Showing papers in "Environmental Earth Sciences in 2014"

Quantitative assessment of the contributions of climate change and human activities on global grassland degradation

Abstract: Grassland degradation received considerable concern because of its adverse impact on agronomic productivity and its capacity to provide goods and service. Climate change and human activities are commonly recognized as the two broad underlying drivers that lead to grassland degradation. In this study, a comprehensive method based on net primary productivity (NPP) was introduced to assess quantitatively the relative roles of climate change and human perturbations on worldwide grassland degradation from 2000 to 2010. The results revealed that at a global scale, 49.25 % of grassland ecosystems experienced degradation. Nearly 5 % of these grasslands experienced strong to extreme significant degradation. Climate change was the dominant cause that resulted in 45.51 % of degradation compared with 32.53 % caused by human activities. On the contrary, 39.40 % of grassland restoration was induced by human interferences, and 30.6 % was driven by climate change. The largest area of degradation and restoration both occurred in Asia. NPP losses ranged between 1.40 Tg C year−1 (in North America) and 13.61 Tg C year−1 (in Oceania) because of grassland degradation. Maximum NPP increase caused by restoration was 17.57 Tg C year−1 (in North America). Minimum NPP was estimated at 1.59 Tg C year−1 (in Europe). The roles of climate change and human activities on degradation and restoration were not consistent at continental level. Grassland ecosystems in the southern hemisphere were more vulnerable and sensitive to climate change. Therefore, climate change issues should be gradually integrated into future policies and plans for domestic grassland management and administration.

Estimating groundwater vulnerability to pollution using a modified DRASTIC model in the Kerman agricultural area, Iran

Abstract: Groundwater contamination from intensive fertilizer application affects conservation areas in a plain. The DRASTIC model can be applied in the evaluation of groundwater vulnerability to such pollution. The main purpose of using the DRASTIC model is to map groundwater susceptibility to pollution in different areas. However, this method has been used in various areas without modification, thereby disregarding the effects of pollution types and their characteristics. Thus, this technique must be standardized and be approved for applications in aquifers and particular types of pollution. In this study, the potential for the more accurate assessment of vulnerability to pollution is achieved by correcting the rates of the DRASTIC parameters. The new rates were calculated by identifying the relationships among the parameters with respect to the nitrate concentration in groundwater. The methodology was implemented in the Kerman plain in the southeastern region of Iran. The nitrate concentration in water from underground wells was tested and analyzed in 27 different locations. The measured nitrate concentrations were used to associate and correlate the pollution in the aquifer to the DRASTIC index. The Wilcoxon rank-sum nonparametric statistical test was applied to determine the relationship between the index and the measured pollution in Kerman plain. Also, the weights of the DRASTIC parameters were modified through the sensitivity analysis. Subsequently, the rates and weights were computed. The results of the study revealed that the modified DRASTIC model performs more efficiently than the traditional method for nonpoint source pollution, particularly in agricultural areas. The regression coefficients showed that the relationship between the vulnerability index and the nitrate concentration was 82 % after modification and 44 % before modification. This comparison indicated that the results of the modified DRASTIC of this region are better than those of the original method.

Groundwater quality assessment using entropy weighted water quality index (EWQI) in Lenjanat, Iran

Abstract: Human health is strongly influenced by water quality which is threatened by the poor quality of polluted groundwater. In this study, the groundwater quality and its suitability for drinking have been studied in Lenjanat plain aquifer, Iran. Fifty-nine groundwater samples from study area were evaluated based on WHO and Iranian standards for drinking water. Groundwater samples from selected monitoring sources were sampled seasonally during 2009–2010. Physical and chemical parameters of groundwater such as electrical conductivity, pH, total dissolved solids, Ca2+, Na+, K+, Mg2+, HCO3 −, SO4 2−, Cl−, F− and NO3 − were determined. During the water quality index calculating process, the weight of each parameter is usually given by experts according to their practical experience, which is subjective, so much useful and valuable information about the water quality gets lost. In order to avoid personal judgments about the weight of parameters, an information entropy method was used to assign weight to each parameter. Calculation of entropy weighted water quality index (EWQI) for groundwater samples showed that in the wet season, over 57 and 74 % of samples were in the range of “excellent” to “medium” quality based on WHO and Iranian standards, respectively. Due to groundwater quality reduction during dry season, 42 and 62 % of samples were in the range of “excellent” to “medium” quality based on WHO and Iranian standards, respectively. The results indicate that application of the EWQI is very useful to help the public and decision-makers will be able to identify and to evaluate groundwater quality in Lenjanat, Iran.

Flood susceptibility mapping using integrated bivariate and multivariate statistical models

Abstract: Flooding can have catastrophic effects on human lives and livelihoods and thus comprehensive flood management is needed. Such management requires information on the hydrologic, geotechnical, environmental, social, and economic aspects of flooding. The number of flood events that took place in Busan, South Korea, in 2009 exceeded the normal situation for that city. Mapping the susceptible areas helps us to understand flood trends and can aid in appropriate planning and flood prevention. In this study, a combination of bivariate probability analysis and multivariate logistic regression was used to produce flood susceptibility maps of Busan City. The main aim of this research was to overcome the weakness of logistic regression regarding bivariate probability capabilities. A flood inventory map with a total of 160 flood locations was extracted from various sources. Then, the flood inventory was randomly split into a testing dataset 70 % for training the models and the remaining 30 %, which was used for validation. Independent variables datasets included the rainfall, digital elevation model, slope, curvature, geology, green farmland, rivers, slope, soil drainage, soil effect, soil texture, stream power index, timber age, timber density, timber diameter, and timber type. The impact of each independent variable on flooding was evaluated by analyzing each independent variable with the dependent flood layer. The validation dataset, which was not used for model generation, was used to evaluate the flood susceptibility map using the prediction rate method. The results of the accuracy assessment showed a success rate of 92.7 % and a prediction rate of 82.3 %.

