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1.
Water Res ; 185: 116150, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-33086462

RESUMO

Historical accumulation of phosphorus (P) in lake sediment often contributes to and sustains eutrophic conditions in lakes, even when external sources of P are reduced. The most cost-effective and commonly used method to restore the balance between P and P-binding metals in the sediment is aluminum (Al) treatment. The binding efficiency of Al, however, has varied greatly among treatments conducted over the past five decades, resulting in substantial differences in the amount of P bound per unit Al. We analyzed sediment from seven previously Al treated Swedish lakes to investigate factors controlling binding efficiency. In contrast to earlier work, lake morphology was negatively correlated to binding efficiency, meaning that binding efficiency was higher in lakes with steeply sloping bathymetry than in lakes with more gradually sloping bottoms. This was likely due to Al generally being added directly into the sediment, and not to the water column. Higher binding efficiencies were detected when Al was applied directly into the sediment, whereas the lowest binding efficiency was detected where Al was instead added to the water column. Al dose, mobile sediment P and lake morphology together explained 87% of the variation in binding efficiency among lakes where Al was added directly into the sediment. This led to the development of a model able to predict the optimal Al dose to maximize binding efficiency based on mobile sediment P mass and lake morphology. The predictive model can be used to evaluate cost-effectiveness and potential outcomes when planning Al-treatment using direct sediment application to restore water quality in eutrophic lakes.


Assuntos
Lagos , Fósforo , Alumínio , Sedimentos Geológicos , Fósforo/análise , Qualidade da Água
2.
Water Res ; 185: 116292, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-33086464

RESUMO

The current study reports the community succession of different toxin and non-toxin producing cyanobacteria at different stages of cyanobacterial harmful algal blooms (CyanoHABs) and their connectivity with nitrogen and phosphorus cycles in a freshwater lake using an ecogenomics framework. Comprehensive high throughput DNA sequencing, water quality parameter measurements, and functional gene expressions over temporal and spatial scales were employed. Among the cyanobacterial community, the lake was initially dominated by Cyanobium during the months of May, June, and early July, and later primarily by Aphanizomenon and Dolichospermum depicting functional redundancy. Finally, Planktothrix appeared in late August and then the dominance switched to Planktothrix in September. Microcystis aeruginosa and Microcystis panniformis; two species responsible for cyanotoxin production, were also present in August and September, but in significantly smaller relative abundance. MC-LR (0.06-1.32 µg/L) and MC-RR (0.01-0.26 µg/L) were two major types of cyanotoxins detected. The presence of MC-LR and MC-RR were significantly correlated with the Microcystis-related genes (16SMic/mcyA/mcyG) and their expressions (r = 0.33 to 0.8, p < 0.05). The metabolic analyses further linked the presence of different cyanobacterial groups with distinct functions. The nitrogen metabolisms detected a relatively higher abundance of nitrite/nitrate reductase in early summer, indicating significant denitrification activity and the activation of N-fixation in the blooms dominated by Aphanizomenon/Dolichospermum (community richness) during nutrient-limited conditions. The phosphorus and carbohydrate metabolisms detected a trend to initiate a nutrient starvation alert and store nutrients from early summer, while utilizing the stored polyphosphate and carbohydrate (PPX and F6PPK) during the extreme ortho-P scarcity period, mostly in August or September. Specifically, the abundance of Aphanizomenon and Dolichospermum was positively correlated with the nitrogen-fixing nif gene and (p < 0.001) and the PPX enzyme for the stored polyphosphate utilization (r = 0.77, p < 0.001). Interestingly, the lake experienced a longer N-fixing period (2-3 months) before non-fixing cyanobacteria (Planktothrix) dominated the entire lake in late summer. The Provo Bay site, which is known to be nutrient-rich historically, had early episodes of filamentous cyanobacteria blooms compared to the rest of the lake.


