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1.
Water quality of rivers is strongly influenced by landscape characteristics of their watershed, including land use /cover types, and their spatial configuration. This research evaluates the effects of land cover changes on the water quality of the Zayandehroud River, which is the most important river in the center of Iran. The main goal of this study was to quantify the change in rangelands, forests, and bare lands in the Zayandehroud river basin, which suffered intense human interference, in a period of 11 years (1997–2008), and to evaluate how landscape patterns (including the number of patches, edge density, percentage of rangelands, forests, and bare lands) influence on the 14 water quality indices (including BOD5, EC, NO3, P, and TDS) measured in 10 stations along the river. Results showed that from 1997 to 2008, bare lands increased from 5.8 to 20 %, while rangelands decreased from 70 to 55 % in the whole basin. The results indicated that water quality was significantly correlated with both the proportions and configuration of rangeland and bare land areas. The total edge (TE) of rangeland area had positive effects on water quality, especially on BOD5 and EC. Percentage of landscape (PLAND) and largest patch index (LPI) metrics of rangeland had positive effect on decreasing nutrient (NO3, PO4). The results showed that water quality was more likely degraded when there was high edge density (ED) of bare lands. Results of this study also revealed that degradation of rangeland lead to the degradation of water quality. Finding of this study highlights the importance of rangeland conservation in water quality management at landscape scale.  相似文献   

2.
The analytical method of S-metolachlor residue and its degradation in cotton and soil in trial field were investigated. S-metolachlor EC (96% w/w) was applied as pre-emergence at dosages of 1,500 and 2,250 ml ha(-1) 3 days after sowing of the cottonseeds in the field. The soil and the plant samples were collected at different intervals and the residues of S-metolachlor were analyzed by GC-ECD. The results showed that the degradation of S-metolachlor in cotton leaves in Beijing and Nanjing coincides with C = 0.1113e(-0.1050t) and C = 0.1177e(-0.1580t), respectively; the half-lives were about 6.6 and 4.4 days. The degradation of S-metolachlor in soil in Beijing and Nanjing coincides with C = 1.0621e(-0.0475) (t), and C = 0.9212e(-0.0548) (t), respectively; the half-lives were about 14.6 and 12.6 days,. At harvest time, the S-metolachlor in cotton seeds and soil samples were detected by GC-ECD and confirmed by GC/MS. The results showed that the residues in cottonseeds were lower than the USA EPA's maximum residue limit of 0.1 mg kg(-1) in cottonseed. It could be considered as safe to human beings and environment.  相似文献   

3.
Land use/land cover (LULC) has a profound impact on economy, society and environment, especially in rapid developing areas. Rapid and prompt monitoring and predicting of LULC’s change are crucial and significant. Currently, integration of Geographical Information System (GIS) and Remote Sensing (RS) methods is one of the most important methods for detecting LULC’s change, which includes image processing (such as geometrical-rectifying, supervised-classification, etc.), change detection (post-classification), GIS-based spatial analysis, Markov chain and a Cellular Automata (CA) models, etc. The core corridor of Pearl River Delta was selected for studying LULC’s change in this paper by using the above methods for the reason that the area contributed 78.31% (1998)–81.4% (2003) of Gross Domestic Product (GDP) to the whole Pearl River Delta (PRD). The temporal and spatial LULC’s changes from 1998 to 2003 were detected by RS data. At the same time, urban expansion levels in the next 5 and 10 years were predicted temporally and spatially by using Markov chain and a simple Cellular Automata model respectively. Finally, urban expansion and farmland loss were discussed against the background of China’s urban expansion and cropland loss during 1990–2000. The result showed: (1) the rate of urban expansion was up to 8.91% during 1998–2003 from 169,078.32 to 184,146.48 ha; (2) the rate of farmland loss was 5.94% from 312,069.06 to 293,539.95 ha; (3) a lot of farmland converted to urban or development area, and more forest and grass field converted to farmland accordingly; (4) the spatial predicting result of urban expansion showed that urban area was enlarged ulteriorly compared with the previous results, and the directions of expansion is along the existing urban area and transportation lines.  相似文献   

