The immobilization of soil contaminants (as one of the regulating ecosystem services) play</span><span style="font-family:"">s</span><span style="font-family:""> v...The immobilization of soil contaminants (as one of the regulating ecosystem services) play</span><span style="font-family:"">s</span><span style="font-family:""> very important role in environment. This regulatory service prevents groundwater contamination and the entry of contaminants into the food chain. The evaluation as well as the spatial distribution of this regulatory service is important for optimal land management in a specific region. Mapping system combining input layers</span><a name="OLE_LINK4"></a><span style="font-family:"">—</span><span></span><span style="font-family:"">slope topography, soil texture, climate region and land use (arable land, grassland)</span><span style="font-family:"">—</span><span style="font-family:"">were created for the analysis and the evaluation of potential of agroecosystem services. Filtering potential was calculated as accumulative function of soil sorption potential and potential of total content of inorganic pollutants evaluated according to The Slovak Soil Law. Calculated potential was categorised into five categories</span><span style="font-family:"">:</span><span style="font-family:""> very low, <span>low, medium, high and very high. Four model areas were selected for the analysis of pollutant filtration, as one of the regulatory agroecosystem services, which </span><span>are located in different climatic areas and different soil-ecological </span>conditions of Slovakia. The greatest differences among model regions can be found in relation to climatic conditions, land use and diversity of soil types. The warm, dry, and lowland region has a higher potential for pollutant filtration than the moderately warm or cold region. These results are consistent with the location of the soil, its properties, processes and functions within the concept of agro-ecosystem services.</span><span style="font-family:""> </span><span style="font-family:"">Based on the results, we can state that the high risk of inorganic contaminants is inherent in soils with low content and qualit展开更多
Effluents containing inorganic contaminants are releasing into the environment untreated despite being hazardous to man and environment. It is costly and unsustainable to use conventional methods to remove them from d...Effluents containing inorganic contaminants are releasing into the environment untreated despite being hazardous to man and environment. It is costly and unsustainable to use conventional methods to remove them from dilute aqueous solution. Adsorption involving granular activated carbon is an alternative method for treating such effluents. Granular activated carbon is structurally strong, highly resistance to attrition and wearing, large and can easily separate from the effluents. However, its surface is highly hydrophobic and has little surface charge thereby reducing its adsorption capacity for anion or cation. This article reviews surfactant modification of activated carbon to enhance its adsorption capacity for inorganic contaminants and key factors affecting the adsorption efficiency. They include initial concentration of contaminants, contact time, solution pH, solution temperature, adsorbent concentration, ionic strength, competing ions, type of surfactant, and surfactant concentration. The modified activated carbon usually shows maximum contaminant uptake around its critical micelles concentration. Surfactant modification reduces specific surface area and/or micro pore volume but hot NaOH or HNO3 treatment before surfactant modification minimises this drawbacks and increases the net surface charge. Overall, surfactant modification is a simple but efficient method of enhancing adsorption capacity of activated carbon for removing anion or cation from aqueous solution. However, a handful publication is available on the regeneration of the spent (saturated) surfactant modified activated carbons. Hence, more research efforts should be directed towards proper regenerating reagents and the optimise conditions such as contact time, concentration, and temperature for regenerating spent modified activated carbons.展开更多
Mineral–microbe interactions indirectly affect the geochemical fluxes and biogeochemical cycling of a large number of elements. Among them are toxic heavy metals (e.g. chromium), radionuclides (uranium and technetium...Mineral–microbe interactions indirectly affect the geochemical fluxes and biogeochemical cycling of a large number of elements. Among them are toxic heavy metals (e.g. chromium), radionuclides (uranium and technetium), and nitrogen. Heavy metals and radionuclides enter the environment from various sources such as mining activity, nuclear weapons production, metallurgical and chemical industries. Other metals, such as lead, arsenic, antimony, and cadmium, are enriched in certain environments by either natural or anthropogenic processes. Because many of these metals and radionuclides are carcinogens, their release into the environment and their fate cause intense scientific and public concern and are the subject of substantial research. Nitrate enters the environment largely through agricultural activity. Human health risks from nitrate uptake from drinking water supplies run the gamut from increased cancer risk to birth defects.展开更多
