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1.
Water Sci Technol ; 82(7): 1339-1349, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33079714

RESUMO

Flax straw biochar (FSBC)-supported nanoscale zero-valent iron (nZVI) composite (nZVI-FSBC) combining the advantages of nZVI and biochar was synthesized and tested for Cr(VI) removal efficiency from aqueous solution. Surface morphology and structure of FSBC and nZVI-FSBC were characterized by scanning electron microscopy, transmission electron microscopy, thermogravimetric analysis, X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and Brunauer-Emmett-Teller techniques, which help to clarify the mechanism of Cr(VI) removal from aqueous solution. The adsorption of Cr(VI) onto FSBC and nZVI-FSBC was best described by the pseudo-second-order and the Sips model. Compared with FSBC, nZVI-FSBC remarkably improved the performance in removing Cr(VI) under identical experimental conditions. Due to the collaborative effect of adsorption and reduction of nZVI-FSBC, the adsorption capacity of nZVI-FSBC for Cr(VI) is up to 186.99 mg/g. The results obtained by XPS, XRD, and FTIR confirmed that adsorption and reduction dominated the processes of Cr(VI) removal by nZVI-FSBC. As a supporter, FSBC not only improved the dispersion of nZVI, but also undertook the adsorption task of Cr(VI) removal. The surface oxygen-containing functional groups of nZVI-FSBC mainly participated in the adsorption part, and the nZVI promoted the Cr(VI) removal through the redox reactions. These observations indicated that the nZVI-FSBC can be considered as potential adsorbents to remove Cr(VI) for environment remediation.


Assuntos
Ferro , Poluentes Químicos da Água , Adsorção , Carvão Vegetal , Cromo , Poluentes Químicos da Água/análise
2.
Water Sci Technol ; 82(7): 1393-1403, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33079718

RESUMO

This work focuses on the treatment of a dye solution, C.I. Basic Blue 41 (BB41), and industrial wastewater by UV/TiO2 photocatalytic process using aqueous catalyst suspensions of titanium dioxide (TiO2), Degussa P25. The procedures were carried out in a semi-pilot scale prototype solar photoreactor under solar radiation. Response surface methodology (RSM) based on Box-Wilson design was applied to assess individual effects of the five main independent parameters: initial dye concentration ([BB41]), TiO2 concentration ([TiO2]), flow rate (Q) initial pH and accumulated solar energy (Qvn) on the decolorization efficiency and to optimise the UV/TiO2 process. Photocatalytic mineralisation was carried out at the optimal conditions found by RSM and results were evaluated by total organic carbon (TOC) abatement for BB41 sloution and industrial wastewater. The optimal conditions found by RSM were: 0.4 g/L, 14.04 mg/L, 1,479.6 L/h, 5.52 and 80 KJ/L for TiO2 concentration, initial dye concentration, flow rate, initial pH and accumulated solar energy, respectively. Photocatalytic mineralisation results show that for accumulated visible solar energy equal to 377.714 kJ/L (after 6 hours of irradiation), under these conditions, the percentage of the initial TOC reduction is about 88% and 85.5% for industrial waste and BB41 solution, respectively.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Concentração de Íons de Hidrogênio , Fotoquímica , Eliminação de Resíduos Líquidos , Águas Residuárias , Poluentes Químicos da Água/análise
3.
Water Sci Technol ; 82(7): 1404-1415, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33079719

RESUMO

In this study, peroxydisulfate (PDS) was successfully activated by UV-irradiation for the degradation of paracetamol (PCT) frequently detected in the environment. Results showed that increasing the initial PDS concentration from 5 to 20 mM promote the removal of PCT from 49.3% to 97.5% after 240 min of reaction time. As the initial PCT concentration increased from 0.066 to 0.132 mM, the degradation efficiency of PCT decreased from 98% to 73% after 240 min of reaction time, while the optimal pH was found to be 6. It is apparent that the degradation rate of PCT was favored by the lamp power regardless of the initial PCT concentration, for 0.132 mM of PCT, the degradation efficiency increased from 73% to 95% when the lamp power increased from 9 to 30 W, respectively. The kinetic of degradation of the PCT was described by a pseudo-second order kinetic model. The model obtained by central composite design led to the following optimal conditions for PCT degradation: 0.132 mM initial PCT concentration, 20 mM PDS dose, pH solution 6 and lamp power 30 W led to the removal of 92% of PCT at 25 °C within 240 min of reaction time.