4.
Assessment of the water quality can enhance understanding of the hydrochemical system and effective management of water resources. To this end, an assessment of water quality was conducted in the Messolonghi-Etoliko and Neochorio region. Surface water and groundwater samples have been collected, treated, and subjected to chemical analysis for the following parameters: Br?, Cl?, F?, NO??, NO??, PO?3?, SO?2?, Li?, Na?, NH??, K?, Mg2?, Ca2?, HCO??, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn. A characterization has been carried out using the Piper trilinear diagram, the United States Salinity Laboratory diagram, and the Wilcox diagram. Assessment of water samples by comparing the recorded values of the water quality parameters with the parametric values established by European Community indicated that the 50% of the surface water samples and 67% of the groundwater samples in the study area are chemically suitable for drinking use. Assessment of water samples from calculation of chemical indexes like sodium adsorption ratio, sodium percentage, residual sodium carbonate, and by comparing the values of the water quality parameters with the water quality limits established by Canadian Council of Minister of the Environment indicated that 75% of the surface water and that all the groundwater samples are chemically suitable for irrigation use.  相似文献   

5.
The region between 10 degrees N and 10 degrees S latitude was known to be congenial for distribution of Pleuromamma species. Diel and ontogenetic migrations were observed for Pleuromamma xiphias. Multivariate analyses such as factor analysis on species' abundance and predictive step-up multiple regression models of water quality parameters: temperature, salinity, dissolved oxygen and their first order interaction effects on Pleuromamma species' abundance, were carried out in the regions, off 10 degrees N, 10 degrees N to 10 degrees S, 10 degrees S to 30 degrees S, along the Somali Coast (38 degrees S-40 degrees S) and a fifth region along the western boundary of the above four regions. Relation between Pleuromamma species' abundance and the water quality parameters showed a decreasing trend in the variability explained (VE) from region 1 (VE = 55.19%) to region 4 (VE = 31.15%) in the models, indicating that the influence of other ecological factors was of higher significance in the south than in the north, with a north south gradient. Indices of diversity (Shannon-Weaver) and evenness (Heips) were calculated and lognormal distributions fitted for these indices were found to be a good fit (p < 0.05). The five regions were compared, based on critical ratio of the diversity index. Shannon-Weaver diversity showed higher values during night collections than day collections, justifying the tendency for diurnal variations. Diversity and dominance were highly (r = 0.95) correlated. A multilinkage cluster analysis by group averaging method for the species, based on the standardised values of log(10) (X + 1) transformed species' abundance, showed that Pleuromamma indica, Pleuromamma gracilis and Pleuromamma abdominalis were not segregated in any of the five regions. Bray and Curtis (1957) coefficient of similarity for the species in the five regions combined together, showed 50% similarity for the cluster containing circum-global species, Pleuromamma piseki, P. gracilis, P. abdominalis and P. borealis. The species, P. indica and P. xiphias entered this cluster at 22% similarity level. Multivariate factor analysis by row normalisation (for species) and column normalisation (for stations), using varimax rotation to simple structure for unique grouping of species as well as stations, carried out in the five regions, showed that the maximum number of species' clusters were obtained in region 2, indicating a higher variability in the ecological conditions in this region than in the other four regions. The significance of the factor model and the differential factor groups of species were also determined in the studied regions. On a broader scale, based on the ecological aspect, the first four regions could be reduced to two regions, viz, region 1 including the north off 10 degrees N, Central Indian Ocean and the area of subtropical convergence, and region 2 consisting exclusively of the equatorial region between 10 degrees N and 10 degrees S based on distribution of Pleuromamma species. The plot of the species abundance with respect to latitude also showed such a demarcation.  相似文献   

6.
In order to characterize the contamination of the Swarzedzkie Lake and generate elemental distribution patterns 18 elements have been determined in samples of water, taken just above the bottom sediments. Analyses were carried out using two instrumental techniques - ICP-OES and ICP-MS. Two main sources of contamination were identified - diffuse pollution from agriculture and stormwater from the town. Three separate groups of elements were distinguished using cluster analysis and two groups using principal component analysis. These three groups are characterized as geogenic elements (Ag, As, Mg and Sb), elements supplied by the agricultural catchment (Ca, Mn, Sr, Na, K and Al) and elements originated from the urban contamination (Ni, Cr, Cu, Fe, V, Ba, Zn and Pb). PCA differentiated the above group of urban elements from the rest, originated from diffuse sources, with exception of alluminium, which was situated between two distinguished groups.  相似文献   

7.
The variations of Cl???, F???, and Fe?+?+? in the underground water during pre- and post-monsoon periods for 2003 have been examined, for two places in Unnao district, by argentrometric titration method (Sodic Land Reclamation Project Uttar Pradesh 1998) and atomic absorption spectrometry (Sodic Land Reclamation Project Uttar Pradesh 1998). The concentration of these ions falls outside the limits prescribed by the World Health Organization (WHO 1984).  相似文献   

