Classifying Pollution Impacts

In assessing the significance of different types of pollution, it is useful to classify them in terms of their spatio-temporal impacts. The spatial dimension defines the extent of the ecosystem impacted (and therefore also the population affected) by the pollutant in question, while the temporal aspect takes into account the kinetics of the impact. Spatial effects are easier to estimate and where needed, weighted to take into account any effects on human health. Temporal impacts are far more difficult to quantify as the impacts are felt by different populations or even different generations. The fact that the polluter and the affected can be so maikedly separated in space and time introduces an ethical dimension to environmental issues. Generally, consumers tend to pay more attention to the needs of the present generation compared to future generations. 

An attempt is made to capture this distinction in the following four-group classification of environmental impacts (Table 1.4) of (i) short-term local impacts, (ii) shortterm global impacts, (iii) long-term local impacts, and (iv) long-term global impacts. 

Local effects as well as the effectiveness of remedial strategies implemented are fairly easy to monitor and validate. For instance, when 700 oil wells in Kuwait were set ablaze by the retreating Iraqi forces in 1991, it spawned a severe local short-term environmental catastrophe. But the extent of damage and the success of control measure used by the lire control teams could be easily monitored. The same was not true of long-term effects of mercury waste being dumped into Minamata Bay in Japan the more serious impacts occurred in the future, while there was no immediate recognition of a threat to local community.  

Short term Eutrophication of lakes due to Oil or chemical spills during 

Long term Discharge of organic Hg into the Stratospheric ozone depletion 

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As shown in the previous chapter, numerous pollutants may be classified in terms of the environmental sector on which they make an impact (e.g., air pollutants). They can also be classified according to the transformations that they undergo in the environment (e.g., chemical substances may be biodegradable or recalcitrant, as discussed below). More importantly, they can be classified by the hazards they pose to human health and the ecosystems. The latter aspects are closely related to the chemical structure and characteristics of the discharged substances and their interactions with the environment and its organisms. 

The harmonized system for classifying chemical substances for the hazards they present to the aquatic environment is based on a consideration of systems existing listed in 4.1.1.7.4. The aquatic environment may be considered in terms of the aquatic organisms that live in the water, and the aquatic ecosystem of which they are part. To that extent, the proposal does not address aquatic pollutants for which there may be a need to consider effects beyond the aquatic environment such as the impacts on human health etc. The basis, therefore, of the identification of hazard is the aquatic toxicity of the substance, although this may be modified by further information on the degradation and bioaccumulation behaviour. 

IChemE metrics of sustainability consist of 49 indicators classified into three main categories economic, environmental and social. The environmental indicators within the IChemE metrics are similar to those in the CWRT metrics. However, there are some differences. The IChemE metrics include the area of land as an environmental indicator. The actual indicators are (i) the sum of directly occupied and affected land per value added and (ii) the rate of land restoration. Other differences relate to the assessment of the relative impacts of pollutants on the environment and human health. The IChemE indicators do not take into account the life-time of chemicals in various media of the environment. The human health indicator is limited to carcinogenic effects and is normalized to benzene. 

Special attention is given waters that are directly threatened or do not meet WQS. These receive Section 303(d) or Section 305 (threatened or impaired waters) classification. Section 303(d) includes those surface water sources impacted by pollutants, whereas nonpollutants impair Section 305 waters. Where the source of aquatic life impairment is unclear, the source receives Section 303(d) classification. Waters classified as threatened or impaired require biennial progress reporting, with prioritization of TMDL levels and WQC established accordingly. 

Irrespective of how it is extracted in mines and used in industry, coal produces three distinct types of pollutants (1) gaseous, (2) liquid, and (3) solid substances, which generally demand quite different preventive or ameliorative measures. In this context, other impacts like noise, subsidence, waste disposal should also be classified as pollutants arising from coal use. Numerous methods have been devised to keep environmental standards at threshold limits and thus minimize pollution damage while at the same time improving woiker productivity, coal quality, and accident prevention schemes. 

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