RESUMEN
Decreasing levels of water quality and elevated concentrations of heavy metals in freshwaters can pose global challenges for drinking water sources. Multivariate statistical techniques have been applied on data matrices of water quality and heavy metals for keen characterization of their spatio-temporal variations, exploration of latent factors, and identification of pollution sources. Non-metric multidimensional scaling (nMDS), canonical correlation analysis (CCA), and structural equation modeling (SEM) were employed to process data matrices of the water quality and heavy metals with 14 parameters measured at 13 sampling sites in Dongjianghu Lake in March, June, August, and December 2016. The sampling sites were grouped into three clusters using the nMDS, suggesting that the increasing order of the water quality levels was approximately midstream < downstream < upstream and lake. The CCA of 14 parameters proved that the Escherichia coli, CODMn, TP, TN, TEMP, DO, and pH were the latent factors to distinguish the sampling sites, suggesting that the natural disturbances further influenced the lake and upstream, while the anthropogenic activities further influenced the midstream and downstream. The CCA of the heavy metals exhibited that the CODMn, F-, and E. coli were the latent factors of the Cu, Zn, and As, while the DO and TEMP were the latent factors of the Cd. This indicated that the Cu, As, and Zn were mainly associated with the anthropogenic activities, while the Cd was predominantly relative to the natural conditions. The SEM of the water quality and heavy metals showed that the weights of CODMn (28.64%), NH3-N (14.96%), BOD5 (14.32%), TN (12.88%), and TP (10.18%) were higher than those of the pH (8.37%), DO (7.73%), TEMP (2.58%), and E. coli (0.34%). This indicated that the former exhibited strong influences on the heavy metals than the latter. Moreover, the CODMn and BOD5 were the key factors of the heavy metals, which should be attributed to the no-point sources, especially the exploitation mining and mill tailings. The water quality assessment by the nMDS, CCA, and SEM can determine the status, trend corresponding to its standards, and trace latent factors and identify possible pollution sources. The study could provide a guide for water quality evaluation and pollution control.
Asunto(s)
Metales Pesados , Contaminantes Químicos del Agua , Monitoreo del Ambiente , Escherichia coli , Sedimentos Geológicos , Lagos , Análisis de Clases Latentes , Metales Pesados/análisis , Análisis Multivariante , Contaminantes Químicos del Agua/análisis , Calidad del AguaRESUMEN
Heavy metal pollution in lake systems has arisen plenty of threats for public health because of its high toxicity, persistence, and bioaccumulation. Whereas heavy metals are inextricably linked with bioavailability in pore water and overlying water. Lake Jiaogang is classified as an important water-carrying lake situated in the northern part of the Anhui Province China. In recent years, water quality in this lake declined due to increasing fishery aquaculture, livestock, and tourism. This study aims to bring insight into the interactions of heavy metal elements across sediment-water interface in Lake Jiaogang. Four representative regions were selected, more than ten heavy metals were chosen to quantify by the Community Bureau of Reference, diffusive gradient in thin-film (DGT), and high-resolution pore water equilibrators. The results showed that most heavy metals corresponded with the reducible fraction, acid-soluble fraction, and oxidizable fraction in the Eastern area (sample 3#) and aquaculture area (sample 4#) were higher than that of emergent plant area (sample 1#), and floating plant area (sample 2#). The average fluxes of heavy metals (except Ni and Zn in sample 3#, F value > 0 pg/cm2/d) in the four sampling sites were observed in the lower reaches (F value < 0 pg/cm2/d). The vertical distribution of heavy metals was extracted by DGT, such as As (exclude 2#), Co, Fe, Mn, and Zn (contain 4#) showed an increased content with increasing depth in the four sampling sites. In the pore and overlying water, concentrations of heavy metals from the sample 3# and 4# were higher than those of sample 1# and 2#. Heavy metal pollution in anthropogenic activity areas was higher than those in areas with ecological vegetation, and risk control in this area should be strengthened.
Asunto(s)
Metales Pesados , Contaminantes Químicos del Agua , China , Monitoreo del Ambiente , Sedimentos Geológicos , Lagos , Metales Pesados/análisis , Medición de Riesgo , Agua , Contaminantes Químicos del Agua/análisis , Calidad del AguaRESUMEN
UV-visible absorption spectroscopy coupled with principal component analysis (PCA) and hierarchical cluster analysis (HCA) was applied to characterize spectroscopic components, detect latent factors, and investigate spatial variations of dissolved organic matter (DOM) in a large-scale lake. Twelve surface water samples were collected from Dongjianghu Lake in China. DOM contained lignin and quinine moieties, carboxylic acid, microbial products, and aromatic and alkyl groups, which in the northern part of the lake was largely different from the southern part. Fifteen spectroscopic indices were deduced from the absorption spectra to indicate molecular weight or humification degree of DOM. The northern part of the lake presented the smaller molecular weight or the lower humification degree of DOM than the southern part. E2/4, E3/4, E2/3, and S2 were latent factors of characterizing the molecular weight of DOM, while E2/5, E3/5, E2/6, E4/5, E3/6, and A2/1 were latent factors of evaluating the humification degree of DOM. The UV-visible absorption spectroscopy combined with PCA and HCA may not only characterize DOM fractions of lakes, but may be transferred to other types of waterscape.
