Trends in central asia: Health risks from large-scale water pollution

At basin sizes, health-risk evaluations are hampered by a lack of data on the pollution state of geographically vast water systems. We show that agricultural and industrial pollutants in groundwater–surface water systems of the Aral Sea Drainage Basin (covering the main part of Central Asia) produce cumulative health hazards above guideline values in downstream surface waters, due to high concentrations of copper, arsenic, nitrite, and to a lesser extent dichlorod in downstream surface waters, using a recipient measurement approach in a terminal water body (DDT). We also conduct trend studies of these high-impact pollutants’ upstream spatial–temporal distribution, examining prominent large-scale spreading processes. The ratio of parent DDT to its breakdown products indicated that discharges or depositions into surface waters were likely recent or continuing. Copper concentrations in river water rise in the spring following thawing and snow melt. The high geographical variability of arsenic contents in river water may be due to its presence in adjacent agricultural areas’ top soil. Groundwater's were shown to be linked with much greater health hazards than surface waters. If the downstream population is forced to convert to groundwater-based drinking water sources due to a lack of surface water, health concerns may skyrocket. Due to continuing irrigation development and climate change, arid areas are particularly susceptible to this issue.