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1.
Environ Monit Assess ; 192(2): 99, 2020 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-31912244

RESUMO

It is widely acknowledged that dams affect sediment transport and water quality. To support water management of reservoirs, it is useful to explore how the fractions of phosphorus (P) in sediments were changed after the dam was built. The aim of this study was to assess the spatial and temporal trends of the P fractions in sediments from the Miyun Reservoir, a pivotal drinking water supply for Beijing City, the capital of China. Nine surface sediment samples, together with a sediment core, were collected. The concentrations of total P (TP) and their fractions were then determined by using a sequential extraction method. The results showed that the reservoir was classified into three areas spatially based on the TP concentrations, i.e., high (Baihe area), medium (transitional area), and low (Chaohe area) concentrations. The concentrations of iron-bound P (BD-P) and metal oxide-bound P (NaOH-P) were higher in the Baihe and Chaohe regions than those in the transitional area and tended to increase with water depth. Dam construction can lead to the concentrations of P increased in sediments and further increase the potential of internal P loadings. This study revealed the effect of dam construction on sedimentary P accumulation. The results will be helpful in better understanding the mobility and bioavailability of P in the aquatic ecosystem, which aim to achieve a more highly targeted environmental management for this important region.

3.
Chemosphere ; 238: 124627, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31548173

RESUMO

Nitrogen contamination remains a severe environmental problem and a major threat to sustainable development worldwide. A systematic analysis of the literature indicates that the partial nitritation-anammox (PN/AMX) process is still actively studied as a viable option for energy-efficient and feasible technology for the sustainable treatment of N- rich wastewaters, since its initial discovery in 1990. Notably, the mainstream PN/AMX process application remains the most challenging bottleneck in AMX technology and fascinates the world's attention in AMX studies. This paper discusses the recent trends and developments of PN/AMX research and analyzes the results of recent years of research on the PN/AMX from lab-to full-scale applications. The findings would deeply improve our understanding of the major challenges under mainstream conditions and next-stage research on the PN/AMX process. A great deal of efforts has been made in the process engineering, PN/AMX bacteria populations, predictive modeling, and the full-scale implementations during the past 22 years. A series of new and excellent experimental findings at lab, pilot and full-scale levels including good nitrogen removal performance even under low temperature (15-10 °C) around the world were achieved. To date, pilot- and full-scale PN/AMX have been successfully used to treat different types of industrial sewage, including black wastewater, sludge digester liquids, landfill leachate, monosodium glutamate wastewater, etc. Supplementing the qualitative analysis, this review also provides a quantitative bibliometrics study and evaluates global perspectives on PN/AMX research published during the past 22 years. Finally, general trends in the development of PN/AMX research are summarized with the aim of conveying potential future trajectories. The current review offers a valuable orientation and global overview for scientists, engineers, readers and decision makers presently focusing on PN/AMX processes.


Assuntos
Compostos de Amônio/análise , Bactérias/metabolismo , Reatores Biológicos/microbiologia , Esgotos/química , Poluentes Químicos da Água/química , Bibliometria , Nitrogênio/análise , Oxirredução , Esgotos/microbiologia , Glutamato de Sódio/análise
4.
Huan Jing Ke Xue ; 40(6): 2705-2714, 2019 Jun 08.
Artigo em Chinês | MEDLINE | ID: mdl-31854662

