For the last two decades the world has undergone a population explosion which has been accompanied by a speeding up of urbanization and land use for industrial and agricultural products. These involve a vast increase ...For the last two decades the world has undergone a population explosion which has been accompanied by a speeding up of urbanization and land use for industrial and agricultural products. These involve a vast increase in the discharge of pollutants into very different receiving water bodies, and have had adverse effects on the various components of the environment. For a long time, human has concerned a little of the natural environment. It is obvious that this variation in surface temperature of the earth increases the level of sea due to snowmelt. So climate change is manifested by many phenomena： floods, droughts, fires, tornadoes, cyclones, earthquakes, volcanic eruptions, diseases etc.. The statement today is dramatic. Entire regions were devastated and many rivers and lakes have become polluted around the world. Pollution has it nature which is hard to be absorbed. Where did the different pollutants come from？ What are the risks to the aquatic environment？ To prevent and combat the general decline of these ecosystems, it is important to distinguish and determine the effects of different sources of pollution and any changes that may suffer the physical environment. The climate depends primarily on changes in earth orbit parameters, which affect the solar radiation received by the earth surface. Therefore, human participates strongly to these changes, for example, pollution is the main reason to argue the greenhouse effect, an increase of anthropogenic carbon dioxide （CO2） into the atmosphere, which promotes global warming to the planet. These modifications are already applied in order to ensure durable development in water resources by controlling discharges into streams to preserve water resources for future generations and to ensure reconciliation between man-climate and environment.展开更多
In Mexico, hazardous and non-hazardous urban solid wastes are commonly disposed of in dumps. Inappropriate waste disposal makes solid waste disposal sites potential sources of pollution and health risks. The objective...In Mexico, hazardous and non-hazardous urban solid wastes are commonly disposed of in dumps. Inappropriate waste disposal makes solid waste disposal sites potential sources of pollution and health risks. The objective of the present study was to evaluate the impact of leachate from a dump on surface water systems. Physical, chemical, and bacteriological characteristics and the volume of leachate were measured. The site of study is located in Zinaprcuaro, Michoac^m, Mexico, and was chosen due to the water supplies were in line with the dump, thus conforming a system to test for movement of toxins. Leachate and water from three ponds located at different distances to the dump were sampled during three months of a year to measure physicochemical and bacteriological parameters, according to the standard methods of the American Public Health Association; the concentration of heavy metals was measured by atomic absorption spectrometry. Most characteristics exceed the maximum permissible limits established for the Mexican legislation regarding wastewater discharges and drinking water. Likewise, analysis of variance showed statistically significant differences between concentrations of pollutants in relation to the distance from the dump of sampled sites and with season of sampling, thus confirming the contamination of water by dump leachate.展开更多
Ten trace and heavy metals （Fe, Mn, Ni, Zn, Cu, Cd, As, Co, Cr and V） were analysed in sediments collected from nine stations at the Tema Port of Ghana, during the dry and wet seasons. Analysis of samples was done u...Ten trace and heavy metals （Fe, Mn, Ni, Zn, Cu, Cd, As, Co, Cr and V） were analysed in sediments collected from nine stations at the Tema Port of Ghana, during the dry and wet seasons. Analysis of samples was done using INAA （instrumental neutron activation analysis） for Mn, V, Cu, As and Cd, and AAS （atomic absorption spectrophotometry） for Fe, Cr, Zn, Ni and Co. The concentrations of metals in sediments followed the orders Fe 〉 V〉 Mn 〉 Cd 〉 Ni 〉 Zn 〉 Cu 〉As, for the dry season and Fe 〉 V 〉 Ni 〉 Cu 〉 Zn 〉 Mn 〉 Cd 〉As, for the wet season. Concentrations of Co and Cr were below detection limit, whiles Cu, Cd and Ni were found to be above the TELs （threshold effect levels） of NOAA＇s （National Oceanic and Atmospheric Administration＇s） SQuiRTs （screening quick reference tables） at most sites. Estimated enrichment factors for individual metals showed very high contamination of the port＇s sediments, with Cd occurring at all sites, and Cu, As, V and Ni occurring at some sites for both dry and wet seasons. Although sediments from the Tema Port were highly enriched with Cd, Cu, Ni and V above natural background levels, the overall PLI （pollution load index） per sampling station considering background values of the analysed elements indicated that metal pollution in the port＇s sediment is below 1, indicating relatively unpolluted sediment.展开更多
