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1.
Sci Total Environ ; 792: 148454, 2021 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-34465049

RESUMO

Nano zero-valent iron particles (nZVI, 0.09 wt%), micro zero-valent iron particles (mZVI, 0.09 wt%), granular activated carbon (GAC, 3.03 wt%), GAC supported nZVI (nZVI/GAC, 3.12 wt%) and nZVI&GAC (nZVI 0.09 wt%, GAC 3.03 wt%) were evaluated for their effects on polychlorinated biphenyls (PCBs) anaerobic reductive dechlorination, detoxification, as well as microbial community structure in Taihu Lake (China) sediment microcosms. The results showed that all of these five materials could stimulate PCBs reductive dechlorination, especially for dioxin-like PCB congeners, and nZVI&GAC had the best removal effect on PCBs. The reduction of total PCBs increased from 13.5% to 33.2%. H2 generated by zero-valent iron corrosion was utilized by organohalide-respiring bacteria (OHRB) to enhance the dechlorination of PCBs predominantly via meta chlorine removal in the short term. The addition of ZVI had little impact on the total bacterial abundance and the microbial community structure. The adsorption of GAC and potential bioremediation properties of attached biofilm could promote the long-term removal of PCBs. GAC, nZVI/GAC, nZVI&GAC had different influences on the microbial structure. These findings provide insights into the biostimulation technique for in situ remediations of PCBs contaminated sediments.


Assuntos
Microbiota , Bifenilos Policlorados , Biodegradação Ambiental , Catálise , Cloro , Sedimentos Geológicos , Ferro , Lagos , Bifenilos Policlorados/análise
2.
BMC Health Serv Res ; 21(1): 948, 2021 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-34503486

RESUMO

BACKGROUND: Maternal mortality is still a challenge in Uganda, at 336 deaths per 100,000 live births, especially in rural hard to reach communities. Distance to a health facility influences maternal deaths. We explored women's mobility for maternal health, distances travelled for antenatal care (ANC) and childbirth among hard-to-reach Lake Victoria islands fishing communities (FCs) of Kalangala district, Uganda. METHODS: A cross sectional survey among 450 consenting women aged 15-49 years, with a prior childbirth was conducted in 6 islands FCs, during January-May 2018. Data was collected on socio-demographics, ANC, birth attendance, and distances travelled from residence to ANC or childbirth during the most recent childbirth. Regression modeling was used to determine factors associated with over 5 km travel distance and mobility for childbirth. RESULTS: The majority of women were residing in communities with a government (public) health facility [84.2 %, (379/450)]. Most ANC was at facilities within 5 km distance [72 %, (157/218)], while most women had travelled outside their communities for childbirth [58.9 %, (265/450)]. The longest distance travelled was 257.5 km for ANC and 426 km for childbirth attendance. Travel of over 5 km for childbirth was associated with adolescent girls and young women (AGYW) [AOR = 1.9, 95 % CI (1.1-3.6)], up to five years residency duration [AOR = 1.8, 95 % CI (1.0-3.3)], and absence of a public health facility in the community [AOR = 6.1, 95 % CI (1.4-27.1)]. Women who had stayed in the communities for up to 5 years [AOR = 3.0, 95 % CI (1.3-6.7)], those whose partners had completed at least eight years of formal education [AOR = 2.2, 95 % CI (1.0-4.7)], and those with up to one lifetime birth [AOR = 6.0, 95 % CI (2.0-18.1)] were likely to have moved to away from their communities for childbirth. CONCLUSIONS: Despite most women who attended ANC doing so within their communities, we observed that majority chose to give birth outside their communities. Longer travel distances were more likely among AGYW, among shorter term community residents and where public health facilities were absent. TRIAL REGISTRATION: PACTR201903906459874 (Retrospectively registered). https://pactr.samrc.ac.za/TrialDisplay.aspx?TrialID=5977 .


