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1.
Huan Jing Ke Xue ; 42(3): 1433-1442, 2021 Mar 08.
Artículo en Chino | MEDLINE | ID: mdl-33742940

RESUMEN

The loss of nitrogen (N) and phosphorus (P) from aquaculture has caused eutrophication of freshwater systems. Here, surface flow constructed wetland (SFCW) planted with Myriophyllum elatinoides were used to treat swine wastewater from a medium-sized hoggery in subtropical Central China. Inflow concentrations of NH4+-N, TN, TP, and COD ranged from 535.4 to 591.09, 682.09 to 766.96, 57.73 to 82.29, and 918.4 to 1940.43 mg·L-1, respectively. The mean removal efficiencies of NH4+-N, TN, TP, and COD were 97.4%, 97.1%, 91.0%, and 90.2%, respectively, and CW1 had the largest contributions of 37.3%, 38.4%, 43.3%, and 27.4%, respectively. Plant N and P uptake ranged 23.87-79.96 g·m-2 and 5.34-18.98 g·m-2, accounting for 19.1% and 20.2% of removal, respectively. Sediment N and P accumulation ranged 19.17-56.62 g·m-2 and 10.59-26.62 g·m-2, accounting for 19.8% and 61.7% of removal, respectively. Multiple linear regression showed that environmental factors explained 79.9% of the N removal and 70.1% of the P removal; DO was the main factor affecting N removal, and sediment adsorption was the key process in P removal. These results show that M. elatinoides constructed wetland can efficiently treat swine wastewater, thereby reduce the discharge of pollutants downstream.


Asunto(s)
Aguas Residuales , Humedales , Animales , China , Nitrógeno/análisis , Fósforo , Porcinos , Eliminación de Residuos Líquidos
2.
Environ Monit Assess ; 193(4): 208, 2021 Mar 23.
Artículo en Inglés | MEDLINE | ID: mdl-33755795

RESUMEN

Increasing gaseous emissions of nitrogen (N) and sulfur (S) associated with oil sands development in northern Alberta (Canada) has led to changing regional wet and dry N and S deposition regimes. We assessed the potential for using bog plant/lichen tissue chemistry (N and S concentrations, C:N and C:S ratios, in 10 plant/lichen species) to monitor changing atmospheric N and S deposition through sampling at five bog sites, 3-6 times per growing season from 2009 to 2016. During this 8-year period, oil sands N emissions steadily increased, while S emissions steadily decreased. We examined the following: (1) whether each species showed changes in tissue chemistry with increasing distance from the Syncrude and Suncor upgrader stacks (the two largest point sources of N and S emissions); (2) whether tissue chemistry changed over the 8 year period in ways that were consistent with increasing N and decreasing S emissions from oil sands facilities; and (3) whether tissue chemistry was correlated with growing season wet deposition of NH4+-N, NO3--N, or SO42--S. Based on these criteria, the best biomonitors of a changing N deposition regime were Evernia mesomorpha, Sphagnum fuscum, and Vaccinium oxycoccos. The best biomonitors of a changing S deposition regime were Evernia mesomorpha, Cladonia mitis, Sphagnum fuscum, Sphagnum capillifolium, Vaccinium oxycoccos, and Picea mariana. Changing N and S deposition regimes in the oil sands region appear to be influencing N and S cycling in what once were pristine ombrotrophic bogs, to the extent that these bogs may effectively monitor future spatial and temporal patterns of deposition.


Asunto(s)
Líquenes , Humedales , Alberta , Ascomicetos , Monitoreo del Ambiente , Nitrógeno/análisis , Yacimiento de Petróleo y Gas , Parmeliaceae , Azufre/análisis
3.
Chemosphere ; 270: 128640, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33757273

RESUMEN

This study assessed the convenience of using magnetic particles (MPs) to reduce phosphorus (P) concentration in treated wastewater. The working hypothesis is that MP addition increases P removal in artificial wastewater treatment ponds. Water samples were collected at the inlet and outlet of a semi-natural pond receiving secondary municipal effluent that is discharged in a Ramsar site (Fuente de Piedra, Málaga, Spain). Then, laboratory batch experiments were run to (i) assess the effect of adding MPs on the chemical composition of treated wastewater, (ii) identify the number of adsorption cycles (by reusing MPs) which are able to trap a high percentage of P (>50%) and (iii) select the optimum ratio between MP mass and initial dissolved inorganic P (DIP) concentration. The results show the suitability of using MPs to remove P in treated wastewater due to both their high equilibrium adsorption capacity (q) and P removal efficiency. Lastly, considering its practical and economical relevance, based on the advantages (P removal efficiency) and disadvantages (economic price), the optimum dose of MPs (0.16 g MP mg-1 P) to achieve a high P removal efficiency (>50%) was identified.


