Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 9.883
Filtrar
1.
Environ Monit Assess ; 193(6): 329, 2021 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-33959823

RESUMEN

The objective of the present work was to obtain scientific information on the ecological health of three freshwater lakes (Awassa, Koka, and Ziway) situated in the Ethiopian Rift Valley by investigating possible trace element contamination accumulated in fish. Accordingly, fish liver and kidney samples were collected from three commercially important fish species (Barbus intermedius, Clarias gariepinus, and Oreochromis niloticus) in the lakes to determine the concentrations of chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), and lead (Pb), using ICP-MS. Trace element concentrations were generally higher in O. niloticus compared with concentrations in B. intermedius and C. gariepinus. Compared to background values of most freshwater fish species, higher liver concentrations of Cu in C. gariepinus and O. niloticus, Mn in O. niloticus, Co in all except B. intermedius, and Zn in C. gariepinus from Lakes Ziway and Awassa were found. Cr, Co, Ni, Cd, and Pb were enriched in kidney, while Mn, Cu, Zn, As, and Se seems retained in the liver tissues. Assessment of transfer factors indicated that bioaccumulation from water and diet occurred, while uptake from sediments was low. Furthermore, the transfer factor values were generally higher for essential elements compared to the non-essential elements. Multivariate statistical analyses showed that the differences between the trace element levels were generally not significant among the lakes (p = 0.672), while significant differences were found between the fish species (p = 0.042), and between accumulation in kidney and liver (p = 0.002).


Asunto(s)
Metales Pesados , Oligoelementos , Contaminantes Químicos del Agua , Animales , Bioacumulación , Monitoreo del Ambiente , Riñón/química , Lagos , Hígado/química , Metales Pesados/análisis , Oligoelementos/análisis , Contaminantes Químicos del Agua/análisis
2.
J Environ Manage ; 289: 112366, 2021 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-33848883

RESUMEN

Pro-environmental behaviours (PEBs) are important for mitigation and restoration efforts in the Anthropocene. As recreationists are motivated to engage in leisure activities to increase their own personal wellbeing, we submit that threats to wellbeing (an egocentric motivator) predict engagement in PEBs amongst recreationists. We also predict that differences in experiences across groups of recreationists leads to differences in PEB engagement. Using an online survey, we test our two hypotheses (if recreationists perceive there is a threat to their wellbeing and that their behaviours can yield environmental successes, then they will be more likely to engage in PEBs, and if recreationists differ in recreational experiences then they will demonstrate differences in PEB engagement) amongst outdoor recreationists, specifically Canadian rainbow trout and steelhead anglers in British Columbia (n = 894 respondents). We define 'threat to wellbeing' as the interaction of environmental threat-perceptions of used environments for fishing, and level of centrality fishing has to one's lifestyle. To test our first hypothesis, we conducted three linear regressions corresponding to three different PEBs related to catch-and-release (C&R) fishing. Our egocentric predictor 'threat to wellbeing' was only significant for one out of the three PEBs tested, showing mixed support for our first hypothesis. It is of note that 'environmental threat perceptions' and one's belief in successes resulting from PEB engagement were found to be significant predictors for all three PEBs tested. These results suggest that predictors of PEB may not always be transferable across PEBs relating to recreational activities, and environmental threat perception and one's belief in successes resulting from PEB engagement are strong predictors of PEBs amongst recreationists. To test our second hypothesis, we conducted a Kruskal Wallis test to determine if there were significant differences across angler groups in PEB predictor scores and PEB engagement and conducted pairwise population Z-tests to determine proportional participation rates across angler groups for the three PEBs and PEB predictors investigated. Experiences were found to shape predictors of PEBs, as well as likelihood to engage in PEBs, as different angler groups targeting different fish (i.e., rainbow trout vs steelhead) and using different aquatic habitats (i.e., rivers vs. lakes) demonstrated significantly different scores for PEB predictors, as well as significantly different likelihood to engage in two of the three PEBs tested. These findings support the notion that recreationists are not a homogenous group, and that their beliefs and resulting behaviours during recreational activities are determined by their experiences in nature and can be influenced by the species with which they interact, and the habitats they use for recreation.