Assuntos
Lagos , Saúde Materna , Adolescente , Estudos Transversais , Parto Obstétrico , Feminino , Instalações de Saúde , Humanos , Gravidez , Cuidado Pré-Natal , Uganda/epidemiologia
3.
J Hazard Mater ; 416: 125818, 2021 08 15.
Artigo em Inglês | MEDLINE | ID: mdl-34492783

RESUMO

Metal pollution poses a significant threat to ecological security and human health. Current research on the causes, sources and distribution of metal pollution in the Yangtze River plain is lacking. This study investigated the accumulation, risk, distribution, and sources of heavy metals in 62 lakes along the Yangtze River, and analyzed the relationship between river-lake connectivity, economic structure, population and metal diffusion. The mean concentrations of Cr, Cu, Hg, Zn, Cd, Pb and As in the surface sediments of these lakes were 90.8, 60.1, 0.06, 102, 0.89, 42.7, and 6.01 mg/kg, respectively. Most (99%) of the lake sediments were contaminated with Cd, and the lakes in the middle reach and southern bank of the Yangtze River had a higher ecological risk. Cr originated from the natural environment, whereas Zn, Cu, Pb, Cd and As were affected by human activities. The lakes disconnected from the Yangtze River had higher concentrations of Cu, Zn, Pb and As, while the lakes connected to the river had higher concentrations of Cd and Cr. This comprehensive analysis determined the pollution characteristics of heavy metals, illustrated the causes of non-point pollution in the Yangtze River plain, and showed that soil-water erosion is important in metal diffusion.


Assuntos
Metais Pesados , Poluentes Químicos da Água , China , Monitoramento Ambiental , Sedimentos Geológicos , Humanos , Lagos , Metais Pesados/análise , Metais Pesados/toxicidade , Medição de Risco , Rios , Poluentes Químicos da Água/análise
4.
Environ Monit Assess ; 193(10): 627, 2021 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-34487242

RESUMO

Nickel determination is important because of its use in many industrial areas and its negative effects on human health. In this study, an ultraviolet-based photochemical vapor generation (UV-PVG) setup was combined with a T-shaped zirconium-coated slotted quartz tube-atom trapping (T-SQT-AT) apparatus to boost the sensitivity of a flame atomic absorption spectrophotometer for nickel determination. Nickel was separated from the sample matrix by converting it into its volatile species prior to online preconcentration by trapping on the zirconium-coated T-SQT inner surface. Analytical performance was maximized by optimizing all variable conditions. The limit of detection (LOD) and limit of quantification (LOQ) were found as 10 and 33 µg/L, respectively. Daphne tea and lake water samples were analyzed under optimum conditions, and there was no detectable nickel in the samples. For this purpose, spiking experiments were carried out for the samples in order to evaluate the applicability and accuracy of the method. The percent recovery values calculated for the two samples spiked at three different concentrations ranged between 90 and 112%. To our best knowledge, this is the first study in literature where UV-PVG was combined with T-SQT-AT for the determination of nickel in daphne tea and lake water samples prior to FAAS determination.


Assuntos
Daphne , Quartzo , Monitoramento Ambiental , Humanos , Lagos , Níquel/análise , Extratos Vegetais , Espectrofotometria Atômica , Chá , Água/análise , Zircônio
5.
Environ Monit Assess ; 193(10): 645, 2021 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-34514553

RESUMO

Phragmites growth in a marsh watershed due to increased salinity has been a crucial issue across the world. The objective of this study was to investigate the salinity movement in the ungagged Mentor Marsh of Ohio, USA, where the salinity had increased due to a number of potential sources causing a decline in the native vegetation and leading to the increased invasive phragmites growth. In this study, we conducted a detailed bathymetric survey and established several monitoring stations to record hourly environmental data in Mentor Marsh. Since Mentor Marsh has a complex hydrologic characteristic, which interacts with Lake Erie due to the backwater effect, a hydrodynamic model, Environmental Fluid Dynamic Code (EFDC +), was developed to simulate the western Mentor Marsh wetland's salinity distribution. We evaluated the model performance by comparing water level, temperature, and salinity using statistical measures for a duration from December 2019 to March 2020. The model was calibrated using the measured time-series data of water temperatures, water levels, and water salinity from monitoring stations in the western basin. The model performance for salinity calibration (R2 = 0.82, RMSE = 0.041, and Pbias = - 1.05%) and validation (R2 = 0.84, RMSE = 0.066, and Pbias = - 2.05%) was good. In the next step, the calibrated model was utilized to investigate the salinity distributions under different inflow and lake level rise conditions. Our analysis suggested that during high-flow conditions, the advection of the saline water from Marsh Creek was vigorous in comparison to the diffusion of salinity mixing by tidal influence pushing the salinity towards Mentor Marsh and resulting in the lower salinity distribution within the model domain. Similarly, when the lake level rise occurred, the model predicted a significant decrease in the salinity of Mentor Marsh near Lake Erie. The average decrease of salinity from the salinity during the base run was - 45.8% near Lake Erie, - 29.7% at the junction of Mentor Marina and Mentor Marsh, - 21.2% in Mentor Marsh, and - 4.4% in Marsh Creek. The analysis further suggested that under high-flow conditions from Marsh Creek, the salinity moved towards Mentor Marsh, especially when lake level rise conditions were considered. This is mainly because the high water level of Lake Erie pushed March Creek towards Mentor Marsh. However, the salinity moved towards Lake Erie from Marsh Creek during low-flow conditions. Presumably, the phragmites growth in the western section seems to be due to the road salt used in winter for deicing purposes.


