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1.
Rev Environ Contam Toxicol ; 251: 1-24, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31011831

RESUMO

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


Assuntos
Exposição Ambiental/análise , Metais Pesados/análise , Poluentes Químicos da Água/análise , Poluição Química da Água/estatística & dados numéricos , Exposição Ambiental/estatística & dados numéricos , Monitoramento Ambiental , Humanos , Lagos , Rios
2.
Rev Environ Contam Toxicol ; 248: 111-189, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-30671689

RESUMO

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


Assuntos
Monitoramento Ambiental , Metais/análise , Mineração , Rios , Poluentes Químicos da Água/análise , Água Doce , Sedimentos Geológicos/química
3.
J Environ Qual ; 48(4): 978-987, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31589677

RESUMO

Controls on nutrient transport in cold, low-relief agricultural regions vary dramatically among seasons. The spring snowmelt is often the dominant runoff and nutrient loading event of the year. However, climate change may increase the proportion of runoff occurring with rainfall, and there is an urgent need to understand seasonal controls on nutrient transport to understand how patterns may change in the future. In this study, we assess patterns and drivers of total P (TP) dynamics in eight streams draining agriculturally dominated watersheds, located in southern Manitoba, Canada. Data from three years of monitoring revealed highly coherent patterns of TP concentrations in streams, with pronounced peaks in the spring and midsummer across the region. This coherent pattern was in spite of considerable interannual variability in the magnitude and timing of discharge; in particular, a major storm event occurred in summer 2014, which resulted in more discharge than the preceding spring melt. Concentration-discharge model fits were generally poor or not significant, suggesting that runoff generation is not the primary driver of TP dynamics in the majority of streams. Seasonal patterns of conductivity and stream temperature suggest that mechanisms controlling TP vary by season; a spring TP concentration maximum may be related to surface runoff over frozen soils, whereas the summer TP maximum may be related to temperature-driven biogeochemical processes, which are not well represented in current conceptual or predictive models. These findings suggest that controls on stream TP concentrations are dynamic through the year, and responses to increases in dormant and nondormant season temperatures may depend on seasonally variable processes.


Assuntos
Fósforo , Rios , Canadá , Monitoramento Ambiental , Estações do Ano , Movimentos da Água
4.
J Environ Qual ; 48(4): 1057-1066, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31589682

RESUMO

Over-the-counter and prescription medications are routinely present at detectable levels in surface and groundwater bodies. The presence of these emerging contaminants has raised both environmental and public health concerns, particularly when the water is used for drinking either directly or with additional treatment. However, the frequency of occurrence, range of concentrations, and potential human health risks are not well understood, especially for groundwater supplies. Private wells are often not tested for contaminants regulated by drinking water standards and are even less frequently tested for emerging contaminants. By partnering with the Pennsylvania Master Well Owner Network, water samples were collected from 26 households with private wells in the West Branch of the Susquehanna River basin in central Pennsylvania in winter 2017. All samples were analyzed for six pharmaceuticals (acetaminophen, ampicillin, naproxen, ofloxacin, sulfamethoxazole, and trimethoprim) and one over-the-counter stimulant (caffeine). At least one compound was detected at each site. Ofloxacin and naproxen were the most and least frequently detected compounds, respectively. Concentrations from the groundwater wells were higher than those of nearby surface water samples. However, risk calculations revealed that none of the concentrations measured in groundwater samples posed significant human health risk. A simple, physicochemical-based modeling approach was used to predict pharmaceutical transport from septic absorption field to groundwater and further elucidate variations in detection frequencies. Findings indicate that although septic tanks may act as contaminant sources for groundwater wells, the human health impacts from trace-level pharmaceuticals that may be present are likely minimal.


Assuntos
Água Subterrânea , Poluentes Químicos da Água , Monitoramento Ambiental , Humanos , Pennsylvania , Rios
5.
J Environ Qual ; 48(5): 1507-1516, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589715

RESUMO

The chemical and stable isotopic compositions (δS and δO) of Xijiang River water in southwest China, were measured to determine the extent of rock weathering and associated CO consumption rates, and to assess the contamination sources of river water. The SO concentration in the river water was in the range of 0.05 to 0.96 mmol L (mean value = 0.32 mmol L) and was characterized by δS values ranging from -9.1 to 5.1‰ (mean value = -2.1‰) and δO values ranging from -0.4 to 10.8‰ (mean value = 5.0‰). The δS and δO values ranged from high to low from the upper reaches to the lower reaches in all the river water samples. The results indicate that the oxidation of sulfide and anthropogenic inputs are the dominant processes affecting SO sources and S cycling of the Xijiang River during high-discharge conditions, which are controlled by regional hydrological processes that are affected by natural processes and anthropogenic inputs.