Occurrence and hydrogeochemistry of fluoride in alluvial aquifer of Weihe River, China

Abstract: Fluoride (F−) has significant impacts on human health. High fluoride groundwater (up to 1.90 mg/L) has been found in upper confined aquifer underlying the first terrace of Weihe River during a hydrogeological investigation for water supply in 2005. To reveal the occurrence and hydrogeochemistry of high F− groundwater, hydrogeochemical tools such as saturation index, ionic ratios and correlation analysis were used in this study. The study shows that the concentrations of most physiochemical parameters from phreatic water, influenced by intensive evaporation and anthropogenic activities such as unregulated sewage and excreta disposal and agricultural practices in the area, are higher than those of confined water. The F− concentration in phreatic water is within the acceptable limits set by China and the World Health Organization (WHO), while that of upper confined water shows a decreasing trend northwestward as the Weihe River approaches, with F− concentration in the first terrace beyond the national and the WHO standards. High F− groundwater is observed in alkaline environment associated with high Na+, pH, HCO3 − and low Ca2+ and Mg2+. The enrichment of F− is controlled by geologic and hydrogeological conditions, fluorine-bearing minerals presented in alluvial formations and their dissolution/precipitation under the alkaline environment along groundwater flow. Ion exchange, human activities and the mixing of different recharge waters may influence the enrichment of F− as well.

Groundwater quality assessment using the Water Quality Index and GIS in Saveh-Nobaran aquifer, Iran

Abstract: Groundwater is the most important natural resource used for drinking by many people around the world, especially in arid and semi-arid areas. The resource cannot be optimally used and sustained unless the quality of groundwater is assessed. Saveh-Nobaran aquifer in Iran is the most important groundwater aquiferous system in the region which is considered a major source for drinking and irrigation. The main objective of this study is to understand the groundwater quality status of Saveh-Nobaran aquifer, followed by attempts to investigate the spatial distribution of groundwater quality parameters to identify places with the best quality for drinking consume within the study area. For this purpose, a set of original data, as yet unpublished, is presented. This paper provides an important contribution for understanding relationship between land use and groundwater quality, and also groundwater depth and groundwater quality. This goal has been achieved with the combined use of the Water Quality Index (WQI) and a geographical information system (GIS). A total of 58 groundwater samples were collected and analyzed for major cations and anions. Spatial distribution maps of pH, TDS, EC, TH, Cl, HCO, SO4, Ca, Mg, Na and K have been created using the kriging method in a GIS environment. From the WQI assessment, over 65 % of the water samples fall within the ‘‘Poor’’, ‘‘Very poor’’ and “unsuitable for drinking” categories, suggesting that groundwater from the center and north-east of the Saveh-Nobaran aquifer is unsuitable for drinking purposes. This research and its results have shown the great combination use of GIS and WQI in assessing groundwater quality. Having a clear view of the geographic areas of groundwater quality, decision makers can plan better for the operation and maintenance of groundwater resources.

Potential ecological risk assessment of heavy metal contamination in sediment and water body around Dhaka export processing zone, Bangladesh

Abstract: Sediments and surface water contamination by the industrial effluents containing heavy metals is the most detrimental environmental impact. Therefore, the present work attempts to determine the status of eight heavy metal distribution in sediments and water samples, and their ecological risks’ assessment in the studied area. The distribution pattern of heavy metals in the water and sediment follows the sequences: Zn > Cu > Pb > Cr > Mn > Ni > As > Cd and Mn > Zn > Cr > Pb > Cu > Ni > As > Cd, respectively. Gross water pollution is observed at different sampling points of Dhalai Beel and Bangshi River. The comparison of sedimentary mean metal concentrations with several environmental contamination monitoring parameters, viz, threshold effect level (TEL), probable effect level (PEL), and severe effect lever (SEL) indicates that the metal levels are less than PEL except Cr. Moreover, the level of contamination degree (C d) and modified degree of contamination (mC d) indicates ‘low’ and ‘nil to low’ degree of contamination, respectively. Pollution load indices (PLI) of the studied area are lower than unity, indicates no pollution. Furthermore, a toxic-response factor is applied to assess the potential ecological risk of these heavy metals into the water body. The results of this study exhibit a low potential ecological risk of heavy metals. The Pearson’s correlation and cluster analysis are also performed to assess the heavy metal interactions in water and sediment samples.