Assuntos
Cianobactérias , Microbiota , Cianobactérias/genética , Proliferação Nociva de Algas , Lagos , Microcystis
3.
Zootaxa ; 4768(3): zootaxa.4768.3.6, 2020 May 04.
Artigo em Inglês | MEDLINE | ID: mdl-33055650

RESUMO

Limia mandibularis, a new livebearing fish of the family Poeciliidae is described from Lake Miragoane in southwestern Haiti on Hispaniola. The new species differs from all other species in the genus Limia by the presence of a well-developed lower jaw, the absence of preorbital and preopercular pores, and preorbital and preopercular canals forming an open groove each. The description of this new Limia species from Lake Miragoane confirms this lake as an important center of endemism for the genus with a total of nine described species so far.


Assuntos
Ciprinodontiformes , Animais , Haiti , Lagos
4.
Zootaxa ; 4780(2): zootaxa.4780.2.3, 2020 May 25.
Artigo em Inglês | MEDLINE | ID: mdl-33055744

RESUMO

An intensive study of cladoceran diversity in Lake Kud-Thing, a Ramsar site of Bueng Kan Province, Thailand, was conducted. One hundred and twenty-five qualitative samples were collected from 15 localities during the period from June 2012 to November 2014. A total of 58 species belonging to 38 genera was recorded. Three species, Chydorus idrisi Sinev 2014, Karualona kwangsiensis (Chiang 1963) and Streblocerus cf. serricaudatus (Fisher 1849) are new records for Thailand. The most species rich family was Chydoridae (32 species, 55% of the encountered species in the lake) followed by Sididae (8 species, 14%) and Macrothricidae (8 species, 14%) while only a single species of Ilyocryptidae was observed. The most frequently encountered planktonic species were Ceriodaphnia cornuta Sars 1885, Bosmina cf. meridionalis Sars 1904 and Ephemeroporus barroisi (Richard 1894). A newly described chydorid, Anthalona spinifera Tiang-nga, Sinev Sanoamuang 2016, was also recorded from this lake. The number of cladocerans recorded in this study is remarkably higher than that of previous studies in other natural lakes (17-40 species) within Thailand. In addition to earlier records, the number of cladocerans of Lake Kud-Thing has been updated to 62 species, about two times higher than that of other lakes in this region. Thus, our results suggest that Lake Kud-Thing is one of the biodiversity hotspots for Cladocera of Southeast Asia.


Assuntos
Cladóceros , Animais , Biodiversidade , Lagos , Plâncton , Tailândia
5.
Zootaxa ; 4766(3): zootaxa.4766.3.5, 2020 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-33056592

RESUMO

Extraordinarily diverse morphologically and ecologically, Lake Baikal's two endemic gammaroidean amphipod clades are both firmly placed within the paraphyletic genus Gammarus, based both on morphological and molecular characters. However, the exact placement of the two Baikal clades remains elusive, making reconstruction of the ancestral state of Baikal endemic radiation difficult. We sequenced 2 mitochondrial and 3 nuclear genes from several species of each of the two clades aiming to represent early branches of the radiation. We also describe two new species of Baikal gammarids, Eulimnogammarus etingovae sp. nov. and Eulimnogammarus tchernykhi sp. nov., with some morphology suggestive of basal position within the radiation. We confirm the two previously demonstrated Baikal clades, but cannot unequivocally support any of the previous hypotheses about affinities of the two Baikal clades within palearctic Gammarus species. Rather, it appears that the two Baikal endemic radiations separated from the rest of freshwater Palearctic forms early and rapidly, probably as part of gammarid diversification during colonization of fresh waters in Middle Eocene.


