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1.
J Environ Qual ; 49(3): 613-627, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016388

RESUMO

Regulatory watershed mitigation programs typically emphasize widespread adoption of best management practices (BMPs) to meet total maximum daily load (TMDL) goals. To comply with the Chesapeake Bay TMDL, jurisdictions must develop watershed implementation plans (WIPs) to determine the number and type of BMPs to implement. However, the spatial resolution of the bay-level model used to determine these load reduction goals is so coarse that the regulatory plan cannot consider heterogeneity in local conditions, which affects BMP effectiveness. Using the Topo-SWAT modification of the Soil and Water Assessment Tool (SWAT), we simulated two BMP adoption scenarios in the Spring Creek watershed in central Pennsylvania to determine if leveraging fine-scale spatial heterogeneity to place BMPs could achieve the same (or better) nutrient and sediment reduction at a lower cost than the state-level WIP BMP adoption recommendations. Topo-SWAT was initialized with detailed land use and management practice information, systematically calibrated, and validated against 12 yr of observed data. After determining individual BMP cost effectiveness, results were ranked to design a cost-effective BMP adoption scenario that achieved equal or greater load reduction as the WIP scenario for 74% of the cost using eight management-based BMPs: no-till, manure injection, cover cropping, riparian buffers, land retirement, manure application timing, wetland restoration, and nitrogen management (15% less N input). Because watersheds of this size typically represent the smallest modeling unit in the Chesapeake Bay Model, results demonstrate the potential to use watershed models with finer inference scales to improve recommendations for BMP implementation under the Chesapeake Bay TMDL.


Assuntos
Nitrogênio/análise , Solo , Conservação dos Recursos Naturais , Pennsylvania , Áreas Alagadas
2.
Water Sci Technol ; 82(5): 954-966, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33031073

RESUMO

The sewage treatment system in this study was operated with only the first stage of a French system of vertical wetlands, composed of two units in parallel and running with an extended feeding cycle (7 days). This research sought to evaluate and relate continuous variables measured in situ (dissolved oxygen (DO), pH and redox potential) throughout the feeding cycle, with measurements at distinct heights along the filter vertical profile. Additionally, the influence of the surface organic sludge deposit was investigated. A close link between the hydraulic behaviour and the effluent quality was verified, with both being related to the batch volume and the instantaneous hydraulic loading rate. The drop in DO as the feed days progressed could be related to the loss of hydraulic conductivity. A thicker sludge layer decreased the aeration capacity of the filter. The effluent was observed to be aerated when percolating through the medium. DO and pH data suggested that nitrification varied along the filter depth, the batch duration and the feed cycle. The monitored parameters may be indicative of the behaviour of other parameters.


Assuntos
Esgotos , Áreas Alagadas , Clima , Nitrificação , Oxigênio
3.
J Environ Qual ; 49(1): 194-209, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33016349

RESUMO

Understanding relationships between an increase in nitrate (NO3 - ) loading and the corresponding effects of wetland vegetation on denitrification is essential to designing, restoring, and managing wetlands and canals to maximize their effectiveness as buffers against eutrophication. Although Phragmites australis (Cav.) Trin. ex Steud. is frequently used to remediate nitrogen (N) pollution, no information is available on how NO3 - concentration may affect plant-mediated denitrification. In the present study, denitrification was measured in outdoor vegetated and unvegetated mesocosms incubated in both summer and winter. After spiking the mesocosms with NO3 - concentrations typical of agricultural drainage water (0.7-11.2 mg N L-1 ), denitrification was quantified by the simultaneous measurement of NO3 - consumption and dinitrogen gas (N2 ) production. Although denitrification rates varied with vegetation presence and season, NO3 - availability exerted a significant positive effect on the process. Vegetated sediments were more efficient than bare sediments in adapting their mitigation potential to an increase in NO3 - , by yielding a one-order-of-magnitude increase in NO3 - removal rates, under both summer (743-6007 mg N m-2 d-1 ) and winter (43-302 mg N m-2 d-1 ) conditions along the NO3 - gradient. Denitrification was the dominant sink for water NO3 - in winter and only for vegetated sediments in summer. Nitrification likely contributed to fuel denitrification in summer unvegetated sediments. Since denitrification rates followed Michaelis-Menten kinetics, P. australis-mediated depuration may be considered optimal up to 5.0 mg N L-1 . The present outcomes provide experimentally supported evidence that restoration with P. australis can work as a cost-effective means of improving water quality in agricultural watersheds.