RESUMO

A comprehensive and scientific understanding of non-point source pollutant transport pathways and source apportionment in combined sewer systems is essential for managing and improving the urban water environment. This study analyzed build-up and wash-off processes of pollutants on road surfaces and in sewers within a catchment of combined sewer systems in a typical old district in Zhuhai. Besides, source apportionment of the entire urban non-point source pollution was investigated by using the mass conservation method. The outcomes revealed that the build-up load of road deposited sediments in the study area was (28.81±10.69) g·m-2. The average wash-off load of road deposited sediments during five different rainfall events was (19.27±10.90) g·m-2 and the wash-off percentage was (52.69±13.3)%. The event mean concentrations of suspended solids (SS) in road runoff were 52-109 mg·L-1, and the event mean concentrations of SS in sewer runoff were 68-158 mg·L-1. Source apportionment analysis showed that road runoff, domestic wastewater, and sewer sediments contributed 39%-72%, <20%, and 13%-56% to SS, respectively. The thickness of sewer sediments increased by 1-14 cm during light and moderate rains, and the thickness decreased by 7-17 cm during heavy rains. It was found that rainfall characteristics affected the contribution percentages of pollution sources. The contribution of pollution from road runoff, domestic sewage, and sewer sediments in combined sewer systems were 2%-52%, 9%-65%, and 8%-81%, respectively. The derived outcomes should be useful for developing recommendations to control non-point source pollution in combined sewer systems and improve urban receiving water quality in China.

5.
Mol Med Rep ; 20(4): 3182-3190, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31432137

RESUMO

Atherosclerosis is a chronic inflammatory disease, and it is a global clinical problem. The development of new and effective therapeutic targets for atherosclerosis is necessary. A number of microRNAs (miRNAs) have been demonstrated to serve a crucial role in atherosclerosis. However, the role of miRNA (miR)­217 in atherosclerosis remains unclear. Therefore, the aim of the present study was to investigate the role and mechanism of miR­217 in atherosclerosis. The level of miR­217 was detected in the blood of patients with atherosclerosis using reverse transcription­quantitative PCR. THP­1 acute monocytic leukemia cells were treated with oxidized low­density lipoprotein (ox­LDL) to develop an atherosclerotic cell model of macrophages. The relationship between miR­217 and sirtuin 1 (SIRT1) was determined by TargetScan and dual luciferase reporter assay. Cell apoptosis was measured by flow cytometry. Production of pro­inflammatory factors and triglyceride (TG) and total cholesterol (TC) levels were also determined. The results demonstrated that miR­217 was significantly upregulated in atherosclerosis. SIRT1 was demonstrated to be a direct target of miR­217 and was downregulated in atherosclerosis. Downregulation of miR­217 significantly inhibited ox­LDL­induced TG and TC level increase, cell apoptosis and the upregulation of the pro­inflammatory factors tumor necrosis factor α, interleukin (IL)­6 and IL­1ß. Additionally, the SIRT1/AMP­activated protein kinase α/NF­κB pathway was at least partially involved in modulating the effects of miR­217 inhibition on THP­1 cells treated with ox­LDL. In addition, the effects of miR­217 downregulation on ox­LDL­treated THP­1 cells were eliminated by SIRT1 silencing. In conclusion, the results of the present study indicated that miR­217 downregulation may relieve atherosclerosis through the inhibition of macrophage apoptosis and inflammatory response by targeting SIRT1.

6.
Transbound Emerg Dis ; 66(6): 2605-2610, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31402584

RESUMO

Wild and domestic aquatic birds are the natural reservoirs of avian influenza viruses (AIVs). All subtypes of AIVs, including 16 hemagglutinin (HA) and nine neuraminidase (NA), have been isolated from the waterfowls. The H5 viruses in wild birds display distinct biological differences from their highly pathogenic H5 counterparts. Here, we isolated seven H5N3 AIVs including three from wild birds and four from domestic ducks in China from 2015 to 2018. The isolation sites of all the seven viruses were located in the region of the East Asian-Australasian Migratory Flyway. Phylogenetic analysis indicated that the surface genes of these viruses originated from the wild bird H5 HA subtype and the N3 Eurasian lineage. The internal genes of the seven H5N3 isolates are derived from the five gene donors isolated from the wild birds or ducks in Eastern-Asia region. They were also divided into five genotypes according to their surface genes and internal gene combinations. Interestingly, two of the seven H5N3 viruses contributed their partial internal gene segments (PB1, M and NS) to the newly emerged H7N4 reassortants, which have caused first human H7N4 infection in China in 2018. Moreover, we found that the H5N3 virus used in this study react with the anti-serum of the H5 subtype vaccine isolate (Re-11 and Re-12) and reacted well with the Re-12 anti-serum. Our findings suggest that worldwide intensive surveillance and the H5 vaccination (Re-11 and Re-12) in domestic ducks are needed to monitor the emergence of novel H5N3 reassortants in wild birds and domestic ducks and to prevent H5N3 viruses transmission from the apparently healthy wild birds and domestic ducks to chickens.