Assuntos
Anfípodes , Animais , Sequência de Bases , Lagos
6.
Environ Monit Assess ; 192(11): 694, 2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-33037931

RESUMO

Evaporation, as the main source of water loss from closed lakes, makes a significant contribution to the water balance equation of the lake and can lead to changes in the chemical composition thereof. The objective of the study was to develop an equation for estimation of evaporation from the water surface with different depths and concentrations. To that end, 48 barrels were used to model evaporation at 6 different depths and 8 different concentrations of salinity. The experiments have been conducted in the same meteorological condition for all the barrels near the Urmia Lake. Data were collected in March 1, 2019, to Aug 31, 2019. Different equations fitted to data for each concentrations of salinity separately with different depths, and the equations with the least errors were selected. A model was then developed for the estimation of evaporation, considering the effect of salinity and depth, and the results were compared with daily measurements. The results were evaluated using the root mean square error (RMSE), correlation coefficient (CC), and Nash-Sutcliffe efficiency coefficient (NS). The results indicated that evaporation (Horizontal row) from water surface with high concentrations of salinity to low concentrations of salinity in different depths had an incremental trend. However, it can be seen in the vertical row that evaporation increased from low depth to high depth, and then decreased at a certain depth (120 cm) while the maximum evaporation rate belonged to 90-cm barrels for each concentration of salinity (in the vertical and horizontal row). At the end, the comparison of evaporation computed from the model and measured data showed that the model estimated evaporation at different depths and concentrations of salinity satisfactorily.


Assuntos
Monitoramento Ambiental , Meteorologia , Lagos , Águas Salinas , Salinidade
7.
Zootaxa ; 4802(3): zootaxa.4802.3.5, 2020 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-33056045

RESUMO

The nemacheilid genus Seminemacheilus is revised. Six species are recognised, three of them described herein as new. All species are endemic to Central Anatolia. Seminemacheilus lendlii from the Sakarya River drainage and the endorheic Lake Aksehir and Eber basins, S. ispartensis from Lake Egirdir basin and S. ahmeti from Sultan Sazligi are valid species. Although Seminemacheilus lendlii and S. ispartensis have almost identical COI sequences, they are distinguished by the shape of the caudal peduncle and the presence of scales on the caudal peduncle in S. ispartensis (vs. absent in S. lendlii). Seminemacheilus attalicus, new species, from Kirkgöz drainage, is distinguished by having a slightly emarginated caudal fin, a central pore in the supratemporal canal and a marbled flank pattern. Seminemacheilus ekmekciae, new species, from Lake Tuz basin is distinguished by having a roundish caudal fin, a short post-dorsal length and large brown blotches fused into stripes on the flank. Seminemacheilus tubae, new species, from Lake Beysehir basin, is distinguished by having a truncate caudal fin and 2-5 (6) supraorbital head pores. Seminemacheilus dursunavsari from the Göksu River drainage is not a valid name and this population is identified as S. tubae.


Assuntos
Cipriniformes , Animais , Cabeça , Lagos , Rios
8.
Zootaxa ; 4819(2): zootaxa.4819.2.2, 2020 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-33055658

RESUMO

Here we present a summary of subfossil chironomids (Diptera: Chironomidae) found in the surface sediments of 52 Tatra Mts. lakes (Slovakia, Poland). Head capsules of 73 morphotypes of 5 subfamilies are described and illustrated. In addition to the previously documented subfossils by Brooks et al. (2007), we present 15 new morphotypes: Diamesa Tatra-type A, Diamesa Tatra-type B, Pseudodiamesa branickii-type, Pseudodiamesa nivosa-type, Pseudokiefferiella parva, Brillia bifida-type, Cricotopus (Paratrichocladius) skirwithensis-type, Cricotopus (Cricotopus) tremulus-type, Cricotopus/Orthocladius I, Eukiefferiella brevicalcar-type, Eukiefferiella claripennis-type B, Orthocladius (Orthocladius) dentifer-type, O. (Mesorthocladius) frigidus, Orthocladius (Euorthocladius) sp. and Tanytarsini indet. Most of these types have possibly broad distribution patterns in Europe. We believe that due to specific features of each region, this paper will serve as a helpful manual for limnologists and paleolimnologists working not only in the Tatra Mts. but also in the whole Carpathian region.


