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1.
Arch Environ Contam Toxicol ; 79(3): 283-297, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-33063196

RESUMO

Silver nanoparticles (AgNP) are widely used as antibacterial agents in both commercial products and for industrial applications. As such, AgNP has a high potential for release into freshwater environments. As part of a whole-lake ecosystem experiment to examine the impacts of AgNP exposure at low µg/L concentrations over multiple years, we evaluated biological responses in Yellow Perch (Perca flavescens) before, during, and after AgNP additions to a freshwater lake. Yellow Perch were monitored for responses to in situ AgNP additions at the cellular (suite of biomarkers), individual (growth, prey consumption, and metabolism), and population (abundance and gross prey consumption) scales. At the cellular level, several biomarkers of oxidative stress in liver tissues revealed down-regulation, including decreased mRNA levels of catalase and glutathione peroxidase in Yellow Perch collected during AgNP exposure, and elevated ratios of reduced to oxidized glutathione. At the individual level, Yellow Perch bioenergetic models revealed that prey consumption and total metabolism significantly declined during AgNP additions and remained depressed one year after AgNP addition. At the population level, Yellow Perch densities and gross prey consumption declined after AgNP was added to the lake. Together, these results reveal a holistic assessment of the negative impacts of chronic exposure to environmentally relevant AgNP concentrations (i.e., µg/L) on Yellow Perch at cellular, individual, and population levels.


Assuntos
Lagos/química , Nanopartículas Metálicas/toxicidade , Percas/metabolismo , Prata/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Catalase/metabolismo , Ecossistema , Metabolismo Energético/efeitos dos fármacos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Modelos Teóricos , Estresse Oxidativo/efeitos dos fármacos , Percas/crescimento & desenvolvimento
2.
Bull Environ Contam Toxicol ; 105(5): 742-749, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-33000334

RESUMO

Inland lakes are important ecosystems for the carbon cycle at both regional and global scales. However, a knowledge gap still exists about the correlations between the partial pressure of CO2 (pCO2) and nutrient dynamics in lakes. In this study, we analysed the long-term dynamics of nutrient and pCO2 in Taihu Lake. Strong spatial heterogeneity was observed with highest nutrient concentrations occurring in the River mouth and significant lower concentrations (p < 0.01) occurring in East Taihu and Other zone. For pCO2, the average values were 1136.81 ± 1240.16 µatm, 433.07 ± 305.45 µatm, and 487.05 ± 414.02 µatm in Rive mouth, East Taihu, and Other zone, respectively. Statistical analysis revealed that pCO2 was significantly and positively related to nutrient (TN: total nitrogen and NH4+: ammonium) concentrations (p < 0.01), but negatively related to Chla (Chlorophyll a) concentrations in River mouth and Other zone (p < 0.01). The parallelism of nutrient concentrations and pCO2 in Taihu Lake highlights the dual effects of external pollution inputs from the surrounding catchment. In addition, progressive mitigation was found for not only nutrients but also pCO2, which was attributed to the previous effort in the environmental protections in Taihu Lake basin. Our results also suggest the importance of long-term monitoring for the future assessment of anthropogenic impacts on nutrient and CO2 dynamics in freshwater lakes.


Assuntos
Dióxido de Carbono/análise , Monitoramento Ambiental/métodos , Lagos/química , Nitrogênio/análise , Fósforo/análise , Poluentes Químicos da Água/análise , China , Clorofila A/análise , Ecossistema , Eutrofização , Rios/química
3.
Chemosphere ; 254: 126844, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32957274

RESUMO

The study aimed to evaluate the impact of iron (Fe) on the physiological and behavioural reaction of Chara tomentosa L. Fe was introduced into the environment in the form of iron chloride, the most common coagulants used in the restoration of water bodies. The investigations concerned the oxidative stress comprising phenolic compounds content, antioxidant activity and photosynthetic pigments concentration. Research was conducted as a laboratory microcosm experiment with one-off application of Fe at the level of 26.8 mg dm-3. Coagulant application caused short-term acidification, increased salinity and deterioration of light conditions. The shading resulted initially from the increase of water colour and turbidity and was followed by covering of the charophytes with a precipitated suspension. C. tomentosa did not activate defensive mechanisms to prevent the shading effect such as intensive elongation and elevated concentration of chlorophylls. Neither oxidative stress nor production of stress-specific phenolic metabolites was found. It was a result of iron coagulant toxicity, which led to cell membrane damage and leakage of cell contents to the water environment. Charophyte growth was significantly impaired, and thalli suffered numerous chlorotic and necrotic spots which extended gradually during experiment and finally caused death of specimens.