Assuntos
Acetaminofen , Poluentes Químicos da Água , Cinética , Sulfatos , Raios Ultravioleta , Poluentes Químicos da Água/análise
4.
Water Sci Technol ; 82(7): 1484-1494, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33079725

RESUMO

Tea waste was carbonized at 400 °C for 45 min and modified with potassium hydroxide (KOH), to enhance the active sites for the adsorption of antibiotics. The developed tea waste activated carbon (TWAC) was used as a novel eco-friendly and cost-effective adsorbent for metronidazole (MZN) removal from aqueous solution. The textural and surface properties of the adsorbent were determined using Brunauer-Emmett-Teller (BET) and FT-Raman analysis. The BET surface was found to have increased from 24.670 to 349.585 after carbonization and KOH modification. The batch experimental parameters were optimized and equilibrium time was found to be 75 min. Linear and non-linear models were carried out on the adsorption isotherm and kinetics to determine the best fit for the adsorption data. The adsorption equilibrium data were well fitted by the Freundlich isotherm and pseudo-second order models, with higher regression correlation (R2) and smaller chi-square (χ2), as predicted by the non-linear model. The thermodynamic results revealed the adsorption of MZN as spontaneous, physical, and consistently exothermic in character. The activation energy value of 7.610 kJ/mol further revealed that the adsorption process is dominated majorly by physical adsorption. The removal of MZN onto TWAC was best described by the non-linear adsorption isotherm and kinetics model.


Assuntos
Carvão Vegetal , Poluentes Químicos da Água , Concentração de Íons de Hidrogênio , Metronidazol , Chá , Poluentes Químicos da Água/análise
5.
Water Res ; 185: 116067, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-33086458

RESUMO

Land-based micropollutants are the largest pollution source of the marine environment acting as the major large-scale chemical sink. Despite this, there are few comprehensive datasets for estimating micropollutant fluxes released to the sea from river mouths. Hence, their dynamics and drivers remain poorly understood. Here, we address this issue by continuous measurements throughout the Rhône River basin (∼100,000 km2) of 1) particulate micropollutant concentrations (persistant organic micropollutants: polychlorobiphenyls [PCBi] and polycyclic aromatic hydrocarbons [PAHs]; emerging compounds: glyphosate and aminomethylphosphonic acid [AMPA]; and trace metal elements [TME]), 2) suspended particulate matter [SPM], and 3) water discharge. From these data, we computed daily fluxes for a wide range of micropollutants (n = 29) over a long-term period (2008-2018). We argue that almost two-thirds of annual micropollutant fluxes are released to the Mediterranean Sea during three short-term periods over the year. The watershed hydro-climatic heterogeneity determines this dynamic by triggering seasonal floods. Unexpectedly, the large deficit of the inter-annual monthly micropollutant fluxes inputs (tributaries and the Upper Rhône River) compared to the output (Beaucaire station) claims for the presence of highly contaminated missing sources of micropollutants in the Rhône River watershed. Based on a SPM-flux-averaged micropollutant concentrations mass balance of the system and the estimates of the relative uncertainty of the missing sources concentration, we assessed their location within the Rhône River catchment. We assume that the potential missing sources of PAHs, PCBi and TME would be, respectively, the metropolitan areas, the alluvial margins of the Rhône River valley, and the unmonitored Cevenol tributaries.