Asunto(s)
Explotaciones Pesqueras , Recreación , Animales , Colombia Británica , Conservación de los Recursos Naturales , Ecosistema , Lagos
3.
J Environ Manage ; 289: 112559, 2021 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-33865026

RESUMEN

This paper aims to present a new quantitative systematic approach to evaluate the effectiveness of utilizing and allocating resources based on the concept of "Work" in physics. This method is examined in the Urmia Lake Basin (ULB), shrinking of which has threatened the life of about five million inhabitants and ecosystem biodiversity. In the proposed approach, the role of three types of financial, human, and environmental resources in the development process is evaluated quantitatively, and they have been compared in two periods before and after the severe reduction of the lake water volume. Results show that although financial resources have increased by 1.9 times in the second period, the effectiveness of the development process has decreased. Therefore, the resources have not been utilized properly in a direction compatible with sustainable development strategies. Additionally, the improperly-spent financial resources on the development projects especially in the second period have had a more destructive role than the human and environmental resources in the ULB crisis.


Asunto(s)
Ecosistema , Lagos , Biodiversidad , Monitoreo del Ambiente , Humanos
4.
Environ Sci Technol ; 55(9): 6459-6466, 2021 05 04.
Artículo en Inglés | MEDLINE | ID: mdl-33797885

RESUMEN

Decline in total phosphorus (TP) during lake reoligotrophication does not apparently immediately influence carbon assimilation or deep-water oxygen levels. Traditional monitoring and interpretation do not typically consider the amount of organic carbon exported from the productive zone into the hypolimnion as a measure of net ecosystem production. This research investigated the carbon-to-phosphorus ratios of suspended particles in the epilimnion, (C:P)epi, as indicators of changing productivity. We report sestonic C:P ratios, phytoplankton biomass, and hypolimnetic oxygen depletion rates in Lake Hallwil, a lake whose recovery from eutrophic conditions has been documented in 35 years of historic water-monitoring data. This study also interpreted long-term (C:P)epi ratios from reoligotrophication occurring in four other lakes. Lake Hallwil exhibited three distinct phases. (i) The (C:P)epi ratio remained low when TP concentrations did not limit production. (ii) (C:P)epi increased steadily when phytoplankton began optimizing the declining P and biomass remained stable. (iii) Below a critical TP threshold of ∼15 to ∼20 mg P m-3, (C:P)epi remained high and the biomass eventually declined. This analysis showed that the (C:P)epi ratio indicates the reduction of productivity prior to classic indicators such as deep-water oxygen depletion.


Asunto(s)
Lagos , Fósforo , Carbono , China , Ecosistema , Monitoreo del Ambiente , Eutrofización , Nitrógeno/análisis , Fósforo/análisis , Fitoplancton
5.
Environ Sci Technol ; 55(9): 6467-6475, 2021 05 04.
Artículo en Inglés | MEDLINE | ID: mdl-33886307

RESUMEN

The continuous flux of organic carbon (OC) from terrestrial ecosystems into inland water is an important component of the global carbon cycle. The buried OC pool in inland water sediments is considerable, and black carbon (BC) is a significant contributor to this OC pool because of the continuous growth in BC emissions. Therefore, determining the effect of BC on total OC burial and variations in the structure of BC during the burial process will contribute significantly to our understanding of lacustrine carbon cycling. This study investigated BC burial and its structural variations in response to anthropogenic drivers using four dated sedimentary cores from a deep plateau lake in China. The BC burial rate rose from 0.96 ± 0.64 g·m-2·y-1 (mean of sedimentary cores pre-1960s) to 4.83 ± 1.25 g·m-2·y-1 (after 2000), which is a 5.48 ± 2.12-fold rise. The increase of char was similar to those of BC. The growth rate of soot was 7.20 ± 4.30 times, which is higher than that of BC and char, increasing from 0.12 ± 0.08 to 0.64 ± 0.23 g·m-2·y-1. There was a decreasing trend in the ratio of char and soot at a mean rate of 62.8 ± 6.46% (excluding core 3) in relation to increased fossil fuel consumption. The contribution of BC to OC burial showed a significant increasing trend from the past to the present, particularly in cores 3 and 4, and the mean contribution of the four cores was 11.78 ± 2.84%. Source tracer results from positive matrix factorization confirmed that the substantial use of fossil fuels has promoted BC burial and altered the BC structure. This has resulted in BC with a higher aromatic content in the lake sediment, which exhibits reduced reactivity and increased stability. The strong correlation between BC and allochthonous total OC indicates that the input pathways of the buried BC in this plateau lake sediment were terrestrial surface processes and not atmospheric deposition.