Assuntos
Carofíceas/efeitos dos fármacos , Ecossistema , Ferro/farmacologia , Fosfatos/farmacologia , Chara/efeitos dos fármacos , Carofíceas/crescimento & desenvolvimento , Precipitação Química , Clorofila/metabolismo , Ferro/toxicidade , Lagos/química , Estresse Oxidativo , Fenóis/análise , Água/química
4.
Bull Environ Contam Toxicol ; 105(5): 679-684, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32915240

RESUMO

The objective of this study was to assess the current chemistry of trace elements in upland headwater lakes in Ireland and determine their trends during the last decade in response to decreasing emissions. Twenty-nine upland lakes were sampled in 2017-2018; 19 were previously sampled in 2007-2008. The 2017-2018 samples were analyzed for conductivity, pH, DOC, and 18 trace elements. The lakes had low element concentrations; only 7 of 18 trace elements were > 1 µg/L (Fe, Al, Zn, Mn, B, Sr and Ba). Nine elements were assessed for significant decadal changes; four elements decreased (B, Co, Mn, and Sr) and one increased (Pb). Their correlation with conductivity, pH, and DOC and the associated changes in those variables partially explained the observed trends. In general, elements that were correlated with DOC did not decrease, while those that were not correlated decreased between the two periods. Despite decreased anthropogenic emissions, ecosystem recovery and climate perturbations can confound or mask the benefits of emissions reductions.


Assuntos
Monitoramento Ambiental/métodos , Lagos/química , Metais Pesados/análise , Oligoelementos/análise , Poluentes Químicos da Água/análise , Altitude , Ecossistema , Irlanda
5.
Ecotoxicol Environ Saf ; 202: 110976, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800235

RESUMO

In this study, we first reviewed the current research progress regarding the presence of environmental microplastics (MPs) in environment in China from 2010 to 2019. Results showed that: (1) current research has primarily focused on river and marine environments rather than soils and dusts, mainly located in eastern China, i.e., the Yangtze river, Poyang lake, Dongting lake, Yellow sea, and Bohai sea; (2) the abundance of MPs found in water bodies (sediments) of the rivers in China ranged from 3.9 to 7900 items·m-3 (19.0 × 103-13600.5 × 103 items·km-2), and 20-24300 items·kg-2 (170-5500 × 106 items·km-2) in the sediments, respectively; in lake water the range was 340-8900 items·m-3 (5 × 103-340 × 105 items·km-2) and 8 to 1200 items·m-2/25-300 items·kg-1 in the sediments, respectively; in marine water the range was 0.003-540 items·m-3 (0-380,100 item·km-2) and 1.3-14700 item·kg-1 in the sediments, respectively; in fish, shellfish, and natural planktons from ocean and freshwater, the range was 0-57 items·individuals-1 (0-168 items·g-1); (3) The absorption and toxicological effects of MPs in freshwater and oceans have mainly focused on polyethylene (PE), polypropylene (PP), and polystyrene (PS); (4) the sources of microplastics in soils and dusts primarily come from urban/town activities; for rivers and lakes (estuary), they primarily come from urban activities; for coastal waters, fishing gear and nets, and the maritime activities were the main sources.


Assuntos
Monitoramento Ambiental/métodos , Sedimentos Geológicos/química , Lagos/química , Microplásticos/análise , Rios/química , Solo/química , Poluentes Químicos da Água/análise , China , Cidades , Poeira/análise , Estuários , Oceanos e Mares , Polietileno/análise , Polipropilenos/análise , Poliestirenos/análise
6.
Ecotoxicol Environ Saf ; 202: 110910, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32800245