Assuntos
Rios , Poluentes Químicos da Água , Monitoramento Ambiental , Sedimentos Geológicos , Mar Mediterrâneo , Poluentes Químicos da Água/análise
6.
Water Res ; 185: 116257, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-33086466

RESUMO

This study identifies causes of rising arsenic (As) concentrations over 17 years in an inter-montane aquifer system located just north of the Trans-Mexican-Volcanic-Belt in the Mesa central physiographic region that is extensively developed by long-screened production wells. Arsenic concentrations increased by more than 10 µg/L in 14% (3/22) of re-sampled wells. Similarly, in a larger scale analysis wherein As concentrations measured in 137 wells in 2016 were compared to interpolated, baseline concentrations from 246 wells in 1999, As concentrations rose more than 10 µg/L in 30% of wells. Between 1999 and 2016, the percentage of all wells sampled in each basin-wide sampling campaign exceeding the World Health Organization's 10 µg/L drinking water limit increased from 38 to 64%. Principal Components Analysis (PCA), step-wise multiple regression, and Random Forest modeling (RF) revealed that high As concentrations are closely associated with high pH and temperature, and high concentrations of fluoride (F), molybdenum (Mo), lithium (Li), sodium (Na) and silica (Si), but low calcium (Ca) and nitrate (NO3) concentrations. Pumping-induced mixing with hot, geothermally impacted groundwater generates alkaline water through hydrolysis of silicate minerals. The rising pH converts oxyanion sorption sites from positive to negative releasing As (and Mo) to pore waters. The negative correlation between nitrate and As concentrations can be explained by conservative mixing of shallow, young groundwater with geothermally influenced groundwater. Therefore water carrying an anthropogenic contaminant dilutes water carrying geogenic contaminants. This process is enabled by long well screens. Over-exploitation of aquifers in geothermal regions for agriculture can drive As concentrations in water from production wells to toxic levels even as the total dissolved solids remain low.


Assuntos
Arsênico , Água Subterrânea , Poluentes Químicos da Água , Arsênico/análise , Monitoramento Ambiental , México , Poluentes Químicos da Água/análise
7.
Sci Total Environ ; 747: 142095, 2020 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-33076209

RESUMO

Despite the detection of a wide range of contaminants in the blood of green turtle populations foraging in three locations of northern Queensland - Upstart Bay, Cleveland Bay and the Howick Group of Reefs, little is known about the effects of these contaminants on turtle health. Newly developed cell-based bioassays using green turtle primary cell cultures provide an ethical, reproducible, and high-throughput method for assessing the risk of chemical exposure sea turtles. In this project, the toxicity of six priority metals (Mn, Co, Mo, As, Sb, Cu) and blood extracts from foraging turtles were tested in two bioassays adapted to green turtle primary skin and liver cells. Cytotoxicity of metals and blood extracts was measured in primary skin fibroblast cells using a resazurin assay. Glutathione-S-transferase (GST) activity was measured in primary skin fibroblasts and primary liver epithelial cells following exposure to metals and blood extracts. Arsenic, molybdenum, cobalt and copper were found to be cytotoxic to green turtle skin cells. Only manganese, cobalt and copper were found to alter GST activity, predominantly in skin cells, indicating a higher sensitivity of green turtle skin cells compared to liver cells. Effect concentrations of metals in both bioassays were above concentrations found in turtle blood. Turtle blood extracts from the three foraging grounds showed differences in cytotoxicity and GST activity. In both assays, blood extracts of turtles from Upstart Bay were the most toxic, followed by those from Cleveland Bay, then the Howick Reefs, suggesting turtles from Upstart Bay and Cleveland Bay may be at risk from current concentrations of organic contaminants. This study demonstrates that species-specific cell-based bioassays can be used effectively to assess chemical risk in sea turtles and their foraging grounds, and could be applied to assess chemical risk in other marine wildlife.