Assuntos
Chironomidae , Animais , Lagos
9.
Zootaxa ; 4768(2): zootaxa.4768.2.3, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-33056523

RESUMO

Sarcocheilichthys vittatus, a new species of gudgeon, is described from the Gan-Jiang and Fu-He flowing into the Poyang Lake Basin in Jiangxi Province, South China. It is similar to S. parvus and S. caobangensis in having a longitudinal black band extending from the snout tip to the caudal-fin base, a character separating them from all other congeneric species, but distinct from S. parvus in having more lateral-line scales, no longitudinal yellowish stripe above the lateral black band on the flank and no barbels, and from S. caobangensis in possessing two shorter lateral lobes of the lower lip restricted only to the side of the lower jaw, no black spots along the dorsal-fin base and a stouter caudal peduncle. Its validity was also warranted by a molecular phylogenetic analysis based on the cyt b gene. Critical notes were provided on some currently recognized Chinese congeners.


Assuntos
Cyprinidae , Animais , China , Lagos , Filogenia
10.
J Environ Qual ; 49(1): 119-127, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33016350

RESUMO

Eutrophication is an issue of concern in many brackish lakes with an agricultural watershed. The amount of snowfall in snowy areas is anticipated to decline because of global climate change. The aim of this study was to assess the impact of changes in the inflow of snowmelt on the nutrient concentrations of a downstream brackish lake. In Lake Ogawara, a brackish lake in a snow-covered agricultural area of Japan, we examined the relationships between inflowing river discharge (D/C) during spring and total nitrogen (TN) and total phosphorus (TP) concentrations in the mixolimnion of the lake ([TNmix ] and [TPmix ], respectively) using 29 yr of monitoring data. In addition, we assessed the causal relationship between the D/C and the lake nutrient concentrations. There was large year-to-year variation in D/C during April (D/CApr ), which accounted for 7-31% of the mixolimnion volume. Significant positive correlations were observed between D/CApr and [TNmix ] from the ensuing April to September. On an annual basis, 49% of the interannual variation of the mean [TNmix ] during the ensuing April to September was explained by the interannual variation of D/CApr . Therefore, D/CApr could be useful as a simple index to [TNmix ] in the ensuing spring to summer. It is notable that the relationships between D/CApr and [TNmix ] from April to September was indicated to be acausal by statistical causal inference. Common climate conditions that increase D/CApr (i.e., a cold winter with a high level of precipitation) were found to drive other biogeochemical processes that increased [TNmix ] during the ensuing spring to summer.


Assuntos
Lagos , Poluentes Químicos da Água/análise , Monitoramento Ambiental , Nitrogênio/análise , Fósforo/análise
11.
J Environ Qual ; 49(5): 1322-1333, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-33016441

RESUMO

Antibiotics and estrogens are recognized as emerging contaminants in the water environment because of their potentially adverse effects on aquatic ecosystems. The concentrations of four steroid estrogens (17α-estradiol, 17ß-estradiol, estrone, and estriol) and eight antibiotics (norfloxacin, levofloxacin, ciprofloxacin, enrofloxacin, metronidazole, sulfapyridine, doxycycline, and sulfamethoxazole) in the Chaohu Lake basin in Anhui province, China, were analyzed along with adjacent wastewater. The levels of the target antibiotics and estrogens were below detection limits (not detected [nd])-89.86 and nd-118.09 ng L-1 , respectively, in the lake water. All of the target antibiotics and estrogens were detected in sediment, and the concentrations ranged widely (nd-35,544 and nd-16,344 ng kg-1 , respectively). Antibiotics and estrogens varied spatially in the study area and mostly came from untreated wastewater. Antibiotics and estrogens were associated with water parameters such as pH and total nitrogen. A significant positive correlation was observed between estriol and levofloxacin concentrations (r = .65; p < .01), indicating that levofloxacin from the same source might have inhibited the microbiological degradation of estriol in the surface water. Overall, the estrogens pose a more severe risk than antibiotics to the Chaohu Lake system. However, co-occurrence of antibiotics may affect the fate of estrogens in the same lake media. More attention should be given to estrogens than to antibiotics in wastewater-affected lake systems.


