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1.
Water Sci Technol ; 83(11): 2809-2828, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-34115633

RESUMO

The horizontal subsurface flow constructed wetland (HFCW) is widely studied for the treatment of wastewater containing emerging organic contaminants (EOCs): pharmaceuticals, personal care products, and steroidal hormones. This study evaluates the performance of HFCW for the removal of these types of EOCs based on the data collected from peer-reviewed journal publications. In HFCW, anaerobic biodegradation is an important removal mechanism of EOCs besides their removal by the filter media (through sedimentation, adsorption, and precipitation) and plant uptake. The average removal efficiency of 18 selected EOCs ranged from 39% to 98%. The moderate to higher removal efficiency of 12 out of 18 selected EOCs in HFCW indicates the suitability of this type of constructed wetland (CW) for the treatment of wastewater containing these EOCs. The reasonably good removal (>50% in most of the cases) of these EOCs in HFCW might be due to the occurrence of anaerobic biodegradation as one of their major removal mechanisms in CWs. Although the effluent concentration of EOCs was substantially decreased after the treatment, the environmental risk posed by them was not fully reduced in most of the cases. For instance, estimated risk quotient of 11 out of 18 examined EOCs was extremely high for the effluent of HFCW.


Assuntos
Poluentes Químicos da Água , Áreas Alagadas , Anaerobiose , Biodegradação Ambiental , Eliminação de Resíduos Líquidos , Águas Residuárias/análise , Poluentes Químicos da Água/análise
2.
Sensors (Basel) ; 21(10)2021 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-34068106

RESUMO

When the use of optical images is not practical due to cloud cover, Synthetic Aperture Radar (SAR) imagery is a preferred alternative for monitoring coastal wetlands because it is unaffected by weather conditions. Polarimetric SAR (PolSAR) enables the detection of different backscattering mechanisms and thus has potential applications in land cover classification. Gaofen-3 (GF-3) is the first Chinese civilian satellite with multi-polarized C-band SAR imaging capability. Coastal wetland classification with GF-3 polarimetric SAR imagery has attracted increased attention in recent years, but it remains challenging. The aim of this study was to classify land cover in coastal wetlands using an object-oriented random forest algorithm on the basis of GF-3 polarimetric SAR imagery. First, a set of 16 commonly used SAR features was extracted. Second, the importance of each SAR feature was calculated, and the optimal polarimetric features were selected for wetland classification by combining random forest (RF) with sequential backward selection (SBS). Finally, the proposed algorithm was utilized to classify different land cover types in the Yancheng Coastal Wetlands. The results show that the most important parameters for wetland classification in this study were Shannon entropy, Span and orientation randomness, combined with features derived from Yamaguchi decomposition, namely, volume scattering, double scattering, surface scattering and helix scattering. When the object-oriented RF classification approach was used with the optimal feature combination, different land cover types in the study area were classified, with an overall accuracy of up to 92%.


Assuntos
Radar , Áreas Alagadas , Algoritmos , Monitoramento Ambiental
3.
Mar Pollut Bull ; 168: 112420, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33971457

RESUMO

This study compared the community structure of macrobenthos in bare tidal areas and vegetated regions under two reclamation patterns, fully enclosed and opened reclamation, in Yangtze wetland, China. Compared with fully enclosed reclamation areas, opened reclamation areas had higher water salinity, higher number of species and abundance, and less disturbed habitat health status. Compared with bare tidal areas, vegetated regions were more suitable for the survival of macrobenthos and its habitat health status was more stable. Salinity, pH and larger soil particle diameter were positively associated with macrobenthic diversity, while total nitrogen and total phosphorus were negatively associated. Overall, compared with fully enclosed reclamation and vegetated regions, opened reclamation and bare tidal areas had less negative effects upon macrobenthic community and habitat health. Opened reclamation is preferred for wetland reclamation, and planting indigenous plants and releasing species adapted to fresh water is beneficial to the restoration of macrobenthic communities.