Assuntos
Tartarugas , Poluentes Químicos da Água , Animais , Bioensaio , Cultura Primária de Células , Queensland , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade
8.
Environ Monit Assess ; 192(11): 721, 2020 Oct 21.
Artigo em Inglês | MEDLINE | ID: mdl-33089438

RESUMO

For most rivers in sub-Saharan Africa, information about pollution indices related to sediments is sparse. Sedimentological research of rivers that empty into Lake Victoria is highly patchy and wide apart. The present study determined the levels and associated risk of As, Cd, Cr, Hg, and Pb in sediments collected from four different sites along the Mara River that empties into Lake Victoria in Tanzania. Samples were collected in the dry and rainy months in 2019. Pollution indices, namely geo-accumulation index (Igeo), enrichment factor (EF), contamination factor (CF), modified contamination degree (mCd), pollution load index (PLI), potential ecological risk factor (Eri), and potential ecological risk index (RI) were used to evaluate the influence of heavy metal contamination in sediments. Dry month mean concentrations, in milligram per kilogram, of heavy metals were as follows: As (11.04 ± 0.13), Cr (1.02 ± 0.29), Cd (0.43 ± 0.05), and Hg (0.01) in the dry month. Respective sediment heavy metal concentrations for the rainy month were 22.22 ± 0.05 mg As/kg, 3.84 ± 0.34 mg Pb/kg, 1.53 ± 0.15 mg Cd/kg, 1.43 mg Cr/kg, and 0.03 mg Hg/kg. Generally, the risk indices showed high values in the rainy month and low values in the dry month, especially for As and Cd-an indication of anthropogenic influence. Correlation coefficient analysis for Pb and Cd showed a strong positive correlation (r = 0.99, p < 0.01)-this may suggest a similar source or similar transport behavior. Special attention needs to be paid with regard to rainy season As and Cd enrichment in the study area.


Assuntos
Rios , Poluentes Químicos da Água , Monitoramento Ambiental , Sedimentos Geológicos , Medição de Risco , Tanzânia , Poluentes Químicos da Água/análise
9.
Water Sci Technol ; 82(5): 829-842, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031063

RESUMO

A high-surface-area and inexpensive activated carbon has been produced from lemon peel using chemical activation with H3PO4 at 500 °C in a N2 atmosphere. Afterwards, the synthesized cobalt nanoparticles using coprecipitation method were adsorbed on the activated carbon surface, and as a result magnetic activated carbon was obtained. Sample characterization has been assessed via X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, nitrogen adsorption-desorption and magnetic properties. It was found that magnetic activated carbon-cobalt nanoparticles (MAC/Co) synthesized had a high saturation magnetization. The MAC/Co revealed super-paramagnetic behaviors at room temperature, and have been readily isolated from solution by using an exterior magnet. Next, adsorption behavior of malachite green and Pb(II) onto the generated MAC/Co has been examined. Sorption kinetics and equilibrium have been studied using batch procedure. The kinetic and isothermal adsorption results were matched completely with the Elovich and Langmuir models, respectively. Based on the Langmuir model, the highest adsorption capacities of malachite green dye and Pb(II) ion respectively were 263.2 and 312.5 mg g-1 at room temperature. Based on the results, the MAC/Co is a probable economic and effective adsorbent that can be employed as a new adsorbent to remove malachite green dye and Pb(II) from wastewater.


Assuntos
Nanopartículas , Poluentes Químicos da Água , Carvão Vegetal , Cobalto , Chumbo , Fenômenos Magnéticos , Corantes de Rosanilina , Águas Residuárias , Poluentes Químicos da Água/análise
10.
Water Sci Technol ; 82(5): 843-850, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031064

RESUMO

Qualitative and quantitative analysis of trace organics in the condensate and its correlation with chemical oxygen demand (COD) is the key to the research on the reuse technology of condensate (condensate) from natural gas to hydrogen production process. The contents of anions, COD, total organic carbon (TOC) and total nitrogen (TN) were measured by ion chromatography and the TOC analyzer. Trace organics in the condensate and its correlation with COD was investigated in this paper. Results show that the contents of COD and TOC is 74.1 and 17.81 mg/L, respectively, and the anions in the condensate are mainly Cl-, I-, and SO42-, etc. The condensate mainly contains small molecule organics including methanol, ethanol and formic acid with the content of 41.4, 2.1 and 3.2 mg/L, respectively. The spiked recovery of methanol, ethanol and formic acid is 96.1%, 100.2% and 103.9% by high performance liquid chromatography (HPLC) and gas chromatography (GC), respectively. Methanol is the main source of COD in the condensate, and the contribution rate reaches up to 83.8%. The removal of trace methanol can significantly reduce the COD of the condensate. This work might provide basic data for reasonable recovery and utilization of condensate in the hydrogen production process.