7.
Int J Antimicrob Agents ; 54(1): 89-94, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31034936

RESUMO

The presence of mobilized colistin resistance (mcr) genes is a global concern. However, data concerning mcr in fresh vegetables, a reservoir for antibiotic resistance genes, are still rare. In this study, mcr genes were analysed in 528 vegetable samples from 53 supermarkets or farmer's markets in 23 cities of 9 provinces in China, and the mcr-positive Enterobacteriaceae were characterized. Nineteen (3.6%) samples carried one or more mcr-positive isolates, and the highest three detection rates were found in carrot, pak choi and green pepper. Twenty-four mcr-1-positive isolates (23 Escherichia coli and one Enterobacter cloacae) were obtained, and E. coli isolates showed high genetic diversity. Different multilocus sequence type (MLST) isolates were also observed within the same sample. All 24 isolates showed multidrug resistance, and 14 carried blaCTX-M genes. Most isolates harbored similarly conjugative IncX4-type (∼33 kb) or IncI2-type (∼60 kb) mcr-1-bearing plasmids. The sequenced prevalent IncX4 plasmid and IncI2 plasmid from tomato were similar to the relevant plasmids from animals and clinical isolates in various countries. mcr-1-bearing IncHI2/ST3 plasmid highly similar to that carrying 14 resistance genes from E. coli of chicken was also observed. In conclusion, a high prevalence of mcr-1 in fresh vegetables was found in China, and the dissemination of mcr-1 was mediated by similar IncX4 or IncI2 plasmids. The plasmids from vegetables showed high similarity to plasmids from clinical isolates, indicating MCR-1-producers in ready-to-eat vegetables may pose a huge threat to public health and measures need to be taken to ensure food safety.


Assuntos
Antibacterianos/farmacologia , Colistina/farmacologia , Farmacorresistência Bacteriana , Enterobacter cloacae/isolamento & purificação , Escherichia coli/isolamento & purificação , Etanolaminofosfotransferase/genética , Verduras/microbiologia , China , Cidades , Enterobacter cloacae/classificação , Enterobacter cloacae/efeitos dos fármacos , Enterobacter cloacae/genética , Escherichia coli/classificação , Escherichia coli/efeitos dos fármacos , Escherichia coli/genética , Plasmídeos/análise
8.
Environ Pollut ; 243(Pt B): 1226-1234, 2018 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-30267919

RESUMO

An in-depth understanding of the impacts of surface roughness on road-deposited sediment (RDS) build-up and wash-off is essential for the estimation of surface runoff loads and design of RDS control measures. In this study, RDS build-up and wash-off dynamic processes were investigated on paired asphalt and concrete road surfaces with 35 days of continuous sampling during different natural rainfall events. Our results showed that RDS build-up loads and grain size composition were affected by surface roughness, while the impact of surface roughness on the length of the dynamic equilibrium period was not notable. Selective wash-off of RDS with different effects according to grain size are more likely to occur on asphalt road surfaces during rainfall-runoff, but the RDS wash-off percentage is not affected by surface roughness during snowmelt-runoff. Both total apparent depression depth and micro-depression structures influence RDS build-up and wash-off dynamics. These results imply that surface roughness has combined effects on RDS build-up and wash-off dynamics during the generation and control of urban diffuse pollution.