Assuntos
Ecossistema , Áreas Alagadas , China , Salinidade , Solo
4.
Mar Pollut Bull ; 168: 112471, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-34000707

RESUMO

Marine litter in mangroves comes mainly from poor waste management practices and its abundance is increased by natural catastrophes occurrence that affects coastal settlements, as occurred in November-2020, when two hurricanes (ETA and IOTA) destroyed homes and deposited litters in mangroves of the Providencia and Santa Catalina islands, in the Colombian Caribbean. This study aims to assess the litter pollution in mangrove forests of these islands after Hurricane IOTA. Litter pollution was high in mangroves near urban areas and low in mangroves with little urban influence. In three mangrove sectors with high pollution, litter densities of 0.4-1.4 items m-2 and masses of 0.1-1.2 kg m-2 were determined; the majority were megalitter (sizes >1 m). Plastics were the most abundant (>60%). Local community is aware of the litter pollution problem and their participation in scientific research and mangroves recovery is key to understanding the impacts of natural and anthropogenic events and for ecosystem conservation.


Assuntos
Tempestades Ciclônicas , Ecossistema , Região do Caribe , Colômbia , Monitoramento Ambiental , Ilhas , Plásticos , Providencia , Resíduos/análise , Áreas Alagadas
5.
Sci Total Environ ; 785: 147316, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-33932675

RESUMO

The conservation level of rare waterbirds reflects the quality of the regional ecological environment and wetlands, and suitable habitat patches and good environmental conditions are bases to support the activities of rare species in habitats. Establishing these conditions is also an important goal of habitat landscape and functional restoration. However, lack of these conditions limits population protection and habitat restoration of rare species. Based on the random forest (RF) algorithm and threshold indicator taxa analysis (TITAN), this paper performed habitat suitability assessment and environmental variable threshold analysis of rare waterbird species in Yancheng coastal wetlands. The results showed that the suitable area proportion of three waterbird species at different habitat sites was less than 20%. The unsuitable area proportions of red-crowned cranes and oriental storks at the CA habitat site were the highest, reaching 86.73% and 85.17%, respectively. In addition, analysis of the importance of environmental variables showed that the main influencing variables affecting the suitable habitat distribution of the three rare waterbirds were habitat type (T_hab), habitat area (A_hab), vegetation coverage (P_fvc), distance to farmland (D_far), distance to reeds (D_ree), ponds density (Ponds), distance to water surface (D_wat) and distance to main roads or seawalls (D_swa). These variables covered the type, area, coverage and distance indicators. With the exception of D_far, Ponds and D_swa, rare waterbirds had response thresholds to each environmental indicator, and these results supported the restoration of landscape structure and function of each habitat site. This study emphasized the importance of foods, water resources and hidden conditions for habitat selection in rare waterbirds. Finally, we proposed the maintenance and restoration patterns of the landscape structure and function of rare waterbird habitats, which are available for other coastal tidal wetlands.


Assuntos
Conservação dos Recursos Naturais , Ecossistema , Animais , Aves , Lagoas , Áreas Alagadas
6.
Sci Total Environ ; 785: 147317, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-33933765

RESUMO

Horticulture has greatly increased in Argentina in recent decades mainly due to increasing greenhouse utilization and agrochemical consumption, thus representing a threat to adjacent water bodies. Riparian wetlands, however, could attenuate agrochemical contamination. The present work therefore compared insecticide concentrations in bottom sediments in addition to sediment toxicity to the amphipod Hyalella curvispina and investigated the macroinvertebrate composition upstream and downstream from a natural wetland in a small stream draining a basin undergoing intense horticultural production. The wetland surface was covered by macrophytes, mainly Thypha sp., and the insecticide concentrations measured downstream from the wetland were significantly lower, at roughly 19% of the upstream values. The growth rates of H. curvispina were significantly higher when exposed to the sediments downstream from the wetland, while the macroinvertebrate-assemblage composition was significantly different upstream and downstream: the snail Pomacea canaliculata was the dominant species upstream while the amphipod H. curvispina was dominant downstream. Pomacea canaliculata is often the dominant species in the regional streams draining agriculture and horticultural basins. Hyalella curvispina is sensitive to pesticide toxicity and is often dominant in streams draining extensive livestock basins and within a biosphere reserve. We conclude that riparian wetlands effectively attenuate horticulture contamination in pampean streams and should therefore be preserved and restored.