Assuntos
Gás Natural , Poluentes Químicos da Água , Análise da Demanda Biológica de Oxigênio , Hidrogênio , Nitrogênio , Poluentes Químicos da Água/análise
11.
Water Sci Technol ; 82(5): 998-1008, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031076

RESUMO

The feasibility of an advanced oxidation process based upon sodium persulfate (SPS) activated simultaneously by heat (50 °C) and nanoscale zero-valent iron (nZVI) on benzene removal was investigated. The experimental results strongly showed the synergistic effect of thermal and nZVI activation to SPS and benzene removal was enhanced with the increase of SPS/nZVI/benzene molar ratio. Specifically, 94% of benzene could be removed in 1 hr at 50 °C at the SPS/nZVI/benzene molar ratio of 10/5/1. The radical scavenger tests and electron paramagnetic resonance (EPR) analysis confirmed that SO4•- was the predominant species contributing to benzene degradation. Further, the effects of the solution matrix on benzene elimination were investigated. The results indicated that benzene destruction in the thermally activated SPS/nZVI system performed better under acidic conditions, and the high concentration of both Cl- and HCO3- had adverse effects on benzene elimination. The test for the performance of benzene degradation in the actual groundwater demonstrated that benzene could be degraded entirely at SPS/nZVI/benzene molar ratio of 40/40/1 at 50 °C, indicating that the synergistic catalysis of thermal and nZVI activation to SPS is exploitable and the thermally activated SPS/nZVI system can be applicable to the remediation of benzene contaminated groundwater.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Benzeno , Ferro , Oxirredução , Poluentes Químicos da Água/análise
12.
Water Sci Technol ; 82(6): 1031-1043, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33055394

RESUMO

This study evaluated the capacity of a pilot-scale high-rate algal pond (HRAP) to remove pharmaceutical compounds (PCs) from domestic wastewater in the city of Santiago de Cali, Colombia. The compounds analyzed included antiepileptics, hypolipidemic drugs, tranquilizers and analgesics, and anti-inflammatory drugs. The HRAP operated under a continuous water flow of 0.2 m3d-1 and a 3-day hydraulic retention time (HRT). Removal efficiencies were high (>70%) for fenofibric acid, ibuprofen, and paracetamol; medium (30-70%) for gabapentin, lamotrigine, fenofibrate, gemfibrozil, diclofenac, ketoprofen, naproxen, and pentoxifylline; and low (<30%) for carbamazepine and its metabolite 10,11-Dihidro-10,11-dihidroxicarbamazepine (CBZ-Diol). The findings herein are similar to other studies, but were obtained with a shorter HRT. These results show that tropical environmental conditions favor photodegradation and contribute to the development of microalgae and the biodegradation process. Twenty microalgae species were identified, with the phylum Chlorophyta as the most abundant, particularly due to its natural introduction. The removal of the PCs also reflected a percentage reduction (>50%) in the ecological hazard posed by most of the compounds, although it is important to note that the hazard from gemfibrozil and ibuprofen remained high even after treatment, indicating the need for complementary treatment.


Assuntos
Águas Residuárias , Poluentes Químicos da Água , Colômbia , Tanques , Clima Tropical , Eliminação de Resíduos Líquidos , Poluentes Químicos da Água/análise
13.
Environ Monit Assess ; 192(11): 704, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-33057810