8.
The information on bacterial community composition (BCC) in Portuguese water bodies is very scarce. Cértima River (central western Portugal) is known to have high levels of pollution, namely organic. In the present work, the BCC from a set of 16 water samples collected from Cértima River Basin and its main tributaries was characterized using 16S rDNA–denaturing gradient gel electrophoresis, a culture-independent molecular approach. Molecular data were related to environmental parameters through multivariate analysis to investigate potential impact of water pollution along the river. Principal component analysis using environmental data showed a water quality gradient from more pristine waters (at the mountain tributaries) to waters with increasingly eutrophic potential (such as Fermentelos Lake). This gradient was mainly defined by factors such as organic and inorganic nutrient sources, electrical conductivity, hydrogen carbonate concentration, and pH. Molecular results showed variations in BCC along Cértima River Basin but in the main river section, a Bacteroidetes phylotype (Flavobacterium sp.) proved to be dominant throughout the river course. Multivariate analysis suggests that spatial variation of BCC along the Cértima River Basin depended mainly on parameters such as Chl a, total suspended solid (TSS), total organic carbon, electrical conductivity, and HCO _boxclose^-_{3}^{-} levels. Bacteroidetes phylotypes were all related to higher electrical conductivity and HCO3-_{3}^{-} levels although some of these were also correlated with high SO42-_{4}^{2-} and others with high soluble reactive phosphorus, nitrate, TN, and Kjeld-N levels. The Gammaproteobacteria occurrence was correlated with high SO42-_{4}^{2-} levels. One of the Betaproteobacteria phylotypes showed to correlate with low redox potential (Eh) and high temperature, pH, TSS, and Chl a levels while another one showed a negative correlation with Chl a values.  相似文献   

9.
Agroforesty systems, which are recommended as a management option to lower the shallow groundwater level and to reuse saline subsurface drainage waters from the tile-drained croplands in the drainage-impacted areas of Jan Joaquin Valley of California, have resulted in excessive boron buildup in the soil root zone. To assess the efficacy of the long-term impacts of soil boron buildup in agroforesty systems, a mathematical model was developed to simulate non-conservative boron transport. The developed dynamic two-dimensional finite element model simulates water flow and boron transport in saturated–unsaturated soil system, including boron sorption and boron uptake by root-water extraction processes. The simulation of two different observed field data sets by the developed model is satisfactory, with mean absolute error of 1.5 mg/L and relative error of 6.5%. Application of the model to three different soils shows that boron adsorption is higher in silt loam soil than that in sandy loam and clay loam soils. This result agrees with the laboratory experimental observations. The results of the sensitivity analysis indicate that boron uptake by root-water extraction process influences the boron concentration distribution along the root zone. Also, absorption coefficient and maximum adsorptive capacity of a soil for boron are found to be sensitive parameters.  相似文献   

10.
The availability of Landsat data allows improving the monitoring and assessment of large-scale areas with land cover changes in rapid developing regions. Thus, we pretend to show a combined methodology to assess land cover changes (LCCs) in the Hamoun Wetland region (Iran) over a period of 30-year (1987–2016) and to quantify seasonal and decadal landscape and land use variabilities. Using the pixel-based change detection (PBCD) and the post-classification comparison (PCC), four land cover classes were compared among spring, summer, and fall seasons. Our findings showed for the water class a higher correlation between spring and summer (R2?=?0.94) than fall and spring (R2?=?0.58) seasons. Before 2000, ~?50% of the total area was covered by bare soil and 40% by water. However, after 2000, more than 70% of wetland was transformed into bare soils. The results of the long-term monitoring period showed that fall season was the most representative time to show the inter-annual variability of LCCs monitoring and the least affected by seasonal-scale climatic variations. In the Hamoun Wetland region, land cover was highly controlled by changes in surface water, which in turn responded to both climatic and anthropogenic impacts. We were able to divide the water budget monitoring into three different ecological regimes: (1) a period of high water level, which sustained healthy extensive plant life, and approximately 40% of the total surface water was retained until the end of the hydrological year; (2) a period of drought during high evaporation rates was observed, and a mean wetland surface of about 85% was characterized by bare land; and (3) a recovery period in which water levels were overall rising, but they are not maintained from year to year. After a spring flood, in 2006 and 2013, grassland reached the highest extensions, covering till more than 20% of the region, and the dynamics of the ecosystem were affected by the differences in moisture. The Hamoun wetland region served as an important example and demonstration of the feedbacks between land cover and land uses, particularly as pertaining to water resources available to a rapidly expanding population.  相似文献   