Asunto(s)
Lagos , Hollín , Carbono/análisis , Secuestro de Carbono , China , Ecosistema , Monitoreo del Ambiente , Sedimentos Geológicos , Hollín/análisis
6.
Environ Sci Technol ; 55(9): 5836-5847, 2021 05 04.
Artículo en Inglés | MEDLINE | ID: mdl-33891400

RESUMEN

Current environmental monitoring studies are generally confined to several target organophosphate esters (OPEs), and there is a lack of strategies for comprehensively screening all potential OPEs in environmental samples. Here, an effective and accurate strategy was developed for the target, suspect, and functional group-dependent screening of OPEs by the use of ultrahigh-performance liquid chromatography-Q Exactive hybrid quadrupole-Orbitrap high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS), and this strategy was applied for the analysis of n = 74 sediment samples (including 23 surface sediment samples and 51 sediment core samples) collected from Taihu Lake (eastern China) in 2019. In these analyzed samples, we successfully identified n = 35 OPEs, and 23 of them were reported in this region for the first time. In addition, this strategy also presented other interesting findings, i.e., (1) OPE concentrations decreased with increasing distance from the coast of the lake; (2) the newly identified 3-hydroxyphenyl diphenyl phosphate (meta-OH-TPHP) was not statistically significantly correlated with triphenyl phosphate (TPHP; r = 0.02494, p = 0.9101) but with resorcinol bis(diphenyl phosphate) (RDP) (r = 0.9271, p < 0.0001) and three other OPEs; and (3) the summed concentrations of aryl OPEs (∑arylOPEs) in sediment core samples exhibited significantly increasing trends as the depth decreased. Collectively, this study provided an effective strategy that was successfully applied for comprehensive screening of OPEs in the sediments of Taihu Lake, and this strategy could have promising potential to be extended to other environmental matrices or samples.


Asunto(s)
Retardadores de Llama , Lagos , China , Monitoreo del Ambiente , Ésteres , Retardadores de Llama/análisis , Organofosfatos
7.
Molecules ; 26(5)2021 Mar 01.
Artículo en Inglés | MEDLINE | ID: mdl-33804535

RESUMEN

Fourier Transform Infrared (FT-IR) spectroscopy and imaging combined with hierarchical cluster analysis (HCA) was applied to analyse biochemical properties of Early Middle Ages hemp (Cannabis sativa L.) bast fibres collected from lake bottom sediment of lake Slone. The examined plant macrofossil material constitutes residues of the hemp retting process that took place in the 7th-8th century. By comparison of three samples: untreated isolated bast fibres, and fibres incubated overnight at 4 and 37 °C, we were able to mimic the retting conditions. Using FT-IR qualitative and semi-quantitative assessment of the primary polysaccharides content, total protein content, and their spatial distribution was performed within the hemp fibres. The concentration of cellulose remained vastly unchanged, while the concentration of lignin and pectin was the highest in the untreated sample. The spatial distributions of compounds were heterogeneous in the untreated and 4 °C-incubated samples, and homogenous in the specimen processed at 37 °C. Interestingly, a higher amide content was detected in the latter sample indicating the highest degree of enzymatic degradation. In this study, we show that the spectroscopic methods allow for a non-destructive evaluation of biochemical composition of plant fibres without preparation, which can be an appropriate approach for studying ancient plant remains.