Assuntos
Salinidade , Áreas Alagadas , Monitoramento Ambiental , Hidrologia , Lagos
6.
Artigo em Inglês | MEDLINE | ID: mdl-34431766

RESUMO

The aerobic primarily chemoorganotrophic actinobacterial strain MWH-Mo1T was isolated from a freshwater lake and is characterized by small cell lengths of less than 1 µm, small cell volumes of 0.05-0.06 µm3 (ultramicrobacterium), a small genome size of 1.75 Mbp and, at least for an actinobacterium, a low DNA G+C content of 54.6 mol%. Phylogenetic analyses based on concatenated amino acid sequences of 116 housekeeping genes suggested the type strain of Aurantimicrobium minutum affiliated with the family Microbacteriaceae as its closest described relative. Strain MWH-Mo1T shares with the type strain of that species a 16S rRNA gene sequence similarity of 99.6 % but the genomes of the two strains share an average nucleotide identity of only 79.3 %. Strain MWH-Mo1T is in many genomic, phenotypic and chemotaxonomic characteristics quite similar to the type strain of A. minutum. Previous intensive investigations revealed two unusual traits of strain MWH-Mo1T. Although the strain is not known to be phototrophic, the metabolism is adjusted to the diurnal light cycle by up- and down-regulation of genes in light and darkness. This results in faster growth in the presence of light. Additionally, a cell size-independent protection against predation by bacterivorous flagellates, most likely mediated by a proteinaceous cell surface structure, was demonstrated. For the previously intensively investigated aerobic chemoorganotrophic actinobacterial strain MWH-Mo1T (=CCUG 56426T=DSM 107758T), the establishment of the new species Aurantimicrobium photophilum sp. nov. is proposed.


Assuntos
Actinobacteria/classificação , Lagos/microbiologia , Fotoperíodo , Filogenia , Actinobacteria/isolamento & purificação , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
7.
J Exp Biol ; 224(7)2021 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-34424981

RESUMO

Animals display remarkable diversity in rest and activity patterns that are regulated by endogenous foraging strategies, social behaviors and predator avoidance. Alteration in the circadian timing of activity or the duration of rest-wake cycles provide a central mechanism for animals to exploit novel niches. The diversity of the >3000 cichlid species throughout the world provides a unique opportunity to examine variation in locomotor activity and rest. Lake Malawi alone is home to over 500 species of cichlids that display divergent behaviors and inhabit well-defined niches throughout the lake. These species are presumed to be diurnal, though this has never been tested systematically. Here, we measured locomotor activity across the circadian cycle in 11 Lake Malawi cichlid species. We documented surprising variability in the circadian time of locomotor activity and the duration of rest. In particular, we identified a single species, Tropheops sp. 'red cheek', that is nocturnal. Nocturnal behavior was maintained when fish were provided shelter, but not under constant darkness, suggesting that it results from acute response to light rather than an endogenous circadian rhythm. Finally, we showed that nocturnality is associated with increased eye size after correcting for evolutionary history, suggesting a link between visual processing and nighttime activity. Together, these findings identify diversity of locomotor behavior in Lake Malawi cichlids and provide a system for investigating the molecular and neural basis underlying variation in nocturnal activity.