Assuntos
Desnitrificação , Nitratos , Nitrogênio , Poaceae , Áreas Alagadas
4.
J Environ Qual ; 49(1): 210-219, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33016351

RESUMO

Reed canary grass (Phalaris arundinacea L.) is an invasive, cool-season grass commonly dominating wetlands with high nutrient loads. Its impact on nitrogen removal via denitrification in wetlands is unknown. Most studies of denitrification in treatment wetlands have focused on the effects of physical or chemical variables and not on the effects of plant roots on the soil environment. The purpose of this study was to measure effects of plant type on denitrification rates in typical wetland soils of the midwestern United States by comparing wet prairie mix, switchgrass-dominated, and reed canary grass plant communities. Nitrate (NO3 - ) removal and other parameters were measured in miniature wetlands, or mesocosms, containing each plant community transplanted from a small agricultural treatment wetland in southern Minnesota. Quantitative polymerase chain reaction analysis was used to quantify the total bacteria population (measured with 16S rRNA genes) and denitrifying gene abundance (measured with nosZ genes) from the rhizosphere of each plant community. The wet prairie mix mesocosms on average removed the most NO3 - in each test (p = .01 and .08). Whereas the wet prairie mix removed the most NO3 - from the surface water (p < .01), reed canary grass removed more from the subsurface (p < .01). Ratios of denitrifying to total bacteria were higher in the wet prairie mix than in the other communities' root zones (p < .05). Results suggest that reed canary grass invasion could reduce denitrification in wetlands, especially during the spring and fall when it is growing but other plants are dormant.


Assuntos
Bactérias/genética , Áreas Alagadas , Meio-Oeste dos Estados Unidos , Minnesota , RNA Ribossômico 16S
5.
J Environ Qual ; 49(1): 106-118, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33016362

RESUMO

Plant nursery runoff commonly contains pesticides and nutrients that often threaten aquatic ecosystems. Constructed wetlands could be a tool to remove pesticides and nutrients from nursery runoff but have not been extensively studied in this setting. Two field-scale constructed wetlands (one subsurface-flow constructed wetland [SFCW] and one free-surface constructed wetland [FSCW]) were implemented and monitored for water quality improvement. The SFCW demonstrated significant mass reduction of 78% or greater for nitrate, orthophosphate, total nitrogen, total phosphorus, and total suspended solids. The SFCW also demonstrated significant mass reduction of 79% or greater for 10 of the 12 pesticide compounds detected in over half of the collected samples. The FSCW demonstrated significant mass reduction of 46% or greater for all nonpesticide analytes except total nitrogen. Loading rate and actual storage volume compared with inflow volume likely affected performance. Reduced size and increased loading rate of the FSCW likely reduced its ability to effectively reduce pesticides. Results from this study indicate that constructed wetlands are likely an effective tool for nursery runoff management. When designing and implementing constructed wetlands, it is important for practitioners to consider the tradeoff between system size (additional cost and land otherwise dedicated to production) and performance.


Assuntos
Poluentes Ambientais , Áreas Alagadas , Ecossistema , Nitrogênio , Fósforo
6.
J Environ Qual ; 49(1): 236-245, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33016366