文摘For the last two decades the world has undergone a population explosion which has been accompanied by a speeding up of urbanization and land use for industrial and agricultural products. These involve a vast increase in the discharge of pollutants into very different receiving water bodies, and have had adverse effects on the various components of the environment. For a long time, human has concerned a little of the natural environment. It is obvious that this variation in surface temperature of the earth increases the level of sea due to snowmelt. So climate change is manifested by many phenomena： floods, droughts, fires, tornadoes, cyclones, earthquakes, volcanic eruptions, diseases etc.. The statement today is dramatic. Entire regions were devastated and many rivers and lakes have become polluted around the world. Pollution has it nature which is hard to be absorbed. Where did the different pollutants come from？ What are the risks to the aquatic environment？ To prevent and combat the general decline of these ecosystems, it is important to distinguish and determine the effects of different sources of pollution and any changes that may suffer the physical environment. The climate depends primarily on changes in earth orbit parameters, which affect the solar radiation received by the earth surface. Therefore, human participates strongly to these changes, for example, pollution is the main reason to argue the greenhouse effect, an increase of anthropogenic carbon dioxide （CO2） into the atmosphere, which promotes global warming to the planet. These modifications are already applied in order to ensure durable development in water resources by controlling discharges into streams to preserve water resources for future generations and to ensure reconciliation between man-climate and environment.
文摘In Mexico, hazardous and non-hazardous urban solid wastes are commonly disposed of in dumps. Inappropriate waste disposal makes solid waste disposal sites potential sources of pollution and health risks. The objective of the present study was to evaluate the impact of leachate from a dump on surface water systems. Physical, chemical, and bacteriological characteristics and the volume of leachate were measured. The site of study is located in Zinaprcuaro, Michoac^m, Mexico, and was chosen due to the water supplies were in line with the dump, thus conforming a system to test for movement of toxins. Leachate and water from three ponds located at different distances to the dump were sampled during three months of a year to measure physicochemical and bacteriological parameters, according to the standard methods of the American Public Health Association; the concentration of heavy metals was measured by atomic absorption spectrometry. Most characteristics exceed the maximum permissible limits established for the Mexican legislation regarding wastewater discharges and drinking water. Likewise, analysis of variance showed statistically significant differences between concentrations of pollutants in relation to the distance from the dump of sampled sites and with season of sampling, thus confirming the contamination of water by dump leachate.
文摘Ten trace and heavy metals （Fe, Mn, Ni, Zn, Cu, Cd, As, Co, Cr and V） were analysed in sediments collected from nine stations at the Tema Port of Ghana, during the dry and wet seasons. Analysis of samples was done using INAA （instrumental neutron activation analysis） for Mn, V, Cu, As and Cd, and AAS （atomic absorption spectrophotometry） for Fe, Cr, Zn, Ni and Co. The concentrations of metals in sediments followed the orders Fe 〉 V〉 Mn 〉 Cd 〉 Ni 〉 Zn 〉 Cu 〉As, for the dry season and Fe 〉 V 〉 Ni 〉 Cu 〉 Zn 〉 Mn 〉 Cd 〉As, for the wet season. Concentrations of Co and Cr were below detection limit, whiles Cu, Cd and Ni were found to be above the TELs （threshold effect levels） of NOAA＇s （National Oceanic and Atmospheric Administration＇s） SQuiRTs （screening quick reference tables） at most sites. Estimated enrichment factors for individual metals showed very high contamination of the port＇s sediments, with Cd occurring at all sites, and Cu, As, V and Ni occurring at some sites for both dry and wet seasons. Although sediments from the Tema Port were highly enriched with Cd, Cu, Ni and V above natural background levels, the overall PLI （pollution load index） per sampling station considering background values of the analysed elements indicated that metal pollution in the port＇s sediment is below 1, indicating relatively unpolluted sediment.