Assuntos
Rios , Poluentes Químicos da Água , China , Monitoramento Ambiental , Isótopos de Oxigênio , Sulfatos , Enxofre
6.
J Environ Qual ; 48(5): 1481-1488, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589716

RESUMO

The primary tool used currently for preventing pesticide drift from entering streams is a no-spray buffer zone. Riparian hedgerows may provide an additional option; however, quantitative information on their effectiveness is limited. To quantify the potential benefit of riparian hedgerows for drift reduction, aerial malathion {diethyl 2-[(dimethoxyphosphorothioyl)sulfanyl]butanedioate} applications on blueberry ( L.) farms with fields adjacent to streams or ditches were monitored. Drift from fields with extensive dense woody riparian vegetation was compared with drift from fields with no dense woody riparian vegetation. Overall, total instream malathion deposition was 96.1% lower at vegetated sites compared with nonvegetated sites. Univariable models identified six variables that were significantly related to decreasing instream total malathion deposition: increasing bank canopy cover, increasing average site canopy cover, increasing canopy angle, increasing the distance between the field edge and vegetation edge, increasing the distance between the field edge and center of stream, and decreasing bank slope. For the variables most feasible for landowners to alter, the following increases could result, on average, in a 26% decrease in the total instream malathion deposition: bank canopy cover (7%), distance between field and vegetation (0.3 m), and distance between field and center of stream (0.9 m). No-spray buffer sizes needed for significant deposition reductions may be large, but for nonvegetated or minimally vegetated streams similar to those studied here, increasing bank canopy cover may give comparable advantages while allowing the use of the entire field area and conferring additional ecosystem benefits such as shading streams and improving habitat.


Assuntos
Ecossistema , Praguicidas , Rios , Madeira
7.
J Environ Qual ; 48(5): 1336-1346, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589719

RESUMO

The broken phosphorus (P) cycle has led to widespread eutrophication of freshwaters. Despite reductions in anthropogenic nutrient inputs that have led to improvement in the chemical status of running waters, corresponding improvements in their ecological status are often not observed. We tested a novel combination of complementary statistical modeling approaches, including random-effect regression trees and compositional and ordinary linear mixed models, to examine the potential reasons for this disparity, using low-frequency regulatory data available to catchment managers. A benthic Trophic Diatom Index (TDI) was linked to potential stressors, including nutrient concentrations, soluble reactive P (SRP) loads from different sources, land cover, and catchment hydrological characteristics. Modeling suggested that SRP, traditionally considered the bioavailable component, may not be the best indicator of ecological impacts of P, as shown by a stronger and spatially more variable negative relationship between total P (TP) concentrations and TDI. Nitrate-N ( < 0.001) and TP ( = 0.002) also showed negative relationship with TDI in models where land cover was not included. Land cover had the strongest influence on the ecological response. The positive effect of seminatural land cover ( < 0.001) and negative effect of urban land cover ( = 0.030) may be related to differentiated bioavailability of P fractions in catchments with different characteristics (e.g., P loads from point vs. diffuse sources) as well as resilience factors such as hydro-morphology and habitat condition, supporting the need for further research into factors affecting this stressor-response relationship in different catchment types. Advanced statistical modeling indicated that to achieve desired ecological status, future catchment-specific mitigation should target P impacts alongside multiple stressors.


Assuntos
Monitoramento Ambiental , Fósforo , Ecossistema , Eutrofização , Água Doce , Rios
8.
J Environ Qual ; 48(5): 1325-1335, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31589730

RESUMO

Transitional ecotones such as vegetated buffer strips, stream banks, and streambeds retain phosphorus (P) in the immediate surroundings of farmland. Yet the fate of P in these ecotones remains unclear. Our objectives were to (i) test the difference in the P pool composition of soil and sediment between sites surrounded by agriculture and forestry and (ii) test whether specific P pools differ among transitional ecotones. Phosphorus pools (by a modified Hedley fractionation scheme) and the degree of P saturation (DPS) were determined in 33 soil and sediment samples from eight farmland and three forest sites. At farmland sites, total P in soil and sediment was more than twofold higher as compared to forestry sites. The proportion of labile inorganic P (Pi) and the DPS were significantly larger in transitional ecotones close to farmland. We further used normalized values for comparing the respective ecotones at the sites. The deviation of each transitional ecotone relative to the respective site average revealed that the normalized total P concentration and proportions of labile and moderately labile Pi were significantly smaller in bed sediment adjacent to farmland as compared to respective stream bank and buffer strip soil, whereas the stable Ca-Pi proportion was larger. The results reflected a decreased Pi sorption capacity in combination with Pi desorption and transfer of Pi into secondary Ca-Pi minerals in bed sediment. In summary, the influence of agriculture increases labile P pools in soil and sediment, which are then subject to a succession of dynamic processes resulting in a partial loss of Pi to the aqueous phase as well as fixation of Pi in the Ca-Pi pool.