文摘The immobilization of soil contaminants (as one of the regulating ecosystem services) play</span><span style="font-family:"">s</span><span style="font-family:""> very important role in environment. This regulatory service prevents groundwater contamination and the entry of contaminants into the food chain. The evaluation as well as the spatial distribution of this regulatory service is important for optimal land management in a specific region. Mapping system combining input layers</span><a name="OLE_LINK4"></a><span style="font-family:"">—</span><span></span><span style="font-family:"">slope topography, soil texture, climate region and land use (arable land, grassland)</span><span style="font-family:"">—</span><span style="font-family:"">were created for the analysis and the evaluation of potential of agroecosystem services. Filtering potential was calculated as accumulative function of soil sorption potential and potential of total content of inorganic pollutants evaluated according to The Slovak Soil Law. Calculated potential was categorised into five categories</span><span style="font-family:"">:</span><span style="font-family:""> very low, <span>low, medium, high and very high. Four model areas were selected for the analysis of pollutant filtration, as one of the regulatory agroecosystem services, which </span><span>are located in different climatic areas and different soil-ecological </span>conditions of Slovakia. The greatest differences among model regions can be found in relation to climatic conditions, land use and diversity of soil types. The warm, dry, and lowland region has a higher potential for pollutant filtration than the moderately warm or cold region. These results are consistent with the location of the soil, its properties, processes and functions within the concept of agro-ecosystem services.</span><span style="font-family:""> </span><span style="font-family:"">Based on the results, we can state that the high risk of inorganic contaminants is inherent in soils with low content and qualit
文摘Effluents containing inorganic contaminants are releasing into the environment untreated despite being hazardous to man and environment. It is costly and unsustainable to use conventional methods to remove them from dilute aqueous solution. Adsorption involving granular activated carbon is an alternative method for treating such effluents. Granular activated carbon is structurally strong, highly resistance to attrition and wearing, large and can easily separate from the effluents. However, its surface is highly hydrophobic and has little surface charge thereby reducing its adsorption capacity for anion or cation. This article reviews surfactant modification of activated carbon to enhance its adsorption capacity for inorganic contaminants and key factors affecting the adsorption efficiency. They include initial concentration of contaminants, contact time, solution pH, solution temperature, adsorbent concentration, ionic strength, competing ions, type of surfactant, and surfactant concentration. The modified activated carbon usually shows maximum contaminant uptake around its critical micelles concentration. Surfactant modification reduces specific surface area and/or micro pore volume but hot NaOH or HNO3 treatment before surfactant modification minimises this drawbacks and increases the net surface charge. Overall, surfactant modification is a simple but efficient method of enhancing adsorption capacity of activated carbon for removing anion or cation from aqueous solution. However, a handful publication is available on the regeneration of the spent (saturated) surfactant modified activated carbons. Hence, more research efforts should be directed towards proper regenerating reagents and the optimise conditions such as contact time, concentration, and temperature for regenerating spent modified activated carbons.
文摘Mineral–microbe interactions indirectly affect the geochemical fluxes and biogeochemical cycling of a large number of elements. Among them are toxic heavy metals (e.g. chromium), radionuclides (uranium and technetium), and nitrogen. Heavy metals and radionuclides enter the environment from various sources such as mining activity, nuclear weapons production, metallurgical and chemical industries. Other metals, such as lead, arsenic, antimony, and cadmium, are enriched in certain environments by either natural or anthropogenic processes. Because many of these metals and radionuclides are carcinogens, their release into the environment and their fate cause intense scientific and public concern and are the subject of substantial research. Nitrate enters the environment largely through agricultural activity. Human health risks from nitrate uptake from drinking water supplies run the gamut from increased cancer risk to birth defects.