Veterinary antibiotics contamination in water, sediment, and soil near a swine manure composting facility

Abstract: Antibiotics have been commonly used to prevent animal diseases and promote livestock productivity. However, its release into the surrounding environments leads to ecological disturbance and risks to human health. This study was conducted to monitor the occurrence and seasonal variations of antibiotics in water, sediment, and soil close to a swine manure composting facility, Korea. Various types of antibiotics such as tetracyclines (TCs) including tetracycline, chlortetracycline, and oxytetracycline, and sulfonamides (SAs) including sulfamethazine, sulfamethoxazole, and sulfathiazole were measured by the high-performance liquid chromatography-tandem mass spectrometry via a solid-phase extraction. In the results it was identified that the variations of measured antibiotics’ concentrations in water, sediment, and soil are depending on the season. The observed concentration levels of TCs were higher in winter than in summer season, indicating that the low temperature is a parameter attributing to interruption of its degradation in water, sediment, and soil. The concentration levels of SAs were significantly higher than those of TCs and in general, all measured antibiotics’ concentrations were also in general higher in Korea when compared to those in other countries. The long-term monitoring of antibiotics’ residues in aquatic and terrestrial environments is necessary.

Radar interferometry techniques for the study of ground subsidence phenomena: A review of practical issues through cases in Spain

Abstract: Subsidence related to multiple natural and human-induced processes affects an increasing number of areas worldwide. Although this phenomenon may involve surface deformation with 3D displacement components, negative vertical movement, either progressive or episodic, tends to dominate. Over the last decades, differential SAR interferometry (DInSAR) has become a very useful remote sensing tool for accurately measuring the spatial and temporal evolution of surface displacements over broad areas. This work discusses the main advantages and limitations of addressing active subsidence phenomena by means of DInSAR techniques from an end-user point of view. Special attention is paid to the spatial and temporal resolution, the precision of the measurements, and the usefulness of the data. The presented analysis is focused on DInSAR results exploitation of various ground subsidence phenomena (groundwater withdrawal, soil compaction, mining subsidence, evaporite dissolution subsidence, and volcanic deformation) with different displacement patterns in a selection of subsidence areas in Spain. Finally, a cost comparative study is performed for the different techniques applied.

GIS-based Evaluation of Water Quality Index of groundwater resources around Tuticorin coastal city, south India

Abstract: Groundwater is a vital source of water for industrial, domestic and agricultural activities in Tuticorin city due to lack of surface water resources; groundwater quality and its suitability for drinking usage were evaluated. A total of 72 groundwater samples were collected from open wells and boreholes during pre and post-monsoon period. Samples were analyzed for physico-chemical properties, major cation and major anions in the laboratory using the standard methods given by the American Public Health Association. The geographic information system-based spatial distribution map of different major elements has been prepared using ArcGIS 9.2. These maps are classified as desirable, maximum permissible and the values that exceed maximum permissible limit are termed as not permissible prescribed by the WHO (2004). From the Piper plot, which gives the cation chemistry, the concentration of the alkalies (Na+ and K+) exceeds the alkaline earths (Ca2+ and Mg2+) and those of strong acids exceeds weak acids. In the case of anions, during the two periods strong acid shows dominance over weak acid and HCO3 − and Cl− have influences almost equal to Na+, which indicate the saltwater intrusion into the freshwater aquifer of the study area. A Canadian Council of Ministers for the Environment Water Quality Index (CCME WQI) map was also generated with the GIS technique to better understand the water portability over space. The categories of water quality evaluated by CCME WQI values of major part of the study area fall under fair category during PRM and good category during the POM period. The CCME WQI is a very useful and an efficient tool to summarize and to report on the monitoring data to the decision makers in order to understand the status of the groundwater quality. Finally, the study concludes that the groundwater quality is impaired by man-made activities, and proper management plan is necessary to protect valuable groundwater resources in Tuticorin city.

MSW landfill site selection by combining AHP with GIS for Konya, Turkey

Abstract: Landfill site selection is a critical issue in the urban planning process because of its enormous impact on the economy, ecology, and the environmental health of the region. Landfill site selection process aims to locate the areas that will minimize hazards to the environment and public health. Multi-criteria evaluation methods are often used for different site selection studies. The purpose of this study was to determine suitable landfill site selection by using the geographical information system and the analytic hierarchy process in the study area. The final index model was grouped into four categories as “low suitable”, “moderate”, “suitable” and “best suitable” with an equal interval classification method. As a result, 12.69 % of the study area was low suitable, 7.27 % was moderately suitable, 13.79 % was suitable, and 15.52 % was the best suitable for landfilling; 50.72 % of the study area is not suitable for a landfilling.

Suitability assessment of deep groundwater for drinking and irrigation use in the Djeffara aquifers (Northern Gabes, south-eastern Tunisia)