RESUMO

Microplastics (MPs) are ubiquitous in the environment and more abundant in the marine environment. Consequently, increasing focus has been put on MPs in oceans and seas, while little importance has been attached to their presence in freshwaters and soils. Therefore, this paper aimed to provide a comprehensive review of the occurrence, analysis and ecotoxicology of MPs. The abundance and distribution of MPs in several typical freshwater systems of China were summarized. It suggested that the surface water of Poyang Lake contained the highest concentration of 34 items/L MPs among all the 8 freshwater systems, and the content of MPs in sediments were higher than that of the surface water. Net-based zooplankton sampling methods are the most frequently utilized sampling methods for MPs, and density separation, elutriation and digestion are three major pretreatment methods. Fourier transform infrared spectroscopy, Raman spectroscopy and pyrolysis-gas chromatography coupled to mass spectrometry are often used to identify the polymer types of MPs. Besides, MPs might damage the digestive tract of various organisms and negatively inhibit their growth, feeding and reproduction. The ways of human exposure to MPs are by ingestion, inhalation and dermal exposure, digestive and respiratory system might be adversely influenced. However, potential health risks of MPs to humans are remained insufficiently researched. Overall, by showing the presence of MPs in freshwaters and soils as well as possible ecotoxicological effects on the environment and humans, this paper provided a framework for future research in this field.


Assuntos
Monitoramento Ambiental , Poluentes Ambientais/análise , Microplásticos/análise , Animais , China , Ecotoxicologia , Monitoramento Ambiental/métodos , Poluentes Ambientais/toxicidade , Cromatografia Gasosa-Espectrometria de Massas , Humanos , Lagos/química , Microplásticos/toxicidade , Oceanos e Mares , Plásticos/química , Solo , Espectroscopia de Infravermelho com Transformada de Fourier , Poluentes Químicos da Água/análise , Zooplâncton
7.
PLoS Negl Trop Dis ; 14(8): e0008406, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32776919

RESUMO

We hypothesized that Cholera (Vibrio cholerae) that appeared along Lake Kivu in the African Rift in the seventies, might be controlled by volcano-tectonic activity, which, by increasing surface water and groundwater salinity and temperature, may partly rule the water characteristics of Lake Kivu and promote V. cholerae proliferation. Volcanic activity (assessed weekly by the SO2 flux of Nyiragongo volcano plume over the 2007-2012 period) is highly positively correlated with the water conductivity, salinity and temperature of the Kivu lake. Over the 2007-2012 period, these three parameters were highly positively correlated with the temporal dynamics of cholera cases in the Katana health zone that border the lake. Meteorological variables (air temperature and rainfall), and the other water characteristics (namely pH and dissolved oxygen concentration in lake water) were unrelated to cholera dynamics over the same period. Over the 2016-2018 period, we sampled weekly lake water salinity and conductivity, and twice a month vibrio occurrence in lake water and fish. The abundance of V. cholerae in the lake was positively correlated with lake salinity, temperature, and the number of cholera cases in the population of the Katana health zone. V. cholerae abundance in fishes was positively correlated with V. cholerae abundance in lake water, suggesting that their consumption directly contaminate humans. The activity of the volcano, by controlling the physico-chemical characteristics of Lake Kivu, is therefore a major determinant of the presence of the bacillus in the lake. SO2 fluxes in the volcano plume can be used as a tool to predict epidemic risks.


Assuntos
Cólera/epidemiologia , Lagos/química , Lagos/microbiologia , Erupções Vulcânicas/efeitos adversos , Animais , República Democrática do Congo/epidemiologia , Condutividade Elétrica , Peixes/microbiologia , Humanos , Concentração de Íons de Hidrogênio , Oxigênio/análise , Ruanda , Salinidade , Dióxido de Enxofre/análise , Temperatura , Vibrio , Microbiologia da Água
8.
Ecotoxicol Environ Saf ; 204: 111064, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32738625

RESUMO

Very limited studies have evaluated the impact of rainfall on the fate of endocrine-disrupting micropollutants in lacustrine systems. This yearlong study investigated monthly fluctuation of bisphenol A (BPA) and 4-nonylphenol (NP) concentrations in both water and sediment samples from Taihu Lake and evaluated the impact of rainfall on their spatiotemporal distribution and partition trends. Results showed that BPA concentration in water was negatively correlated to rainfall while NP concentrations in both phases were positively related to rainfall. The spatial distribution of NP in the lake water was season specific with the lakeshore area higher than the central area during the wet season and a reversed pattern during the dry season. The spatial distributions of sediment-associated NP and BPA in both phases were not significantly different among seasons. Contrary partition tendencies were observed for BPA and NP that BPA tended to desorb from sediment and NP tended to be adsorbed during the wet season while the trends were reversed during the dry season. This study suggests that rainfall could affect the occurrence, distribution and environmental fate of micropollutants and should be considered in the monitoring program and risk assessment.