Asunto(s)
Cannabis/química , Celulosa/análisis , Sedimentos Geológicos/análisis , Lagos/química , Lignina/análisis , Imagen Molecular/métodos , Tallos de la Planta/química , Espectroscopía Infrarroja por Transformada de Fourier
8.
Artículo en Inglés | MEDLINE | ID: mdl-33909549

RESUMEN

A Gram-stain-negative, aerobic, flagellated, non-spore-forming, rod-shaped bacterium, named B2R-29T, was isolated from water collected from a crater lake on Da Hinggan mountain, PR China. Strain B2R-29T was oxidase- and catalase-positive. On the basis of the results of 16S rRNA gene sequence analyses, strain B2R-29T clearly belonged to the family Oxalobacteraceae, class Betaproteobacteria and showed the highest similarity to Undibacterium oligocarboniphilum EM1T (97.4 %) and to the other species of Undibacterium (less than 96.8 %). In the phylogenetic tree, strain B2R-29T formed a clade with U. oligocarboniphilum EM1T and Undibacterium squillarum CMJ-9T, indicating that is a member of the genus Undibacterium. Digital DNA-DNA hybridization and average nucleotide identity analyses were performed and the values between strain B2R-29T and its closely related Undibacterium species were less than 75.1 % and 16.9 %, respectively. The chemotaxonomic data of B2R-29T were as follows: major uniquinone, Q-8; predominant polar lipids, phosphatidylethanolamine, diphosphatidylglycerol and phosphatidylglycerol; major fatty acids, C16 : 0 and summed feature 3 (C16 : 1 ω7c / C16 : 1 ω6c); predominant polyamines, putrescine, 2-hydroxyputrescine and spermidine. The DNA G+C content was 51.7 mol% from the genomic sequencing data. In accordance with the phenotypic, physiological and chemotaxonomic properties mentioned above, strain B2R-29T represents a novel species of the genus Undibacterium for which the name Undibacterium crateris sp. nov. is proposed. The type strain is B2R-29T (=CGMCC 1.13792T=KCTC 72018T).


Asunto(s)
Lagos/microbiología , Oxalobacteraceae/clasificación , Filogenia , Técnicas de Tipificación Bacteriana , Composición de Base , China , ADN Bacteriano/genética , Ácidos Grasos/química , Hibridación de Ácido Nucleico , Oxalobacteraceae/aislamiento & purificación , Fosfolípidos/química , Poliaminas/química , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Ubiquinona/química
9.
Huan Jing Ke Xue ; 42(5): 2276-2286, 2021 May 08.
Artículo en Chino | MEDLINE | ID: mdl-33884797

RESUMEN

Bacteria are the key components of water ecosystems, and play important roles in material and energy cycle processes. To understand the changes in the bacterioplankton community in frozen lakes, we collected 15 "bottom ice" samples and 15 "surface water" samples under the ice sheet from Dali Lake, which is an inland closed lake in the Inner Mongolia Plateau. Combined with comparisons of the physicochemical proxies between "bottom ice" and "surface water" samples, the phylum community characteristics of the bacterioplankton were analyzed in detail. Although the bacterioplankton were mainly comprised of Proteobacteria, Actinobacteria, Cyanobacteria, Bacteroidetes, and 11 other phyla in the "bottom ice" and "surface water", the average relative abundances of the dominant planktonic bacteria were clearly different. For example, the average relative abundance of Proteobacteria was approximately 63.64% in the "bottom ice" samples, but decreased to approximately 26.75% in the surface water samples, which was visibly smaller than the relative abundance of Actinobacteria with an average value of approximately 39.10%. We concluded that the changes in the contents of nutrient elements and physicochemical proxies must be the primary factors influencing the changes in the bacterioplankton community in the frozen Dali Lake. The changes in the physicochemical proxies could have been responsible for the changes in the bacteria community in the "bottom ice" and "surface water". Otherwise, the different physiological characteristics of the planktonic bacteria phyla caused the different responses to the changes in the contents of the nutrient elements and physicochemical proxies in the frozen lake. For example, the major bacterioplankton phyla were mainly influenced by the changes in total phosphorus and dissolved total phosphorus in the "bottom ice" and by the changes in dissolved inorganic phosphorus and ammonia nitrogen in the "surface water". The results will provide basic data to analyze the lake ecological environment in Northern China.