Assuntos
Monitoramento Ambiental , Sedimentos Geológicos/análise , Movimentos da Água , Cidades , Chuva , Poluentes Químicos da Água/análise
9.
J Environ Manage ; 228: 55-64, 2018 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-30212675

RESUMO

Small dams are widely constructed in urban rivers as landscape engineering practice, which increasingly cause eutrophication problems. Phosphorus retention in dammed rivers is a critical factor driving eutrophication, but it is little known in urban landscape river systems controlled by small dams. In this study, we investigated the retention of different phosphorus species along an urban landscape river with 30 rubber dams. We found that 42.5% (7.69 metric tons/yr) of the total phosphorus (TP) was trapped within dams, of which total particulate phosphorus (TPP) retention load accounted for 81.5%. From first river segment BBF-4# to the segments further downstream, the TP retention rate sharply decreased from 47.6% to -8.3%-9.2%, and phosphorus was mainly retained in the uppermost segment of the dammed river. The retention rate of dissolved reactive phosphorus (86.3%) was higher than that of TPP (40.3%) because of biological uptake. Further, with a retention rate of -11.3%, the dammed river was a net source of dissolved organic phosphorus. Different hydrological regimes, due to seasonal events and dam management, greatly influenced phosphorus retention within the dammed river, resulting in higher retention loads in the rainy season than in the dry season, and very low retention loads in the snowmelt season, with 1.48, 0.55 and 0.06 t/month, respectively. Our findings imply that management practices should focus on reducing the phosphorus export from the upper watershed and improving the hydrodynamic conditions of the dammed urban landscape river with regard to eutrophication.


Assuntos
Fósforo/análise , Rios/química , Eutrofização , Diques de Borracha , Estações do Ano , Poluentes Químicos da Água/análise
10.
Huan Jing Ke Xue ; 39(9): 4096-4104, 2018 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-30188050

RESUMO

Different combinations of low impact development (LID) technologies can be applied for control of urban non-point source pollution. There are currently few evaluations of urban non-point source pollution and pollution load reduction based on a combination of porous asphalt and bio-retention. Taking Shenzhen International Low Carbon City as an example, road-deposited sediments were collected prior to and after rainfall events. Runoff was monitored under six typical rainfall events, from porous asphalt and the inlet/outlet of bio-retention. Through analysis of changes in the process of "build-up-wash-off-transport" of pollutant loads, the average build-up of road-deposited sediments in the study area was found to be (15.80±3.79) g·m-2; the mass percentage of road-deposited sediments (size>250 µm) was approximately 65.14%. The average wash-off percentage of six different intensity rainfall events was 17.15%, and road-deposited sediments (size<105 µm) were carried by 62.71%-74.94%. The average pollution loads of surface runoff pollutants SS, TN, and TP were 2.02, 0.025, and 0.0013 g·m-2, respectively. The removal rates of SS, TN, and TP through porous asphalt under infiltration and filtration were 70.26%, 46.29%, and 19.27%, respectively. The secondary purification removal rates of runoff water in bio-retention were 85.25%, 20.22%, and 70.27%, respectively. Pollutant loads into Dingshan River totaled 0.08, 0.011, and 0.0003 g·m-2, representing 4.05%, 43.47%, and 24.39% of runoff. The combination thus had a significant effect on runoff purification. Through quantitative research on the formation of non-point source pollution, this paper provides a scientific basis for estimating pollution loads of urban non-point source pollution and evaluating the performance of LID projects. It makes suggestions for the popularization and application of LID and sponge city design in China.

11.
Vet Microbiol ; 222: 11-17, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30080665

RESUMO

H4 and H9 avian influenza viruses (AIVs) are two of the most prevalent influenza viruses worldwide. The co-existence of H4 and H9 viruses in multiple avian species provides an opportunity for the generation of novel reassortants and for viral evolution. The diversity of the biological characteristics of the reassortants enhances the potential threat to the poultry industry and to public health. To evaluate the reassortment of these viruses and the potential public risk of the reassortants, we co-infected chickens with H4N6 and H9N2 viruses derived from poultry and tested the replication and virulence of the reassortant viruses in mice. A high frequency of reassortment was detected in chickens after co-infection with these two viruses and nine reassortants of six genotypes were purified from the chicken samples. Two H9N2 reassortants containing the PA of the parent H4N6 virus showed higher virulence than the parent H9N2 virus, revealing the significant role of the H4N6 wt virus PA gene in viral reassortment. Analysis of the polymerase activity of the ribonucleoprotein (RNP) complex in vitro suggested that the PA of H4N6 wt origin enhanced polymerase activity. Our results indicate that co-infection of an avian individual with the H4N6 and H9N2 viruses leads to a high frequency of reassortment and generates some reassortants that have higher virulence than the wild-type viruses in mammals. These results highlight the potential public risk of the avian influenza reassortants and the importance of surveillance of the co-existence of the H4N6 and H9N2 viruses in avian species and other animals.