Assuntos
Inseticidas , Poluentes Químicos da Água , Agricultura , Animais , Argentina , Monitoramento Ambiental , Horticultura , Inseticidas/análise , Inseticidas/toxicidade , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/toxicidade , Áreas Alagadas
7.
Sci Total Environ ; 786: 147368, 2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-33965831

RESUMO

Additional treatment of wastewater, such as constructed wetlands (CWs), is a possible solution to reduce the discharge of antibiotics and antibiotic resistance genes (ARGs) from households and industry to the environment. This study aims to investigate the occurrence and removal of antibiotics and ARGs by two full scale CWs operated at different hydraulic retention times (HRT), namely 1 day and 3 days. Both CWs were receiving the same wastewater treatment plant (WWTP) effluent. Temporally and spatially distributed sampling of water and sediment was conducted for one year and samples were analyzed for antibiotics and ARGs by using LC-MS/MS and qPCR. Results showed that both CWs removed antibiotics significantly with a comparable overall removal of 28%-100%, depending on the type of antibiotics. However, some of the antibiotics showed higher concentration after the CW treatment. Five antibiotics (tiamulin, tylosin, oxytetracycline, sulfamethoxazole and trimethoprim) were the most abundant (>1500 ng/l on average) in winter. Meanwhile, ermB was the most abundant (average of 5.0 log) in winter compared to summer (average of 3.5 log). Other ARGs did not show a significant increase or decrease between winter and summer. ARGs were removed from the wastewater by 0.8 to 1.5 log. The HRT did not influence the removal of either the antibiotics or the ARGs. A strong correlation was found between sul genes and intI1. The results also revealed a positive and a negative relationship from sampling point 1 to sampling point 5: a positive relation between abundance of antibiotics, ARGs, and of NO3-N, NH4-N, TP, COD and a negative relation between antibiotics, ARGs and temperature. This relationship showed the effect between antibiotics and ARGs concentrations with physicochemical parameters and nutrients. The ability of CWs to reduce the input of micropollutants into the environment makes CWs a potential post treatment to WWTP.


Assuntos
Poluentes Químicos da Água , Áreas Alagadas , Antibacterianos , Cromatografia Líquida , Resistência Microbiana a Medicamentos/genética , Genes Bacterianos , Espectrometria de Massas em Tandem , Eliminação de Resíduos Líquidos , Águas Residuárias/análise , Poluentes Químicos da Água/análise
8.
Bioresour Technol ; 335: 125236, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33991883

RESUMO

Six laboratory-scale constructed wetlands (CWs) were used to quantify the nitrogen removal (NR) capacity in the treatment of saline wastewater at high (6:1) and low (2:1) carbon-nitrogen ratios (C/N), with and without bioaugmentation of aerobic-denitrifying bacterium. Sustained high-efficiency nitrification was observed throughout the operation. However, under different C/N ratios, although the bioaugmentation of aerobic-denitrifying bacterium promoted the removal of NO3--N and TN, there were still great differences in denitrification. Molecular biology experiments revealed ammonia-oxidizing archaea, together with the Nitrosomonas and Nitrospira, led to highly efficient nitrification. Furthermore, aerobic-denitrifying bacterium and sulfur-driven denitrifiers were the core denitrification groups in CWs. By performing these combined experiments, it was possible to determine the optimal CW design and the most relevant NR processes for the treatment of salty wastewater. The results suggest that the bioaugmentation of salt-tolerant functional bacteria with multiple NR pathways are crucial for the removal of salty wastewater pollutants.