Asunto(s)
Ecosistema , Lagos , China , Plancton , Agua
10.
Ying Yong Sheng Tai Xue Bao ; 32(4): 1509-1517, 2021 Apr.
Artículo en Chino | MEDLINE | ID: mdl-33899420

RESUMEN

Methanotrophs are important and unique prokaryotes widely distributed in the nature. They can oxidize methane and live at a moderate temperature in the conditions withpH=7. In addition, many methanotrophs have been isolated from various special conditions within a wide range of pH value and temperature, including acid sphagnum moss wetlands, acid forest soils, hot springs and high-temperature geothermal areas near volcanic craters, soda-saline lakes, and marine sediments. Here, we introduced the classification, properties and influencing factors of methanotrophs in these special conditions, and reviewed relevant technological researches and engineering applications, with the aim to facilitate further studies of natural biodiversity as well as global carbon and hydrogen cycles.


Asunto(s)
Metano , Sphagnopsida , Bacterias , Lagos , Oxidación-Reducción , Filogenia
11.
Artículo en Inglés | MEDLINE | ID: mdl-33806592

RESUMEN

Wetlands are unique ecosystems formed by the interaction between land and water on Earth. Poyang Lake, which is a part of China's largest freshwater lake wetland, is well known for its ecological and economic importance. This study uses a social-ecological system (SES) framework that integrates watershed and human activities; we used action scenarios to analyse the influencing factors, solutions, and feedback mechanisms involved in the SES framework. We chose Nanchang, Jiujiang, and Shangrao in the Poyang Lake wetlands of the Jiangxi province as the study areas to provide a problem-oriented analytical strategy for the organic interface between ecological conservation and green development. The key issues indicate that the Poyang Lake region faces multiple problems, such as ecosystem structural changes and environmental pollution, caused by anthropological activities, inefficient implementation of conservation policies, and insufficient funding for pollution prevention and control. Our findings provide a systematic solution for major conservation and development issues in the Poyang Lake region and are adapted to the characteristics of the lake. We also provide a theoretical reference and direction for the implementation of green development and modernisation of ecological governance in the Great Lakes basin in China.


Asunto(s)
Ecosistema , Lagos , China , Monitoreo del Ambiente , Humanos , Desarrollo Sostenible
12.
Water Sci Technol ; 83(7): 1728-1738, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33843755

RESUMEN

Restoration of submerged macrophytes is one of the important measures for ecological treatment of eutrophic lakes. The changes in physical and chemical conditions caused by submerged macrophytes also affect the process of benthic nitrogen cycling. The growth period of Potamogeton crispus is mainly in winter. In order to understand the effect of submerged macrophytes growing in winter on nitrification rate and denitrification rate in the process of nitrogen cycling, experiments were carried out from winter to summer with vegetated and non-vegetated treatments. The results showed that the effect of submerged macrophytes on water temperature was not significant in winter. The nitrogen cycling was mainly affected by variables, which were inorganic nitrogen and dissolved oxygen. Submerged macrophytes had little effect on nitrification rate, but had a certain inhibition on denitrification rate by providing oxygen from photosynthesis. In total, submerged macrophytes growing in winter have little effect on nitrogen cycling in sediment. However, submerged macrophytes growing in winter can increase the attachment surface of microbes and inhibit resuspension of sediment, which play a complementary role to submerged macrophytes growing in summer for maintaining stability of eutrophic lakes.


Asunto(s)
Lagos , Potamogetonaceae , Sedimentos Geológicos , Nitrificación , Nitrógeno , Fotosíntesis
13.
Environ Monit Assess ; 193(5): 260, 2021 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-33839952

RESUMEN

Longitudinal monitoring studies (between 2006 and 2019) of the chemical composition of the water from the Angara River source (the runoff of Lake Baikal) revealed the interannual, year-round and monthly cyclicity in the distribution of some trace elements vis-à-vis their concentrations. The change in the concentrations of elements was contingent on the season, the temperature of the air and water, the activity of phyto- and zooplankton and regional changes in the environment (floods, earthquakes, fires, tourism, ships, technogenesis etc.). We compared the concentrations of trace elements present in the water samples from the Angara source and the water samples from Lake Baikal with the maximum permissible concentration values for drinking water. The calculated (median) concentrations for water samples from the Angara source, which spanned the entire study period, were close to the data obtained for the Baikal water.