Assuntos
Galinhas/virologia , Coinfecção/veterinária , Vírus da Influenza A Subtipo H9N2/genética , Vírus da Influenza A/genética , Infecções por Orthomyxoviridae/veterinária , Vírus Reordenados/genética , Animais , Coinfecção/virologia , Evolução Molecular , Feminino , Humanos , Vírus da Influenza A Subtipo H9N2/fisiologia , Vírus da Influenza A/fisiologia , Influenza Aviária/epidemiologia , Influenza Aviária/virologia , Influenza Humana/epidemiologia , Influenza Humana/prevenção & controle , Influenza Humana/virologia , Camundongos , Camundongos Endogâmicos BALB C , Mutação , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/virologia , Filogenia , Saúde Pública , Vírus Reordenados/isolamento & purificação , Vírus Reordenados/patogenicidade , Ribonucleoproteínas/genética , Virulência , Replicação Viral
12.
Chemosphere ; 211: 557-565, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30092536

RESUMO

Understanding pollutant transport process and source apportionment is critical to urban stormwater pollution mitigation. Previous studies have investigated transport and sources of road deposited sediments (RDS) and sewer sediments individually, and most of these studies focused on stormwater pollution in combined sewer systems. However, studies about pollutant transport and source apportionment of the entire urban non-point source pollution process in separate sewer systems are lacking. This study analyzed particle size distribution and chemical pollutants in five media during the entire pollutant process including RDS, roof runoff, road runoff, sewer sediments, and sewer runoff. The outcomes found that mass percentage of fine particles became greater during pollutant transport in stormwater runoff. According to transport characteristics, particles were grouped into three types: particles <20 µm, 20-105 µm, and >105 µm. Particles <20 µm had the highest mobility capacity and particles >105 µm had the lowest mobility capacity, while mobility capacity of particles 20-105 µm was uncertain. Pollutant concentrations in road runoff were significantly influenced by rainfall intensity and pollutant concentrations in sewer runoff could become lower during rainy seasons ignoring rainfall intensity. RDS was the main contributor of heavy metals while organic matter and nutrients were primarily contributed by sewer sediments. Roof runoff, road runoff and sewer sediments contributed 5.35%, 69.24% and 25.41% particles to urban receiving water, respectively. Based on the outcomes, several suggestions were given for stormwater management.


Assuntos
Monitoramento Ambiental/métodos , Poluição Ambiental/análise , Poluição Difusa/análise , Esgotos/química
13.
Environ Sci Pollut Res Int ; 25(21): 21070-21085, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29767311

RESUMO

Uncertainty analysis is an important prerequisite for model application. However, the existing phosphorus (P) loss indexes or indicators were rarely evaluated. This study applied generalized likelihood uncertainty estimation (GLUE) method to assess the uncertainty of parameters and modeling outputs of a non-point source (NPS) P indicator constructed in R language. And the influences of subjective choices of likelihood formulation and acceptability threshold of GLUE on model outputs were also detected. The results indicated the following. (1) Parameters RegR2, RegSDR2, PlossDPfer, PlossDPman, DPDR, and DPR were highly sensitive to overall TP simulation and their value ranges could be reduced by GLUE. (2) Nash efficiency likelihood (L1) seemed to present better ability in accentuating high likelihood value simulations than the exponential function (L2) did. (3) The combined likelihood integrating the criteria of multiple outputs acted better than single likelihood in model uncertainty assessment in terms of reducing the uncertainty band widths and assuring the fitting goodness of whole model outputs. (4) A value of 0.55 appeared to be a modest choice of threshold value to balance the interests between high modeling efficiency and high bracketing efficiency. Results of this study could provide (1) an option to conduct NPS modeling under one single computer platform, (2) important references to the parameter setting for NPS model development in similar regions, (3) useful suggestions for the application of GLUE method in studies with different emphases according to research interests, and (4) important insights into the watershed P management in similar regions.