Asunto(s)
Contaminantes Químicos del Agua , Purificación del Agua , Fenómenos Magnéticos , Fosfatos , Fósforo/análisis , España , Eliminación de Residuos Líquidos , Aguas Residuales , Contaminantes Químicos del Agua/análisis , Humedales
4.
Chemosphere ; 270: 128664, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33757276

RESUMEN

Bisphenol A (BPA) is one of the widely detected endocrine disrupting chemicals in coastal sediment. Biodegradation is a vital pathway of BPA elimination in sediment. However, the impact of vegetation on BPA degradation in coastal sediment is still unclear. In this study, the differences of BPA biodegradation and the functional microbial community and metabolic pathway were explored between mangrove forest and mudflat sediments. A nearly complete BPA attenuation was detected in 4 days in mudflat sediment but 8 days in forest sediment. Bacterial abundance varied greatly in different sediment types. Bacterial community structure changed with BPA biodegradation, dependent on sediment type. During the degradation, the proportions of Alphaproteobacteria and Gammaproteobacteria were higher in BPA amended microcosms than in un-amended microcosms. With BPA biodegradation, a substantial increase in Novosphingobium and Croceicoccus occurred in forest sediment and mudflat sediment, respectively. Additionally, two divergent BPA biodegradation pathways were proposed based on functional annotation and KEGG pathway database. The abundance of functional genes also varied with BPA biodegradation, dependent on sediment type. Gene pcaGH decreased, while genes ligK and pcaD increased in both sediment types. Gene pcaB showed a remarkable increase in forest sediment but a decrease in mudflat sediment. Therefore, BPA degradation and the associated microbial community and metabolic pathway differed between mudflat and mangrove forest sediments.


Asunto(s)
Contaminantes Químicos del Agua , Humedales , Compuestos de Bencidrilo/análisis , Biodegradación Ambiental , Sedimentos Geológicos , Fenoles , Contaminantes Químicos del Agua/análisis
5.
Bioresour Technol ; 329: 124897, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33657501

RESUMEN

This study proposed a novel intermittent-aeration constructed wetland (CW) to resolve the vertical loss of oxygen in tertiary treatment. Compared to the non-aeration CW, the intermittent-aeration CW presented a better removal performance (90.8% chemical oxygen demand, 94.3% ammonia nitrogen, 91.5% total nitrogen and 94.1% total phosphorus) at a dissolved oxygen of 3 mg L-1 and hydraulic retention time of 2 days. It was mainly attributed to the higher abundance and greater diversity of bacterial community due to the oxygen supply. High-throughput sequencing indicated that high abundance of phyla Proteobacteria (35.34%) and Bacteroidetes (18.20%) in intermittent-aeration CW were responsible for simultaneous nitrogen and phosphorus removal. Besides, the dominant families Burkholderiaceae (11.16%), Microtrichales (6.88%) and Saprospiraceae (6.50%) were also detected, which was vital to hydrolyze and utilize complex organic matters. In general, oxygen supply upregulated the metabolism pathways of amino acid and carbohydrate, bringing a greater biodegradation potential for removing contaminants.


Asunto(s)
Nitrógeno , Humedales , Análisis de la Demanda Biológica de Oxígeno , Humanos , Nutrientes , Fósforo , Eliminación de Residuos Líquidos
6.
Bioresour Technol ; 329: 124890, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33662852

RESUMEN

This study investigated the influence of salinity on pollutant removal and bacterial community within a partially saturated vertical flow constructed wetland (PS-VFCW). High removal rates of NH4+-N (88.29 ± 4.97-100 ± 0%), total inorganic nitrogen (TIN) (50.00 ± 7.21-62.81 ± 7.21%) and COD (91.08 ± 2.66-100 ± 0%) were achieved at 0.4-2.4% salinity levels. The removal of ammonia, TIN and organic matter occurred mainly in unsaturated zone. Salt-adaptable microbes became the dominant bacteria with salinity elevated. The proportion of ammonia-oxidizing bacteria (AOB) in the 0-5 cm depth layer (unsaturated zone) decreased obviously as the salinity increased to 2.4%. Nitrite-oxidizing bacteria (NOB) in the 0-5 cm depth layer showed a decreasing trend with elevated salinity. Denitrifying bacteria (DNB) in the 0-5 cm depth layer maintained high abundance (27.70-53.60%) at 0.4-2.4% salinity levels. At 2.4% salinity, AOB, NOB and DNB were observed in the unsaturated zones and saturated zones, and showed higher abundance in the unsaturated zone.