Asunto(s)
Oligoelementos , Contaminantes Químicos del Agua , Ecosistema , Monitoreo del Ambiente , Lagos , Federación de Rusia , Contaminantes Químicos del Agua/análisis
14.
Extremophiles ; 25(3): 257-265, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33837855

RESUMEN

We assessed the diversity of fungal DNA present in sediments of three lakes on Vega Island, north-east Antarctic Peninsula using metabarcoding through high-throughput sequencing (HTS). A total of 640,902 fungal DNA reads were detected, which were assigned to 224 taxa of the phyla Ascomycota, Rozellomycota, Basidiomycota, Chytridiomycota and Mortierellomycota, in rank order of abundance. The most abundant genera were Pseudogymnoascus, Penicillium and Mortierella. However, a majority (423,508, 66%) of the reads, representing by 43 ASVs, could only be assigned at higher taxonomic levels and may represent taxa not currently included in the sequence databases used or be new or previously unreported taxa present in Antarctic lakes. The three lakes were characterized by high sequence diversity, richness, and moderate dominance indices. The ASVs were dominated by psychrotolerant and cosmopolitan cold-adapted Ascomycota, Basidiomycota and Mortierellomycota commonly reported in Antarctic environments. However, other taxa detected included unidentified members of Rozellomycota and Chytridiomycota species not previously reported in Antarctic lakes. The assigned diversity was composed mainly of taxa recognized as decomposers and pathogens of plants and invertebrates.


Asunto(s)
Código de Barras del ADN Taxonómico , Lagos , Regiones Antárticas , Biodiversidad , ADN de Hongos/genética , Hongos/genética , Islas
15.
Nat Commun ; 12(1): 2406, 2021 04 23.
Artículo en Inglés | MEDLINE | ID: mdl-33893318

RESUMEN

Understanding Earth's response to climate forcing in the geological past is essential to reliably predict future climate change. The reconstruction of continental climates, however, is hampered by the scarcity of universally applicable temperature proxies. Here, we show that heterocyte glycolipids (HGs) of diazotrophic heterocytous cyanobacteria occur ubiquitously in equatorial East African lakes as well as polar to tropical freshwater environments. The relative abundance of HG26 diols and keto-ols, quantified by the heterocyte diol index (HDI26), is significantly correlated with surface water temperature (SWT). The first application of the HDI26 to a ~37,000 year-long sediment record from Lake Tanganyika provides evidence for a ~4.1 °C warming in tropical East Africa from the last glacial to the beginning of the industrial period. Given the worldwide distribution of HGs in lake sediments, the HDI26 may allow reconstructing SWT variations in polar to tropical freshwater environments and thereby quantifying past continental climate change.


Asunto(s)
Cambio Climático , Cianobacterias/metabolismo , Agua Dulce/microbiología , Glucolípidos/metabolismo , Lagos/microbiología , Calibración , Cianobacterias/citología , Geografía , Sedimentos Geológicos/microbiología , Tanzanía , Temperatura
16.
J Environ Radioact ; 233: 106608, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33812179

RESUMEN

Dissolution fluxes of stable (127I) and radioactive (129I) isotopes of iodine from a brackish lake sediment beside a spent nuclear fuel reprocessing plant in Japan were evaluated through two kinds of experiments: incubation using a sediment core sample for 24 h, and observation of 127I and 129I concentrations in sedimentary pore water. For 127I, the dissolution flux evaluated in the incubation experiment was comparable with that obtained from the vertical gradient of 127I concentration in pore water in the observation experiment. This suggests that degradation of organic matter in the surface sediment is an important source of dissolved 127I found in the water. For 129I, the dissolution flux estimated in the incubation experiment showed negative values, indicating the transfer of 129I to the sediment from the overlying water (i.e., absorption). Moreover, the flux evaluated from the observation experiment was positive. This result suggests that degradation of organic matter in the surface sediment is scarcely important to the supply of 129I from the sediment to the water in the studied lake. The dissolution flux of 129I estimated in the observation experiment was smaller than the absorption flux of 129I in the incubation experiment. This potentially indicates that the dissolution of sedimentary 129I does not significantly change 129I concentrations in the water and sediment of the lake. This hypothesis was consistent with previous research conducted for the studied lake.