Assuntos
Ciclídeos , Animais , Evolução Biológica , Ecossistema , Lagos , Malaui , Filogenia
8.
Artigo em Inglês | MEDLINE | ID: mdl-34444365

RESUMO

UE regulations focus on methods of water quality monitoring and their use in rational management practices. This study investigated horizontal and vertical variations of electrical conductivity (EC), pH, dissolved oxygen (DO), and chlorophyll a (Chl-a) in a shallow polymictic lake. Monitoring of short-term variability of physical and chemical lake water parameters is a critical component in lake management, as it influences aquatic life. Based on the field research, maps of spatial distribution of the parameters were drawn. Using two methods: (1) a classical approach to water column measurements, from the top to the bottom (TB), in which the reference point is always a surface layer (SL), and (2) a newly introduced method of lake water quality monitoring based on a nearest neighbor (NN) approach; a comparison of higher and lower layers of the water column. By subtracting partial maps of spatial variability for different depths, final raster images were obtained. The NN method is rather absent in the limnology literature worldwide. Vertical and horizontal variability of the tested parameters in the polymictic, shallow Lake Bikcze (Poland) was presented in the results. In the presented paper, the commonly used TB method emphasized the role of the surface layer in shaping the variability of physicochemical parameters of lake waters. It shows a general trend of parameters' changes from the top, to the bottom. The newly presented NN method, which has a major advantage in its simplicity and objectivity, emphasized structural differentiation within the range of variability. The nearest neighbor method was more accurate in showing the actual structure of fluctuation of parameters with higher fluctuation in the water column. Its advantage is a detailed recognition of the vertical variability of selected parameters in the water column. The method may be used regardless of the lake depth, its location in climatic zone, and/or region.


Assuntos
Lagos , Qualidade da Água , Clorofila A , Monitoramento Ambiental , Polônia
9.
Water Res ; 202: 117399, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34333297

RESUMO

Lanthanum modified bentonite (LMB) has been applied to eutrophic lakes to reduce phosphorus (P) concentrations in the water column and mitigate P release from sediments. Previous experiments suggest that natural organic matter (NOM) can interfere with phosphate (PO4)-binding to LMB and exacerbate lanthanum (La)-release from bentonite. This evidence served as motivation for this study to systematically determine the effects of NOM, solution pH, and bentonite as a La carrier on P removal. We conducted both geochemical modeling and controlled-laboratory batch kinetic experiments to understand the pH-dependent impacts of humic and fulvic acids on PO4-binding to LMB and La release from LMB. The role of bentonite was studied by comparing PO4 removal obtained by LMB and La3+ (added as LaCl3 salt to represent the La-containing component of LMB). Our results from both geochemical modeling and batch experiments indicate that the PO4-binding ability of LMB is decreased in the presence of NOM, and the decrease is more pronounced at pH 8.5 than at 6. At the highest evaluated NOM concentration (28 mg C L-1), PO4-removal by La3+ was substantially lower than that by LMB, implying that bentonite clay in LMB shielded La from interactions with NOM, while still allowing PO4 capture by La. Finally, the presence of NOM promoted La-release from LMB, and the amount of La released depended on solution pH and both the type (i.e., fulvic/humic acid ratio) and concentration of NOM. Overall, these results provide an important basis for management of P in lakes and eutrophication control that relies on LMB applications.


Assuntos
Bentonita , Lantânio , Concentração de Íons de Hidrogênio , Lagos , Fosfatos , Fósforo
10.
Water Res ; 202: 117434, 2021 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-34388474

