagen structure in forensic and WWII samples, while highly degraded in archaeological samples. Using the whole spectral domain for separation between samples from different contexts proved to be fast and simple, with no manipulation beyond baseline correction and normalization of spectra necessary. However, a dataset with samples of known origin is required for the learning model and predictions. A less accurate alternative is separation based on combining ratios of peaks correlating to organics and minerals in the bone, which eliminated overlapping and managed to classify the majority of the samples correctly as archaeological, WWII, or forensic.


Assuntos
Amidas/análise , Restos Mortais/química , Osso e Ossos/química , Carbonatos/análise , Ciências Forenses/métodos , Fosfatos/análise , Colágeno/isolamento & purificação , Conjuntos de Dados como Assunto , Humanos , Análise de Componente Principal , Eslovênia , Espectroscopia de Infravermelho com Transformada de Fourier , II Guerra Mundial
20.
Environ Geochem Health ; 42(7): 1833-1862, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31691178

RESUMO

Groundwater quality in the alluvial plains of Punjab has special significance and needs great attention since it is the foremost source of drinking, irrigation and industrial uses. The present research work emphasizes the integrated hydrogeochemical and chemometric statistical approaches to appraise the geochemical processes and source apportionment of the groundwater in the alluvial plains of Jalandhar district, Punjab, India. The human health risk assessment was also performed to quantify the potential non-carcinogenic impacts of nitrate and fluoride on human health through ingestion of groundwater. For this purpose, 41 groundwater samples were collected from different groundwater abstraction units and analysed for pH, electrical conductivity, total dissolved solids, total hardness, total alkalinity and major ions (Ca2+, Mg2+, Na+, K+, HCO3-, CO32-, SO42-, NO3-, F-, Cl- and PO43-) using standard protocols. Drinking water quality index and Revelle index showed that groundwater samples fall under poor to unfit water class and salinization along the south-western portion of the study region shows poor water quality. The results of the hazard index (HIingestion) show 68% and 46.34% of the groundwater samples have HI > 1 for children and adults. The non-carcinogenic health risk assessment of nitrate (NO3-) and fluoride (F-) on the local population indicated that the children are more vulnerable through direct ingestion of drinking water than adults. Piper diagram and saturation index reveal that Ca2+-Mg2+-HCO3- is the dominant hydrochemical facies and oversaturated with calcite, dolomite and aragonite minerals in the groundwater. Gibbs diagrams, chloro-alkaline indices and scatter plots show that the hydrochemistry of the groundwater is mainly governed by aquifer material interaction such as weathering of silicate, carbonate rock, halite dissolution and cation exchange process. Chemometric statistical techniques revealed that the source identification of parameters such as Ca2+, Mg2+, Na+, K+, HCO3-, CO3- and F- is originated from geogenic factors, whereas NO3-, SO42-, Cl- and PO43- are from the anthropogenic origin. Therefore, urgent and efficient measures must be taken to combat groundwater pollution and reduce human health risk in the study area.


Assuntos
Fluoretos/análise , Água Subterrânea/análise , Nitratos/análise , Qualidade da Água , Adulto , Carbonato de Cálcio/química , Carbonatos/análise , Criança , Exposição Dietética/efeitos adversos , Exposição Dietética/análise , Água Potável , Monitoramento Ambiental , Fluoretos/toxicidade , Humanos , Índia , Magnésio/química , Poluentes Químicos da Água/análise
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