Assuntos
Compostos Benzidrílicos/análise , Disruptores Endócrinos/análise , Monitoramento Ambiental/métodos , Lagos/química , Fenóis/análise , Chuva/química , Poluentes Químicos da Água/análise , China , Medição de Risco , Estações do Ano , Análise Espaço-Temporal
9.
J Chromatogr A ; 1629: 461476, 2020 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-32841771

RESUMO

Core-shell structured magnetic covalent organic frameworks (Fe3O4@COFs) were synthesized via a facile approach at room temperature using 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 2,5-dibromo-1,4-benzenedicarboxaldehyde (DBDA) as two building blocks for the first time. The Fe3O4@COFs were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier-transform infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), vibrating sample magnetometry (VSM), nitrogen adsorption-desorption isotherms, and zeta potentiometric analysis. The Fe3O4@COFs had a high specific surface area (141.94 m2·g-1) and uniform pore size distribution (average 4.53 nm). They also demonstrated good magnetic response (32.49 emu·g-1) and good thermal and chemical stabilities. Furthermore, adsorption experiments were conducted to evaluate the adsorption capacities and adsorption times of Fe3O4@COFs to diphenylamine (DPA) and its analogs, including benzidine (BZ), 1-naphthylamine (1-NA), 4-phenylphenol (4-PP), and O-tolidine (O-TD). From the experimental results, the maximum adsorption capacities of DPA, 1-NA, 4-PP, BZ, and O-TD were calculated as 246.25, 95.20, 85.85, 107.20, and 123.55 mg·g-1, respectively. A duration of 20 min was sufficient for adsorption. The Fe3O4@COFs were explored as adsorbents for magnetic solid-phase extraction (MSPE) of DPA and its analogs, and the MSPE parameters, including adsorbent dosage, extraction time, pH, ionic strength, desorption solvent, desorption time, and desorption frequency were optimized. Combined with HPLC using diode-array detection, a simple, fast, and sensitive method was proposed to detect DPA and its analogs, which exhibited good linearity (r >0.9946) in the range of 0.1-100 µg·mL-1. Moreover, the low limits of detection (ranging from 0.02 to 0.08 µg·mL-1, S/N = 3), low limits of quantitation (ranging from 0.05 to 0.30 µg·mL-1, S/N = 10), good precision with low relative SDs (<5.86% for intra-day and <6.44% for inter-day) were obtained. Finally, Fe3O4@COFs were applied to the effective MSPE of DPA and its analogs in actual samples chosen from the natural environment, and good recoveries (ranging from 79.97 to 122.52%) were observed.


Assuntos
Difenilamina/análogos & derivados , Difenilamina/isolamento & purificação , Fenômenos Magnéticos , Estruturas Metalorgânicas/química , Extração em Fase Sólida/métodos , Adsorção , Compostos Férricos/química , Concentração de Íons de Hidrogênio , Lagos/química , Limite de Detecção , Magnetismo/métodos , Estruturas Metalorgânicas/ultraestrutura , Concentração Osmolar , Reprodutibilidade dos Testes , Solventes/química , Espectroscopia de Infravermelho com Transformada de Fourier , Fatores de Tempo , Água/química , Difração de Raios X
10.
PLoS One ; 15(8): e0237836, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32841245

RESUMO

Lake Kivu, East Africa, is well known for its huge reservoir of dissolved methane (CH4) and carbon dioxide (CO2) in the stratified deep waters (below 250 m). The methane concentrations of up to ~ 20 mmol/l are sufficiently high for commercial gas extraction and power production. In view of the projected extraction capacity of up to several hundred MW in the next decades, reliable and accurate gas measurement techniques are required to closely monitor the evolution of gas concentrations. For this purpose, an intercomparison campaign for dissolved gas measurements was planned and conducted in March 2018. The applied measurement techniques included on-site mass spectrometry of continuously pumped sample water, gas chromatography of in-situ filled gas bags, an in-situ membrane inlet laser spectrometer sensor and a prototype sensor for total dissolved gas pressure (TDGP). We present the results of three datasets for CH4, two for CO2 and one for TDGP. The resulting methane profiles show a good agreement within a range of around 5-10% in the deep water. We also observe that TDGP measurements in the deep waters are systematically around 5 to 10% lower than TDGP computed from gas concentrations. Part of this difference may be attributed to the non-trivial conversion of concentration to partial pressure in gas-rich Lake Kivu. When comparing our data to past measurements, we cannot verify the previously suggested increase in methane concentrations since 1974. We therefore conclude that the methane and carbon dioxide concentrations in Lake Kivu are currently close to a steady state.