Asunto(s)
Monitoreo de Radiación , Contaminantes Químicos del Agua , Monitoreo del Ambiente , Sedimentos Geológicos , Radioisótopos de Yodo , Japón , Lagos , Solubilidad , Contaminantes Químicos del Agua/análisis
17.
An Acad Bras Cienc ; 93(2): e20190144, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-33852669

RESUMEN

The Chapala Lake is one of the most polluted lakes in Mexico, due to the in flow of effluents from several industrial plants, the lake accumulates pollutants such as chromium(VI) which is considered important for aquatic ecosystem. This study aimed was to evaluate the ability to decrease the concentration of chromium (VI) by Lysinibacillus macroides 2(1B)104A, isolated from sediments of the Chapala Lake. The strain was identified through 16S rRNA sequencing and phylogenetic analysis. Results showed that this strain grows in concentrations of 50, 100, 200 and 300 mgL-1 Cr(VI), in pH ranging 6 to 7, showing 79.508% reduction in concentration 50 mgL-1, determining that the reduction occurs extracellularly. Likewise, it was observed that Lysinibacillus macroides reduced the concentration of Cr(IV) in the broth, it was not observed that the bacteria could sequester Cr(VI) in the membrane or intracellularly. However, it reduced the concentration of Cr(VI) in the broth. Lysinibacillus macroides 2(1B)104A isolate showed having the ability that decrease the concentration of Cr(VI), which makes it a viable options for bioremediation of water polluted with this metal.


Asunto(s)
Ecosistema , Lagos , Bacillaceae , Cromo/análisis , Concentración de Iones de Hidrógeno , México , Oxidación-Reducción , Filogenia , ARN Ribosómico 16S/genética
18.
Water Res ; 197: 117083, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33813168

RESUMEN

Particulate organic carbon (POC) sources, which regulate dissolved organic carbon, sediment organic carbon, and inorganic carbon via deposition, degradation, and mineralization, play an important role in lake ecosystems. Linear or Bayesian algorithms on isotope and n-alkanes have been widely used to identify the source proportion of organic carbon. However, the applicability of these methods is ambiguous because of the unilateral advantages of each model and trace factors. To test the applicability of the various methods for identifying POC sources, we analyzed dual isotopes and n-alkanes in surface water samples of Lake Taihu, and Multi-source mixing model and Bayesian mixing model were used to distinguish between endogenous and exogenous contributions. Carbon isotope presented a clear advantage in West Taihu (-21.85 ± 0.78‰) and Southwest Taih (-22.61 ± 1.35‰); nitrogen isotope also showed high values in Meiliang Bay (9.76 ± 0.92‰). The majority of the lake was dominated by short-chain n-alkanes, except for East Taihu Lake (dominated by medium-chain n-alkanes) and areas with riverine input (dominated by long-chain n-alkanes). Different principles between the Bayesian mixing model (based on the Markov Chain Monte Carlo algorithm) and the Multi-source mixing model (based on linear estimation) caused discrepancies in the estimations of source contributions. But the fraction of chemical compounds during the migration process, and the overlap of potential sources play important role in the inconsistency of results. The estimations from the different models were consistent in indicating the dominance of endogenous organic carbon in Lake Taihu (mean of 60.18 ± 20.26%), particularly in the north and western regions (West Taihu, Meiliang Bay, and Southwest Taihu). This was likely due to algal aggregation influenced by human activities and climatic factors.