Assuntos
Modelos Teóricos , Fósforo/análise , Poluição da Água/análise , China , Funções Verossimilhança , Incerteza
14.
Environ Sci Pollut Res Int ; 25(7): 6969-6979, 2018 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-29273986

RESUMO

Quantifying road-deposited sediment (RDS) wash-off is critical in estimating pollutant load and for supporting the designs of urban storm water low-impact development (LID) best management practices (BMPs). The objective of this study was to identify a simple and effective small-scale wash-off load estimation and prediction method suitable for BMP engineering. The reliabilities, complexities, and applicabilities of four prediction methods (i.e., the event mean concentration (EMC) equation method, the exponential equation method, and the RDS mass difference before and after rainfall event method, and the RDS index model) were tested for three sites (i.e., a newly built area, and built-up area, and conservation area) during five natural rainfall events. Taking the calculations by the EMC method as standard results revealed the following. (1) The degree of agreement of the methods with the standard results in descending order was exponential equation method > RDS index model > RDS mass difference. (2) The degree of complexity of the studied methods in descending order was exponential equation method > the EMC equation method > the RDS index model > the RDS mass difference. (3) When considering the applicability of the models in terms of LID-BMP engineering, the RDS index model could be considered optimal for supporting the design of urban storm water BMPs.


Assuntos
Monitoramento Ambiental/métodos , Modelos Teóricos , Material Particulado/análise , Chuva , Movimentos da Água , Poluentes Químicos da Água/análise , China , Cidades , Propriedades de Superfície
15.
Sci Total Environ ; 613-614: 1130-1139, 2018 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-28954374

RESUMO

Intense Low-Impact Development (LID) construction in China could lead to increasingly severe stormwater and receiving water pollution due to the lack of appropriate regulation for mitigating pollution from LID construction. Samples of road-deposited sediments (RDS) were collected from 50 study sites at seven LID construction stages and four road hierarchies to analyze the pollution process and determine the size of the region influenced by LID construction. Six heavy metals were analyzed, and the RDS index model was adopted to estimate the potential heavy metal load washed off by stormwater runoff. Analysis of variance revealed that the excavation and gravel filling of rain gardens and excavation of porous pavements were critical LID construction stages that contributed the largest masses of RDS per unit area to road surfaces. Although the concentration of heavy metals at LID construction sites was lower than at sites without LID construction, the load of heavy metals washed off from LID construction was much higher. In addition, the sizes of regions influenced by accumulated RDS from LID construction descended in the following order: arterial road (600-775m)>collector road (150-200m)>access road (100-150m)>laneway (20-30m). According to the characteristics of LID construction at the study sites, the potential total solid loads in stormwater throughout China were estimated to reach 36,694t by 2020 and 146,777t by 2030. According to the results of analysis, several recommendations are provided for designing LID construction regulations to mitigate stormwater pollution.