Abstract: The multilayered Djeffara aquifer system, south-eastern Tunisia, has been intensively used as a primary source to meet the growing needs of the various sectors (drinking, agricultural and industrial purposes). The analysis of groundwater chemical characteristics provides much important information useful in water resources management. Detailed knowledge of the geochemical evolution of groundwater and assessing the water quality status for special use are the main objective of any water monitoring study. An attempt has been made for the first time in this region to characterize aquifer behavior and appreciate the quality and/or the suitability of groundwater for drinking and irrigation purposes. In order to attend this objective, a total of 54 groundwater samples were collected and analyzed during January 2008 for the major cations (sodium, calcium, magnesium and potassium), anions (chloride, sulfate, bicarbonate), trace elements (boron, strontium and fluoride), and physicochemical parameters (temperature, pH, total dissolved salts and electrical conductivity). The evolution of chemical composition of groundwater from recharge areas to discharge areas is characterized by increasing sodium, chloride and sulfate contents as a result of leaching of evaporite rock. In this study, three distinct chemical trends in groundwater were identified. The major reactions responsible for the chemical evolution of groundwater in the investigated area fall into three categories: (1) calcite precipitation, (2) gypsum and halite dissolution, and (3) ion exchange. Based on the physicochemical analyses, irrigation quality parameters such as sodium absorption ratio (SAR), percentage of sodium, residual sodium carbonate, residual sodium bicarbonate, and permeability index (PI) were calculated. In addition, groundwater quality maps were elabortaed using the geographic information system to delineate spatial variation in physico-chemical characteristics of the groundwater samples. The integration of various dataset indicates that the groundwater of the Djeffara aquifers of the northern Gabes is generally very hard, brackish and high to very high saline and alkaline in nature. The water suitability for drinking and irrigation purposes was evaluated by comparing the values of different water quality parameters with World Health Organization (WHO) guideline values for drinking water. Piper trilinear diagram was constructed to identify groundwater groups where the relative major anionic and cationic concentrations are expressed in percentage of the milliequivalent per liter (meq/l), and it was demonstrated that the majority of the samples belongs to SO4–Cl–Ca–Na, Cl–SO4–Na–Ca and Na–Cl hydrochemical facies. As a whole, all the analyzed waters from this groundwater have revealed that this water is unsuitable for drinking purposes when comparing to the drinking water standards. Salinity, high electric conductivity, sodium adsorption ratio and sodium percentages indicate that most of the groundwater samples are inappropriate for irrigation. The SAR vary from medium (S2) to very high (S4) sodicity. Therefore, the water of the Djeffara aquifers of the northern Gabes is dominantly of the C4–S2 class representing 61.23 % of the total wells followed by C4–S3 and C4–S4 classes at 27.27 and 11.5 % of the wells, respectively. Based on the US Salinity Classification, most of the groundwater is unsuitable for irrigation due to its high salt content, unless certain measures for salinity control are undertaken.

Appraisal of land use/land cover of mangrove forest ecosystem using support vector machine

Abstract: Human activities in many parts of the world have greatly changed the natural land cover. This study has been conducted on Pichavaram forest, south east coast of India, famous for its unique mangrove bio-diversity. The main objectives of this study were focused on monitoring land cover changes particularly for the mangrove forest in the Pichavaram area using multi-temporal Landsat images captured in the 1991, 2000, and 2009. The land use/land cover (LULC) estimation was done by a unique hybrid classification approach consisting of unsupervised and support vector machine (SVM)-based supervised classification. Once the vegetation and non-vegetation classes were separated, training site-based classification technology i.e., SVM-based supervised classification technique was used. The agricultural area, forest/plantation, degraded mangrove and mangrove forest layers were separated from the vegetation layer. Mud flat, sand/beach, swamp, sea water/sea, aquaculture pond, and fallow land were separated from non-vegetation layer. Water logged areas were delineated from the area initially considered under swamp and sea water-drowned areas. In this study, the object-based post-classification comparison method was employed for detecting changes. In order to evaluate the performance, an accuracy assessment was carried out using the randomly stratified sampling method, assuring distribution in a rational pattern so that a specific number of observations were assigned to each category on the classified image. The Kappa accuracy of SVM classified image was highest (94.53 %) for the 2000 image and about 94.14 and 89.45 % for the 2009 and 1991 images, respectively. The results indicated that the increased anthropogenic activities in Pichavaram have caused an irreversible loss of forest vegetation. These findings can be used both as a strategic planning tool to address the broad-scale mangrove ecosystem conservation projects and also as a tactical guide to help managers in designing effective restoration measures.

The spatial distribution characteristics of soil salinity in coastal zone of the Yellow River Delta

Abstract: In coastal area, salinization is a common and serious problem for crop cultivation and ecological restoration of degraded wetlands. Therefore, the soil salinity has attracted increasing attention from farmers, government and environmental scientists. The factors controlling the soil salinity distribution have become a hot point in saline soil studies. In this study, statistics and geostatistics were used to explore the distribution of soil salinity in the Yellow River Delta (YRD) based on 150 soil samples that were collected in June 2010. Besides the experimental work, a geographical information system technique was adopted in this study. The results showed that the soil salinity ranged from 0.11 to 10.50 dS m−1 and the salinity in topsoil was higher than that in subsoil in the YRD, indicating that the salt in subsoil moved up and accumulated in topsoil as a function of evaporation. There was a significant difference among soil salinity spatial variances from different soil depths in the YRD. Generally, soil salinity of the topsoil was higher than that of the subsoil. Meanwhile, there were significant positive correlations in soil salinity between different soil depths. In addition, landforms, land uses, soil types and soil texture were important factors affecting soil salinity. The current distribution of soil salinity resulted from the comprehensive effects of anthropogenic activities and natural processes. The present study results suggest that the impacts of human activities were critical factors for salt redistribution in the coastal wetlands, which should be valuable for agricultural management and ecological restoration in the YRD.