Assuntos
Gases/análise , Lagos/química , África Oriental , Dióxido de Carbono/análise , Metano/análise , Pressão , Risco
11.
PLoS One ; 15(8): e0237605, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32804934

RESUMO

The vertical distribution of radiocarbon (14C) was examined in the bottom sediment core, taken from Lake Druksiai, which has served as a cooling pond since 1983 for the 26 years of the Ignalina Nuclear Power Plant (INPP) operation using two RBMK-1500 reactors (Russian acronym for"Channelized Large Power Reactor"). 14C specific activity was measured in alkali-soluble and -insoluble fractions of the sediment layers. Complementary measurements of the 210Pb and 137Cs activity of the samples provided the possibility to evaluate the date of every layer formation, covering the 1947-2013 period. In addition, 14C distribution was examined in the scales of pelagic fish caught between 1980 and 2012. Our measurements reveal that, during the period 1947-1999, the radiocarbon specific activity in both fractions exhibits a parallel course with a difference of 5 ± 1 pMC (percent of modern carbon) being higher in alkali-soluble fraction, although 14C specific activity in both fractions increased by 11.4-13.6 pMC during the first 15 years of plant operation. However, during the 2000-2009 period, other than previously seen, a dissolved inorganic carbon (DIC) → aquatic primary producers → sediments 14C incorporation pattern occurred, as the radiocarbon specific activity difference between alkali-soluble and -insoluble fractions reached 94, 25, and 20 pMC in 2000, 2006, and 2008, respectively. Measurements in different sediment fractions allowed us to identify the unexpected organic nature of 14C contained in liquid effluences from the INPP in 2000-2009. The discrepancy between 14C specific activity in fish scales samples and DIC after 2000 also confirmed the possibility of organic 14C contamination. Possible reasons for this phenomenon might be industrial processes introduced at the INPP, such as the start of operation of the cementation facility for spent ion exchange resins, decontamination procedures, and various maintenance activities of reactor aging systems and equipment.


Assuntos
Radioisótopos de Carbono/análise , Sedimentos Geológicos/análise , Lagos/química , Monitoramento de Radiação/métodos , Animais , Radioisótopos de Césio/análise , Peixes/crescimento & desenvolvimento , Radioisótopos de Chumbo/análise , Lituânia , Centrais Nucleares
12.
Proc Natl Acad Sci U S A ; 117(35): 21488-21494, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32817550

RESUMO

Lakes are considered the second largest natural source of atmospheric methane (CH4). However, current estimates are still uncertain and do not account for diel variability of CH4 emissions. In this study, we performed high-resolution measurements of CH4 flux from several lakes, using an automated and sensor-based flux measurement approach (in total 4,580 measurements), and demonstrated a clear and consistent diel lake CH4 flux pattern during stratification and mixing periods. The maximum of CH4 flux were always noted between 10:00 and 16:00, whereas lower CH4 fluxes typically occurred during the nighttime (00:00-04:00). Regardless of the lake, CH4 emissions were on an average 2.4 higher during the day compared to the nighttime. Fluxes were higher during daytime on nearly 80% of the days. Accordingly, estimates and extrapolations based on daytime measurements only most likely result in overestimated fluxes, and consideration of diel variability is critical to properly assess the total lake CH4 flux, representing a key component of the global CH4 budget. Hence, based on a combination of our data and additional literature information considering diel variability across latitudes, we discuss ways to derive a diel variability correction factor for previous measurements made during daytime only.


Assuntos
Lagos/química , Metano/análise , Metano/biossíntese , Ritmo Circadiano , Monitoramento Ambiental , Estações do Ano
13.
Huan Jing Ke Xue ; 41(2): 734-742, 2020 Feb 08.
Artigo em Chinês | MEDLINE | ID: mdl-32608732