RESUMO

Mercury (Hg) was measured in the muscle, liver, and gonads of Haemulopsis elongatus and Pomadasys macracanthus from Mazatlán (SE Gulf of California) to determine the relationships of the hepatosomatic index (HSI) and gonadosomatic index (GSI) of fish with Hg concentrations in the corresponding tissues. Health risk to consumers was assessed by using the hazard quotient (HQ), considering the average rate of fish consumption in Mexico and Hg concentration in the edible tissue. In H. elongatus, the highest Hg levels were measured in the liver (3.748 µg g-1); in P. macracanthus, the highest Hg concentration was quantified in the muscle (0.574 µg g-1). In P. macracanthus, the HSI was negatively correlated with Hg concentration in the liver; in H. elongatus, there was also a negative relationship between Hg levels in gonads and the GSI. Mean HQ values in Haemulopsis elongatus (0.005) and Pomadasys macracanthus (0.002) were below the value (HQ ≥ 1) of concern. The significant reduction of HSI and GSI with Hg increase in the liver and gonads may suggest that Hg bioaccumulation in these fish shows adverse physiological effects. Though HQ values in both species were below the unit, i.e., the consumption of the muscle from this species does not represent a health risk, it is necessary to carry out surveys of fish consumption rates in coastal areas of Mexico to do a more precise health risk assessment associated to Hg intake.


Assuntos
Mercúrio , Poluentes Químicos da Água , Animais , Bioacumulação , California , Monitoramento Ambiental , Mercúrio/análise , México , Medição de Risco , Poluentes Químicos da Água/análise
14.
Environ Monit Assess ; 192(11): 705, 2020 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-33063182

RESUMO

The present study aimed at evaluating the levels of microbiological contamination, total petroleum hydrocarbons (TPHs), and heavy metals (As, Cd, Hg, and Pb) in the edible tissues of commonly consumed fish (8 species) collected from the marine area of Tripoli, Northern Lebanon. Total coliform levels in all sampled fish, and Escherichia coli levels in Liza ramada only, exceeded the permissible limits set by FAO/WHO 2002. Staphylococcus aureus counts were within the recommended thresholds, while sulfate-reducing bacteria levels were the highest in fish of the genus Liza. Salmonella species and Listeria monocytogenes were not detected in all fish analyzed. Analysis of heavy metals levels showed that arsenic exhibited the highest levels among the assessed metals in all genera. Levels of As in Epinephelus, Diplodus, Oblada, and Liza were above the acceptable limits, while Cd levels were below the permissible limits set by the European Commission. Significant negative correlation was found between levels of As and Hg in muscle tissues and fish size (length). Levels of TPHs were the highest in fish of the genus Epinephelus. Significant difference in TPHs contamination was found within three fish genera, with Epinephelus being the most contaminated.


Assuntos
Metais Pesados , Petróleo , Poluentes Químicos da Água , Animais , Monitoramento Ambiental , Contaminação de Alimentos/análise , Hidrocarbonetos , Líbano , Metais Pesados/análise , Poluentes Químicos da Água/análise
15.
Waste Manag ; 118: 591-599, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33010690

RESUMO

Landfill leachate, as a complex medium with a high concentration of organic and mineral materials, is a serious problem for the environment. In the current study, the saline landfill leachate of Bushehr coastal city (Iran) was treated using ultraviolet/ultrasonic waves/peroxymonosulfate system. The initial TOC and TDS of the studied leachate was 915 mg/L and 7390 mg/L, respectively. The system had the maximum efficiency at conditions of pH 3, peroxymonosulfate (PMS) of 4 mM, and reaction time of 150 min. Based on the findings, the initial ratio of BOD5/COD (0.66) was reduced to 0.38 using the developed system. After treatment of the landfill leachate at the optimal condition, the values of COD, BOD5, and UV254 were reached to 983 mg/L, 348 mg/L, and 10.16 cm-1, respectively. The concentration of all studied elements (except Pb, As, and Ca) increased after purification. According to the GC-mass spectrometry, the molecular weight and concentration of organic matter in raw leachate were higher than that of the treated one. The studied system had an energy consumption value of 86 kW·h/m3 for the treatment of landfill leachate. The results confirm the effectiveness of the ultraviolet/ultrasonic waves/PMS system for the treatment of high saline landfill leachate.