Asunto(s)
Contaminantes Ambientales , Humedales , Amoníaco , Bacterias , Desnitrificación , Nitrificación , Nitrógeno/análisis , Salinidad , Aguas Residuales
7.
Ecotoxicol Environ Saf ; 214: 112045, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33711577

RESUMEN

Vegetated coastal ecosystems have an important role as contaminant filters. Temporal variations in concentrations, enrichment factors (EF), and fluxes of trace elements (As, Cd, Co, Cr, Cu, Ni, Pb, V, and Zn) were evaluated in 210Pb-dated sediment cores from salt marsh and seagrass ecosystems at San Quintín Bay (Mexican northern Pacific). Trace element contamination was negligible in seagrass sediments, but minor to severe, depending on the element, in salt marsh cores, owing to higher organic carbon and fine sediment contents. EF temporal variation in salt marsh cores was attributed to agriculture technology changes (e.g. installation of greenhouses, and improved irrigation and fertilization systems). Trace element flux ratios increased during the past 100 years, likely caused by steadily increasing sediment accumulation rates promoted by land-use changes in the catchment. The conservation of salt marsh areas is important to preserve their function as contaminants biofilters and the health of adjacent ecosystems.


Asunto(s)
Monitoreo del Ambiente , Oligoelementos/análisis , Contaminantes Químicos del Agua/análisis , Humedales , Agricultura , Ecosistema , Sedimentos Geológicos , México
8.
Zootaxa ; 4927(4): zootaxa.4927.4.4, 2021 Feb 16.
Artículo en Inglés | MEDLINE | ID: mdl-33756690

RESUMEN

The Australian Scirtidae species previously identified as misplaced in the widespread genus Prionocyphon Redtenbacher are revisited as well as their possible relationship with the Australian genus Macrodascillus (Lea) using sequence data from the mitochondrial gene, cytochrome oxidase subunit 1 and two nuclear genes, elongation factor 1-alpha and Topoisomerase. The study confirmed the conclusion of Cooper et al. (2014) that the species did not belong in Prionocyphon. The study also included a species from each of three possibly related genera, Chameloscyphon Watts, Daploeuros Watts and Dasyscyphon Watts. Chameloscyphon huonensis Watts, Dasyscyphon victoriaensis Watts and Daploeuros lamingtonensis Watts were recovered as separate lineages with C. huonensis linking with Das. victoriaensis and Dap. lamingtonensis isolated. The species previously included in Prionocyphon were shown to belong in two genera, Macrodascillus and a new genus Perplexacara: Perplexacara caementum (Watts) new combination, P. latusmandibulara (Watts) new combination, P. macroflavida (Watts) new combination, Macrodascillus scalaris (Lea), M. insolitus (Watts) new combination and M. lamingtonensis (Watts) new combination.


Asunto(s)
Escarabajos , Animales , Australia , Escarabajos/genética , Genes Mitocondriales , Biología Molecular , Humedales
9.
Water Res ; 195: 116996, 2021 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-33721673

RESUMEN

To investigate the role of granular activated carbon (GAC) on nitrogen removal performance of elemental sulfur-based constructed wetlands (S0-based CWs), three systems were constructed according to the different configurations in the functional layer, namely S-CW (S0 added in the functional layer), CSC-CW (GAC, S0 and GAC placed in layers in the functional layer) and SC-CW (S0 and GAC mixed evenly in the functional layer). In CSC-CW and SC-CW, the volumetric ratio of S0:GAC was 9:1. Three CWs were operated under four different hydraulic retention times (HRTs) ranged from 48 h to 6 h. Over the experiment, total inorganic nitrogen (TIN) removal rates of the three CWs were 3.1 - 23.6 g m-2 d-1, 3.5 - 24.1 g m-2 d-1 and 3.4 - 11.5 g m-2 d-1, respectively; CSC-CW remained high TIN removal efficiency (from 74.7 ± 20.2 % to 93.4 ± 1.9 %) while SC-CW had significant lower values when HRT = 6 h (29.8 ± 30.1 %). Mass balance and high-throughput sequencing analysis revealed that mixotrophic denitrification at the sulfur layer and simultaneous nitrification-denitrification (SND) at the rhizosphere played the major role in N removal from CSC-CW (> 95 %). GAC addition facilitated the growth of Iris pseudacorus with the final fresh weight increased from 33.9 gFW ind-1 to 82.3 gFW ind-1 in CSC-CW and 82.7 gFW ind-1 in SC-CW. This study optimizes the practical application of S0-based CWs amended with GAC for N removal from carbon-limited wastewater.