Assuntos
Purificação da Água , Áreas Alagadas , Desnitrificação , Nitrificação , Nitrogênio , Águas Residuárias
9.
Sci Total Environ ; 773: 145632, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33940741

RESUMO

Mangrove ecosystems are natural nitrogen removal systems that are primarily mediated by nitrogen cycle microorganisms, but their relative contributions to nitrogen transformation and removal in mangrove sediments under anthropogenic nitrogen input needs further resolution and characterization. Here, we investigated the responses and the relative contributions of ammonia-oxidizing archaea (AOA), ammonia-oxidizing bacteria (AOB), anaerobic ammonium oxidizing (anammox) bacteria and denitrifying bacteria after spiking urea into mangrove sediments incubated in a laboratory microcosm experiment for four weeks. During incubation, the diversity, abundances and transcription levels of the hzo genes for anammox bacteria, amoA genes for AOA and AOB, and nirS genes for denitrifying bacteria were monitored using targeted gene clone library analyses and quantitative PCR assays at the DNA and RNA levels. The results showed that mangrove sediments harbour habitat-specific anammox bacteria which related to Candidatus Scalindua and Candidatus Kuenenia clades. Mangrove specific AOA related to deep branched clades within Candidatus Nitrososphaera and Candidatus Nitrosotalea, and AOB related to Nitrosomonas and Nitrosospira were also detected in the collected sediment samples. Growth and activity of AOA were detected at all levels of amendment of nitrogen input, whereas AOB growth was detectable only at the high-level nitrogen input (1.5 mg urea per gram of dry sediment) with no amoA transcripts and lower abundance than AOA. The abundance and transcription levels of the nirS gene were higher (~1000 times) than those of the hzo gene in all groups. Pearson correlation analysis demonstrated that the abundance of both AOA and AOB amoA genes had a significant positive correlation with the nirS gene (p < 0.01). These results indicated that nitrification (primarily mediated by the AOA)-denitrification process played the most important role in nitrogen removal from the amendment of nitrogen short-term input in the mangrove sediments.


Assuntos
Nitrogênio , Áreas Alagadas , Archaea/genética , Ecossistema , Sedimentos Geológicos
10.
Water Sci Technol ; 83(9): 2100-2117, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33989179

RESUMO

This study was performed to evaluate the spatial and temporal distribution of major ions in water samples of a newly designated Ramsar site, namely Kabar Tal (KT) wetland of Bihar. Samples were collected during summer, monsoon, and winter seasons. The analytical and GIS results show that concentration of electrical conductivity, chloride, and nitrate are higher in summer than monsoon and winter. However, the concentration of major cations such as sodium, potassium, calcium, and magnesium are higher in winter than monsoon and summer. In addition, major anions like sulphate and phosphate concentration is higher during monsoon than summer and winter. Multivariate statistical tool (discriminant analysis) results suggest that temperature, pH, electrical conductivity, sulphate, and potassium are the major parameters distinguishing the water quality in different seasons. The study confirms that seasonal variations are playing a major role in the hydrochemistry of KT wetland. Overall, this work outlines the approach towards proper conservation and utilization of wetlands and to assess the quality of surface water for determining its suitability for agricultural purposes. Overall, this work highlights the approach towards estimating the seasonal dynamics of chemical species in KT wetland and its suitability for irrigation purposes.