RESUMO

Despite massive financial investment in mitigation, eutrophication remains a major water quality problem and management priority. Eutrophication science-well established for lakes-is not as well developed for rivers, and scientific understanding of how rivers respond to eutrophication management is far more limited. Long-term data are required to evaluate progress, but such datasets are relatively rare for rivers. We analyzed 23 years of water quality data for the Charles River, a major urban river system in the northeastern U.S.A., to examine nutrient and phytoplankton biomass (chl-a) responses to decades of phosphorus (P) management. Using the more novel and robust approach of quantile regression, we identified statistically and ecologically significant declines in both total phosphorus (TP) and chl-a over time, but only for middle percentiles. Statistically high concentrations of TP and chl-a persist-the segments of the data of greatest concern to managers and the public-and yet this critical result is concealed by statistical tests often employed in eutrophication studies that only evaluate mean changes. TP, temperature, precipitation, and river segment jointly explain the most chl-a variation observed at the decadal scale. Spatial variation is also considerable: despite a significant decline in TP, the impounded lower river exhibits no long-term trend in chl-a and continues to experience annual blooms of harmful cyanobacteria-a lagging response comparable to that of a recovering eutrophic lake. Despite long-term successes in reducing P, chl-a, and cyanobacteria in the Charles River system, we did not detect any significant, long-term change in the attainment of statutory compliance, illustrating the protracted and complex nature of the river's response. Our analysis demonstrates the need for high-frequency, long-term water quality data to evaluate the progress of eutrophication management in urban rivers, and the utility of quantile regression for detecting critical trends in the occurrence of statistically low-frequency but ecologically high-impact events, including blooms of harmful cyanobacteria.


Assuntos
Monitoramento Ambiental , Rios , China , Clorofila A , Eutrofização , Lagos , Nitrogênio/análise , Fósforo/análise
11.
Ecotoxicol Environ Saf ; 223: 112627, 2021 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-34390983

RESUMO

Distribution of methylsiloxanes in environment is still far from being well studied. Little is known about the concentrations and associated risks of these chemicals in river-lake systems. This study investigated the occurrence of twelve methylsiloxanes (D4-D6, L5-L13) in the sediments from Lake Chaohu and its inflowing rivers, China, and found the total concentrations (ng/g dry weight) were in the range of 47.1-496 and 239-3593, respectively. Linear congeners were dominant, representing a median of 62.8% and 58.7% of the total concentrations found in the lake and its inflowing rivers, respectively. In general, the concentrations of sediment methylsiloxanes in the investigated river-lake system were low to moderate, compared with the results reported previously in other waters. Source assessment indicated that the emissions from industrial activities and the use of silicone-containing products were the main contributors of sediment methylsiloxanes in the investigated waters. D4 and D5 in 18.5% and 11.1% of river sediment samples might pose ecological risks to fish. The risks from the linear congeners in sediments in the area were not estimated due to no related benchmarks available. More studies are needed to investigate the occurrence of these chemicals and associated risks in aquatic environment.


Assuntos
Rios , Poluentes Químicos da Água , Animais , China , Monitoramento Ambiental , Sedimentos Geológicos , Lagos , Poluentes Químicos da Água/análise
12.
J Environ Sci (China) ; 107: 205-217, 2021 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-34412783

RESUMO

Interactions between dissolved organic matter (DOM) and bacteria are central in the biogeochemical cycles of aquatic ecosystems; however, the relative importance of biodegradable dissolved organic carbon (BDOC) compared with other environmental variables in structuring the bacterial communities needs further investigation. Here, we investigated bacterial communities, chromophoric DOM (CDOM) characteristics and physico-chemical parameters as well as examined BDOC via bioassay incubations in large eutrophic Lake Taihu, China, to explore the importance of BDOC for shaping bacterial community structures and co-occurrence patterns. We found that the proportion of BDOC (%BDOC) correlated significantly and positively with the DOC concentration and the index of the contribution of recent produced autochthonous CDOM (BIX). %BDOC, further correlated positively with the relative abundance of the tryptophan-like component and negatively with CDOM aromaticity, indicating that autochthonous production of protein-like CDOM was an important source of BDOC. The richness of the bacterial communities correlated negatively with %BDOC, indicating an enhanced number of species in the refractory DOC environments. %BDOC was identified as a significant stronger factor than DOC in shaping bacterial community composition and the co-occurrence network, suggesting that substrate biodegradability is more significant than DOC quantity determining the bacterial communities in a eutrophic lake. Environmental factors explained a larger proportion of the variation in the conditionally rare and abundant subcommunity than for the abundant and the rare bacterial subcommunities. Our findings emphasize the importance of considering bacteria with different abundance patterns and DOC biodegradability when studying the interactions between DOM and bacteria in eutrophic lakes.