RESUMO

Spatial and temporal characteristics of release fluxes of sediment nitrogen (N) and phosphorus (P) were investigated in the high-risk period of algal blooms in Lake Erhai. Moreover, the influence factors were examined. Results show that the release flux of N and P increased in recent years, exhibiting a clear increase in the period from 2009 to 2013, and a slight increase in the period since 2013. The release flux of dissolved total nitrogen (DTN) ranged between 11.71-14.15 mg·(m2·d)-1, within which the release flux of dissolved organic nitrogen (DON) and dissolved inorganic nitrogen (DIN) were 6.39-8.42 mg·(m2·d)-1 and 5.31-5.73 mg·(m2·d)-1, accounting for 58% and 42% of the DTN, respectively. The release flux of dissolved total phosphorus (DTP) ranged between 0.11-0.14 mg·(m2·d)-1, within which the release flux of dissolved organic phosphorus (DOP) and dissolved inorganic phosphorus (DIP) were 0.04-0.05 mg·(m2·d)-1 and 0.07-0.09 mg·(m2·d)-1, accounting for 34% and 66% of the DTP, respectively. The distribution of release flux of N showed a decreasing order:south > north > middle, while P was north > middle > south. The release flux of N increased by 17%, 13% and 23%, and the release flux of P increased by 19%, 28%, and 29% in north, middle, and south part of Lake Erhai from 2009 to 2018. Comparing the years 2009, 2013 and 2018, although the contents of N and P were stable, the release flux of N and P in the sediment was enhanced due to increasing pH and decreasing DO. Therefore, the increasing release of nitrogen and phosphorus from sediments, caused by changes in the water environment factors, should be paid attention to for the protection of Lake Erhai.


Assuntos
Eutrofização , Lagos/química , Nitrogênio/análise , Fósforo/análise , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental , Sedimentos Geológicos/química , Análise Espaço-Temporal
14.
Arch Environ Contam Toxicol ; 79(2): 246-257, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32607658

RESUMO

In this work, rare minnow (Gobiocypris rarus) was applied as a sentinel organism and set in cages at control and test sampling sites in Donghu Lake for 4 weeks in March, June, September, and December 2016 to assess the biological toxicity of in situ water. Sampling for active biomonitoring and physicochemical variables was performed weekly. The control was obtained from the outdoor pool of the Institute of Hydrobiology, China. Superoxide dismutase, lipoperoxidation, metallothioneins, acetylcholinesterase activity, and Vtg mRNA expression were determined as biomarkers during the field exposure period. Survival and growth also were monitored to evaluate the overall physiological condition of the fish. The seasonal changes of organic pollutants and trace metals (As, Hg, Cr, Cu, Zn, Cd, Pb) in surface water were determined. The integrated biomarker response (IBR) index was applied to summarize biomarker responses and correlate stress levels with concentrations of organic pollutants and trace metals in the surface water. Results indicated that complex pollution by persistent organic pollutants and heavy metals was present in Donghu Lake and that the in situ exposed organisms were stressed. Moreover, the complex pollution of Donghu Lake in summer and autumn was more serious than that in spring and winter. Active biomonitoring combined with IBR analysis enabled good discrimination among different exposure seasons. The proposed protocol with caged rare minnow revealed marked biological effects caused by the investigated Lake and a useful approach that can easily be extended to monitor water pollution.


Assuntos
Cyprinidae/fisiologia , Monitoramento Ambiental , Poluentes Químicos da Água/metabolismo , Animais , China , Cyprinidae/crescimento & desenvolvimento , Poluição Ambiental/análise , Lagos/química , Mercúrio/análise , Metalotioneína , Metais Pesados/análise , Poluentes Químicos da Água/análise
15.
Proc Natl Acad Sci U S A ; 117(29): 17063-17067, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32631997

RESUMO

Little is known about the exchange of gaseous nitrogen (N2) with the atmosphere in freshwater systems. Although the exchange of N2, driven by excess or deficiencies relative to saturation values, has little relevance to the atmospheric N2 pool due to its large size, it does play an important role in freshwater and marine nitrogen (N) cycling. N-fixation converts N2 to ammonia, which can be used by microbes and phytoplankton, while denitrification/anammox effectively removes it by converting oxidized, inorganic N to N2 We examined N2 saturation to infer net biological nitrogen processes in 34 lakes across 5° latitude varying in trophic status, mixing regime, and bathymetry. Here, we report that nearly all lakes examined in the upper Midwest (USA) were supersaturated with N2 (>85% of samples, n = 248), suggesting lakes are continuously releasing nitrogen to the atmosphere. The traditional paradigm is that freshwaters compensate for N-limitation through N-fixation, but these results indicate that lakes were constantly losing N to the atmosphere via denitrification and/or anammox, suggesting that terrestrial N inputs are needed to balance the internal N cycle.