RESUMO

Antimicrobials used in livestock production can be present in manure via excretion in the feces and/or urine. Application of raw or processed (composted or stockpiled) manure to crop and pasture land as a plant nutrient source can result in antimicrobial transport to surface waters via rainfall or snowmelt runoff. Little is known regarding antimicrobial persistence in aquatic ecosystems. Consequently, dissipation of environmentally relevant concentrations of three veterinary antimicrobials (lincomycin, chlortetracycline, and sulfamethazine) was studied in three wetlands on the Canadian Prairies. Study wetlands were fortified in the fall to simulate antimicrobial transport via rainfall runoff from fall manure applications to the wetland catchments. After fortification, water column concentrations of all three antimicrobials decreased through September and October. Plotting natural logarithm values of antimicrobial concentration against time resulted in linear relationships for all three antimicrobials, indicating that the summation of all dissipation processes for each antimicrobial could be described by first-order kinetics. The slopes of the three plots were significantly different, indicating that the order of dissipation was lincomycin < sulfamethazine < chlortetracycline. Consequently, the dissipation DT50 (time required for 50% antimicrobial dissipation) values for lincomycin (14.0 d), sulfamethazine (7.0 d), and chlortetracycline (3.3 d) were significantly different. The longer DT50 values of lincomycin and sulfamethazine suggest that environmentally relevant concentrations of these antimicrobials may affect bacterial production in prairie wetlands.


Assuntos
Anti-Infecciosos , Clortetraciclina , Canadá , Ecossistema , Pradaria , Lincomicina , Sulfametazina , Áreas Alagadas
7.
J Environ Qual ; 49(3): 723-734, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016394

RESUMO

Groundwater withdrawal has increased over the past several decades throughout the U.S. Upper Midwest, yet impacts of pumping on groundwater-dependent wetlands remain understudied. Here, we compared measures of floristic quality, hydrologic conditions, and nutrient availability in pairs of more-impacted fens and less-impacted fens throughout Wisconsin. Floristic quality was significantly lower in more-impacted fens than in less-impacted fens, the result of the disappearance of rare and specialist species and the increase in richness and cover of non-native and weedy species. Plots within more-impacted fens generally had lower root-zone volumetric water content, greater depth to water table, and higher available nitrogen and phosphorus than within less-impacted fens, although nonuniformly among or within sites. Lower volumetric water content predicted plot-level declines in floristic quality, richness of rare or specialist species, an increase in the number of non-native or problematic species, and an increase in cover of non-native and problematic species. Our results strongly suggest that groundwater withdrawals have substantial negative impacts on nearby fen quality and furthering imperilment of several species they contain.


Assuntos
Água Subterrânea , Hidrologia , Nitrogênio , Áreas Alagadas , Wisconsin
8.
J Environ Qual ; 49(3): 735-744, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-33016396

RESUMO

Nonpoint-source nitrogen (N) loads in the U.S. Corn Belt are a major concern both for local impacts on receiving waters and for contributing to hypoxia in the Gulf of Mexico. Nonpoint-source nutrient loads can be ameliorated by a combination of in-field and offsite practices, and wetland restoration is a particularly promising approach for reducing N loads from agricultural drainage. However, there is considerable variability among wetlands, and adequate performance data are available for relatively few systems receiving unregulated nonpoint-source loads. We measured N mass balances of 26 restored wetlands receiving a wide range of unregulated, naturally varying hydraulic and nutrient loads to evaluate the N removal performance of these systems and the effects of major factors controlling their performance. Nitrogen loads were primarily in the form of nitrate, and all of the wetlands were effective in reducing both nitrate and total N loads. Nitrate N and total N removal rates averaged 1,500 and 1,440 kg N ha-1  yr-1 , respectively, with the slightly lower total N removal rates reflecting a small net export of reduced N (averaging 66 kg N ha-1  yr-1 ). Average nitrate and total N removal rates were substantially higher than typically reported for Corn Belt wetlands but comparable with highly loaded systems elsewhere. Nitrate removal efficiency ranged from 9 to 92% and was strongly related to hydraulic loading rate and temperature. Results demonstrate the substantial capacity of wetlands to reduce unregulated and highly variable nonpoint-source N loads over a broad range of weather and loading conditions and provide a reasonable basis for predicting average wetland performance based on hydraulic loading rate, temperature, and nitrate concentration.