Assuntos
Poluentes Químicos da Água , Cidades , Irã (Geográfico) , Peróxidos , Salinidade , Poluentes Químicos da Água/análise
16.
Environ Monit Assess ; 192(11): 685, 2020 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-33026535

RESUMO

The Anzali wetland (located in northern Iran) and many parts of its catchment are considered important habitats for the swan mussel (Anodonta cygnea). The habitat of this native bioindicator mussel is being threatened in many locations of the catchment due to various anthropogenic activities. The present study aimed to apply a classification tree model (J48 algorithm) to predict the habitat preferences of A. cygnea in 12 sampling sites based on various water quality and physical-habitat variables. The species was present in 50% of sampling sites, while it was absent in the remaining of the sampling sites. In total, 144 samples of A. cygnea (72 presence and 72 absence instances) were monthly measured together with the abiotic variables during 1-year study period (2017-2018). For the CT model, two-thirds of datasets (96 instances) served as a training and the remainder was employed for the validation set (48 instances). Among 25 environmental variables introduced to the model (with pruning confidence factor = 0.10, threefold cross-validation and 5 times randomization effort), the validity of 6 variables was confirmed by the model in all three subsets. Water salinity, flow velocity, water depth and water turbidity were jointly predicted by the model in three subsets. The model predicted that the absence of A. cygnea might be associated with increasing flow velocity, total phosphate and water turbidity. In contrast, the presence of A. cygnea might be related to decreased water depth and increased calcium concentration. The model also confirmed that all predicted variables for the species might be completely dependent on the water salinity. According to the chi-square test (x2 = 26.53, p < 0.05), the habitat condition of A. cygnea is influenced by significant variations in the spatio-temporal patterns.


Assuntos
Anodonta , Poluentes Químicos da Água , Animais , Ecossistema , Monitoramento Ambiental , Irã (Geográfico) , Poluentes Químicos da Água/análise
17.
Environ Monit Assess ; 192(11): 683, 2020 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-33026556

RESUMO

The main objective of this research was to investigate the impact of the construction of Karkheh Dam in 2001 (referred to as the intervention time), on groundwater quality. The time series of total dissolved solids (TDS) and other water quality data including potassium (K+), sodium (Na+), magnesium (Mg2+), calcium (Ca2+), bicarbonate (HCO3-), sulfate (SO42-), and chloride (Cl-) for the period between 1996 and 2012 were analyzed. The magnitude of the trend by Sen's slope estimator for HCO3-, SO42-, and TDS was 0.005, - 0.02 and - 3.04, where a decline expected for SO42- and TDS, whereas for HCO3-, an increase was expected. According to the Pettitt's test, the mean of TDS decreased from 2306.9 mg/l between 1996 and 2002 to 797.2 mg/l between 2002 and 2012. During this time, the standard deviation of TDS declined from 2187.1 to 132.0 mg/l. The results of change point detection by the Pruned Exact Linear Time (PELT) algorithm were consistent with that of Pettitt's test providing confirmation that a change point in Ca2+, Mg2+, SO42-, and TDS time series data occurred in 2002.The findings from intervention analysis using the Bayesian structural time series (BSTS) technique showed that TDS concentration during the post-intervention period had an average value of 1127 mg/l compared with 1972 mg/l, before the dam construction. The time series of TDS demonstrated a decrease of about 43% following the intervention time.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Teorema de Bayes , Monitoramento Ambiental , Irã (Geográfico) , Poluentes Químicos da Água/análise
18.
Environ Monit Assess ; 192(11): 671, 2020 Oct 03.
Artigo em Inglês | MEDLINE | ID: mdl-33009943