Assuntos
Carbono , Lagos , Bactérias , Carbono/análise , China , Ecossistema
13.
Huan Jing Ke Xue ; 42(9): 4319-4331, 2021 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-34414730

RESUMO

Dissolved organic matter (DOM) plays an important role in the evolution of microbial communities. Meanwhile, ecological water delivery is an important feature of Baiyangdian Lake. To explore how the structure of the aerobic denitrification bacteria community responds to DOM during the water delivery period, the DOM components of water were examined and high-throughput sequencing of aerobic denitrification bacteria was performed. The results showed significant differences in DOM concentration in Baiyangdian Lake, with the estuary area exhibiting lower DOM concentrations. The water exhibited strong autogenous source, while DOM in the estuary area had a higher molecular weight and degree of humification. Three protein-like substances (C1, C2, and C4) and one humic-like substance (C3) were identified through PARAFAC. The protein-like substances accounted for the major proportion of DOM, which was consistent with the results of fluorescence regional integration (FRI). The genera of the water body were mainly in the Protebacterice phylum, including Cupriavidus, Aeromonas, Thauera, Shewanella, and Pseudomonas. Meanwhile, Cupriavidus, Thauera, Shewanella, Agrobacterium, and Pseudomonas were the main indicator species, according to random forest (RF) analysis. Through network analysis, 35 key nodes of the network were obtained, belonging to Thauera, Cupriavidus, and Unclassified_bacteria, respectively. Redundancy analysis (RDA) showed that a humic-like substance was the main environmental factor regulating the whole structure of the aerobic denitrification bacterial community, while protein-like substances played important roles in changes to the indicator species and key nodes of the community. Overall, protein-like substances could provide an important reference for selecting carbon sources during the screening of efficient and cold resistance aerobic denitrification bacteria that are adapted to actual water bodies.


Assuntos
Desnitrificação , Lagos , Bactérias/genética , Estuários , Água
14.
Braz J Biol ; 83: e244494, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34378660

RESUMO

Since water is one of the essentials for life, the presence and quality of water in the habitat is extremely important. Therefore, water quality change and management of Lake Aygir was investigated in this study. For this, water samples collected from the lake and the irrigation pool between May 2015 and May 2016 were analyzed monthly. Spectrophotometric, titrimetric and microbiological methods were used to determine the water quality. According to some water quality regulations, HCO3, NH4, Cu, Mo, Br, fecal coliform and total suspended solid (TSS) values were found above the limit values. The other 29 parameters comply with Turkish national and international legislations. Lake Aygir was negatively affected by the surrounding settlements and agricultural activities. It is thought that the water resource should be monitored periodically and remedial studies should be done to prevent parameters exceeding the limits. However, Lake Aygir was generally suitable for drinking, use, fishing and irrigation.


Assuntos
Lagos , Poluentes Químicos da Água , Monitoramento Ambiental , Pesqueiros , Turquia , Poluentes Químicos da Água/análise , Qualidade da Água
15.
Toxins (Basel) ; 13(7)2021 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-34357943

RESUMO

Cyanobacteria are ubiquitous photosynthetic microorganisms considered as important contributors to the formation of Earth's atmosphere and to the process of nitrogen fixation. However, they are also frequently associated with toxic blooms, named cyanobacterial harmful algal blooms (cyanoHABs). This paper reports on an unusual out-of-season cyanoHAB and its dynamics during the COVID-19 pandemic, in Lake Avernus, South Italy. Fast detection strategy (FDS) was used to assess this phenomenon, through the integration of satellite imagery and biomolecular investigation of the environmental samples. Data obtained unveiled a widespread Microcystis sp. bloom in February 2020 (i.e., winter season in Italy), which completely disappeared at the end of the following COVID-19 lockdown, when almost all urban activities were suspended. Due to potential harmfulness of cyanoHABs, crude extracts from the "winter bloom" were evaluated for their cytotoxicity in two different human cell lines, namely normal dermal fibroblasts (NHDF) and breast adenocarcinoma cells (MCF-7). The chloroform extract was shown to exert the highest cytotoxic activity, which has been correlated to the presence of cyanotoxins, i.e., microcystins, micropeptins, anabaenopeptins, and aeruginopeptins, detected by molecular networking analysis of liquid chromatography tandem mass spectrometry (LC-MS/MS) data.