Assuntos
Fósforo , Solo , Agricultura , Monitoramento Ambiental , Rios
9.
Water Sci Technol ; 80(3): 408-417, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31596252

RESUMO

Trash is one of major pollutants in urban runoff. Some studies have been conducted to verify the different impacts of land use on trash generation in a qualitative way and focused on the performance of trash control measures. Few studies have explored the human impacts on trash generation or developed a quantitative model to describe the phenomenon. This paper examined the impact of human activity on trash generation. Spatial regimes on high trash generation areas were identified using the selected variables from best subset model regression and validated with Moran's I scatter plot and spatial analysis of variance. Bidirectional spatial lag regression with regimes was performed to develop the final model to explain the spatial distribution of trash generation and identify its major causes. The result showed that economic status and occupation of the population were correlated with trash accumulation and the dominant land use type, and the distance to rivers most affected trash generation. The effects of these indicators were different within and outside the high trash generation areas.


Assuntos
Resíduos/estatística & dados numéricos , Cidades , Resíduos de Alimentos , Humanos , Los Angeles , Eliminação de Resíduos , Rios , Fatores Socioeconômicos
10.
Water Sci Technol ; 80(3): 551-562, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31596266

RESUMO

Exposure to antibiotics, biocides, chemical preservatives, and heavy metals in different settings such as wastewater treatment plants (WWTPs) may apply selective pressure resulting in the enrichment of multiple resistant, co- and cross-resistant strains of bacteria. The purpose of this study was to identify and characterize potentially pathogenic triclosan (TCS) - and/or, chloroxylenol (PCMX) tolerant bacteria from sewage and river water in the North-West, Potchefstroom, South Africa. Several potential pathogens were identified, with Aeromonas isolates being most abundant. Clonal relationships between Aeromonas isolates found at various sampling points were elucidated using ERIC-PCR. Selected isolates were characterized for their minimum inhibitory concentrations against the biocides, as well as antibiotic resistance profiles, followed by an evaluation of synergistic and antagonistic interactions between various antimicrobials. Isolates were also screened for the presence of extracellular enzymes associated with virulence. High-performance liquid chromatography revealed the presence of both biocides in the wastewater, but fingerprinting methods did not reveal whether the WWTP is the source from which these organisms enter the environment. Isolates exhibited various levels of resistance to antimicrobials as well as several occurrences of synergy and antagonisms between the biocides and select antibiotics. Several isolates had a very high potential for virulence but further study is required to identify the specific virulence and resistance genes associated with the isolates in question.


Assuntos
Desinfetantes , Eliminação de Resíduos Líquidos , Águas Residuárias/microbiologia , Antibacterianos , Farmacorresistência Bacteriana/genética , Testes de Sensibilidade Microbiana , Rios , Esgotos , África do Sul
11.
J Water Health ; 17(5): 749-761, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31638026

RESUMO

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


Assuntos
Água Potável , Purificação da Água/métodos , Brasil , Condutividade Elétrica , Monitoramento Ambiental , Rios , Poluentes Químicos da Água/análise , Qualidade da Água
12.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 31(4): 374-381, 2019 Sep 25.
Artigo em Chinês | MEDLINE | ID: mdl-31612671

