Where Have All the Toxic Chemicals Gone?a

Abstract

ABSTRACTMany municipal, industrial, domestic and farm water supplies throughout the country are derived from wells tapping shallow aquifers that have a high contamination potential from surface derived sources. Unfortunately, water samples from most of these wells are not analyzed on a regular basis even for bacteria or simple chemical pollutants such as nitrate. Practically none of them are routinely checked for more serious contaminants such as viruses, weed killers, pesticides, trace metals, and an almost countless number of toxic chemical compounds commonly used in our environment and eventually discarded in garbage dumps, waste‐burial grounds, or disposal wells. Because of this, the possibility of serious ground‐water contamination often is not discovered until a high degree of contamination is present.Microorganisms contained in water may be effectively removed by filtration in a short distance of travel through fine‐grained earth materials. However, most toxic chemical compounds are not. Instead, these are carried by precipitation recharge to surficial ground‐water reservoirs. After entry such contaminants move downgradient through the aquifer materials, usually at rates of only a few feet per year with little if any dilution, to natural discharge points such as streams, lakes and swamps, or to pumping wells.Ground‐water contamination occurrences from nitrate, arsenic, chromate, cadmium, chlorinated hydrocarbons, and a large number of other toxic chemicals are increasing. These show that a serious threat to public health may be imminent unless all surficial and underground disposal sites of toxic chemicals are located, the extent and magnitude of ground‐water contamination from each site evaluated, and corrective measures applied where necessary.