Assuntos
Poluentes Químicos da Água , Áreas Alagadas , Monitoramento Ambiental , Sistemas de Informação Geográfica , Índia , Estações do Ano , Água , Poluentes Químicos da Água/análise
11.
Artigo em Inglês | MEDLINE | ID: mdl-33974534

RESUMO

A Gram-stain-negative, strictly aerobic and oval-shaped bacterial strain with a flagellum, designated GS-10T, was isolated from mangrove wetland sediment. GS-10T grew at 20-40 °C (optimum, 37 °C), in the pH range of 5.0-11.0 (optimum, 6.0-8.0) and under various NaCl concentrations from 1 to 11 % (w/v) (optimum, 5-6 %). The respiratory quinone was ubiquinone-10, and the predominant polar lipids were phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. The major fatty acids (>10 % of the total fatty acids) were summed feature 4 (C17 : 1iso I/anteiso B) and summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c). The G+C content of the genomic DNA was 63.71 %. On the basis of the results from comparative analysis of the 16S rRNA gene sequence, GS-10T represents a member of the family Rhodobacteraceae and had the highest sequence similarity to Thalassobius gelatinovorus CECT 4357T (97.47 %), followed by Lutimaribacter pacificus W11-2BT (97.03 %), Marivita cryptomonadis CL-SK44T (96.83 %), Thalassobius autumnalis CECT 5118T (96.75 %) and Thalassobius mediterraneus CECT 5383T (96.68 %). Phylogenetic trees based on 16S rRNA gene sequences, multilocus sequence analysis (MLSA) and whole genome sequences revealed that GS-10T clustered with species within the genus Thalassobius. The average nucleotide identity (ANI) and the average amino acid identity (AAI) values were calculated from complete genome sequences and indicated that GS-10T represented a novel species of the genus Thalassobius, and the name Thalassobius mangrovi sp. nov. is proposed for this species. The type strain of Thalassobius mangrovi is GS-10T (=MCCC 1K03624T=KCTC 82131T).


Assuntos
Sedimentos Geológicos/microbiologia , Filogenia , Rhodobacteraceae/classificação , Técnicas de Tipagem Bacteriana , Composição de Bases , China , DNA Bacteriano/genética , Ácidos Graxos/química , Fosfolipídeos/química , RNA Ribossômico 16S/genética , Rhodobacteraceae/isolamento & purificação , Análise de Sequência de DNA , Áreas Alagadas
12.
Chemosphere ; 275: 130050, 2021 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-33984907

RESUMO

Micropollutants (MPs) are organic chemicals that are present in the environment at low concentrations (ng/L-µg/L), for example pharmaceuticals. A constructed wetland (CW) is a promising post-treatment technique to remove MPs from wastewater effluent. Selecting a suitable material for support matrix is important when designing such a CW. Nine materials were studied as potential support matrices: Light Expanded Clay Aggregates (LECA), compost, bark, granulated activated carbon (GAC), biochar, granulated cork, lava rock, sand and gravel. Batch experiments were conducted to study MP removal by nine materials in phosphate buffer with 5 or 50 µg/L MPs, or wastewater effluent with 50 µg/L of MPs. GAC and biochar removed almost all MPs in both phosphate buffer and wastewater effluent, followed by bark, compost, granulated cork. Sand, gravel, LECA and lava rock removed less than 30% of most MPs in both matrixes. Based on set criteria (e.g. removal efficiency), biochar, bark, compost, LECA and sand were selected, and used in combinations in column studies to test their overall performance. A combination of bark and biochar performed the best on MP removal, as 4 MPs were highly (70%-100%) removed, 4 MPs were moderately (30%-70%) removed while only 3 MPs were hardly removed. The main flow regime of this combination was both plug flow and dispersive flow. Moreover, we hypothesized to apply bark and biochar in a CW. Based on the assumptions and calculations, some benefits are expected, such as increasing MP removal and extending operation time.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Eliminação de Resíduos Líquidos , Águas Residuárias , Poluentes Químicos da Água/análise , Áreas Alagadas
13.
J Environ Sci (China) ; 104: 53-68, 2021 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-33985748