Assuntos
Lagos , Nitrogênio/análise , Argônio/análise , Gases de Efeito Estufa/análise , Lagos/análise , Lagos/química , Minnesota , Fixação de Nitrogênio , Oxigênio/análise
16.
Ecotoxicol Environ Saf ; 203: 111003, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32678765

RESUMO

Consumption of fish is one of the predominant sources of human exposure to per- and polyfluoroalkyl substances (PFASs). In this study, the effect of various cooking methods (boiling, steaming, grilling and frying) on the levels of PFASs in fish muscle and the intake of PFASs was explored by using grass carp collected from Tangxun Lake, Wuhan, China. Perfluorooctane sulfonate (PFOS) was the predominant PFASs in raw fish fillets, with the concentrations ranging from 59.6 to 136 ng/g ww, followed by perfluorobutane sulfonate (PFBS) (7.73-51.9 ng/g ww). The concentrations of long-chain PFASs in fish increased after cooking, while those of short-chain PFASs decreased. The amounts of PFASs in the cooked fish fillets decreased except PFOS. Short-chain PFASs, including PFBS and perfluoroheptanoic acid (PFHpA), were dominant in cooking juice. The highest amounts of PFBS in the juices were observed after boiling and frying, even higher than those in cooked fish fillets, suggesting that the release of short-chain PFASs to the cooking juices could not be neglected. Based on these results, the intake of short-chain PFASs amount through cooked fish fillets slightly decreased, but the intake of PFOS amount increased. However, consumption of cooking juice (fish soup) could increase the exposure risk of PFBS. Comprehensively considering the increase of PFOS and decrease of total PFASs, boiling may be the relatively better method to cook fish. As PFASs are ubiquitous and inevitable in aquatic food, it is thus important to choose appropriate cooking processes and dietary habits for reducing the intake of different PFASs from fish.


Assuntos
Carpas , Culinária/métodos , Exposição Dietética/análise , Fluorcarbonetos/análise , Poluentes Químicos da Água/análise , Animais , Carpas/metabolismo , China , Fluorcarbonetos/química , Humanos , Lagos/química , Alimentos Marinhos/análise , Poluentes Químicos da Água/química
17.
Chemosphere ; 260: 127623, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32668363

RESUMO

The global demand of lithium is rising steadily, and many industrially advanced countries may find it hard to secure an uninterrupted supply of lithium for meeting their manufacturing demands. Thus, innovative processes for lithium recovery from a wide range of natural reserves should be explored for meeting the future demands. In this study, a novel integrated approach was investigated by combining nanofiltration (NF), membrane distillation (MD) and precipitation processes for lithium recovery from salt-lake brines. Initially, the brine was filtered with an NF membrane for the separation of lithium ions (Li+) from competing ions such as Na+, K+, Ca2+ and Mg2+. The extent of permeation of metal ions by the NF membrane was governed by their hydrated ionic radii. Rejection by NF membrane was 42% for Li, 48% for Na and 61% for K, while both the divalent cations were effectively rejected (above 90%). Importantly, in the NF-permeate, Mg2+/Li+ mass ratio reduced to less than 6 (suggested for lithium recovery). The result showed that MD can enrich lithium with a concentration of 2.5 for raw brine and 5 for NF-treated brine. Following the enrichment of NF-permeate by the MD membrane, a two-stage precipitation method was used for the recovery of lithium. X-ray diffraction confirmed the precipitation of lithium as well as the formation of lithium carbonate crystals.


Assuntos
Lagos/química , Lítio/análise , Poluentes Químicos da Água/análise , Cátions Bivalentes , Destilação , Íons , Lítio/química , Sais , Sódio , Cloreto de Sódio , Poluentes Químicos da Água/química
18.
Bull Environ Contam Toxicol ; 105(2): 307-316, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32564098

RESUMO

It has recently been reported that plateau lakes have been seriously polluted by organic matter, however, the sources of this organic matter and their relative contributions remain unknown. In this study, to determine the sources and composition of the organic matter in the Hulun Lake basin during the spring-thaw period, a total of twenty-three sampling sites were investigated. Results showed high levels of organic matter pollution in the surface water of Hulun Lake, with an average COD values of 119.35 mg L-1. Organic matter came from natural sources as well as a variety of anthropogenic activities. The direct sources included urbanization, industrial and residential wastewater discharge, and emission from burning fossile fuels. A large indirect source was organic matter from tumbleweed decomposition, which had increased due to desertification caused by overgrazing. The principal component analysis showed that organic matter from Hulun lake shared composition and sources with the upstream sections of the natural tributaries and the downstream section of the artificial tributary. The artificial inflow river contributed more organic matter than the other tributaries. Notably, a large portion of organic matter in Hulun Lake came from decomposing tumbleweed concentrated in the downstream section of one of the natural rivers. New indirect consequences of human activities must be factored into the rule and regulations that protect plateau lake ecosystems alongside the direct effects of established human activities.