Assuntos
Águas Residuárias , Poluentes Químicos da Água/análise , Antibacterianos/análise , China , Ecossistema , Monitoramento Ambiental , Estrogênios/análise , Lagos/análise
12.
Bull Environ Contam Toxicol ; 105(4): 565-571, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32918564

RESUMO

Fish consumption from contaminated water-bodies is a serious health issue. This study conducted to reveal the presence of heavy metals and bisphenols in Vembanad lake, an exploiting tourist spot in Kerala, receiving untreated agricultural, domestic, municipal, and industrial effluents. We evaluated aquatic contaminant impact on hepatic stress markers in Etroplus suratensis from fragile Vembanad lake. The significant difference in water physiochemical parameters, the concentration of heavy metals, and bisphenols (BPA and BPS) were studied. Hepatic tissue of E. suratensis inhabited in lake featured with high iron (11.29 ± 0.39 ppm) and BPA (0.02412 ± 0.0031 µg/mL) content along with an increased hepatic stress marker and distorted hepatic structure. The study highlights the presence of high iron and BPA in edible fish. The study recommends monitoring of physiochemical characters of freshwater lakes is essential for better survival of freshwater flora and fauna.


Assuntos
Compostos Benzidrílicos/toxicidade , Ciclídeos , Exposição Ambiental/efeitos adversos , Fígado/efeitos dos fármacos , Metais Pesados/toxicidade , Fenóis/toxicidade , Sulfonas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Biomarcadores , Feminino , Índia , Lagos , Fígado/anatomia & histologia , Fígado/metabolismo , Masculino
13.
Ecotoxicol Environ Saf ; 203: 110984, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888605

RESUMO

The use of water for drinking and agriculture requires knowledge of its toxicity. In this study, we compared the use of genetically modified bioluminescent (GMB) bacteria whose luminescence increases in the presence of toxicants and Chinese Hamster Ovary (CHO) cells for the characterization of the toxicity of water samples collected from a lake and streams, hydroponic and aquaponic farms, and a wastewater treatment plant. GMB bacteria were used to probe genotoxicity, cytotoxicity and reactive oxygen species-induced effects in the whole water samples. Unlike GMB bacteria, the use of CHO cells requires XAD resin-based pre-concentration of toxic material present in water samples for the subsequent cytotoxicity assay. In addition to the examination of the toxicity of the water from the different sources, the GMB bacteria were also used to test the XAD extracts diluted to the concentrations causing 50% growth inhibition of the CHO cells. The two biomonitoring tools provided different results when they were used to test the above-mentioned diluted XAD extracts. A pre-concentration procedure based on adsorption by XAD resins with subsequent elution was not sufficient to represent the material responsible for the toxicity of the whole water samples toward the GMB bacteria. Therefore, the use of XAD resin extracts may lead to major underestimates of the toxicity of water samples. Although the toxicity findings obtained using the GMB bacteria and CHO cells may not correlate with each another, the GMB bacteria assay did provide a mechanism-specific biomonitoring tool to probe the toxicity of water samples without a need for the pre-concentration step.


Assuntos
Bactérias , Monitoramento Biológico/métodos , Água Potável/análise , Lagos/análise , Rios , Águas Residuárias/análise , Animais , Bactérias/genética , Células CHO , Cricetulus , Hidroponia , Luminescência , Microrganismos Geneticamente Modificados/genética , Eliminação de Resíduos Líquidos
14.
Sci Total Environ ; 741: 140451, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32886973