16.
Environ Sci Pollut Res Int ; 24(35): 27201-27214, 2017 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-28965271

RESUMO

China is undergoing a rapid transition from a rural to an urban society. This societal change is a consequence of a national drive toward economic prosperity. However, accelerated urban development resulting from rapid population migration from rural to urban lands has led to high levels of untreated sewage entering aquatic ecosystems directly. Consequently, many of these regions have been identified as hot spots of riverine nitrogen (N) pollution because of the increasing level of urban point-source discharge. In order to address this concern, we assessed effects of urban development on ammonia-nitrogen (AN) loads using a panel data regression model. The model, expressed as an exponential function of anthropogenic N inputs multiplied by a power function of streamflow, was applied to 20 subwatersheds of the Huai River Basin for the years 2003-2010. The results indicated that this model can account for 81% of the variation in annual AN fluxes over space and time. Application of this model to three scenarios of urban development and sewage treatment (termed urbanization priority, sustainable development, and environmental priority) suggests that future N pollution will inevitably deteriorate if current urban environmental management and investment are not significantly improved. Stronger support for environmental management is very critical to alleviate N pollution and improve water quality. More effort should focus on improving sewage treatment and the N removal rate of the current sewage system in light of the increasing degree of urbanization.


Assuntos
Amônia/análise , Migração Humana , Nitrogênio/análise , Rios/química , Urbanização , Poluentes Químicos da Água/análise , China , Monitoramento Ambiental , Modelos Teóricos , População Rural , População Urbana , Qualidade da Água
17.
Artigo em Inglês | MEDLINE | ID: mdl-28788078

RESUMO

Particle grain size is an important indicator for the variability in physical characteristics and pollutants composition of road-deposited sediments (RDS). Quantitative assessment of the grain-size variability in RDS amount, metal concentration, metal load and GSFLoad is essential to elimination of the uncertainty it causes in estimation of RDS emission load and formulation of control strategies. In this study, grain-size variability was explored and quantified using the coefficient of variation (Cv) of the particle size compositions, metal concentrations, metal loads, and GSFLoad values in RDS. Several trends in grain-size variability of RDS were identified: (i) the medium class (105-450 µm) variability in terms of particle size composition, metal loads, and GSFLoad values in RDS was smaller than the fine (<105 µm) and coarse (450-2000 µm) class; (ii) The grain-size variability in terms of metal concentrations increased as the particle size increased, while the metal concentrations decreased; (iii) When compared to the Lorenz coefficient (Lc), the Cv was similarly effective at describing the grain-size variability, whereas it is simpler to calculate because it did not require the data to be pre-processed. The results of this study will facilitate identification of the uncertainty in modelling RDS caused by grain-size class variability.


Assuntos
Monitoramento Ambiental , Metais/análise , Tamanho da Partícula , Poluentes do Solo/análise , Emissões de Veículos/análise , Pequim , Cidades , Veículos Automotores , População Rural
18.
Environ Pollut ; 223: 676-684, 2017 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28196722

RESUMO

Inter-basin water transfer projects might cause complex hydro-chemical and biological variation in the receiving aquatic ecosystems. Whether machine learning models can be used to predict changes in phytoplankton community composition caused by water transfer projects have rarely been studied. In the present study, we used machine learning models to predict the total algal cell densities and changes in phytoplankton community composition in Miyun reservoir caused by the middle route of the South-to-North Water Transfer Project (SNWTP). The model performances of four machine learning models, including regression trees (RT), random forest (RF), support vector machine (SVM), and artificial neural network (ANN) were evaluated and the best model was selected for further prediction. The results showed that the predictive accuracies (Pearson's correlation coefficient) of the models were RF (0.974), ANN (0.951), SVM (0.860), and RT (0.817) in the training step and RF (0.806), ANN (0.734), SVM (0.730), and RT (0.692) in the testing step. Therefore, the RF model was the best method for estimating total algal cell densities. Furthermore, the predicted accuracies of the RF model for dominant phytoplankton phyla (Cyanophyta, Chlorophyta, and Bacillariophyta) in Miyun reservoir ranged from 0.824 to 0.869 in the testing step. The predicted proportions with water transfer of the different phytoplankton phyla ranged from -8.88% to 9.93%, and the predicted dominant phyla with water transfer in each season remained unchanged compared to the phytoplankton succession without water transfer. The results of the present study provide a useful tool for predicting the changes in phytoplankton community caused by water transfer. The method is transferrable to other locations via establishment of models with relevant data to a particular area. Our findings help better understanding the possible changes in aquatic ecosystems influenced by inter-basin water transfer.