11.
Physical and chemical parameters have been analyzed in water samples from a brackish water lagoon, Küçükçekmece, located on the western outskirts of Istanbul. Samples were collected every two months for a year from nine sampling stations. Of the parameters measured, temperature, pH, salinity, nitrate and phosphate showed changes when compared with the previously published data. The lagoon was found eutrophic as it was reported previously. Sulphate and COD levels were higher when compared with the standards established by the Turkish Water Pollution and Control Regulation. Additionally, concentrations of heavy metals (Cd, Co, Cr, Cu, Mn, Ni, Pb, Zn) in water and bottom sediments were measured and compared with the standards established by the Turkish Water Pollution and Control Regulation and with the previously published data. The results were analysed statistically with respect to location and any relationships between the concentration of the elements in corresponding water and sediment samples were examined. Principal Component Analysis of water samples allowed us to discriminate three areas affected mainly by heavy metal contamination, possibly due to industrial, commercial and/or urban activities. Generally, the concentrations of the heavy metals were higher at stations near the three estuaries, suggesting a direct influence of the three creeks on the pollution of the Küçükçekmece Lagoon. Although elevated levels of Cd were recorded in several water samples, it was not detected in sediment. On the other hand, a particularly high level of Cr pollution was recorded most of the water and sediment samples.  相似文献   

12.
13.
Six samples of the red seaweed Plocamium cartilagineum (two both from Helgoland/Germany, Ireland, and the Antarctic) were analyzed by stable isotope analysis. The bulk δ(13)C values (-31 to -38‰) confirmed that this seaweed was exceptionally highly depleted in (13)C. The δ(15)N values were in the reported range for algae, and a moderate correlation between (13)C and (15)N content was observed. These measurements indicated that the season had a higher impact on the δ(13)C values than the location. Compound specific carbon isotope analysis by gas chromatography coupled with isotope ratio mass spectrometry (GC-IRMS) was used to verify an even stronger depletion in (13)C in the halogenated natural product (HNP) MHC-1 isolated from the seaweed samples. The δ(13)C values of MHC-1 in the range -42 to -45‰ are the lightest determined to date for polyhalogenated compounds in the molecular mass range between 250 and 800 Da. MHC-1 was also isolated from two fish samples. The much higher (13)C content in MHC-1 from the fish samples (-35.6 to -39.2‰) indicated carbon isotope enrichment due to partial transformation. In processes such as the reductive debromination, the partial transformation is associated with an increase in the (13)C content in the remaining non-metabolized share of a compound. Stable isotope analysis may thus provide insights into the degree of transformation of HNPs in environmental samples.  相似文献   

14.
This study presents the usefulness of multivariate statistical techniques, such as correlation matrix, cluster analysis, and factor analysis, for the evaluation and interpretation of complex water quality data sets of Brahmani–Koel river along the Rourkela Industrial Complex, India, and the apportionment of pollution sources/factors. The correlation study suggests that dissolved heavy metals, biochemical oxygen demand (BOD), and chemical oxygen demand (COD) are contributed by anthropogenic sources. The results of R-mode factor analyses revealed that anthropogenic contributions are responsible for increase in metals of the river water, which is mainly responsible for contamination of the river. It also reflected that the level of pollution in the river was very high. The factor score plot and loading plot have been drawn, which indicate that the polluted stations are identified by the heavy metals. The relationships among the stations are highlighted by cluster analysis, represented in dendograms to categorize different levels of contamination. An attempt has been made to study the degree of contamination of the river waters by using a tool like enrichment ratio (ER). The ER for heavy metal concentrations concluded that metals like Ni, Co, Cr, and Fe are showing high enrichment with respect to global background and metal ions like Fe, Mn, Cu, and Zn show high enrichment with respect to local background.  相似文献   

15.
As part of a regional study by the Atlantic Slope Consortium (ASC) to develop ecological and socioeconomic indicators of aquatic ecosystem condition, we developed and tested a protocol for rapidly assessing condition of the stream, wetland, and riparian components of freshwater aquatic ecosystems. Aspects of hydrology, vegetation, in-stream and wetland characteristics, and on-site stressors were measured in the field. The resulting metrics were used to develop an index of overall condition, termed the Stream–Wetland–Riparian (SWR) Index. Values of this Index were compared to existing biotic indices and chemical measures, and to a Landscape Index created using satellite-based land cover data and a geographic information system (GIS). Comparisons were made at several levels of spatial aggregation and resolution, from site to small watershed. The SWR Index and associated Landscape Indices were shown to correlate highly with biological indicators of stream condition at the site level and for small contributing areas. The landscape patterns prevalent throughout the entire watershed do not necessarily match the patterns found adjacent to the stream network. We suggest a top-down approach that managers can use to sequentially apply these methods, to first prioritize watersheds based on a relative condition measure provided by the Landscape Index, and then assess condition and diagnose stressors of aquatic resources at the subwatershed and site level.  相似文献   

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