TY - JOUR T1 - Conservation in action JF - Journal of Soil and Water Conservation SP - 57A LP - 61A VL - 62 IS - 3 AU - Rod Bodkin AU - James Kern AU - Phillip McClellan AU - Arthur J. Butt AU - Charles Martin Y1 - 2007/05/01 UR - http://www.jswconline.org/content/62/3/57A.abstract N2 - WHAT IS TDS? “Total dissolved solids” (TDS) is a measure of all of the dissolved constituents in water with the exception of dissolved gases. The primary anions are carbonates, chlorides, sulfates, and nitrates. The primary cations are sodium, calcium, potassium, and magnesium. TDS and conductivity are often related because conductivity is the ability of an aqueous solution to carry an electric current. This relationship depends on the concentration of different ions present, their valence, and the temperature of the solution. WHY IS TDS A CONCERN? TDS and elevated conductivity have been identified as a probable cause of biological impairments in high gradient mountain streams in the southern coalfield areas of Virginia, Kentucky, and West Virginia. In these streams, conductivity is strongly and significantly correlated to degrading biological conditions and impairment. In some of these streams, no other stressor was identified. Typically, streams in the Central Appalachian ecoregion are very dilute with conductivities often less than 40 μmhos cm−1. Furthermore, the benthic macroinvertebrate communities that inhabit these streams are dominated by highly sensitive pollution intolerant species. In areas impacted by mine drainage, conductivities are often elevated and range from 500 to 2,000 … ER -