Assuntos
Qualidade da Água , Áreas Alagadas , Desnitrificação , Nitratos , Nitrogênio/análise
9.
J Environ Qual ; 49(5): 1435-1444, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33016451

RESUMO

Chlortetracycline (CTC), an antimicrobial administered as a feed additive to cattle, swine, and poultry, is present in the corresponding manure. Land application of raw or processed (composted or stockpiled) manure provides a mechanism by which CTC (and other antimicrobials) enters the environment and becomes available for transport to surface receiving waters via rainfall or snowmelt runoff. Chlortetracycline has been detected in Canadian surface waters, but little has been reported on its fate in aquatic ecosystems. To address this knowledge gap, the dissipation of CTC-enol was monitored in deionized water and water typical of wetlands within the prairie region of Canada. In deionized water, CTC-enol tautomerized to CTC-keto, and both tautomers epimerized to 4-epi-CTC-enol and 4-epi-CTC-keto, respectively. Irreversible isomerization to iso-CTC occurred, which then epimerized to 4-epi-iso-CTC. In wetland water, although tauterization of CTC-enol to CTC-keto occurred, there was no evidence of the formation of the 4-epimers of either CTC-enol or CTC-keto. The major product formed in the wetland water was iso-CTC, some of which epimerized to 4-epi-iso-CTC. Although CTC-enol was shown to tautomerize to CTC-keto, the concentration of CTC-keto remained low in both deionized and wetland water, suggesting that the isomerization of CTC-enol to iso-CTC most likely occurred via CTC-keto. The dissipation of CTC-enol in wetland water was described by pseudo first-order kinetics with a DT50 (time required for 50% dissipation) value of 4.8 h. The short DT50 value of CTC and reduced antimicrobial activity of iso-CTC and 4-epi-iso-CTC suggest a lower probability for selection for CTC-resistant bacteria in Canadian Prairie aquatic ecosystems.


Assuntos
Clortetraciclina , Animais , Canadá , Bovinos , Ecossistema , Pradaria , Isomerismo , Suínos , Áreas Alagadas
11.
Zootaxa ; 4858(3): zootaxa.4858.3.2, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33056218

RESUMO

Temnocephala iheringi Haswell, 1893 was recorded in Marisa planogyra Pilsbry, 1933 and Pomacea maculata Perry, 1810. Also, Temnocephala amatoi sp. nov. was described from Pomacea scalaris (d'Orbigny, 1835). The mollusks were collected from temporary ponds at Ypiranga Farm, Poconé, Mato Grosso, Brazil. The new species differs from six other species of Temnocephala Blanchard, 1849 epibionts on molluks by having the following combination of characters: 1. a short and curved cirrus; 2. a narrow introvert with approximately 22 longitudinal rows of spines with 13 spines each; 3. internal spines with a narrow base, longer on the base of the introvert and smaller in the distal portion; 4. a single and asymmetrical vaginal sphincter and; 5. elliptical, longer than wide epidermal 'excretory' syncytial plates (EPs) with a excretory pore displaced to the anterior portion of the plate. Temnocephala lamothei Damborenea Brusa, 2008 has a curved cirrus, similar in size to the new species' cirrus. However, the introvert is not swollen with an oblique proximal margin, marked with a thickened oblique ring and two rows of 45-50 thin spines, differentiating the species from T. amatoi sp. nov.. When comparing the specimens of T. iheringi from Poconé with the redescription of the species from Southern Brazil previously published by the authors, we found significant intraspecific variation in the size of the adhesive disk, pharynx length, shaft and introvert length, spines of the introvert length, as well as differences in the number of paranephrocytes. The size of the EPs and, when comparing with published data from Uruguayan and Argentinean specimens, the body size also showed important differences. We hypothesize that the host species may be the cause of the intraspecific variations found. Overall, the record of two new hosts for T. iheringi, the intraspecific variation found in this species and its geographical distribution being expanded 418 km further to the north, together with the description of a new species, add acknowledgment to the Rhabdocoela fauna in the Brazilian Pantanal.