Assuntos
Cianobactérias , Proliferação Nociva de Algas , Lagos/microbiologia , Toxinas Bacterianas/análise , Toxinas Bacterianas/toxicidade , COVID-19/epidemiologia , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Cianobactérias/genética , DNA Bacteriano/análise , Monitoramento Ambiental , Atividades Humanas , Humanos , Itália/epidemiologia , Microcystis , Pandemias , SARS-CoV-2 , Imagens de Satélites
16.
Water Res ; 203: 117510, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34375930

RESUMO

Long-term trends in riverine nutrient availability have rarely been linked to both phytoplankton composition and functioning. To explore how the changing availability of N and P affects not only phytoplankton abundance and composition but also the resource use efficiency of N, P, and CO2, a 25-year time series of water quality in the lower Han River, Korea, was combined with additional measurements of riverine dissolved organic carbon (DOC) and CO2. Despite persistent eutrophication, recent decreases in P relative to N have been steep in the lowest reach, increasing the annual mean mass ratio of N to P (N/P) from 24 (1994-2015) to 65 (2016-2018). While Chl a and cyanobacterial abundance exhibited overall positive and inverse relationships with P concentrations and N/P, respectively, severe harmful algal blooms (HABs) concurred with short-term increases in P and temperature. Microcystis often dominated HABs at low N/P that usually favors N-fixing cyanobacteria such as Anabaena. In the middle and lower reaches, phytoplanktonic P use efficiency was typically lower at low N/P. V-shaped relationships between N/P and CO2 concentrations, together with longitudinal upward shifts in the inverse relationship between Chl a and CO2, implied that eutrophication-enhanced phytoplankton biomass could turn into a significant source of CO2. after passing a threshold. The combined results suggest that cyanobacterial dominance co-limited by P availability and temperature can lower planktonic P use efficiency, while enhancing riverine CO2 emissions at low N/P ratios.


Assuntos
Cianobactérias , Fitoplâncton , Dióxido de Carbono , Eutrofização , Proliferação Nociva de Algas , Lagos , Nutrientes
17.
Water Res ; 203: 117489, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34450464

RESUMO

Shallow lakes are considered important contributors to emissions of nitrous oxide (N2O), a powerful greenhouse gas, in aquatic ecosystems. There is a large degree of uncertainty regarding the relationship between N2O emissions and the progress of lake eutrophication, and the mechanisms underlying N2O emissions are poorly understood. Here, N2O emission fluxes and environmental variables in different lakes along a trophic state gradient in the Yangtze River basin were studied. N2O emission fluxes were -1.0-53.0 µg m-2 h-1 and 0.4-102.9 µg m-2 h-1 in summer and winter, respectively, indicating that there was marked variation in N2O emissions among lakes of different trophic state. The non-linear exponential model explained differences in N2O emission fluxes by the degree of eutrophication (p < 0.01). TN and chl-a both predicted 86% of the N2O emission fluxes in shallow lakes. The predicted N2O emission fluxes based on the IPCC EF5r overestimated the observed fluxes, particularly those in hyper-eutrophic lakes. These findings demonstrated that nutrient-rich conditions and algal accumulation are key factors determining N2O emission fluxes in shallow lakes. Furthermore, this study also revealed that temperature and algae accumulation-decomposition determine an N2O emission flux in an intricate manner. A low temperature, i.e., winter, limits algae growth and low oxygen consumption for algae decomposition. The environment leaves a high dissolved oxygen concentration, slowing down N2O consumption as the final step of denitrification. In summer, with the oxygen consumed by excess algal decomposition, the N2O production is limited by the complete denitrification as well as the limited substrate supply of nitrate by nitrification in hypoxic or anoxic conditions. Such cascading events explained the higher N2O emission fluxes from shallow lakes in winter compared with summer. This trend was amplified in hyper-eutrophic shallow lakes after algal disappearance. Collectively, algal accumulation played a dual role in stimulating and impeding N2O emissions, especially in hyper-eutrophic lakes. This study expands our knowledge of N2O emissions from shallow lakes in which eutrophication is underway.