Asunto(s)
Nitrógeno , Humedales , Carbón Orgánico , Desnitrificación , Azufre , Eliminación de Residuos Líquidos , Aguas Residuales
10.
Water Res ; 194: 116958, 2021 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-33662685

RESUMEN

Methane (CH4) and nitrous oxide (N2O) are the most powerful greenhouse gases globally; recent emissions exceed previous estimates. The potential link between N2O reduction and CH4 oxidation in anoxic wetland sediments would be a sink for both gases, which has attracted broad attention. To explore the simultaneous N2O and CH4 biotransformation, wetland sediments were used to inoculate an enrichment reactor, continuously fed with CH4 and N2O for 500 days. After enrichment, the CH4 oxidation rate reached 2.8 µmol·g-1dw·d-1, which was 800-fold higher than the rate of the wetland sediments used as inoculum. Moreover, stable isotopic tracing proved CH4 oxidation was driven by N2O consumption under anoxic conditions. Genomic sequencing showed that the microbial community was dominated by methanotrophs. Species of Methylocaldum genus, belonging to γ-Proteobacteria class, were significantly enriched, and became the predominant methanotrophs. Quantitative analysis indicated methane monooxygenase and nitrous oxide reductase increased by 38- and 8-fold compared to the inoculum. As to the potential mechanisms, we propose that N2O-driven CH4 oxidation was mediated by aerobic methanotrophs solely or along with denitrifying bacteria under hypoxia. Electrons and energy are generated and transferred in the oxidative phosphorylation pathway. Our findings expand the range of electron acceptors associated with CH4 oxidation as well as elucidate the significant role of methanotrophs relative to both carbon and nitrogen cycles.


Asunto(s)
Gases de Efecto Invernadero , Óxido Nitroso , Humanos , Hipoxia , Metano/análisis , Óxido Nitroso/análisis , Humedales
11.
Environ Monit Assess ; 193(4): 183, 2021 Mar 12.
Artículo en Inglés | MEDLINE | ID: mdl-33712944

RESUMEN

In a world where pristine water is becoming scarcer, the need to reuse water becomes imperative. In this context explaining the water quality, purpose fitness and the parameters or conditions of the water body to adjust so as to improve its quality, are of great relevance. The goal of the present study was the use of water, riverine, and biodiversity quality indices to assess the condition of the studied urban wetland, since no single index can provide a complete health assessment of a water body. Decision trees were also used to elucidate the best water parameters to mend in order to recover the overall health of the urban wetland. The decision trees identified relevant physicochemical parameters as well as their approximate concentration at which a healthy water environment can be sustained for zooplankton and proved to be a powerful and simple alternative to customary approaches. Suspended particles and phosphates proved to be important parameters with concentrations approximately lower than 88 mg L-1 and 11 mg L-1, respectively, for a good biodiversity index of zooplankton. Ammonia, total coliforms, BOD, nitrates, and sodium were the main parameters that affected the water quality index. The vegetation coverage and its structure were the driving factors in the riverine quality index of the wetland.


Asunto(s)
Monitoreo del Ambiente , Humedales , Animales , Biodiversidad , Árboles de Decisión , Calidad del Agua
12.
mBio ; 12(2)2021 03 16.
Artículo en Inglés | MEDLINE | ID: mdl-33727350

RESUMEN

Global warming was proposed to be a contributing cause for the nearly simultaneous emergence of different clades of Candida auris as a nosocomial pathogen in different continents. The global warming emergence hypothesis posits that C. auris existed in the environment prior to its clinical recognition and became pathogenic for humans because of thermal adaptation in response to climate change. The isolation of C. auris from two sites in the remote Andaman Islands establishes it as an environmental organism, a necessary condition for the hypothesis. The observation that one environmental isolate grew slower at mammalian temperatures than clinical strains is consistent with the notion that their ancestor recently adapted to higher temperatures. The knowledge that C. auris can be recovered from the environment should prompt additional searches to define its ecological niches, and the analysis of future environmental isolates will provide evidence for validating or refuting the global warming emergence hypothesis.


