ENVIRONMENTAL ISSUES

Diatoms as Pollution Measuring Tools

Diatoms as Pollution Measuring Tools

Introduction

Freshwater resources and habitats are especially sensitive to changes because of their limited availability and dependence on hydrologic patterns affected by land use, flow modifications, and precipitation. The water quality and biological integrity are essential to society as healthy stream ecosystems provide valuable services, which would be difficult and costly to replace. Humans rely directly on freshwater for consumption, agriculture, food, purification of pollutants, and aesthetics. Organisms in streams, wetlands, and lakes not only provide these essential ecosystem services, often unrealized by society, but they are also crucial to biogeochemical cycling that is inextricably linked to terrestrial ecosystems and humans (Smucker & Vis, 2011, pp. 1191-1203).

Impact of Pollution on Ecosystems

Human impacts to watersheds can impair stream ecosystem structure and function, subsequently impacting downstream processes in larger rivers, estuaries, and ocean coasts, with the most severe example being algal blooms and subsequent anoxic dead zones in coastal areas. Hence, stream restoration and conservation, which are inextricably linked to land use in watersheds, are of critical importance from local to global scales (Brookshire et al. 2005). Fish consumption and swimming advisories are just two examples of negative consequences people see repeatedly, but what is not at the forefront of societal concern is the loss of ecosystem integrity and the functional services provided by stream communities (Blanco & Becares, 2010, pp. 18-25).

Research has been conducted for valuation of market goods and services provided by freshwater ecosystems, such as consumption, transportation, pollution disposal, and irrigation, but the value of nonmarket goods, such as biodiversity, aesthetics, and interactions between aquatic and terrestrial ecosystem processes are often neglected. Nevertheless, public awareness and appreciation of stream ecosystem services has been rising. Increased efforts are needed for restoring and preserving the natural functions of ecosystems, which would benefit biodiversity, biological communities, and society at local, regional, and global levels.

Billions of dollars are spent for restoring polluted rivers, and research is needed which will integrate ecosystem structural integrity and services with “the science of ecological restoration and design” (Zheng & Liu, 2010, pp. 1510-24). Acid mine drainage (AMD) and agriculture are the two prominent anthropogenic impacts to streams in the Western Allegheny Plateau (WAP) of Ohio. AMD is a ruinous legacy of pre-regulation coal mining that impacts several thousand stream kilometers throughout many various states. At least 732 stream kilometers in the WAP of Ohio, more than 7200 kilometers in the Mid-Atlantic Highlands, and up to 24% of stream miles in particular eco-regions are impaired by AMD.

Biogeochemical cycle of silicon

The use of silica by diatoms dominate the biogeochemical cycle of silicon in the oceans, as each atom from continental erosion passes through diatomaceous an average of 39 times before they accumulate in marine sediments. Silica is the main limiting nutrient for the growth of diatoms, so it is a factor that marine primary production.

The silicon retained in the membranes of diatoms can pass to the sediment, to irreversibly when accumulated and radiolarites ...