Discuss some human activities which cause river pollution.
Answers
Humans have long used air, land and water resources as ‘sinks’ into which we dispose of the wastes we generate. These disposal practices leave most wastes inadequately treated, thereby causing pollution. This in turn affects precipitation, surface waters, and groundwater , as well as degrading ecosystems . The sources of pollution that impact our water resources can develop at different scales (local, regional and global) but can generally be categorized according to nine types. Identification of source types and level of pollution is a prerequisite to assessing the risk of the pollution being created to both the aquatic systems and, through that system, to humans and the environment. With the knowledge of the principal sources of the pollution, the appropriate mitigation strategy can be identified to reduce the impact on the water resources.
ACID RAIN IMPACTS ON WATER RESOURCES
Atmospheric contamination from industrial plants and vehicle emissions leads to dry and wet deposition. This causes acidic conditions to develop in surface water and groundwater sources and at the same time leads to the destruction of ecosystems. Acid deposition impairs the water quality of lakes and streams by lowering pH levels (i.e. increasing acidity), decreasing acid-neutralizing capacity, and increasing aluminum concentrations. High concentrations of aluminium and increased acidity reduce species diversity and the abundance of aquatic life in many lakes and streams. While fish have received most attention to date, entire food webs are often negatively affected. Despite improvements, it still remains a critical situation that impacts water resources and ecosystems in some developed regions of Europe and in North America. The situation remains an important issue in several developing countries (for example in China, India, Korea, Mexico, South Africa and Viet Nam) where there are typically lower emission controls and inadequate monitoring and evaluation (Bashkin and Radojevic, 2001). In recognition of this, UNEP and the Stockholm Environmental Institute are sponsoring programmes such as RAPIDC (Rapid Air Pollution in Developing Countries) with the aim of identifying sources and sensitive areas and measuring levels of acid rain. Extensive funding from ADB is now being used to source reductions in several Asian nations. The problem has broad transboundary implications as acid rain can get carried over long distances from polluting areas to other countries. For example, Japan is impacted by Korean and Chinese emissions, while Canada, in addition to its own sources, receives substantive emissions from the US.
As reported by Driscoll et al. (2001), there are still impacts to water quality in northeastern US and eastern Canada, even though improved conditions developed after the introduction of the Clean Air Act and its amendments (1992).
41 percent of lakes in the Adirondacks of New York and 15 percent of all lakes in New England exhibit signs of chronic and/or episodic acidification. Only modest improvements in acid-neutralizing capacity have occurred in New England with none in the Adirondacks or Catskills of New York. Elevated concentrations of aluminum have been measured in acid-impacted surface waters throughout the Northeast.
Acid rain and its deposition processes
IMPACTS TO SURFACE WATER QUALITY FROM HUMAN ACTIVITY
The challenge of how to improve water quality by rehabilitation and protection of lakes, streams, reservoirs, wetlands and related surface water bodies is a growing global concern, typified by the recent European Commission Water Framework Directive (EC, 2000). However, surface water pollution risks, particularly in developing nations, remain relatively widespread. A valuable initial step in identifying the nature and extent of water quality impacts linked to pollution is to distinguish their point (PS) and non-point sources (NPS). PS pollution is commonly linked directly to end-of-pipe releases from industry and municipal wastes. Its control is more direct and quantifiable and in many developed countries its mitigation has been linked to treatment achieving lower contaminant concentrations before discharge. NPS pollution occurs when contaminants from diverse and widely spread sources are transported by runoff into rivers, lakes, wetlands, groundwater and coastal areas. This type of pollution is more difficult to address as there are a large number of sources, for example, varied agricultural areas all of which are using pesticides and nutrients. Today, however, NPS pollution is receiving more attention as its impacts are becoming evident over large areas in lakes, streams and groundwater and can also be linked to the degradation of aquatic freshwater and marine ecosystems.
Humans are the main cause of water pollution, which is triggered in many ways: by the dumping of industrial waste; due to temperature rise, that cause the alteration of water by reducing the oxygen in its composition