Source control, mitigation

All efforts to prevent or correct LAQ problems should include an effort to identify and control pollutant sources. Source control is generally the most cost effective approach to mitigating LAQ problems in which point sources of contaminants can be identified. In the case of a strong source, source control may be the only solution that will work. The following are categories and examples of source control ... 

To maintain acceptable indoor air quality, the concentration of pollutants known to degrade indoor air quality and affect human health must be controlled. If the origin of the contaminant is known, it is more effective to exercise source control over any mitigation strategy. If the origin of the contaminants is not known, building ventilation and air cleaning and filtration are the two most commonly used processes to dilute or remove all types of contaminants from the indoor air and maintain acceptable indoor environmental conditions. 

Skiba U., Fowler D., and Smith K. A. (1997) Nitric oxide emissions from agricultural soils in temperate and tropical climates sources, controls and mitigation options. Nutr. Cycl. Agroecosyst. 48, 139-153. 

Lake Tahoe Atmospheric pollution stress. Low drainage ratio = atmosphere important nitrogen source. Tertiary sewage treatment limited success because sensitivity to nitrogen rather than phosphorus. Mitigation via nonpoint-source controls but atmospheric sources difficult to control = further degradation likely. 

Requirements for the availability of the electrical power sources should be stated for all operational states. These include off-site sources on-site generators (diesels and gas turbines, including associated fuel reserves) batteries and associated control protective, distribution and switching devices. The operability requirements should be such that sufficient power will be available to supply all safety related equipment necessary for safe shutdown of the plant, and for the mitigation and control of accident conditions. The operabihty requirements should determine the necessary power, redundancy of supply lines, maximum permissible time delays and necessary duration of the emergency power supply. Equivalent requirements should be stated for other power sources (for example, the pneumatic power system). Particular care should be taken to ensure that electrical supplies remain adequate in shutdown operations, when many systems and components will be out of service for maintenance. 

Once the contaminant is identified, the troubleshooter must determine how the material entered the feedstock stream. Process controls must be identified and implemented to mitigate the contaminant source. 

Dilution is attributed to the large amounts of air that are entrained by the spray. As a result of air entrainment, dispersion behavior is altered for materials that exhibit negative buoyancy upon release. This is found to be effective in controlling flammability hazards that are located close to the release source. If an explosion does occur, some of the energy will be absorbed in the breakup of the water spray droplets, thereby mitigating the explosions impact. 

Lake Washington Point-source (wastewater) nutrient stress. Mitigated via diversion of nutrient source downstream and chance biological control of phytoplankton. Rapid recovery. 

Lake Victoria Nonpoint-source stresses atmospheric and land use + internal nutrient loading controlled by wet-dry seasons. Low drainage ratio and high basin evapotranspiration = atmosphere important nutrient source. Further degradation likely because little mitigation. 

However, no published literature is available for heavy metal contents contributed by Jua Kali enterprises to the environment. The results of this study will help the National Environmental and Management Authority (NEMA) to set control measures to reduce pollution due to heavy metals released from such sites to water bodies. The mushrooming of Jua Kali metallurgical enterprises in major towns in Kenya is of a major concern as they do not observe or adhere to any strict control in their discharges through effluents, emissions (atmospheric) and solid waste disposal with respect to these metals.The purpose of this paper is to provide evidence that Jua Kali enterprises are a point source of heavy metals to the environment and therefore to recommend that mitigation measures should be put in place to control such pollution. 

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