RESUMO

OBJECTIVE: To investigate the spatial distribution of Oncomelania hupensis snail habitats at the administrative village scale in schistosomiasis-endemic areas of Hubei Province, so as to provide scientific bases for precise control of O. hupensis snails in the province. METHODS: Data regarding snail distribution at the village level in Hubei Province in 2017 were collected to create a spatial analysis database of snail distribution in Hubei Province. The spatial aggregations of O. hupensis distribution were analyzed using Moran's I index and Local Moran's I index. In addition, the distances from schistosomiasis-endemic villages to the Yangtze River were captured using the software ArcGIS 13.0, and their correlations with area of snail habitats were examined with the Spearman correlation method. RESULTS: O. hupensis snails were mainly distributed in 5 450 endemic villages from 63 counties of 13 cities in Hubei Province in 2017. The global spatial autocorrelation analysis showed spatial aggregations in the areas of historically accumulated snail habitats, current areas of snail habitats, areas of snail habitats outside the embankment and snail habitats inside the embankment (all Z Scores > 0, all P values < 0.05), and no spatial aggregation was seen in the areas of snail habitats in hilly areas (Z Score > 0, P > 0.05). There were four types of spatial distribution of historically accumulated areas of snail habitats, areas of current snail habitats, areas of snail habitats outside the embankment and snail habitats inside the embankment, including the high-high type (H-H type), high-low type (H-L type), low-high type (L-H type) and random distribution type, and a high percentage of the H-H type was found. There were 340, 125 and 110 endemic villages with the H-H type of areas of historically accumulated snail habitats, current areas of snail habitats and areas of snail habitats outside the embankment, and these villages were mainly concentrated in Wuhan and Jingzhou cities, with almost consistent spatial aggregation locations. There were 319 endemic villages with the H-H type of distribution of snail habitats inside the embankment, which were mainly distributed in Jingzhou, Xiaogan and Huangshi cities. In addition, the areas of historically accumulated snail habitats, current areas of snail habitats and areas of snail habitats outside the embankment negatively correlated with the distance from the endemic villages to the Yangtze River (r = -0.094, P < 0.01; r = -0.225, P < 0.01; r = -0.177, P < 0.01). CONCLUSIONS: The clustering areas of snail habitats along the Yangtze River Basin, notably the villages near the Yangtze River are key regions for snail monitoring and control in Hubei Province.


Assuntos
Distribuição Animal , Rios , Esquistossomose , Caramujos , Animais , China/epidemiologia , Ecossistema , Humanos , Rios/parasitologia , Schistosoma/fisiologia , Esquistossomose/epidemiologia , Esquistossomose/prevenção & controle , Esquistossomose/transmissão , Caramujos/parasitologia , Caramujos/fisiologia , Análise Espacial
13.
Zhongguo Xue Xi Chong Bing Fang Zhi Za Zhi ; 31(4): 434-435, 2019 Sep 19.
Artigo em Chinês | MEDLINE | ID: mdl-31612683

RESUMO

OBJECTIVE: To analyze the surveillance data after schistosomiasis transmission interruption from 1985 to 2018, so as to provide scientific basis for the future prevention and control of schistosomiasis. METHODS: The data pertaining to snail survey, surveillance of schistosomiasis in humans and livestock, and health education were collected and analyzed in Songjiang District after schistosomiasis transmission interruption from 1985 to 2018. RESULTS: From 1985 to 2018, there were 8 townships, 68 villages and 1 462 settings with snails in Songjiang District, covering an area of 96.399 hm2. There were 4 townships and 59 villages with snails newly identified in previously schistosomiasis non-endemic areas, with emerging snail habitats of 60.161 hm2. A total of 26 148 snails were captured, and no infections were detected. The snail habitats were mainly distributed in the river course, ditches and farmlands, which accounted for 45.28%, 33.17% and 21.55% of total snail habitats, respectively. A total of 245 955 humans were subjected to the serological test, with a positive rate of 0.03%, and 37 humans were subjected to the parasitological test, with 3 positives detected. These three egg-positives were all imported chronic cases with schistosomiasis. A total of 9 109 livestock were detected using the serological test, and no infection was found. Most of the awareness rate of schistosomiasis control knowledge and the rate of correct behavior formation were over 80% in residents and students. CONCLUSIONS: The achievements of schistosomiasis control are consolidated in Songjiang District; however, there are still risk factors of schistosomiasis transmission, including residual snails, snail diffusion and importation of external source of infection. The future surveillance of schistosomiasis should focus on snails and sources of infection.