Asunto(s)
Monitoreo del Ambiente/métodos , Sustancias Húmicas/análisis , Lagos/química , Contaminantes del Agua/análisis , China , Peso Molecular , Análisis Multivariante , Compuestos Orgánicos/análisis , Análisis de Componente Principal , Espectrometría de Fluorescencia/métodos , Rayos UltravioletaRESUMEN
Eight typical sampling sites were chosen to investigate the phytoplankton community structure and to assess the eutrophication degree of Baiyangdian Lake in 2009. Our results showed that among the total 133 species identified, Cyanophyta, Chlorophyta, and Bacillariophyta dominated the phytoplankton community. In spring, Chlorophyta and Bacillariophyta were the dominant phyla, and the dominant species included Chlorella sp., Chroomonas acuta Uterm., and Microcystis incerta Lemm.; the density of the phytoplankton ranged from 496 × 10(4) to 6256 × 10(4) cells/L with an average of 2384 × 10(4) cells/L. However, Chlorophyta and Cyanophyta became the dominant phyla in summer, and the dominant species were Chlorella sp., Leptolyngbya valderiana Anagn., and Nephrocytium agardhianum Nageli.; the density of the phytoplankton varied from 318 × 10(4) to 4630 × 10(4) cells/L with an average of 1785 × 10(4) cells/L. The density of the phytoplankton has increased significantly compared to the previous investigations in 2005. The index of Carlson nutritional status (TSIM) and the dominant genus assessment indicated that the majority of Baiyangdian Lake was in eutrophic state.
Asunto(s)
Eutrofización , Fitoplancton , Humedales , Biodiversidad , China , Lagos , Fitoplancton/clasificaciónRESUMEN
Both AMBI and M-AMBI could effectively assess the benthic ecological status of estuaries and coastal systems with soft sediments, and show the response of benthic communities to human pressures and natural changes. To monitor the ecological status of Yangtze River Estuary, macroinvertebrate samples and environmental data were collected in April 2009. Results showed that the benthic habit of Yangtze River Estuary was disturbed to various degrees, especially in the watersheds of Hangzhou Bay, coastal areas of Zhoushan islands and in the inner part of Yangtze River Estuary, which was related to land resourced discharges, eutrophication and large amounts of coastal projects. No significant difference was found between the calculation results of AMBI and M-AMBI based on density and biomass, as indicated by one-way Analysis of Variance (ANOVA). Compared with AMBI, M-AMBI could be more effective to assess the ecological status of Yangtze River Estuary because M-AMBI matched the community structure and environmental variables better. Moreover, according to results of Pearson correlation and linear regression analysis, significant negative relationships were found between the eutrophication index both in the surface and bottom water layers and M-AMBI, but no significant relationship was found between the eutrophication index and AMBI. Therefore, M-AMBI could be more suitable in indicating the eutrophication stress of Yangtze River Estuary.
Asunto(s)
Ecosistema , Monitoreo del Ambiente , Invertebrados/crecimiento & desarrollo , Contaminantes Químicos del Agua/análisis , Animales , China , Estuarios , Eutrofización , Océanos y Mares , RíosRESUMEN
For full understanding of the bacterial community in the intertidal zones of Bohai Bay, China, we used pyrosequencing-based approach to analyze the 16S rRNA gene of bacteria in the sediments from the two typically intertidal zones - Qikou (Qi) and Gaoshaling (Ga). Results showed that, at a 0.03 distance, the sequences from the Qi sediment were assigned to 3252 operational taxonomic units (OTUs) which belong to 34 phyla, 69 classes and 119 genera, while the 3740 OTUs from the Ga sediment were affiliated with 33 phyla, 66 classes and 146 genera. Comparing the bacterial communities inhabiting in the two intertidal sediments, we observed significant difference in the dominant composition and distribution at phylum, class and genus levels. Canonical correspondence analysis (CCA) showed that the median grain size and DO were the most important factors regulating the bacterial abundance and diversity, while the other environmental factors have effects with different degree.
Asunto(s)
Bacterias/clasificación , Sedimentos Geológicos/microbiología , Microbiología del Agua , Bacterias/genética , Biodiversidad , China , ADN Bacteriano , Agua de Mar/microbiología , Análisis de Secuencia de ADNRESUMEN
It is important precondition to enact viable lake nutrients control standard for lake control and management. Now China is shortage of study on nutrients control standard considering of the regional and nutrient difference. In this paper, five-step method for nutrient control standard is built following the principle of commonality, possibility and practicability. The monitoring data from 1994 to 2005 were divided into six groups according to chlorophyll-a content. Every group is a representative of one grade, oligotrophication, mesotrophication, low eutrophication, middle eutrophication, high eutrophication and extro-eutrophication respectively. In every group, total nitrogen, total phosphate and transparency were analyzed by frequency method, and 50% frequent values were applied. Results came out that the nutrient control standard for Taihu lake is as follows: Chlorophyll-a content were < 1.6 mg x m(-3), 1.6-10 mg x m(-3), 10-26 mg x m(-3), 26-64 mg x m(-3), 64-160 mg x m(-3), > 160 mg x m(-3). Transparence is 0.7 m, 0.4 m, 0.3 m, 0.3 m, 0.3 m and 0.25 m. Total phosphate is 0.03 mg x L(-1), 0.04 mg x L(-1), 0.06 mg x L(-1), 0.09 mg x L(-1), 0.12 mg x L(-1), 0.18 mg x L(-1). Total Nitrogen is 0.6 mg x L(-1), 1.7 mg x L(-1), 2.2 mg x L(-1), 3.2 mg x L(-1), 4.2 mg x L(-1), 6.2 mg x L(-1). This study would offer the experience for enacting nutrient control standard in the other lake region of China, also would offer the theoretic support for eutrophication control in China.