Assuntos
Ecossistema , Monitoramento Ambiental , Aprendizado de Máquina , Fitoplâncton/isolamento & purificação , Microbiologia da Água , Recursos Hídricos , China , Clorófitas/citologia , Cianobactérias/citologia , Cianobactérias/isolamento & purificação , Diatomáceas/citologia , Diatomáceas/isolamento & purificação , Fitoplâncton/citologia , Estações do Ano , Máquina de Vetores de Suporte
19.
Environ Sci Pollut Res Int ; 23(20): 21008-21019, 2016 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-27488715

RESUMO

Eutrophication is one of the greatest threats to global freshwater ecosystems. The phytoplankton responses to nutrient inputs vary in different water bodies, so it is particularly important to determine the nutrient thresholds and synergistic interactions between nutrients in different freshwater ecosystems. Field sampling and bioassay experiments were conducted to determine the thresholds of soluble reactive phosphorus (SRP), nitrate-nitrogen (NO3-N), and ammonium-nitrogen (NH4-N) in Miyun Reservoir. A separate nutrient addition bioassay was designed to assess the synergistic interactions between these nutrients. Chlorophyll a (Chl a) concentrations were used to estimate phytoplankton biomass. The results showed the following: (1) nutrient threshold bioassay indicated that eutrophication thresholds of SRP, NO3-N, and NH4-N should be targeted at below 0.04 mg P L-1, 0.5 mg N L-1, and 0.3 mg N L-1, respectively, to limit the growth of phytoplankton. (2) The stimulatory effect of "NH4-N plus P" on phytoplankton biomass was greater than "NO3-N plus P" at the same N concentration, and "NH4-N plus NO3-N" did not show such associated stimulatory effect as "NH4-N plus P" or "NO3-N plus P". (3) The average concentrations of total phosphorus (TP), NO3-N, and NH4-N in Miyun Reservior were 0.017 mg P L-1, 0.620 mg N L-1, and 0.143 mg N L-1, respectively. The reservoir-wide average Chl a is below 20 µg L-1 on an annual basis. (4) Ammonium was an important factor for the growth of phytoplankton and inputs of both NH4-N and NO3-N should be reduced to control bloom formation. Our findings imply that although P load reduction is important, appropriate reductions of all forms of N in watershed is recommended in the nutrient management strategy for Miyun Reservoir.


Assuntos
Eutrofização , Nitrogênio/análise , Fósforo/análise , Poluentes Químicos da Água/análise , Compostos de Amônio/análise , Biomassa , Clorofila/análise , Clorofila A , Ecossistema , Água Doce , Nitratos/análise , Fitoplâncton/crescimento & desenvolvimento
20.
Environ Sci Pollut Res Int ; 23(18): 18512-23, 2016 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-27289374

RESUMO

Much attention had been paid to reducing external loading of nutrients to improve water quality, while internal loading from sediment, which has been largely neglected, is also an important source for water eutrophication. The internal load in deep lakes or reservoirs is not easy to be detected and be quantified. In this study, three different methods (mass balance method, Fick's law, and regression equation) were combined to calculate the gross or/and net P release from sediment using limited data. Our results indicated that (1) the methods of mass balance and regression equation give similar results of sediment P release rate, with values of 0.889 and 0.902 mg m(2) d(-1), respectively, while the result of Fick's law was much lower (0.400 mg m(2) d(-1)); (2) Hot periods of sediment releasing were suggested to occur from March to April and from August to September, which correspond to periods of high risks of algae blooms. The remaining months of the year were shown as net nutrient retention; (3) for the whole region, Baihedam and Chaohekuqu were identified as zones with a higher possibility to release P from sediment. (4) P loading to the Miyun Reservoir was greater in the inflow than in the outflow, suggesting a portion of the inflow P load was retained in the water or sediment; hence, release of sediment P may continue to be a major source of phosphorus in the future.


Assuntos
Sedimentos Geológicos/química , Lagos/química , Qualidade da Água , China , Eutrofização
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