Asunto(s)
Candida , Candidiasis , Animales , Candida/genética , Calentamiento Global , Humanos , India , Islas , Humedales
13.
Sci Total Environ ; 768: 144993, 2021 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-33736320

RESUMEN

The recently discovered complete ammonia oxidizers (comammox), which are ubiquitous in various natural and artificial ecosystems, have led to a paradigm shift in our understanding of aerobic nitrification. The coastal salt marsh covered by various plant species is an important ecosystem to link nitrogen cycles of terrestrial and marine environments; however, the distribution and structure of comammox in such ecosystems have not been clearly investigated. Here, we applied quantitative PCR and partial nested-PCR to investigate the abundance and community composition of comammox in salt marsh sediment samples covered by three plant types along the southern coastline of China. Our results showed a predominance of comammox clade A in majority of the samples, suggesting their ubiquity and the important role they play in nitrification in salt marsh ecosystems. However, variations by the sites were found when comparing the abundance of subclades of comammox clade A. Redundancy analysis demonstrated a coexistence pattern by comammox clade A.1 with ammonia-oxidizing archaea and comammox clade A.2 with canonical ammonia-oxidizing bacteria, indicating their differences in potential niche preference. However, the abundance of comammox clade B was lower than that of comammox clade A and other ammonia oxidizers in most samples. Moreover, pH and salinity were found to be the most significant factors affecting comammox community structures, suggesting their roles in driving niche partitioning of comammox, whereas plant types did not show a significant effect on the comammox community structure. Our study provided insights into the abundance, community diversity, and niche partitions of comammox, broadening the current understanding of the relationship of comammox with other ammonia oxidizers in salt marsh ecosystems.


Asunto(s)
Amoníaco , Ecosistema , Archaea , Bacterias/genética , China , Nitrificación , Oxidación-Reducción , Filogenia , Humedales
14.
Sci Total Environ ; 770: 144791, 2021 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-33736401

RESUMEN

The coupling between constructed wetlands and reservoir (CWs-R) afforded a novel ecosystem to improve the water quality and increase the emergency storage capacity of micro-polluted river drinking water source. In this study, spectroscopic characteristics of DOM in YL CWs-R ecosystem were first systematic studied based on a three-year field monitoring to investigate the chemical composition, sources and track the involved biogeochemical processes in the ecosystem. Three humic-like components (C1, C2, and C4, em >380 nm) and one protein-like component (C3, em < 380 nm) were identified by PARAFAC model. Significant spatiotemporal variations in concentration and composition of FDOM were observed in YL CWs-R ecosystem. The improved water transparency (SD) and, the increased hydraulic retention time (HRT) along YL CWs-R ecosystem enhance photochemical processes, leading to significant decreases in the intensities of humic-like components in effluent (P < 0.05) with lower degrees of aromaticity, molecular weights, and humification (decrease in HIX and increases in SR and BIX). In contrast, no significant spatial difference was observed for protein-like component (P > 0.05), which implies that the biodegradation and production of protein-like component may balance each other in the CWs-R ecosystem. The ecological pond unit plays a major role in the removal and transformation of DOM, especially in summer, while wetland purification unit contributes little to DOM reduction. In addition, the decay of aquatic macrophytes in wetland purification unit and the risk of algal bloom in the ecological pond unit might become important autochthonous sources of DOM, especially in summer and autumn. These findings are critical for further understanding the transformation processes of DOM in large-scale CWs-R ecosystems, and could provide important implications to improve sustainable safety of drinking water sources.


