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261.
262.
Rahim Aguejdad Thomas Houet Laurence Hubert-Moy 《Environmental Modeling and Assessment》2017,22(6):591-606
Using land use and cover change (LUCC) models for the urban growth planning, environmental assessment, and decision-making needs the establishment of an appropriate level of confidence in their performance. The objective of this research is to explore the importance of using multiple assessment techniques in order to fairly evaluate the performance of land use models. An application is conducted by using the Land Change Modeler for Ecological Sustainability (LCM) which is an empirical and transition potential model. LCM is applied to model the agricultural to developed areas transition in Rennes metropolitan area (France). The land demand is estimated using the Markov Chain model; whereas, the transition potential map is implemented using the Multi-Layer Perceptron Neural Network (MLP) method based on historical changes and driving variables. The model performance is assessed based on a variety of the most commonly used validation techniques. At the study area level, the correctness and disagreement analysis shows that LCM performs better at predicting the amount than the allocation of developed areas. Additionally, landscape metrics reveal that LCM tends to predict a fragmented urban form, which seems evident because of the large number of the individual urban patches. At the municipality level, the error budget analysis shows that the model performance, which varies highly between different subareas, needs to be improved. Moreover, the cross-tabulation between the transition potential map and both the observed and the predicted agricultural to developed areas transitions reveals that the order of the transition potential values does not perfectly fit the observed change; whereas, the predicted change is not solely limited to areas with high potential. 相似文献
263.
Nilufar Islam Rehan Sadiq Manuel J. Rodriguez Christelle Legay 《Environmental monitoring and assessment》2016,188(5):304
Inactivating pathogens is essential to eradicate waterborne diseases. However, disinfection forms undesirable disinfection by-products (DBPs) in the presence of natural organic matter. Many regulations and guidelines exist to limit DBP exposure for eliminating possible health impacts such as bladder cancer, reproductive effects, and child development effects. In this paper, an index named non-compliance potential (NCP) index is proposed to evaluate regulatory violations by DBPs. The index can serve to evaluate water quality in distribution networks using the Bayesian Belief Network (BBN). BBN is a graphical model to represent contributing variables and their probabilistic relationships. Total trihalomethanes (TTHM), haloacetic acids (HAA5), and free residual chlorine (FRC) are selected as the variables to predict the NCP index. A methodology has been proposed to implement the index using either monitored data, empirical model results (e.g., multiple linear regression), and disinfectant kinetics through EPANET simulations. The index’s usefulness is demonstrated through two case studies on municipal distribution systems using both full-scale monitoring and modeled data. The proposed approach can be implemented for data-sparse conditions, making it especially useful for smaller municipal drinking water systems. 相似文献
264.
The poor operational status of some wastewater treatment plants often result in the discharge of inadequately treated effluent into receiving surface waters. This is of significant public health concern as there are many informal settlement dwellers (ISDs) that rely on these surface waters for their domestic use. This study investigated the treatment efficiency of two independent wastewater treatment plants (WWTPs) in Durban, South Africa and determined the impact of treated effluent discharge on the physicochemical and microbial quality of the receiving water bodies over a 6-month period. Presumptive Escherichia coli isolates were identified using biochemical tests and detection of the mdh gene via PCR. Six major virulence genes namely eae, hly, fliC, stx1, stx2, and rfbE were also detected via PCR while antibiotic resistance profiles of the isolates were determined using Kirby-Bauer disc diffusion assay. The physicochemical parameters of the wastewater samples ranged variously between 9 and 313.33 mg/L, 1.52 and 76.43 NTUs, and 6.30 and 7.87 for COD, turbidity, and pH respectively, while the E. coli counts ranged between 0 and 31.2?×?103 CFU/ml. Of the 200 selected E. coli isolates, the hly gene was found in 28 %, fliC in 20 %, stx2 in 17 %, eae in 14 %, with stx1 and rfbE in only 4 % of the isolates. Notable resistance was observed toward trimethoprim (97 %), tetracycline (56 %), and ampicillin (52.5 %). These results further highlight the poor operational status of these WWTPs and outline the need for improved water quality monitoring and enforcement of stringent guidelines. 相似文献
265.
266.
Jarmo Poikolainen Juha Piispanen Jouni Karhu Reijo Seppänen Eero Kubin 《Environmental monitoring and assessment》2014,186(7):4299-4307
This study measured heavy metal and nutrient concentrations of two feather mosses during the periods of dry storage. Samples (Hylocomium splendens, Pleurozium schreberi) were collected in the nationwide moss surveys carried out on the permanent sample plots of the 8th Finnish National Forest Inventory in 1985–86, 1990, 1995 and 2000. A small amount of each moss sample was analyzed soon after collection, and the remainder was dried and stored at the Paljakka environmental specimen bank (ESB). The 108 stored samples from 27 plots were reanalyzed in 2008. Concentrations of heavy metals (Cd, Cr, Cu, Fe, Ni, Pb, Zn) and nutrients (Ca, K, Mg, P) were determined and compared for each survey year. Overall, Fe, Pb and Cr concentrations decreased, and Cu concentrations increased significantly during storage. The greatest decrease was observed in samples from plots where their initial concentrations were the highest. Changes in the concentrations of Cd, Ni and Zn were less pronounced. The loss of heavy metals is likely due to drying when cell membranes rupture and some of the surface material is lost. K, P and, to some extent, Mg concentrations increased during storage, whereas Ca did not change significantly. Nutrient increase is probably due to their movement from older to younger growths during the initial phase of drying. Ca is mostly bound to cell walls and is not easily released. Results emphasize the importance of establishing the intended use of a stored moss prior to sampling, in order to select and optimize an appropriate storage technique. 相似文献
267.