Assuntos
Esquistossomose , Caramujos , Animais , China/epidemiologia , Ecossistema , Humanos , Gado/parasitologia , Vigilância da População , Prevalência , Rios , Esquistossomose/epidemiologia , Esquistossomose/prevenção & controle , Caramujos/parasitologia
14.
Ann Parasitol ; 65(3): 287-291, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31599557

RESUMO

The nematode parasites can cause mechanical injuries such as irritation or atrophy of tissue and occlusions of the digestive tract, blood vessels or other ducts in their hosts. Some species belonging to the family Camallanidae have been the focus of histopathological studies because they lacerate the host´s intestinal wall with their buccal capsule. In this study, we describe the histopathological effects produced by Procamallanus (Spirocamallanus) pintoi in the small fish Corydoras micracanthus from Lesser River, in the northwest of Argentina, South America. The samples were processed with routine histology techniques. At light microscopy, specimens of P. (S.) pintoi were observed occupying the lumen of the gut. The histopathological sections revealed damage to the host intestine with the total destruction of the mucosa and submucosa, observed mainly in the region which is surrounding the buccal capsule of parasites. Moreover, an inflammatory reaction was observed with lymphatic accumulations in the affected tissue. This kind of degenerative and necrotic changes in the mucosa could affect negatively the absorption function of the host intestine, which may have adverse effects of the health status of fish. The present study provides the firs data about the histopathological effects of P. (S.) pintoi in C. micracanthus.


Assuntos
Peixes-Gato , Doenças dos Peixes , Nematoides , Infecções por Nematoides , Animais , Argentina , Peixes-Gato/parasitologia , Doenças dos Peixes/patologia , Infecções por Nematoides/patologia , Infecções por Nematoides/veterinária , Rios
15.
An Acad Bras Cienc ; 91(3): e20180494, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31618409

RESUMO

Invasive populations of macrophytes are widely distributed and have been successfully introduced and established in freshwater habitats. Hydrilla verticillata was first recorded in 2005 in the Upper Paraná River floodplain and in 2007 at the Itaipu Reservoir (Brazil-Paraguay border, ca. 300 km downstream from its first record). However, its genetic variability within different sites in South America is unknown. We used nucleotide sequences corresponding to the trnL-trnF fragment cpDNA to genetically characterize populations of H. verticillata in different ecosystems of the Upper Paraná River basin. The results indicated an absence of genetic differentiation within and between populations of the basin, and even individuals collected 600 km apart belonged to the same haplotype. Moreover, H. verticillata populations of the Upper Paraná River basin also matched the dioecious biotype haplotype of the Southern United States and Asia. The identification of this single haplotype suggests that one founder genotype was introduced and established successfully in the Upper Paraná River basin, then, as a consequence of vegetative reproduction and the dispersal of propagules, spread to different habitats. However, firm conclusions about this inference can only be obtained with markers of biparental inheritance.


Assuntos
Ecossistema , Hydrocharitaceae/genética , Rios , Brasil , DNA de Cloroplastos , Variação Genética , Espécies Introduzidas , Análise de Sequência de DNA
16.
An Acad Bras Cienc ; 91(3): e20180692, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31618411

RESUMO

The assessment of biotic-habitat relationships provides key information to predict biotic responses to perturbations and important tools for river management and monitoring. This study aimed to assess the spatial distribution of Ephemeroptera and Trichoptera in mountain streams of central Argentina. We evaluated the effect of seasonality and identified the variables conditioning the abundance of the assemblages and the habitat with the highest taxonomic richness. Sampling was carried out in four streams (Carcarañá River basin) during high and low water periods. Three lotic habitats were sampled: riffles, coarse substrate runs, and fine substrate runs; and physicochemical and habitat variables were measured. We found differences in assemblage composition, among the 25 genera of Ephemeroptera and Trichoptera, at the habitat level. The most important variables affecting distribution patterns were substrate and flow type, but macroalgae and organic matter (twigs, leaves, and detritus) were also important predictors. Riffles maintained the highest richness but when considering only the Ephemeroptera taxa, fine substrate runs emerged also as an important habitat for these taxa. Our study provided valuable ecological information related to habitat preference of taxa with a key role in stream functioning and of great usefulness for the monitoring of lotic systems.


Assuntos
Ecossistema , Monitoramento Ambiental/métodos , Ephemeroptera/fisiologia , Neópteros/fisiologia , Rios , Animais , Argentina , Ephemeroptera/classificação , Neópteros/classificação , Análise de Componente Principal , Especificidade da Espécie
17.
Water Sci Technol ; 80(4): 707-716, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31661450

RESUMO

Bioretention is an effective technology for urban stormwater management, but the nutrient removal in conventional bioretention systems is highly variable. Thus, a pilot bioretention column experiment was performed to evaluate the nutrient control of systems with commercial activated carbon and river sediment-derived biochar. Significant chemical oxygen demand (COD) and total phosphorus (TP) leaching were found with the addition of activated carbon and biochar, but total nitrogen (TN) leaching was significantly improved when activated carbon was used as the medium. During a semi-synthetic runoff experiment, the bioretention systems containing two types of fluvial biochar showed relatively better COD and TN control (average mass removal efficiencies and cumulative removal efficiencies) than commercial activated carbon. However, the average TP mass removal efficiency with commercial activated carbon (95% ± 3%) was significantly higher than biochar (48% ± 20% and 56 ± 14%). The addition of biochar in the media increased the nitrogen removal efficiency, and the addition of activated carbon significantly increased the phosphorous removal efficiency. Therefore, both biochar and activated carbon are effective materials for bioretention, and fluvial biochar provides an alternative approach to comprehensively utilize river sediment.