Assuntos
Monitoramento Ambiental , Lagos/química , Poluentes Químicos da Água/análise , China , Ecossistema , Atividades Humanas , Rios , Estações do Ano , Qualidade da Água
19.
Chemosphere ; 257: 127161, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32526465

RESUMO

Sediments exposed to sunlight can serve as an important source of dissolved organic carbon (DOC) and nutrients to overlying waters. However, the photochemical release processes of dissolved organic matter (DOM) from resuspended sediments and the characteristics of photoreleased DOM are not fully understood. In this study, excitation-emission matrix fluorescence combined with parallel factor analysis (EEMs-PARAFAC) was used to study the photochemical release of DOM qualitatively and quantitatively. The EEMs-PARAFAC demonstrated that the photoreleased DOM is dominated by humic-like substances, and the photorelease process could be consist of the photoproduction and photodegradation of DOM. The concurrent photodegradation may result in the underestimation of photoreleased DOM. Moreover, the significant increases in DOC content and fluorescence intensity of humic-like components along with increasing nitrate and ferric ion indicated that nitrate and ferric ion could facilitate the photoproduction of DOM through the photochemical produced hydroxyl radical. However, the decreases in DOC and fluorescence intensity were also observed at high concentration of nitrate and ferric ion, owing to the photodegradation of DOM by redundant hydroxyl radical. All of these results suggest that EEMs-PARAFAC is an effective and sensitive analytical technique for evaluating DOM photoreleased from suspended lake sediments and previous studies may underestimate photochemical release of DOM from sediments due to the overlook of the subsequently photodegradation of these released DOM. Thus, the photochemical release of DOM and its associated pollutants from suspended particles in shallow and eutrophic lakes should be more significant then should be paid more attention.


Assuntos
Modelos Químicos , Análise Fatorial , Fluorescência , Substâncias Húmicas/análise , Lagos/química , Nitratos/análise , Processos Fotoquímicos , Fotólise , Espectrometria de Fluorescência , Luz Solar
20.
Environ Geochem Health ; 42(11): 3765-3778, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32594418

RESUMO

The heavy metal contamination of the aquatic ecosystem is still prevalent even after reduction of the external anthropogenic inputs of the metals. The release of labile heavy metals from the sediments into the water is a potential risk, responsible for the contamination of the aquatic system. Herein, samples of sedimentary column cores were collected in Nansi Lake, and the distribution profiles of the labile and soluble metals (Cd, Cu, Ni, Pb, and Zn) were obtained by the diffusive gradient in thin films (DGT) and the high-resolution dialysis (HR-peeper) technique. Furthermore, the mobility, bioavailability and release risk of the heavy metals were assessed using the results of geochemical sequential extraction, DGT as well as the DGT-induced fluxes in sediments (DIFS) model. The results showed that the profile characteristics of the DGT-labile and soluble heavy metals showed irregular distribution in the sediment cores and Cd, Pb, Zn had an obvious positive correlation with Fe/Mn (p < 0.05). Ni, Cu, and Zn existed primarily in the residual fraction (accounting for 58-76%), while Cd and Pb existed in the reducible fraction (accounting for 50-67%). The Cd and Ni (0.027-0.185) had higher mobility coefficients compared with Pb, Cu, and Zn (0-0.011), and positive diffusive fluxes also proved that Cd and Ni were easy to be released from the sediments. In addition, the R values of five metals (0.18-0.85) ranged between Rdiff to 0.95, indicating that all the metals had partially sustained case from the sediments solid phase. Based on the DIFS model, the five metals had weak mobility from the sediment to pore water, but the release risks in the Nansi Lake should also be of concern, especially for the highly mobile Cd and Ni in the Dushan Lake.


Assuntos
Sedimentos Geológicos/química , Lagos/química , Metais Pesados/análise , Poluentes Químicos da Água/análise , Disponibilidade Biológica , China , Monitoramento Ambiental/métodos , Sedimentos Geológicos/análise , Lagos/análise , Metais Pesados/química , Metais Pesados/farmacocinética , Modelos Teóricos , Poluentes Químicos da Água/química , Poluentes Químicos da Água/farmacocinética
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