Seawater intrusion and coastal aquifer management in China: a review

Abstract: Seawater intrusion has been an important topic in hydrogeology in China in recent decades. The rapid growth of the population and economy in the coastal regions has been consuming a tremendous amount of groundwater resources and has increased the extent of seawater intrusion. The spatial discrepancy of water resource distribution has caused the studies of seawater intrusion into China to mainly be concentrated on the area around the Bohai Sea in the northern part of China. The total area of seawater-intruded land due to excessive groundwater utilization in the area was estimated to be approximately 2,457 km2 in 2003. Great efforts have been made to mitigate the extent of seawater intrusion and to secure more freshwater resources, including building monitoring networks, subsurface barrier and groundwater reservoirs, and artificial infiltration facilities. Management projects over the years were evaluated to satisfy the objectives and to provide valuable experiences for future research and planning. It is expected that the coastal groundwater conditions of the northern region will improve through the development of a national water resource plan, such as the ongoing south-to-north water diversion project.

Assessment of soil salinization based on a low-cost method and its influencing factors in a semi-arid agricultural area, northwest China

Abstract: An investigation of soil salinization was carried out in the Nanshantaizi area (Northwest China) with WET Sensor. This device can measure such soil parameters as bulk soil electrical conductivity, water content, and the pore water electrical conductivity that are important for soil salinization assessments. A distribution map of soil salinization was produced, and the factors influencing soil salinization and its processes were discussed in detail. The study shows that moderately salinized to salt soils are mainly observed in the alluvial plain, where groundwater level is high and lateral recharge water contains high salinity. Nanshantaizi is covered by slightly salinized soils. The soil salinization distribution estimated by WET Sensor is generally consistent with the actual levels of salinization. Soil salinity in Nanshantaizi is mostly of natural origin and accumulated salts could leach to deeper soils or aquifers by water percolation during irrigation. Groundwater evaporation, groundwater level depth and quality of recharge water are important factors influencing soil salinization in the alluvial plain.

Time-series analysis of subsidence associated with rapid urbanization in Shanghai, China measured with SBAS InSAR method

Abstract: River delta plains (deltas) are susceptible to subsidence producing undesirable environmental impact and affecting dense population. The City of Shanghai, located in the easternmost of Yangtze Delta in China, is one of the most developed regions in China that experiences the greatest land subsidence. Excessive groundwater withdrawal is thought to be the primary cause of the land subsidence, but rapid urbanization and economic development, mass construction of skyscrapers, metro lines and highways are also contributing factors. In this paper, a spatial–temporal analysis of the land subsidence in Shanghai was performed with the help of the Small Baseline Subset Interferometric Synthetic Aperture Radar. Twenty l-band ALOS PALSAR images acquired during 2007–2010 were used to produce a linear deformation rate map and to derive time series of ground deformation. The results show homogeneous subsidence within the research area, but exceptionally rapid subsidence around skyscrapers, along metro lines, elevated roads and highways was also observed. Because groundwater exploitation and rapid urbanization responsible for much of the subsidence in the Shanghai region are expected to continue, future subsidence monitoring is warranted.

Composition of selected heavy metals in road dust from Kuala Lumpur city centre

Abstract: This study was carried out in order to determine the concentration of heavy metals, e.g., lead (Pb), cadmium (Cd), copper (Cu), zinc (Zn), iron (Fe), manganese (Mn), nickel (Ni) and chromium (Cr) in road dust in Kuala Lumpur’s city centre. Samples were collected from four sampling locations, each of which had four sampling points and three replications. Heavy metals from different fractions of particles separated by different diameter sizes: d Mn > Zn > Pb > Ni > Cr > Cd. The fact that Cd had the highest enrichment factor value (EF) for all particle sizes indicates that anthropogenic activities contributed to the presence of this metal. There was also a higher EF value for heavy metals in small particle (Fraction A), compared to Fraction B and C, which suggests that fine particles were being produced through anthropogenic activities. Cluster analysis and principal component analysis demonstrated the likelihood of the heavy metals detected in the road dust, originating from road traffic and industrial activities.

Standardized precipitation evaporation index (SPEI)-based drought assessment in semi-arid south Texas

Abstract: The coastal semi-arid region of south Texas is known for its erratic climate that fluctuates between long periods of drought and extremely wet hurricane-induced storms. The standard precipitation index (SPI) and the standard precipitation evaporation index (SPEI) were used in this study in conjunction with precipitation and temperature projections from two general circulation models (GCMs), namely, the National Center for Atmospheric Research (NCAR) Parallel Climate Model (PCM) and the UK Meteorological Office Hadley Centre model (HCM) for two emission scenarios—A1B (~720 ppm CO2 stabilization) and B1 (~550 ppm CO2 stabilization) at six major urban centers of south Texas spanning five climatic zones. Both the models predict a progressively increasing aridity of the region throughout the twenty-first century. The SPI exhibits greater variability in the available moisture during the first half of the twenty-first century while the SPEI depicts a downward trend caused by increasing temperature. However, droughts during the latter half of the twenty-first century are due to both increasing temperature and decreasing precipitation. These results suggest that droughts during the first half of the twenty-first century are likely caused by meteorological demands (temperature or potential evapotranspiration (PET) controlled), while those during the latter half are likely to be more critical as they curtail moisture supply to the region over large periods of time (precipitation and PET controlled). The drought effects are more pronounced for the A1B scenario than the B1 scenario and while spatial patterns are not always consistent, the effects are generally felt more strongly in the hinterlands than in coastal areas. The projected increased warming of the region, along with potential decreases in precipitation, points toward increased reliance on groundwater resources which are noted to be a buffer against droughts. However, there is a need for human adaptation to climate change, a greater commitment to groundwater conservation and development of large-scale regional aquifer storage and recovery (ASR) facilities that are capable of long-term storage in order to sustain groundwater availability. Groundwater resource managers and planners must confront the possibility of an increased potential for prolonged (multi-year) droughts and develop innovative strategies that effectively integrate water augmentation technologies and conservation-oriented policies to ensure the sustainability of aquifer resources well into the next century.