Assuntos
Platelmintos , Turbelários , Animais , Brasil , Feminino , Moluscos , Áreas Alagadas
12.
J Environ Radioact ; 222: 106324, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32892898

RESUMO

Radium is a naturally occurring radioactive element commonly found at low levels in natural systems such as lacustrine or marine sediments. Anthropogenic activities including former uranium mining activities can lead to the dissemination of radium isotopes having high radiological toxicities, which potentially threaten the safety of nearby environments. Although radium mobility in oxidized environments is known to be largely governed by sorption/desorption onto Fe and Mn oxyhydroxides and coprecipitation with sulfate minerals (e.g. barite), little is known regarding its behavior under reducing conditions, which are the conditions typically encountered in organic-rich systems such as wetlands and lake sediments. The present study aims at understanding the behavior of long-lived radium isotopes (226Ra and 228Ra), during early diagenesis of lake sediments contaminated by former uranium mining activities. Solid and pore water concentrations of 226Ra and 228Ra were determined using ultra low background gamma spectrometry, which allowed improvement of detection limits and measurement accuracy. This study shows that the downcore distribution of radium isotopes is closely related to the reductive dissolution of iron and manganese oxyhydroxides below the sediment-water interface. The resulting diffusive fluxes of 226Ra and 228Ra (4.1 10-25 and 4.7 10-28 mol cm-2.s-1) are however significantly lower than other radium-impacted environments, such as uranium mill tailings pond and phosphate industry-impacted sediments, and are similar to those reported for natural marine environments. Hence, in the reduced lake sediments of Saint-Clement, the major fraction of radium is trapped by the solid phase, while early diagenesis only induces a slight mobility of this radioelement.


Assuntos
Mineração , Monitoramento de Radiação , Rádio (Elemento) , Urânio , Sedimentos Geológicos , Rádio (Elemento)/análise , Áreas Alagadas
13.
Environ Monit Assess ; 192(10): 635, 2020 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-32918115

RESUMO

Wetlands are among the most vulnerable and dynamic ecosystems of the world. Any change in the anthropogenic footprint or climate affects the health of these pristine ecologically and socioeconomically important ecosystems. In the present study, land use land cover changes (LULCC) and fragmentation of natural landscape changes in an urban wetland, Khushalsar, located in the heart of the Srinagar City, were assessed using high-resolution satellite data, geospatial modeling approach, and ground observations over the last ~ 5 decades (1965 and 2018). The spatiotemporal changes in LULC of the wetland were assessed for 3 time periods that include 1965-1980, 1980-2018, and 1965-2018. Additionally, landscape fragmentation tool (LFT) was used to quantify fragmentation of land cover. The analysis of LULCC indicated that built-up areas in the vicinity of the wetland increased by 510% between 1965 and 2018. The aquatic vegetation and marshy lands increased by 150% and 33% respectively. The area under agriculture, plantation, open water, and barren lands decreased mostly taken over by built-up areas. Within the wetland, the area under open water spread reduced by 75% while the aquatic vegetation increased by 150% from 1965 to 2018. The built-up areas including roads also showed a substantial increase. The LFT analysis revealed four categories of landscapes i.e., patch, edge, perforated, and core areas. Since the natural land cover types were taken over by land use predominantly built-up areas, the core natural areas and perforated landscapes in the Khushalsar shrunk by 34% and 94% respectively indicating fragmentation of natural environment. The lack of sewage treatment facility, reckless unplanned urbanization within and in the vicinity of the wetland, is responsible for the degradation of the Khushalsar wetland.


Assuntos
Ecossistema , Áreas Alagadas , Cidades , Conservação dos Recursos Naturais , Monitoramento Ambiental , Índia , Tecnologia de Sensoriamento Remoto
14.
Proc Biol Sci ; 287(1934): 20201680, 2020 09 09.
Artigo em Inglês | MEDLINE | ID: mdl-32901574

RESUMO

In this investigation, we used a combination of field- and laboratory-based approaches to assess if influenza A viruses (IAVs) shed by ducks could remain viable for extended periods in surface water within three wetland complexes of North America. In a field experiment, replicate filtered surface water samples inoculated with duck swabs were tested for IAVs upon collection and again after an overwintering period of approximately 6-7 months. Numerous IAVs were molecularly detected and isolated from these samples, including replicates maintained at wetland field sites in Alaska and Minnesota for 181-229 days. In a parallel laboratory experiment, we attempted to culture IAVs from filtered surface water samples inoculated with duck swabs from Minnesota each month during September 2018-April 2019 and found monthly declines in viral viability. In an experimental challenge study, we found that IAVs maintained in filtered surface water within wetlands of Alaska and Minnesota for 214 and 226 days, respectively, were infectious in a mallard model. Collectively, our results support surface waters of northern wetlands as a biologically important medium in which IAVs may be both transmitted and maintained, potentially serving as an environmental reservoir for infectious IAVs during the overwintering period of migratory birds.