Assuntos
Ecossistema , Lagos , China , Eutrofização , Óxido Nitroso/análise , Rios
18.
Chemosphere ; 277: 130260, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-34384176

RESUMO

The fraction transformation from stable to mobile forms in sediments is continuous, slow, and spontaneous chain reactions causing static risks to the aquatic system. However, this process may change into abrupt, rapid, and dynamic paths when certain physicochemical conditions changed. Using the Delayed Geochemical Hazard (DGH) model, comprehensive methods combing both static and dynamic risk assessment were therefore conducted to evaluate the aforementioned processes. By applying these methods, arsenic (As) pollution in surface sediments of the Baiyangdian Lake (BYD Lake) was investigated thoroughly as a case study area. The results showed that the total As concentrations in those sediment samples ranged from 4.87 to 17.94 mg/kg, with an average of 8.75 mg/kg. In a fraction, Fe and Mn were observed to pose effects on the surface-adsorbed (AsS) and residual fractions (AsR) with the coefficient analysis. The static risk assessment showed that both the contamination and ecological risk are at a low level in the total content but a low to moderate risk in the fraction. The dynamic risk assessment posted the potential transformation paths of As in the sediments, indicating a trend of potential DGH burst in 45.24%-78.57% of the BYD Lake. In summary, this study provides a methodology for the risk assessment of arsenic that may extend to other heavy metal(loid)s combining static and dynamic processes in sediments.


Assuntos
Arsênio , Metais Pesados , Poluentes Químicos da Água , China , Monitoramento Ambiental , Sedimentos Geológicos , Lagos , Metais Pesados/análise , Medição de Risco , Poluentes Químicos da Água/análise
19.
Environ Pollut ; 285: 117501, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34380215

RESUMO

Biodiversity loss is often an important driver of the deterioration of ecosystem functioning in freshwater ecosystems. However, it is far from clear how multiple ecosystem functions (i.e., ecosystem multifunctionality, EMF) relate to biodiversity across the benthic-pelagic habitats of entire ecosystems or how environmental stress such as eutrophication and heavy metals enrichment might regulate the biodiversity-EMF relationships. Here, we explored the biodiversity and EMF across benthic-pelagic habitats of the large eutrophic Lake Taihu in China, and further examined abiotic factors underlying the spatial variations in EMF and its relationships with biodiversity. In our results, EMF consistently showed positive relationships to the biodiversity of multiple taxonomic groups, such as benthic bacteria, bacterioplankton and phytoplankton. Both sediment heavy metals and total phosphorus significantly explained the spatial variations in the EMF, whereas the former were more important than the latter. Further, sediment heavy metals mediated EMF through the diversity of benthic bacteria and bacterioplankton, while nutrients such as phosphorus in both the sediments and overlaying water altered EMF via phytoplankton diversity. This indicates the importance of pollution in regulating the relationships between biodiversity and EMF in freshwater environments. Our findings provide evidence that freshwater biodiversity loss among phytoplankton and bacteria will likely weaken ecosystem functioning. Our results further suggest that abiotic factors such as heavy metals, beyond nutrient enrichment, may provide relatively earlier signals of impaired ecosystem functioning during eutrophication process.


Assuntos
Ecossistema , Lagos , Biodiversidade , Eutrofização , Fitoplâncton
20.
Environ Pollut ; 285: 117636, 2021 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-34380226

RESUMO

Increasing chloride concentrations from road salt applications are an emerging threat to freshwater diversity in cold weather regions. Few studies have focused on how road salt affects freshwater biota and even fewer have focused on how the rate of exposure alters organism responses. We hypothesized that road salt concentrations delivered gradually would result in slower population declines and more rapid rebounds due to evolved tolerance. To test this hypothesis, we examined the responses of freshwater lake organisms to four environmentally relevant salt concentrations (100, 230, 860, and 1600 mg Cl-/L) that differed in application rate (abrupt vs. gradual). We used outdoor aquatic mesocosms containing zooplankton, filamentous algae, phytoplankton, periphyton, and macroinvertebrates. We found negative effects of road salt on zooplankton and macroinvertebrate abundance, but positive effects on phytoplankton and periphyton, likely resulting from reduced grazing. Only rarely did we detect a difference between abrupt vs gradual salt applications and the directions of those differences were not consistent. This affirms the need for additional research on how road salt pollution entering ecosystems at different frequencies and magnitudes will alter freshwater communities.


Assuntos
Ecossistema , Poluentes Químicos da Água , Animais , Lagos , Fitoplâncton , Cloreto de Sódio , Poluentes Químicos da Água/toxicidade , Zooplâncton
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