Effects of biochar, cow bone, and eggshell on Pb availability to maize in contaminated soil irrigated with saline water

Abstract: Toxicity of heavy metals adversely affects environment and human health. Organic materials derived from natural matters or wastes have been applied to soils to reduce the mobility of contaminants such as heavy metals. However, the application of cow bone powder (CB), biochar (BC), and eggshell powder (ES) is rarely investigated for the reduction of Pb bioavailability in soils irrigated with saline water. The objective of this study was to assess the effectiveness of CB, BC, and ES additions as immobilizing substances on Pb bioavailability in shooting range soil irrigated with deionized and saline water. Each additive of CB, BC, and ES at 5 % (w/w) was mixed with soils and then the deionized and saline water were irrigated for 21 days. With deionized water irrigation, the soils treated with CB, BC, and ES exhibited higher pH when compared with saline water irrigation. With saline water irrigation, the electrical conductivity, water-soluble anions, and cations were significantly increased in soils treated with CB, BC, and ES. The water-soluble Pb in soils treated with CB, BC, and ES was significantly decreased with saline water irrigation. On the other hand, the water-soluble Pb in soil treated with CB was increased with deionized water irrigation. Only BC with saline water irrigation decreased the Pb concentration in maize shoots.

Effects of salt solutions on the hydro-mechanical behavior of compacted GMZ01 Bentonite

Abstract: In this study, the effects of salinity of infiltrating solutions on the swelling strain, compressibility, and hydraulic conductivity of compacted GMZ01 Bentonite were investigated. After swelling under vertical load using either distilled water or NaCl solutions with concentrations of 0.1, 0.5 M, and 1 M, laboratory oedometer tests were conducted on the compacted GMZ01 Bentonite. Based on the oedometer test results, hydraulic conductivity was determined using the Casagrande’s method. Results show that the swelling strain of highly compacted GMZ01 Bentonite decreases as the concentration of NaCl solution increases. The compression index C c * increases and then turns to decrease with an increase in the vertical stress or a decrease in the void ratio for different solutions, and the C c * decreases as the concentration of NaCl solution increases. The secondary consolidation coefficient C α increases linearly with the increase of the compression index C c * . Furthermore, a bi-linear relationship between the swelling index C s * and the secondary consolidation coefficient C α can be characterized clearly. The hydraulic conductivity increases as the concentration of NaCl solution increases, however, this increase can be prevented if a high confining stress is applied.

Landslide susceptibility assessment using object mapping units, decision tree, and support vector machine models in the Three Gorges of China

Abstract: Due to the particular geographical location and complex geological conditions, the Three Gorges of China suffer from many landslide hazards that often result in tragic loss of life and economic devastation. To reduce the casualty and damages, an effective and accurate method of assessing landslide susceptibility is necessary. Object-based data mining methods were applied to a case study of landslide susceptibility assessment on the Guojiaba Town of the Three Gorges. The study area was partitioned into object mapping units derived from 30 m resolution Landsat TM images using multi-resolution segmentation algorithm based on the landslide factors of engineering rock group, homogeneity, and reservoir water level. Landslide locations were determined by interpretation of Landsat TM images and extensive field surveys. Eleven primary landslide-related factors were extracted from the topographic and geologic maps, and satellite images. Those factors were selected as independent variables using significance testing and correlation coefficient analysis, including slope, profile curvature, engineering rock group, slope structure, distance from faults, land cover, tasseled cap transformation wetness index, reservoir water level, homogeneity, and first and second principal components of the images. Decision tree and support vector machine (SVM) models with the optimal parameters were trained and then used to map landslide susceptibility, respectively. The analytical results were validated by comparing them with known landslides using the success rate and prediction rate curves and classification accuracy. The object-based SVM model has the highest correct rate of 89.36 % and a kappa coefficient of 0.8286 and outperforms the pixel-based SVM, object-based C5.0, and pixel-based SVM models.

Geospatial assessment of soil erosion vulnerability at watershed level in some sections of the Upper Subarnarekha river basin, Jharkhand, India

Abstract: Undulating landscapes of Chhotanagpur plateau of the Indian state of Jharkhand suffer from soil erosion vulnerability of varying degrees. An investigation was undertaken in some sections of the Upper Subarnarekha River Basin falling within this state. An empirical equation known as Universal Soil Loss Equation (USLE) was utilized for estimating the soil loss. Analysis of remote sensing satellite data, digital elevation model (DEM) and geographical information system (GIS)–based geospatial approach together with USLE led to the soil erosion assessment. Erosion vulnerability assessment was performed by analyzing raster grids of topography acquired from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global DEM data. LANDSAT TM and ETM+ satellite data of March 2001 and March 2011 were used for inferring the land use–land cover characteristics of the watershed for these years, respectively. USLE equation was computed within the GIS framework to derive annual soil erosion rates and also the areas with varying degrees of erosion vulnerability. Erosion vulnerability units thus identified covered five severity classes of erosion ranging from very low (0–5 ton ha−1 yr−1) to very severe (> 40 ton ha−1 yr−1). Results indicated an overall increase of erosion in the year 2011 as compared to the erosion computed for the year 2001. Maximum soil erosion rate during the year 2001 was found up to 40 ton ha−1 yr−1, whereas this went up to 49.80 ton ha−1 yr−1 for the year 2011. Factors for the increase in overall erosion could be variation in rainfall, decrease in vegetation or protective land covers and most important but not limited to the increase in built-up or impervious areas as well.