Assuntos
Patos/virologia , Vírus da Influenza A , Influenza Aviária/virologia , Áreas Alagadas , Animais , América do Norte
15.
Nat Commun ; 11(1): 4547, 2020 09 11.
Artigo em Inglês | MEDLINE | ID: mdl-32917880

RESUMO

Biodiversity loss can alter ecosystem functioning; however, it remains unclear how it alters decomposition-a critical component of biogeochemical cycles in the biosphere. Here, we provide a global-scale meta-analysis to quantify how changes in the diversity of organic matter derived from plants (i.e. litter) affect rates of decomposition. We find that the after-life effects of diversity were significant, and of substantial magnitude, in forests, grasslands, and wetlands. Changes in plant diversity could alter decomposition rates by as much as climate change is projected to alter them. Specifically, diversifying plant litter from mono- to mixed-species increases decomposition rate by 34.7% in forests worldwide, which is comparable in magnitude to the 13.6-26.4% increase in decomposition rates that is projected to occur over the next 50 years in response to climate warming. Thus, biodiversity changes cannot be solely viewed as a response to human influence, such as climate change, but could also be a non-negligible driver of future changes in biogeochemical cycles and climate feedbacks on Earth.


Assuntos
Biodiversidade , Aquecimento Global , Compostos Orgânicos/química , Plantas/química , Biodegradação Ambiental , Biomassa , Florestas , Pradaria , Áreas Alagadas
16.
Chemosphere ; 254: 126926, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957303

RESUMO

In less than a decade, bioelectrochemical systems/microbial fuel cell integrated constructed wetlands (electroactive wetlands) have gained a considerable amount of attention due to enhanced wastewater treatment and electricity generation. The enhancement in treatment has majorly emanated from the electron transfer or flow, particularly in anaerobic regions. However, the chemistry associated with electron transfer is complex to understand in electroactive wetlands. The electroactive wetlands accommodate diverse microbial community in which each microbe set their own potential to further participate in electron transfer. The conductive materials/electrodes in electroactive wetlands also contain some potential, due to which, several conflicts occur between microbes and electrode, and results in inadequate electron transfer or involvement of some other reaction mechanisms. Still, there is a considerable research gap in understanding of electron transfer between electrode-anode and cathode in electroactive wetlands. Additionally, the interaction of microbes with the electrodes and understanding of mass transfer is also essential to further understand the electron recovery. This review mainly deals with the electron transfer mechanism and its role in pollutant removal and electricity generation in electroactive wetlands.


Assuntos
Fontes de Energia Bioelétrica , Eletricidade , Transporte de Elétrons , Águas Residuárias , Purificação da Água/métodos , Áreas Alagadas , Eletrodos , Microbiota , Águas Residuárias/análise , Águas Residuárias/microbiologia
17.
Mar Pollut Bull ; 159: 111482, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32892917

RESUMO

Microplastics have received widespread attention as an emerging contaminant, but limited information was available during wetland restoration. The occurrence and characteristics of microplastics and their interaction with heavy metals in surface sediments from the Jinjiang Estuarine restored mangrove wetland were investigated. The abundance of microplastics ranged from 490 ± 127.3 to 1170 ± 99.0 items/500 g dry sediment, and the restored regions were much higher than mudflats, indicating mangrove restoration promoted its accumulation. Polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) were the main materials of microplastics after Raman spectroscopy identification. SEM-EDS images illustrated the mechanical erosion and chemical weathering on microplastics' surface, and Cr, Zn, Pb, and Cd were observed in elemental composition. The contents of Cr, Ni, Cu, Zn, Pb, As, and Cd accumulated in microplastics were not correlated with their total concentrations in sediments except for Hg, indicating that they might not be derived from sediments.