RESUMO

Constructed wetlands (CWs) have been introduced to and developed in China for environmental engineering over the most prosperous three decades (1990-2020). To study the origin, development process, and future trend of CWs, this review summarized a wide range of literatures between 1990 and 2020 by Chinese authors. Firstly, the publication number over years, research highlights, and the author contributions with the most published papers in this field were conducted through bibliometric analysis. Secondly, the most principal components of CWs, substrates and macrophytes were summarized and analyzed. Thirdly, the typical application cases from traditional CWs, pond systems to combined pond-wetland systems were presented. In China, CWs were predominately distributed in the east of the so-called 'Hu Huanyong Line'. Therefore CWs were limited by the socio-economic level and climatic conditions. It is unquestionable that the overall level of China's CWs has improved significantly, and one of the most prominent features has started towards the plural pattern development. There has been a trend of large-scale or low-cost CW application in the recent years. However, lifecycle research and management are required for better strategies in the future.


Assuntos
Eliminação de Resíduos Líquidos , Áreas Alagadas , China , Águas Residuárias/análise
14.
Sci Total Environ ; 787: 147438, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34000538

RESUMO

Mangrove forest is a key ecosystem between land and sea, and provides many services such as trapping sediments and contaminants. These contaminants include trace metals (TM) that can accumulate in mangroves soil and biota. This paper innovates by the comparative study of the effects of the watershed inputs on TM distribution in mangrove soil, on roots bioconcentration factors of two species (Avicennia marina and Rhizophora stylosa), and on Fe plaque formation and immobilization of these TM. Two mangrove forests in New Caledonia were chosen as study sites. One mangrove is located downstream ultramafic rocks and a Ni mine (ultrabasic site), whereas the second mangrove ends a volcano-sedimentary watershed (non-ultrabasic site). TM concentrations (Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Zn) were measured in soil, porewaters, and roots of both species via ICP-OES or Hg analyzer. Analyzed TM were significantly more concentrated in soils at the ultrabasic site with Fe, Cr, and Ni the most abundant. Iron, Mn, and Ni were the most concentrated in the roots with mean values of 9,651, 192, and 133 mg kg-1 respectively. However, the bioconcentration factors (BCF) of Fe (0.16) and Ni (0.11) were low due to a lack of ions in the dissolved phase and potential uptake regulation. The uptake of TM by mangrove trees was influenced by concentrations in soil, but more importantly by their potential bioavailability and the physiological characteristics of each species. TM concentrations and BCF were lower for R. stylosa probably due to less permeable root system. A. marina limits TM absorption through Fe plaque formation on its pneumatophores with a capacity to retain TM up to 94% for Mn. Mean Fe plaque formation is potentially correlated to Fe concentration in soil. Eventually, framboids of pyrite were observed within root tissues in the epidermis of A. marina's pneumatophores.


Assuntos
Metais Pesados , Oligoelementos , Ecossistema , Monitoramento Ambiental , Sedimentos Geológicos , Metais Pesados/análise , Nova Caledônia , Oligoelementos/análise , Áreas Alagadas
15.
J Environ Manage ; 292: 112578, 2021 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-33965685

RESUMO

To investigate the effect of a constructed wetland (CW) with steel slag as the filler on water contaminated by low phosphorus levels, a multistage pond CW system was designed in this study. Low-phosphorus polluted river water was used as the research object. This study explored the effects of using steel slag as a CW filler on phosphorus removal and the total phosphorus (TP) purification effect of the wetland system. The results showed that the TP removal rates in the ecological pond, oxidation pond, surface flow wetlands and submerged plant pond were 5.17%, 8.02%, 21.56%, and 16.31%, respectively. Intermittent increases in phosphorus concentration were observed in the reactors and were caused by the decay of plant tissues, which released pollutants. Because steel slag was added to the filler, the TP concentrations in the effluent of the first- and second-level horizontal subsurface CWs increased by 151.13% and 16.29%, respectively, compared to the influent concentration. The 20th to 40th days of the test run was a period of rapid phosphorus release of the system. The use of steel slag has a potential risk of phosphorus release when applied in CWs used to purify low-phosphorus contaminated water bodies.