Asunto(s)
Ecosistema , Humedales , China , Espectrometría de Fluorescencia , Agua
15.
Sci Total Environ ; 770: 145382, 2021 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-33736409

RESUMEN

The rise in sea-level and the increase in frequency and intensity of extreme weather events (i.e., storms and associated surges) are expected to strongly impact coastal areas. The gradual impacts of sea-level rise may allow species to display adaptive responses to overcome environmental changes. In contrast, the abruptness of marine submersions during extreme weather events can induce changes that may exceed the ability of species to respond to brutally changing environments. Yet, site-specific topographical features may buffer the expected detrimental effects of marine submersions on wildlife. In order to test such topographical effects, we examined the long-term consequences of a major marine submersion (storm Xynthia) on the amphibian communities of two French Atlantic coastal wetlands that slightly differ in their topography and, thus, their susceptibility to marine submersion. Amphibians were monitored on 64 ponds for up to 13 years, using acoustic and visual methods, in conjunction with environmental parameters (e.g., pond topology, vegetation, salinity). We found that the amphibian communities at the two neighboring sites displayed different responses to the marine submersion linked to storm Xynthia. As predicted, slight differences in local topography induced strong differences in local magnitude of the landward marine surge, influencing salinization dynamics and associated consequences on wildlife (amphibians). The different species responses show that amphibian richness can recover to that of pre-storm conditions, but with significant changes in the composition of the community. Our results suggest that amphibian presence post-submersion in coastal wetlands results from an interaction between species traits (e.g., tolerance to elevated salinity), site-specific topography, and environmental parameters. Finally, our study emphasizes that relatively modest landscaping management may be critical to allow wildlife to successfully recover after a marine submersion.


Asunto(s)
Inmersión , Humedales , Anfibios , Animales , Salinidad , Elevación del Nivel del Mar
16.
Sci Total Environ ; 770: 144761, 2021 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-33736424

RESUMEN

Intensified Mn redox cycling could enhance nutrient removal in constructed wetlands (CWs). In this study, Mn oxides (birnessite-coated sand) were used as the matrix in horizontal flow CWs (HFCWs) with a microbial electrolysis cell (MEC) (E-B-CW) or without an MEC (B-CW). The model CWs were developed to investigate the capacities and mechanisms of nitrogen removal with increased Mn redox cycling. The results showed that E-B-CW had the highest average removal efficiencies for NH4-N, NO3-N and TN, followed by B-CW and control HFCW (C-CW). The Mn(III) oxides (MnOOH or Mn2O3) and the Mn(IV) oxide (MnO2) were all detected in E-B-CW and B-CW, while the matrix in E-B-CW had much more Mn(IV) oxides than B-CW. Interestingly, clustering heat map showed that ammonification and nitrate reduction were related to Mn-oxidizing bacteria and the relative abundance of Mn-oxidizing bacteria in E-B-CW was highest due to the re-oxidation of Mn(II) by the MEC.


Asunto(s)
Nitrógeno , Humedales , Desnitrificación , Electrólisis , Compuestos de Manganeso , Óxidos , Eliminación de Residuos Líquidos , Aguas Residuales
17.
Environ Monit Assess ; 193(4): 157, 2021 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-33660072

RESUMEN

The protection of wetlands is essential for sustainable development. The particular hydrology of wetlands creates conditions for the formation of hydric soils. Hydric soils are formed in oxide-reducing environments and perform important removal and re-oxidation of Fe and Mn oxides and hydroxides. They are also characterized by the formation of a superficial horizon enriched by the accumulation of organic matter. The objective of this study was to determine the concentration of essential (Co, Cu, Fe, Mn, Ni, Zn) and toxic (Al, Cd, Pb) elements in the soil solution in a wetland, surrounded by an intense agricultural activity area. The concentrations of the elements were evaluated according to the level of hydromorphy (border to the center) and the depth of the soil. The physical fractionation of these elements was also assessed (total and < 30 kDa), and the results were compared with the chemical speciation of these elements. Despite the high total concentrations of Al and Fe, the concentration of these elements was very low in the < 30 kDa fraction, which suggests that these elements are complexed with organic matter, in the form of hydroxides. Evidence of removal of Fe and Mn from the surface horizon was observed at the center of the wetland, where the highest level of hydromorphy is found. The results showed that the concentration of metals in the fraction < 30 kDa is insignificant, suggesting that the mechanisms of precipitation and/or adsorption to soil colloids play an important role in the regulation of this ecosystem.