Ilijević K Gržetić I Živadinov I Popović A 《Environmental monitoring and assessment》2012,184(5):2805-2828
Seasonal spatial and temporal changes of selected eco-chemical parameters in section of the Danube River flowing through Serbia
were analyzed. Data for electrical conductivity (EC), dry and suspended matter, residue on ignition, chemical oxygen demand
(COD), biochemical oxygen demand (BOD-5), ultraviolet extinction, dissolved oxygen (DO), oxygen saturation, pH, nitrates,
total phosphorus, and nitrogen were collected between 1992 and 2006. The use of monthly medians combined with linear regression
and two-sided t test has been proven to be the best approach for resolving trends from natural variability of investigated parameters and
for determining trend significance. Patterns of temporal changes between different months were examined. It was also determined
that spatial trends of some parameters oscillate in predictable manner, increasing in one part of the year and declining in
the other. Regression slope coefficients, an excellent indicator for determining when the water quality is changing the most
along the course of the Danube, reach their maximum during summer for temperature (t), electric conductivity, nitrates, and total N, while in the same season suspended matter, COD, BOD-5, DO, and oxygen saturation
coefficients reach their minimum. Correlations for used data sets of selected parameters were analyzed for better understanding
of their behavior and mutual relations. It was observed that as Danube flows through Serbia, its general eco-chemical status
either stagnates or improves, but the rate of river self-purification often depends on the season of the year. 相似文献
268.
Fish scales as indicators of wastewater toxicity from an international water channel Tung Dhab drain
The effect of wastewater exposure on scales and chromatophores of freshwater fish Channa punctatus was studied using wastewater dilutions (60–100%) from an international water channel Tung Dhab drain at an interval of 15
and 30 days. The exposed fish showed significant alterations such as uprooted and damaged lepidonts and dispersal of chromatophores.
These observations strongly suggest that fish scales can be successfully employed as indicators of wastewater pollution. 相似文献
269.
In 1998, the Agrio and Guadiamar rivers underwent an enormous environmental disaster caused by the rupture of the Aznalcóllar
tailings dam and the release of 6 hm3 of pyrite sludge and acidic water. Both rivers run over recent alluvial materials which form a small-sized aquifer which
is however important because underground water feeds the flow of the rivers. This work analyzes the state of groundwater 10 years
after the spill. Before the dam failure, this aquifer was already contaminated in the zone nearest to the mine, to which the
impact of the spill was added. Contamination levels in the alluvial aquifer of the Agrio River have decreased remarkably.
However, they are still important, with acidic pH values and high concentrations of toxic elements (maximum values of 16 mg/L
of Zn and 15 mg/L of Al). There are also important levels of contamination in the Guadiamar alluvial area closest to the mine,
as well as in specific zones located further south. The concentration of toxic elements is mainly controlled by pH. The evolution
of contaminant levels show a sharp decrease after the first years following the spill, followed by a subsequent stabilization.
It is necessary to take measures for the recovery of the aquifer because, otherwise, groundwater will continue contributing
contaminants into the Agrio and Guadiamar rivers. 相似文献
270.
Ghumman AR Ahmad MM Hashmi HN Kamal MA 《Environmental monitoring and assessment》2012,184(5):3153-3163
Hill torrents cause a lot of environmental and property damage in Pakistan every year. Proper assessment of direct runoff in the form of hill torrents is essential for protection of environment, property, and human life. In this paper, direct surface runoff hydrograph (DSRH) was derived for a large catchment using the geomorphologic instantaneous unit hydrograph concept. The catchment with hill torrent flows in semi-arid region of Pakistan was selected for this study. It was divided into series of linear cascades and hydrologic parameters required for Nash's conceptual model, and were estimated using geomorphology of the basin. Geomorphologic parameters were derived from satellite images of the basin and ERDAS and ArcGIS were used for data processing. Computer program was developed to systematically estimate the dynamic velocity, its related parameters by optimization and thereby to simulate the DSRH. The data regarding rainfall-runoff and satellite images were collected from Punjab Irrigation and Power Department, Pakistan. Model calibration and validation was made for 15 rainfall-runoff events. Ten events were used for calibration and five for validation. Model efficiency was found to be more than 90% and root mean square error to be about 5%. Impact of variation in model parameters (shape parameter and storage coefficient) on DSRH was investigated. For shape parameter, the number of linear cascades varied from 1 to 3 and it was found that the shaper parameter value of 3 produced the best DSRH. Various values of storage coefficient were used and it was observed that the value determined from geomorphology and the dynamic velocity produced the best results. 相似文献