Assuntos
Purificação da Água , Áreas Alagadas , Nitrogênio , Fósforo , Rios , Aço , Eliminação de Resíduos Líquidos , Água
16.
J Environ Manage ; 292: 112750, 2021 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-33991828

RESUMO

Constructed wetlands (CWs) have been proved to be an alternative to the treatment of various wastewater. However, there are few studies focused on the removal performance and mechanisms of pollutants in pilot-scale CWs packed with novel solid carbon. In this study, we investigated the effect of poly-3-hydroxybutyrate-co-3-hydroxyvalerate/polyacetic acid (PHBV/PLA) blends as carbon source on pollutant's transformation, microbial communities and functional genes in pilot-scale aeration-anoxic two-stage CWs for polishing rural runoff in southern China. Results showed a striking improvement of TN removal in CWs with PHBV/PLA blends (64.5%) compared to that in CWs with ceramsite (52.9%). NH4+-N (61.3-64.6%), COD (40.4-53.8%) and TP (43.6-47.1%) were also removed effectively in both two CWs. In addition, the strains of Rhodocyclaceae and Bacteroidetes were the primary denitrifiers on the surface of PHBV/PLA blends. Further, the aerobic stage induced gathering of 16 S and amoA genes and the anoxic zone with PHBV/PLA blends increased the nirS genes, which fundamentally explained the better denitrification performance in CW based on PHBV/PLA blends. Consequently, this study will provide straightforward guidance for the operation of engineering CWs packed with polymers to govern the low-C/N rural wastewater.


Assuntos
Purificação da Água , Áreas Alagadas , Carbono , China , Desnitrificação , Nitrogênio , Eliminação de Resíduos Líquidos , Águas Residuárias
17.
BMC Ecol Evol ; 21(1): 91, 2021 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-34011287

RESUMO

BACKGROUND: The functioning of ecosystems is highly variable through space and time. Climatic and edaphic factors are forcing ecological communities to converge, whereas the diversity of plant assemblages dampens these effects by allowing communities' dynamics to diverge. This study evaluated whether the growing season phenology of wetland plant communities within landscapes is determined by the climatic/edaphic factors of contrasted regions, by the species richness of plant communities, or by the diversity of plant assemblages. From 2013 to 2016, we monitored the phenology and floristic composition of 118 wetland plant communities across five landscapes distributed along a gradient of edaphic and climatic conditions in the Province of Québec, Canada. RESULTS: The growing season phenology of wetlands was driven by differences among plant assemblage within landscapes, and not by the species richness of each individual community (< 1% of the explained variation). Variation in the growing season length of wetlands reflected the destabilizing effect of climatic and edaphic factors on green-up dates, which is opposed to the dampening effect of plant assemblage diversity on green-down dates. CONCLUSIONS: The latter dampening effect may be particularly important in the context of increasing anthropogenic activities, which are predicted to impair the ability of wetlands to adapt to fluctuating environmental conditions. Our findings suggest that stakeholders should not necessarily consider local species-poor plant communities of lower conservation value to the global functioning of wetland ecosystems.


Assuntos
Ecossistema , Áreas Alagadas , Biodiversidade , Canadá , Quebeque , Estações do Ano
18.
J Environ Manage ; 292: 112769, 2021 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-34015614