Effectiveness of zinc application to minimize cadmium toxicity and accumulation in wheat (Triticum aestivum L.)

Abstract: Cadmium (Cd) is a highly toxic heavy metal and its presence in soil is of great concern due to the danger of its entry into the food chain. Among many others, proper plant nutrition is an economic and practicable strategy for minimizing the damage to plants from Cd and to decrease Cd accumulation in edible plant parts. The study was carried out to compare the effectiveness of soil and foliar applications of zinc (Zn) to minimize Cd accumulation in wheat grains. The results revealed that the exposure of plants to Cd decreased plant growth and increased Cd concentration in the shoots and grains of wheat, when compared with unexposed plants. Foliar application of 0.3 % zinc sulfate solution effectively decreased Cd concentration in wheat grains. Foliar application of Zn at a suitable concentration can effectively ameliorate the adverse effects of Cd exposure and decrease the grain Cd concentration of wheat grown in Cd-contaminated soil.

Impacts of wave energy and littoral currents on shoreline erosion/accretion along the south-west coast of Kanyakumari, Tamil Nadu using DSAS and geospatial technology

Abstract: The present study investigates the impact of wave energy and littoral current on shorelines along the south-west coast of Kanyakumari, Tamil Nadu, India. The multi-temporal Landsat TM, ETM+ images acquired from 1999 to 2011 were used to demarcate the rate of shoreline shift using GIS-based Digital Shoreline Analysis System. The statistical analysis such as net shoreline movement and end point rate were determined from the multi-temporal shoreline layers. Moreover, the wave energy and seasonal littoral current velocity were calculated for each coastal zone using mathematical equations. The results reveal that the coastal zones, which include Kanyakumari, Kovalam, Manavalakurichi and Thengapattinam coasts, consisting of maximum wave energy along with high velocity of littoral current, have faced continuous erosion processes. The estimated wave energy along these zones ranges from 6.5 to 8.5 kJ/km2 and the observed current velocity varies from 0.22 to 0.32 m/s during south-west and north-east monsoons. The cumulative effect of these coastal processes in the study area leads to severe erosion that is estimated as 300.63, 69.92, 54.12 and 66.11 m, respectively. However, the coastal zones, namely Rajakkamangalam, Ganapathipuram, Muttam and Colachel, have experienced sediment deposits due to current movement during the north-east monsoon. However, the trend changes during the south-west monsoon as a result of sediment drift through backwash. The spatial variation of shoreline and its impact on wave energy and the littoral current have been mapped using the geo-spatial technology. This study envisages the impact of coastal processes on site-specific shorelines. Hence, the study will be effective for sustainable coastal zone management.

Heavy metals contamination in road dust in Delhi city, India

Abstract: Road dust samples were collected from four different areas having different landuse patterns: industrial, heavy traffic, residential and mixed use in Delhi city of India. The samples were analyzed for Ba, Co, Cr, Cu Fe, Mn, Ni, Pb and Zn by ICP-AES. Results indicate high levels of Co, Cr, Cu, Mn and Ni in samples collected from industrial area. Ba, Pb and Zn showed higher concentration levels in heavy traffic area while Fe did not show any discernible variation between the localities. The concentrations of Fe, Mn, Ba, Zn, Cr, Cu, Pb, Ni and Co showed a decreasing trend. The content of heavy metals was comparable to those in other cities in the world. A multivariate statistical approach which includes Pearson’s correlations and principal component analysis was used to identify the possible sources of metals in the road dust. Enrichment factors were estimated for further confirming the sources of contamination. Significant positively correlations between road dust metals Cu–Mn–Co–Cr–Ni suggest that major common source of origin is industrial activities. A meaningful correlation between Ba and Zn, and a moderate positive correlation between Pb and Ba indicate the influence of traffic activities. Enrichment factors calculation indicated that Pb, Cu, Cr and Zn are moderately enriched whereas Co, Ni and Mn are less enriched while Ba exhibited very low enrichment in the dust samples. The results indicate that industrial and vehicular traffic are the two major sources. Traffic appears to be responsible for the high levels of Zn, Cu and Ba. High concentration of Co, Cr, Cu and Mn may be due to industrial sources.

Recycling waste from natural stone processing plants to stabilise clayey soil

Abstract: For the countries with a developed stone industry the waste generated in the natural stone processing plants pose environmental and economic problems. The utilisation of stone waste in various areas is still under research. In addition, there are only a limited number of studies concerning the use of stone waste obtained from processing plants in the stabilisation of clayey soil. Furthermore, none of the studies in the literature investigated the effect of the characteristics of the stone on the stabilisation of the soil. This is the first study that compares the efficiency of the waste calcitic marble, dolomitic marble and granite powder as additives for the stabilisation of clayey soil. Artificial soil samples were prepared in the laboratory using bentonite and kaolinite. Natural stone waste powder was added to the soil samples at different percentages, and the index and compaction parameters of the stabilised soil were analysed. The results showed that the types of waste powder used in this study, like lime, could be used as stabilisers. As the percentage of additives increased, the plasticity index of the clayey soil decreased and the physical properties of the soil changed from clay to silt. In terms of compaction parameters, the use of all types of natural waste powder in the study resulted in a decrease in the optimum water content and an increase in the maximum dry unit weight. The lowest optimum water content and the highest maximum dry unit weight were obtained from the dolomitic marble powder.