RESUMO

The present study aimed to determine the spatial and temporal variations in trophic state and identify potential causes for these variations in 60 Korean reservoirs. Empirical models were developed using the relations of nutrients (total phosphorus, TP, and total nitrogen, TN) with chlorophyll-a (CHL-a) for efficient lake managements. The empirical models indicated that TP was the key regulating factor for algal growth in agricultural (R2 = 0.69) and power generation (R2 = 0.50) reservoirs. The CHL-a:TP and TN:TP ratios, indicators of phosphorus limitation, were used to validate the phosphorus reduction approach. The mean CHL-a:TP ratio of agricultural reservoirs was 0.60, indicating that algal chlorophyll is potentially limited by TP than any other factors. Agricultural, multipurpose, and power generation reservoirs, based on the N:P ratios, were more P- limited systems than natural lakes and estuarine reservoirs. The trophic state index (TSI) of Korean reservoirs varied between mesotrophy to hypereutrophy based on values of TSI (TP), TSI (CHL-a), and TSI (SD). Agricultural reservoirs were hypereutrophic using the criteria of TSI (CHL-a) and blue-green algae dominated the algal community. Analysis of trophic state index deviation (TSID) indicated that agricultural reservoirs were primarily P limited and other factors had minor effect. In contrast, the trophic status of estuarine and power generation reservoirs and natural lakes was largely modified by non-algal turbidity. Our outcomes may be effectively used for Korean lakes and reservoirs management.


Assuntos
Monitoramento Ambiental , Eutrofização , China , Clorofila/análise , Lagos , Nitrogênio/análise , Nutrientes , Fósforo/análise , República da Coreia
15.
Sci Total Environ ; 741: 140527, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32886999

RESUMO

Pollution with microplastics has become an environmental concern worldwide. Yet, little information is available on the distribution of microplastics in lakes. Lake Ziway is one of the largest lakes in Ethiopia and is known for its fishing and drinking water supply. This study aims to examine the distribution of plastic particles, of all sizes (micro- and small macro-plastics) in four of the major fish species of the lake and in its shoreline sediment. The gastrointestinal tracts analysis showed that 35% of the sampled fishes ingested plastic particles. The median number of particles per fish was 4 (range 1-26). Benthic (Clarias gariepinus) and benthopelagic (Cyprinus carpio and Carassius carassius) fish species were found to contain a significantly higher number of plastic particles in comparison to the planktivorous fish species (Oreochromis niloticus). More fishes ingested plastic particles in the wet compared to the dry season. The maximum plastic size (40 mm fibre) was found in C. carpio. Estimated median mass of plastic particles in fish was 0.07 (0.0002-385.2) mg/kg_ww. Fish and sediment samples close to known potential sources of plastic particles had a higher plastic ingestion frequency (52% of the fish) and higher plastic concentration compared to the other parts of the lake. The median count and mass of plastic particles measured in sediment of the lake were 30,000 (400-124,000) particles/m3 and 764 (0.05-36,233) mg/kg_dw, respectively, the upper limits of which exceed known effect thresholds. Attenuated total reflection (ATR) - Fourier-transform infrared (FTIR) spectroscopy showed that polypropylene, polyethylene and alkyd-varnish were the dominant polymers in fishes and in sediment. The plastic particles size distributions were Log-linear and were identical for plastic particles found in fish and in sediment, suggesting strong benthic-pelagic coupling of plastic particles transfer.


Assuntos
Carpas , Poluentes Químicos da Água/análise , Animais , Monitoramento Ambiental , Etiópia , Peixes , Lagos , Microplásticos , Plásticos
16.
Environ Monit Assess ; 192(10): 623, 2020 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-32895730

RESUMO

Urmia Lake, as the largest lake in Iran borders, has a special role in the ecosystem of the region. The water level in this lake declines in recent year remarkably, so monitoring the lake water quality is important from an environmental view. In this research, the changes in the qualitative variables of the lake water (including electrical conductivity (EC), pH, total dissolved solids (TDS), and sodium adsorption ratio (SAR)) are compared with the changes in the lake's water level based on the Mann-Kendall nonparametric test. Further, abrupt change points in the time series of quality variables were detected by the Pettitt test. Studies were carried out on samples collected from five different stations during 2005-2015. The results showed that the water level of Urmia Lake had a significant decreasing trend and also, except for TDS, the other investigated quality variables had negative trends during the studied period. It was observed that in general, the values of the Z statistic in the stations located in the eastern part of the lake were more than the stations located in the western part, and also the stations located in the northern parts had a higher trend than those in the south of the bridge.