RESUMO

Irregular withdrawals from water resources followed by the increase of the cultivation lands and the construction of Marun and Jarahi Dams on upstream rivers of the Shadegan Wetland have led to severe hydrological changes as well as increased salinity of the wetland inflow in some periods. The aim of this study is to develop a simulator-optimizer coupling model for proper planning and management of resource allocation to the upstream of Shadegan Wetland. In addition to maximizing the supply of basin demands during the operation period, this model aims to reduce the salinity of the inflow to Shadegan Wetland. Due to the importance of the wetland as a seasonal habitat for birds and the importance of protecting its ecosystem, the development of a quantitative-qualitative optimization model for optimal use of available water resources is the aim of this study. First, based on current conditions, the prepared model is developed as a reference scenario for a future 30-year period(2021-2050). To achieve the best system efficiency in terms of quality and quantity, the optimization is performed by means of the NSGA-II algorithm. The results indicate that the optimizer model performs appropriately in supplying various demands and also decreasing the salinity of the inflow to Shadegan Wetland compared to the reference scenario so that in addition to supplying the demands with more than92% reliability in the whole system, it is expected that the salinity of the river at the entrance to Shadegan Wetland to be reduced by about50%., especially in low water months. The coupling model proposed in this research is applicable for other study areas with quantitative-qualitative operation approach and is able to detect critical points of rivers in terms of quantity and quality. This model has also the capability of providing optimal solutions for improving river conditions as well as downstream ecosystems.


Assuntos
Recursos Hídricos , Áreas Alagadas , Ecossistema , Monitoramento Ambiental , Reprodutibilidade dos Testes , Rios
19.
J Environ Manage ; 292: 112813, 2021 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-34030018

RESUMO

Constructed wetland (CW) has obvious advantages in wastewater treatment of medium and small towns. However, there is a lack of health monitoring research on CW system clogging. The electrical conductivity (EC) of wastewater purified by CW is related to the concentration of pollutants, which can reflect the CW clogging. The objectives of this study are to reveal the mechanisms of CWs substrate clogging from the perspective of wastewater EC changes, and provide an important reference for the health evaluation of CWs. The EC changes of nine CWs substrates (quartz sand, zeolite, gravel, coarse sand, straw biochar, sludge biochar, clay ceramsite, fly ash ceramsite and shale ceramsite) under different conditions (purified water, wastewater and wastewater + NaCl) were tested, and comparative analysis was used to reveal the influence of different substrate materials on the change of wastewater EC. The results show that the adsorption ability of substrate material isn't the main factor affecting the EC of wastewater, and the soluble component in the material is the important factor to cause the difference of EC increment. Under the condition of 0.4-1.0 g L-1 NaCl concentration, the adsorption of substrate materials had little effect on the EC of wastewater, and the effect of NaCl used in CW tracer experiment was good. Quartz sand, coarse sand, gravel and sludge biochar have little influence on the change of wastewater EC. Other materials that have great influence on the change of wastewater EC can be treated by modifying or controlling the mixing ratio. The results are of great significance to reveal the clogging state of CW system and to carry out health assessment research.


Assuntos
Águas Residuárias , Áreas Alagadas , Condutividade Elétrica , Esgotos , Eliminação de Resíduos Líquidos
20.
Biol Lett ; 17(5): 20210037, 2021 05.
Artigo em Inglês | MEDLINE | ID: mdl-33947219

RESUMO

Mangroves are among the most carbon-dense ecosystems on the planet. The capacity of mangroves to store and accumulate carbon has been assessed and reported at regional, national and global scales. However, small-scale sampling is still revealing 'hot spots' of carbon accumulation. This study reports one of these hotspots, with one of the largest-recorded carbon stocks in mangroves associated with sinkholes (cenotes) in the Yucatan Peninsula, Mexico. We assessed soil organic carbon (SOC) stocks, sequestration rates and carbon origin of deep peat soils (1 to 6 m). We found massive amounts of SOC up to 2792 Mg C ha-1, the highest value reported in the literature so far. This SOC is primarily derived from highly preserved mangrove roots and has changed little since its deposition, which started over 3220 years ago (±30 BP). Most cenotes are owned by Mayan communities and are threatened by increased tourism and the resulting extraction and pollution of groundwater. These hot spots of carbon sequestration, albeit small in area, require adequate protection and could provide valuable financial opportunities through carbon-offsetting mechanisms and other payments for ecosystem services.


Assuntos
Sequestro de Carbono , Ecossistema , Carbono , México , Solo , Áreas Alagadas
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