Removal of cationic dye methylene blue (MB) from aqueous solution by ground raw and base modified pine cone powder

Abstract: The adsorption capacity of raw and sodium hydroxide-treated pine cone powder in the removal of methylene blue (MB) from aqueous solution was investigated in a batch system. It was found that the base modified pine cone exhibits large adsorption capacity compared with raw pine cone. The extent of adsorption capacity was increased with the increase in NaOH concentration. Overall, the extent of MB dye adsorption increased with increase in initial dye concentration, contact time, and solution pH but decreased with increase in salt concentration and temperature for both the systems. Surface characteristics of pine cone and base modified pine cone were investigated using Fourier transform infrared spectrophotometer and scanning electron microscope. Equilibrium data were best described by both Langmuir isotherm and Freundlich adsorption isotherm. The maximum monolayer adsorption capacity was found to be 129.87 mg g−1 at solution pH of 9.02 for an initial dye concentration of 10 ppm by raw pine cone. The base modified pine cone showed the higher monolayer adsorption capacity of 142.25 mg g−1 compared with raw pine cone biomass. The value of separation factor, R L, from Langmuir equation and Freundlich constant, n, both give an indication of favourable adsorption. The various kinetic models, such as pseudo-first-order model, pseudo-second-order model, intraparticle diffusion model, double-exponential model, and liquid film diffusion model, were used to describe the kinetic and mechanism of adsorption process. Overall, kinetic studies showed that the dye adsorption process followed pseudo-second-order kinetics based on other models. The different kinetic parameters, including rate constant, half-adsorption time and diffusion coefficient, were determined at different physicochemical conditions. A single-stage bath adsorber design for the MB adsorption onto pine cone and modified pine cone has been presented based on the Langmuir isotherm model equation. Thermodynamic parameters, such as standard Gibbs free energy (ΔG 0), standard enthalpy (ΔH 0) and standard entropy (ΔS 0), were also calculated.

Evaluating Boolean, AHP and WLC methods for the selection of waste landfill sites using GIS and satellite images

Abstract: The city of Saqqez has a population of 140,000 people, making it one of the largest cities in Iran. Population growth, consumerism, and change in eating habits, such as the increased use of packaged products, is causing the accumulation of waste in this city to increase. In this study, the selection of a waste landfill site for Saqqez focused on 13 layers of geography information that was used by the IDRISI and Arc GIS software. Different models of the analytic multi-criteria decision-making process, such as an analytical hierarchy process (AHP), weighted linear combination (WLC), and Boolean logic, were used to manage layers to establish specific databases for urban waste landfills. Satellite images (Landsat ETM+ and SPOT 5), proposed sites and a land use map of the study area were also used. The results of this study indicated that two methods (AHP and WLC) in the early stages had better decision-making powers for locating landfill sites when compared to Boolean logic. Overlapping and compounding the similarities between these models in Arc GIS software, a 74-ha site was found. This site will be able to accept 130 tons of waste per day for the next 20 years.

Spatial distribution and contamination assessment of heavy metals in surface soils of Hassi Messaoud, Algeria

Abstract: An increase in heavy metal pollution in the soils of Hassi Messaoud (Algeria) due to intense industrialization and urbanization has become a serious environmental problem. There are three large industrial complexes that have been established in the region of Hassi Messaoud for petroleum extraction field and refinery. The region hosts several industrial facilities which are the main sources for hazardous wastes. Surface soil samples from 58 sampling sites (systematically sampled; 1 × 1 km regular grid), including different functional areas in Hassi Messaoud, were collected and analyzed. The results showed that the average concentrations of Cu, Ni, Mn, Pb and Zn in soil of Hassi Messaoud were up to 13.17, 35.78, 121.21, 130.97 and 61.08 mg/kg, respectively. Ni concentrations were comparable to background values, while Cu, Mn, Pb and Zn concentrations were higher than their corresponding background values. Among the functional areas, the industrial regions displayed the highest metal concentrations, while the lowest concentrations occurred in rural soil. Principal component analysis coupled with cluster analysis showed that: (1) Pb and Zn had anthropogenic sources; and (2) Ni, Cu and Mn were associated with parent materials. Contaminations in soils were classified as geoaccumulation index and enrichment factor. Pollution index values of Cu, Ni, Mn, Pb and Zn varied in the range of 0.04–5.41, 0.46–2.49, 0.01–5.73, 0.62–152.9 and 0.09–53.01, with mean values of 1.32, 1.08, 1.26, 5.64 and 3.1, respectively. The integrated pollution index (IPI) of all the analyzed samples varied from 0.42 to 31.59, with a mean of 2.48, and more than 5.45 % of samples are extremely contaminated; 18.18 % are heavily contaminated; 60 % are moderately contaminated; and others are low contaminated. The spatial distribution of IPI showed that desert and rural areas displayed relatively lower heavy metal contamination in comparison with other areas.