Assuntos
Lagos , Qualidade da Água , Ecossistema , Monitoramento Ambiental , Irã (Geográfico)
17.
Infect Dis Poverty ; 9(1): 121, 2020 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-32867849

RESUMO

BACKGROUND: Intestinal schistosomiasis was not considered endemic in Lake Malawi until November 2017 when populations of Biomphalaria pfeifferi were first reported; in May 2018, emergence of intestinal schistosomiasis was confirmed. This emergence was in spite of ongoing control of urogenital schistosomiasis by preventive chemotherapy. Our current study sought to ascertain whether intestinal schistosomiasis is transitioning from emergence to outbreak, to judge if stepped-up control interventions are needed. METHODS: During late-May 2019, three cross-sectional surveys of primary school children for schistosomiasis were conducted using a combination of rapid diagnostic tests, parasitological examinations and applied morbidity-markers; 1) schistosomiasis dynamics were assessed at Samama (n = 80) and Mchoka (n = 80) schools, where Schistosoma mansoni was first reported, 2) occurrence of S. mansoni was investigated at two non-sampled schools, Mangochi Orphan Education and Training (MOET) (n = 60) and Koche (n = 60) schools, where B. pfeifferi was nearby, and 3) rapid mapping of schistosomiasis, and B. pfeifferi, conducted across a further 8 shoreline schools (n = 240). After data collection, univariate analyses and Chi-square testing were performed, followed by binary logistic regression using generalized linear models, to investigate epidemiological associations. RESULTS: In total, 520 children from 12 lakeshore primary schools were examined, mean prevalence of S. mansoni by 'positive' urine circulating cathodic antigen (CCA)-dipsticks was 31.5% (95% confidence interval [CI]: 27.5-35.5). Upon comparisons of infection prevalence in May 2018, significant increases at Samama (relative risk [RR] = 1.7, 95% CI: 1.4-2.2) and Mchoka (RR = 2.7, 95% CI: 1.7-4.3) schools were observed. Intestinal schistosomiasis was confirmed at MOET (18.3%) and Koche (35.0%) schools, and in all rapid mapping schools, ranging from 10.0 to 56.7%. Several populations of B. pfeifferi were confirmed, with two new eastern shoreline locations noted. Mean prevalence of urogenital schistosomiasis was 24.0% (95% CI: 20.3-27.7). CONCLUSIONS: We notify that intestinal schistosomiasis, once considered non-endemic in Lake Malawi, is now transitioning from emergence to outbreak. Once control interventions can resume after coronavirus disease 2019 (COVID-19) suspensions, we recommend stepped-up preventive chemotherapy, with increased community-access to treatments, alongside renewed efforts in appropriate environmental control.


Assuntos
Surtos de Doenças , Esquistossomose Urinária/epidemiologia , Esquistossomose mansoni/epidemiologia , Anti-Helmínticos/uso terapêutico , Criança , Estudos Transversais , Humanos , Lagos , Malaui/epidemiologia , Morbidade , Praziquantel/uso terapêutico , Prevalência , Fatores de Risco , Esquistossomose Urinária/complicações , Esquistossomose Urinária/tratamento farmacológico , Esquistossomose mansoni/complicações , Esquistossomose mansoni/tratamento farmacológico , Instituições Acadêmicas
18.
J Environ Sci (China) ; 97: 120-131, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32933727

RESUMO

Despite laboratory experiments that have been performed to study internal heavy metal release, our understanding of how heavy metals release in shallow eutrophic lakes remains limited for lacking in-situ evidence. This study used automatic environmental sensors and a water sampling system to conduct high-frequency in-situ observations (1-hr intervals) of water environmental variables and to collect water samples (3-hr intervals), with which to examine the release of internal heavy metals in Lake Taihu, China. Under conditions of disturbance by strong northerly winds, sediment resuspension in both the estuary area and the lake center caused particulate heavy metal resuspension. However, the patterns of concentrations of dissolved heavy metals in these two areas were complex. The concentrations of dissolved Se and Mo increased in both areas, indicating that release of internal dissolved Se and Mo is triggered by sediment resuspension. The concentrations of dissolved Ni, Zn, As, Mn, Cu, V, and Co tended to increase in the estuary area but decrease in the lake center. The different trends between these two areas were controlled by pH and cyanobacteria, which are related to eutrophication. During the strong northerly winds, the decrease in concentrations of dissolved heavy metals in the lake center was attributable primarily to absorption by the increased suspended solids, and to growth-related assimilation or surface adsorption by the increased cyanobacteria. The findings of this study suggest that, short-term changes of environmental conditions are very important in relation to reliable monitoring and risk assessment of heavy metals in shallow eutrophic lakes.