Asunto(s)
Carbono , Sedimentos Geológicos , Alcanos , Teorema de Bayes , Carbono/análisis , Isótopos de Carbono/análisis , China , Ecosistema , Monitoreo del Ambiente , Humanos , Lagos
19.
J Environ Radioact ; 233: 106611, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33857821

RESUMEN

The sediments deposited in Lake Kevojärvi (69°45N, 27°00'E) in northernmost Finland were investigated for radioactivity. Freeze cores recovered from the 35-m deep basin has preserved a distinct succession of annual laminations deposited between 1909 and 2015. The basic varve structure is composed of a detrital snowmelt layer and an organic-rich post-snowmelt layer lying on top of the snowmelt layer. The past nuclear events have been preserved in the lake sediment. In order to study these, sediment freeze with annual sediment laminations were recovered from the lake bottom and measured for gamma emitting radionuclides. A total of 53 sediment subsamples, each incorporating sediment from one to two varves i.e. sediment deposited during one to two years, were taken for gamma spectroscopy measurements using low-background HPGe detector system. The measurements showed large variations in 137Cs and 241Am concentrations between different laminae marking different nuclear events in history. This highly resolved profile revealed a detailed record of anthropogenic radioactive fallout from atmospheric nuclear weapons testing during 1950s and 1960s and the Chernobyl accident in 1986. The measured 137Cs concentrations varied between 0.6 and 229 Bq/kg dry weight (dw) while the measured 241Am concentrations varied between 0.6 and 6.4 Bq/kg dw. The 137Cs showed downward migration in the sediment column since 137Cs was also found in varves dating before 1945. The first clear increase in 137Cs concentration was observed in 1956 varve and the 137Cs concentrations were found to peak in the 1964, 1970 and 1986 varves. The 241Am was first observed in 1957 varve and the concentrations peaked in 1960-1962, 1964 and 1970 varves. This demonstrated that 241Am can be a complementary chronostratigraphic marker to 137Cs in sediment. A time delay of one to two years was observed between the years of intensive atmospheric nuclear weapons testing and the increased 137Cs and 241Am concentrations in the sediment varves. In the 210Pb concentrations long-time periods of low (~1930-1950 and ~1990-2000) and high concentrations (~1950-1980) were observed. The reason for large variation was the amount of sediment input. The Constant rate of supply (CRS) model results showed good agreement with the varve counting. The model results showed that the 210Pb deposition has been constant over the last 80 years and no effect of climate change to the 210Pb deposition was observed.


Asunto(s)
Monitoreo de Radiación , Contaminantes Radiactivos del Agua , Radioisótopos de Cesio/análisis , Finlandia , Sedimentos Geológicos , Lagos , Contaminantes Radiactivos del Agua/análisis
20.
J Environ Sci (China) ; 103: 246-254, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33743906

RESUMEN

Water transfer is becoming a popular method for solving the problems of water quality deterioration and water level drawdown in lakes. However, the principle of choosing water sources for water transfer projects has mainly been based on the effects on water quality, which neglects the influence in the variation of phytoplankton community and the risk of algal blooms. In this study, algal growth potential (AGP) test was applied to predict changes in the phytoplankton community caused by water transfer projects. The feasibility of proposed water transfer sources (Baqing River and Jinsha River) was assessed through the changes in both water quality and phytoplankton community in Chenghai Lake, Southwest China. The results showed that the concentration of total nitrogen (TN) and total phosphorus (TP) in Chenghai Lake could be decreased to 0.52 mg/L and 0.02 mg/L respectively with the simulated water transfer source of Jinsha River. The algal cell density could be reduced by 60%, and the phytoplankton community would become relatively stable with the Jinsha River water transfer project, and the dominant species of Anabaena cylindrica evolved into Anabaenopsis arnoldii due to the species competition. However, the risk of algal blooms would be increased after the Baqing River water transfer project even with the improved water quality. Algae gained faster proliferation with the same dominant species in water transfer source. Therefore, water transfer projects should be assessed from not only the variation of water quality but also the risk of algal blooms.


Asunto(s)
Monitoreo del Ambiente , Agua , China , Cianobacterias , Eutrofización , Lagos , Nitrógeno/análisis , Fósforo/análisis , Fitoplancton , Calidad del Agua
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...