Assuntos
Carvão Vegetal , Rios , Nutrientes , Fósforo
19.
Ying Yong Sheng Tai Xue Bao ; 30(10): 3463-3472, 2019 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-31621233

RESUMO

A total of six treatments, including continuous conventional tillage (CT), rotary tillage (RT), subsoiling (ST), no-tillage (NT), conventional-no tillage (CT-NT) and subsoiling-no tillage (ST-NT), were conducted to examine the effects of different tillage types on soil aggregates distribution and stability of irrigated sierozem on continuous 8-year-tillage maize fields in the Gansu Yellow River irrigated area in 2014-2017. The results showed that the aggregation and stability of large aggregates in 0-40 cm soil layer were increased by NT and ST-NT treatments, while the size distribution and stability in plough layer were significantly decreased by CT and RT treatments due to strong soil disturbance. Compared with RT, the mechanical stability of aggregates under dry sieving NT was the best. The contents of >0.25 mm aggregate (R0.25), mean weight diameter (MWD) and geometric mean diameter (GMD) increased by 5.8%, 8.0%, and 13.0%, respectively, and fractal dimension (D) decreased by 3.6%. The water-stable aggregates in ST-NT was the best, with R0.25, MWD and GMD increased by 55.3%, 15.1% and 8.7%, respectively, and D value decreased by 0.8%. The percentage of aggregate destruction (PAD) and unstable aggregate index (ELT) of NT and ST-NT treatments were the lowest. PAD was reduced by 5.9% and 7.7% compared with RT, ELT was reduced by 5.8% and 7.2%, respectively. All the results indicated that the subsoiling-notillage (ST-NT) rotation mode was more conducive to the enhancement of soil aggregate content and stability and consistent with the local farmers operating habits, which would be an ideal tillage method and had certain application value for the sustainable agricultural development in this area.


Assuntos
Rios , Solo , Agricultura , China , Zea mays
20.
Ying Yong Sheng Tai Xue Bao ; 30(10): 3518-3526, 2019 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-31621239

RESUMO

To explore the effects of Spartina alterniflora invasion in a seaward direction on variations of inorganic sulfur forms in marsh soils, the levels of inorganic sulfur forms (H2O-S, Adsorbed-S, HCl-Soluble-S and HCl-Volatile-S) were determined in bare flat (BF, before invasion), S. alterniflora marsh after seaward invasion for one year (SA') and S. alterniflora marsh after seaward invasion for three years (SA) in Shanyutan of the Minjiang River estuary with the method of space-for-time substitution. Results showed that the seaward invasion of S. alterniflora altered the stocks and distribution of inorganic sulfur form in marsh soils. Compared with BF, the contents of H2O-S, Adsorbed-S and HCl-Volatile-S in soils of SA increased by 52.6%, 78.2% and 21.0%, respectively, while that of HCl-Soluble-S decreased by 3.4%. In contrast, the levels of H2O-S, Adsorbed-S and HCl-Soluble-S in soils of SA' increased by 43.9%, 70.6% and 29.6%, respectively, whereas that of HCl-Volatile-S decreased by 11.6%. The contents of total inorganic sulfur (TIS) in soils of SA and SA' increased by 40.7% and 37.8%, while the stocks of TIS increased by 26.8% and 31.4%, respectively. The key factors affecting different forms of inorganic sulfur in marsh soils had changed due to the seaward invasion of S. alterniflora. In particular, the key factors affecting the variations of H2O-S contents changed from soil grain composition and bulk density in BF to soil organic matter in SA' and SA. The seaward invasion of S. alterniflora significantly increased the content of TIS in marsh soils, which was mainly contributed by H2O-S and Adsorbed-S. Thus, it was concluded that the seaward invasion of S. alterniflora significantly increased the supply capacity of available sulfur in marsh soils, which, to some extent, accelerated its seaward invasion.


Assuntos
Solo , Áreas Alagadas , China , Estuários , Espécies Introduzidas , Poaceae , Rios , Enxofre
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