Assuntos
Metais Pesados/análise , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental , Sedimentos Geológicos , Lagos
19.
J Environ Sci (China) ; 97: 169-179, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32933732

RESUMO

Total contents of metals in soil and sediments on the Tibetan Plateau of China have been widely analyzed, but existing information is insufficient to effectively evaluate metal ecological risk because of a lack of metal bioavailability data. In this study, distribution, potential risk, mobility and bioavailability of metals in sediments of Lake Yamdrok Basin in Tibet of China were explored by combined use of total digestion, sequential extraction and the diffusive gradient in thin-films (DGT). Average concentrations of Cr, Ni, Cu, Zn, As, Cd and Pb in surface sediments were 31.25, 30.31, 22.00, 45.04, 31.32, 0.13 and 13.39 mg/kg, respectively. Higher levels of metals were found near the inflowing rivers. Residual form was dominant in Cr, Ni, Zn, Cd and Pb, and reducible form was dominant in As and Cd. Metals in surface sediments showed a low enrichment degree overall, but Cd and As had higher ecological risk levels than the other metals. Furthermore, there was a larger average proportion of exchangeable form of As (20.4%) and Cd (9.0%) than the other metals (1.7%-3.3%), implying their higher mobility and release risk. Average DGT-labile concentrations of Cr, Ni, Cu, Zn, As, Cd and Pb were 0.5, 4.5, 0.7, 25.1, 60.0, 0.22 and 1.0 µg/L, respectively. The DGT-labile As was significantly correlated with extractable As forms (p< 0.01), suggesting that extractable As in sediments acts as a "mobile pool" for bioavailable As. These results suggest potential risks of As and Cd, especially As, deserve further attention in Lake Yamdrok Basin.


Assuntos
Metais Pesados/análise , Poluentes Químicos da Água/análise , Disponibilidade Biológica , China , Monitoramento Ambiental , Sedimentos Geológicos , Lagos , Medição de Risco , Tibet
20.
PLoS One ; 15(9): e0237668, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32877434

RESUMO

Water hyacinth has been progressively advanced in Lake Tana since 2011 and covered vast areas of the lakeshore. The aim of this study was to assess how the lakeshore covered by the weed mats affected the socioeconomic of the local community. The study was based on a survey of 405 households, 8 group discussions and interviews of 15 key informants conducted from January to March 2018. The results revealed that crop production, livestock feed supply, water supply, fishing, the health of local people and livestock were impacted negatively by the infestation of water hyacinth. The range of socioeconomic problems caused by the weed generally implied the real impacts on the lives of local communities and national economic development. The efforts made to control water hyacinth has costed huge labor and financial resources. The results revealed that close to 800,000 human labor dedicated to manual removal of the weed from 2012 to 2018 and above one million USD spent for procurement of harvester machines and bioagent experiments. In spite of the devotion of huge labor and spending of a lot of money, the expansion of the weed has not controlled. Poor coordination of controlling efforts, dumping of harvested dense mats of the weed in the lakeshore, lack of genuine participation of the local people are principal factors for the failure of the controlling efforts A coordination of various stakeholders thus is needed to make eradicating methods more effective. Other alternative options should also be considered to control the weed expansion.


Assuntos
Eichhornia/fisiologia , Lagos , Animais , Produtos Agrícolas/crescimento & desenvolvimento , Etiópia , Características da Família , Geografia , Humanos , Gado , Fatores Socioeconômicos , Inquéritos e Questionários , Abastecimento de Água
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