Asunto(s)
Metales Pesados , Contaminantes del Suelo , Brasil , Ecosistema , Monitoreo del Ambiente , Metales Pesados/análisis , Suelo , Contaminantes del Suelo/análisis , Humedales
18.
J Vis Exp ; (168)2021 02 15.
Artículo en Inglés | MEDLINE | ID: mdl-33645568

RESUMEN

Roots extensively interact with their soil environment but visualizing such interactions between roots and the surrounding rhizosphere is challenging. The rhizosphere chemistry of wetland plants is particularly challenging to capture because of steep oxygen gradients from the roots to the bulk soil. Here a protocol is described that effectively preserves root structure and rhizosphere chemistry of wetland plants through slam-freezing and freeze drying. Slam-freezing, where the sample is frozen between copper blocks pre-cooled with liquid nitrogen, minimizes root damage and sample distortion that can occur with flash-freezing while still minimizing chemical speciation changes. While sample distortion is still possible, the ability to obtain multiple samples quickly and with minimal cost increases the potential to obtain satisfactory samples and optimizes imaging time. The data show that this method is successful in preserving reduced arsenic species in rice roots and rhizospheres associated with iron plaques. This method can be adopted for studies of plant-soil relationships in a wide variety of wetland environments that span concentration ranges from trace-element cycling to phytoremediation applications.


Asunto(s)
Elementos , Imagenología Tridimensional/métodos , Raíces de Plantas/química , Rizosfera , Humedales , Liofilización , Oryza/anatomía & histología , Suelo/química
19.
Ying Yong Sheng Tai Xue Bao ; 32(2): 486-494, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33650357

RESUMEN

Based on the high resolution record of fossil pollen data from a 190 cm sediment profile collected in a Betula microphylla-dominated wetland of Ebinur Lake in Xinjiang, we aimed to reveal the changes of vegetation and environment in this wetland over the past 3900 years. Results showed that, in the period between 3420 cal. aBP and 3940 cal. aBP, this area was a desert landscape dominated by plants from Chenopodiaceae and Artemisia. During the period of 2830-3420 cal. aBP, this area became a desert steppe dominated by Thelypteris palustris, surrounded by desert plants mainly composed of Chenopodiaceae and Artemisia. In the period between 2640 and 2830 cal. aBP, Typha pollen increased and occupied a dominant position. The area thus became a typical desert intrazonal wetland mainly composed of Typha. In the period between 1200 and 2640 cal. aBP, Phragmites australis began to grow vigorously and became the dominant species. In the period between 660 and 1200 cal. aBP, the population of Betula expanded rapidly, and P. australis plants continued to grow. During the period of 340-660 cal. aBP, the population of B. microphylla became the dominant species, and the abundance of P. australis decreased. However, there was still some P. australis wetlands in the area. Over the past 340 years, as the area of wetlands decreased and the surface water gradually declined, B. microphylla had grown on swampy meadow soils with suitable moisture conditions. In the past 200 years especially, the sharp increases of Chenopodiaceae pollen in palynological assemblage was closely related to the enhancement of human activities and climate change, resulting in the degradation of wetlands and endangerment of B. microphylla. Therefore, it is necessary to strengthen the protection of wetlands and endangered species in this area.


Asunto(s)
Lagos , Humedales , Betula , China , Humanos , Suelo
20.
Ying Yong Sheng Tai Xue Bao ; 32(2): 571-580, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33650367

RESUMEN

Peat bogs, which cover only 3% of the global land surface, store about 30% of the global soil carbon (C), and are important carbon pools in terrestrial ecosystems. Dissolved organic matter (DOM) is an important part of carbon cycle in peatland, and also an important participant in biogeo-chemical process of peat. The variation of redox ability of DOM and inorganic ions in surface water, groundwater, and pore water of two sampling peatland (minerotrophic fen, LB; ombrotrophic bog, OS) were analyzed using novel electrochemical method and stable carbon isotope. The results showed that in the LB plot, inorganic elements were rich, and that anaerobic respiration dominated by inorganic electron acceptor was the main process. The redox ability differed across different LB water sources (surface water, groundwater, and pore water), which was mainly affected by the actual redox potentials. Iron and sulfate were generally in reduced state in the profile of pore water. The reaction level and depth of redox active groups of DOM which participated in redox process were influenced by inorganic electron acceptor. In the OS plot, organic matter was extremely rich, and organic electron acceptor contributed significantly in redox process. The redox ability of OS water samples from different sources performed differently, which was also mainly attributed to the actual redox potentials. The redox ability of pore water profile was affected by the chemical composition in peat substance at different depths. Therefore, electron accepting capacities (EAC) and oxidation index (OI) values could be used to identify the redox conditions along the gradient and to indicate the redox state of organic matter in aquatic systems.


Asunto(s)
Agua Subterránea , Suelo , Carbono , Ecosistema , Humanos , Humedales
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