RESUMO

Plastic pollution is an emerging issue faced worldwide owing to rapid urbanization and extensive use of plastic products. The objective of this study was to determine and highlight the spatial distribution of microplastics (MPs) in the top soils of different land use types of an urbanized city, i.e., Lahore, Pakistan, influenced by different human activities. Soil samples (n = 40) were collected from eight different land use groups including agricultural areas, drains, dumping sites, industrial areas, lawns, parks, roadsides, and wastelands to represent the influence of corresponding human actions. After cleaning the samples through wet peroxide digestion and density separation, MPs were identified under a stereomicroscope. The range of MPs in top soils within Lahore district varied from 1750 to 12,200 MPs/kg with an average of 4483 ± 2315 MPs/kg. The highest concentration of MPs was present in the parks while the lowest numbers of MPs were enumerated in soil from dumping sites. About 99% of the identified MPs particles were fibers, sheets, and fragments in shape while foams and beads accounted for the rest. Moreover, among the size ranges, the large size MPs (300-5000 µm) were found in the majority (41.16%) followed by the fine size MPs (50-150 µm; 30.67%) and medium size MPs (150-300 µm; 28.17%). The current level of MPs pollution attracts the attention of researchers for a more comprehensive investigation in the future. It also incites the policy-makers to implement the regulations to prevent plastic pollution and its environmental implications.


Assuntos
Solo , Poluentes Químicos da Água/análise , Cidades , Monitoramento Ambiental , Humanos , Microplásticos , Paquistão , Plásticos
19.
J Environ Qual ; 49(1): 119-127, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33016350

RESUMO

Eutrophication is an issue of concern in many brackish lakes with an agricultural watershed. The amount of snowfall in snowy areas is anticipated to decline because of global climate change. The aim of this study was to assess the impact of changes in the inflow of snowmelt on the nutrient concentrations of a downstream brackish lake. In Lake Ogawara, a brackish lake in a snow-covered agricultural area of Japan, we examined the relationships between inflowing river discharge (D/C) during spring and total nitrogen (TN) and total phosphorus (TP) concentrations in the mixolimnion of the lake ([TNmix ] and [TPmix ], respectively) using 29 yr of monitoring data. In addition, we assessed the causal relationship between the D/C and the lake nutrient concentrations. There was large year-to-year variation in D/C during April (D/CApr ), which accounted for 7-31% of the mixolimnion volume. Significant positive correlations were observed between D/CApr and [TNmix ] from the ensuing April to September. On an annual basis, 49% of the interannual variation of the mean [TNmix ] during the ensuing April to September was explained by the interannual variation of D/CApr . Therefore, D/CApr could be useful as a simple index to [TNmix ] in the ensuing spring to summer. It is notable that the relationships between D/CApr and [TNmix ] from April to September was indicated to be acausal by statistical causal inference. Common climate conditions that increase D/CApr (i.e., a cold winter with a high level of precipitation) were found to drive other biogeochemical processes that increased [TNmix ] during the ensuing spring to summer.


Assuntos
Lagos , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Nitrogênio/análise , Fósforo/análise
20.
J Environ Qual ; 49(1): 128-139, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33016363

RESUMO

The Variable Volume Water Model (VVWM), the receiving water body model for the USEPA regulatory assessment of aquatic pesticide exposures, is composed of a set of static and quasistatic receiving water body conceptual models, but research comparing performance of these models to observations is limited. The water body models included are the constant volume (CVol), constant volume with overflow (CVO), and varying volume with overflow (VVO) models. This work quantified the performance of these three VVWM conceptual models compared with atrazine observations in 50 community water systems (CWSs), and the effect of alternative conceptual models on estimated environmental concentrations of pesticides in regulatory screening assessments. The 50 selected CWSs most relevant to the static and quasistatic VVWM concepts were small in size, with estimated time to peak flow of <1.5 d for consistency with the daily runoff assumption in USEPA landscape Pesticide Root Zone Model (PRZM). The CVO and VVO conceptual models resulted in similar distributions of bias across CWSs with the median result being close to no bias, but the CVol model resulted in overestimation in the majority of CWSs with median model bias near three times the observed values. At present, the CVol conceptual model parameterized with conservative input assumptions has been the regulatory standard invoked in VVWM, yet our results showed that a more physically correct conceptual model (CVO or VVO) could be invoked in regulatory exposure modeling for ecological risk assessment, reducing structural model bias while still allowing users to introduce conservative model inputs for screening purposes.


Assuntos
Atrazina , Praguicidas/análise , Praguicidas/toxicidade , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Modelos Teóricos , Água
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