Assuntos
Metais Pesados/análise , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental , Estuários , Sedimentos Geológicos , Microplásticos , Plásticos , Áreas Alagadas
18.
J Environ Sci (China) ; 97: 45-53, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32933739

RESUMO

Estuarine wetland is the transitional interface linking terrestrial with marine ecosystems, and wetland microbes are crucial to the biogeochemical cycles of nutrients. The soil samples were collected in four seasons (spring, S1; summer, S2; autumn, S3; and winter, S4) from Suaeda wetland of Shuangtaizi River estuary, Northeast China, and the variations of bacterial community were evaluated by high-throughput sequencing. Soil properties presented a significant seasonal change, including pH, carbon (C) and total nitrogen (TN), and the microbial diversity, richness and structure also differed with seasons. Canonical correspondence analysis (CCA) and Mantel tests implied that soil pH, C and TN were the key factors structuring the microbial community. Gillisia (belonging to Bacteroidetes) and Woeseia (affiliating with Gammaproteobacteria) were the two primary components in the rhizosphere soils, displaying opposite variations with seasons. Based on PICRUSt (Phylogenetic Investigation of Communities by Reconstruction of Unobserved States) prediction, the xenobiotics biodegradation related genes exhibited a seasonal decline, while the majority of biomarker genes involved in nitrogen cycle showed an ascending trend. These findings could advance the understanding of rhizosphere microbiota of Suaeda in estuarine wetland.


Assuntos
Chenopodiaceae , China , Estuários , Filogenia , Rios , Estações do Ano , Solo , Microbiologia do Solo , Áreas Alagadas
19.
Water Sci Technol ; 82(2): 386-400, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32941179

RESUMO

For the utilization of nitrogen and phosphorus in rural sewage tailwaters after biological treatment, four systems were examined regarding their ability to purify tailwaters of rural domestic sewage: a hydroponic vegetable system (HV), a subsurface flow constructed wetland (SFCW), a compound system with HV followed by SFCW (HV-SFCW), and a compound system with SFCW followed by HV (SFCW-HV). Parameters of the four systems were optimized to maximize the utilization efficiency of nitrogen and phosphorus, and the characteristics and pollutant removal efficiency of the process were investigated. Moreover, the edible security of vegetables was also evaluated. Results showed that the optimal hydraulic loadings for the four systems were 0.2, 0.3, 0.3, and 0.3 m3/(m2·d) (the lowest being the HV), respectively. In the combined system of HV-SFCW, high contribution proportions of the HV unit to the removal of chemical oxygen demand (COD), total nitrogen (TN) and total phosphorus (TP) were obtained, reaching 46.7%, 58.1%, and 53.7%. The heavy metal content of plants harvested met the standards of the National Food Safety Standard Limit of Pollutants in Food (GB 2762-2012). Overall, the compound HV-SFCW system achieved the best performance, ensuring that effluent water quality met national standards and realized the effective utilization of nitrogen and phosphorus.


Assuntos
Ipomoea , Esgotos , Hidroponia , Nitrogênio/análise , Fósforo , Verduras , Eliminação de Resíduos Líquidos , Áreas Alagadas
20.
Ambio ; 49(11): 1797-1807, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32918721

RESUMO

Constructed wetlands (CWs) are one of the main countermeasures to reduce diffuse phosphorus (P) losses, but there is still a lack of systematic guidance accounting for spatially variable effects of hydraulic and P load on P retention. We present a three-step modelling approach for determining suitable placement of CWs in four different size groups (0.1-1.0 ha), based on incoming hydraulic and P load. The modelled hypothetical CW area was only 17% of that previously estimated and area of efficient CWs is even lower. The mean area-specific P retention increased with CW size. However, the spatial variation in retention was large for all size groups and largest (6-155 kg ha-1 year-1) for the smallest CWs due to highly variable incoming P loads, showing the possible benefits of targeted placement of CWs. The presented modelling approach has also flexibility to include and account for possible future changes in land cover and management.


Assuntos
Fósforo , Áreas Alagadas , Eliminação de Resíduos Líquidos
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