Competitividad Ancash: Fomento de la competitividad empresarial en la región

HYDROLOGIC SYSTEM

JAMESA. JACOBS

Environmental Bio-Systems, Inc. Mill Valley, California

TIMOTHYK. PARKER Groundwater Resources of California

Sacramento, California

Laboratory methods have improved dramatically during the past decade with much lower detection levels enabling some interesting results of human impact on the condition of the hydrologic system. Low levels of organic contaminants are present in surface and groundwaters throughout the nation. Methyl tert butyl ether (MtBE) and some chlorinated solvents have been measured at low levels in public supply wells near rivers. Low levels of chloroform and other trihalomethanes produced as a result of the water disinfection process (also called disinfection byproducts) appear nearly ubiquitous in the urban environment. The source of disinfection byproducts is from the use and application of treated water in the urban environment for landscape irrigation, transport of household wastewater through leaky sewer systems, and also from leaky water pipe systems emanating form water treatment plants. An additional constituent which has low risk-based level, N-nitrosodimethylamine (NDMA), has also been found associated with water treatment plant disinfection byproducts.

A well-known nation wide study was conducted by the U.S. Geological Survey (USGS) in 1999 to 2000. The USGS collected surface water samples from 139 streams in 30 states across the lower 48 states (Fig. 1). The streams tended to be downstream of intense urban or livestock areas and consequently were suspected of contamination. The surface water samples were analyzed for organic wastewater contaminants (OWCs). The results of the surface water sample evaluation were published in Environmental Science & Technology (1) and in a USGS Open-File Report (2).

The USGS found that 80% of the streams sampled generally contained low concentrations of OWCs in the <1.0µg/L range, impacted primarily by residential, industrial, and agricultural products. Seven chemical groups (steroids, nonprescription drugs, insect repellent, detergent metabolites, disinfectants, plasticizers, and fire retardants) were found in more than 60% of the stream samples, and three groups (detergent metabolites, steroids, and plasticizers) contributed to almost 80% of the total measured concentration. More than one-third (33 of 95 target OWCs) of the chemicals detected are known or are suspected of exhibiting at least weak hormonal activity and have the potential to disrupt normal endocrine function (Fig. 2).

One source of the chemicals identified is products and materials typically used in farming and industry. Addi- tionally, a significant contribution was from residential

EXPLANATION Sampling site

0 125 250 500 Miles

Figure 1. Sampling locations of USGS study (courtesy of USGS, Ref. 1).

80 F requency of detection, % 60 40 20 0 Coprostanol(5) Cholesterol(5) N - N -Dieth yltoluamide(4) Caff eine(4) T ri(2-chloroeth yl) phosphate(4) T riclosan(4) 4-Non ylphenol(4) 4-Non ylphenol monoetho xylate(4) Ethanol, 2-b uto xy-phosphate(4) 4-Octylphenol monoetho xylate(4) Bisphenol-A(4) Cotinine(3) 4-Non ylphenol dietho xylate(4) 5-Meth yl-1H-benz otr iaz ole(4) Fluor anthene(4) 1,7-Dimeth ylxanthine(3) Pyrene(4) T rimethopr im(3) 1,4-Dichlorobenz ene(4) Diazinon(4) 4-Meth yl phenol(4) Acetaminophen(3) T etr achloroeth ylene(4) 4-Octylphenol dietho xylate(4) Er ythrom ycin-H 2 O(1) Estr iol(5) Lincom ycin(1) Sulf ametho xaz ole(3) Phthalic an yh ydr ide(4) Carbar yl(4)

Figure 2. Most frequently detected compounds. The analytical method number is provided (in parentheses) at the end of each compound name (1).

62 WATER CONTAMINATION BY LOW LEVEL ORGANIC WASTE COMPOUNDS IN THE HYDROLOGIC SYSTEM use, drugs typically found in the medicine cabinet, and

disposed of as is or as processed human waste in toilets and sinks. Some commonly detected constituents include caffeine in 70.6% of the samples at a maximum concen- tration of 5.7µg/L, insect repellent N, N-diethyltoluamide in 74.1% of the samples at a maximum concentration of 1.1µg/L, plant/animal steroid cholesterol in 84.3% of the samples at a maximum concentration of 60µg/L, and fecal steroid coprostanol in 85.7% of the samples at a maxi- mum concentration of 150µg/L. The USGS study shows that many of the chemicals used in modern life survive human waste processing, current wastewater treatment plant processing, as well as biodegradation in the nat- ural environment, and are detected as contaminants in potential water supplies.

A long list of contaminants have been documented in surface waters throughout the country partly due to the low laboratory detection levels. Considering the interconnection of surface water and groundwater, and the ability of these contaminants to move in the subsurface environment, our shallow groundwater resources are vulnerable to and likely impacted by contamination from these surface water sources. In California, the Ambient Groundwater Monitoring and Assessment Program (GAMA) implemented by the State Water Resources Control Board (SWRCB) is a program to assess the water quality and relative susceptibility of groundwater resources to contamination throughout the state. This assessment of relative contamination vulnerability is made based on the results of two types of analyses that are not routinely carried out at public water supply wells: ultra low-level measurement (part per trillion) of volatile organic compounds (VOCs), and groundwater age dating (using the tritium-helium- 3 method). In addition, stable isotopes of oxygen are measured to help determine recharge water source location. Interpreted together with existing water quality and hydrogeologic data, these parameters assist in assessing the flow field of a groundwater basin, and indicate the degree of interconnection between near- surface sources (or potential sources) of contamination, and deeper groundwater pumped at high capacity production wells.

In GAMA studies that were conducted by the USGS and Lawrence Livermore National Laboratory under contract to SWRCB, the two most frequently detected volatile organic compounds were disinfection by products (trihalomethanes) dominantly chloroform, and methyl tert butyl ether (MtBE), which were found more frequently and at higher concentration in samples from rivers than in samples from nearby shallow public supply wells, suggesting the rivers may be the source of the groundwater occurrences (4,5). Additionally, chloroform was found associated with wellhead disinfection systems and may be present due to back-flushing of treated water (6). In one study of the Los Angeles Basin area, it was determined that the overall distribution of low level VOCs in groundwater was related to the hydrological and engineered recharge facilities (4). In a study of the Sacramento area, the frequent detection of one VOC (Perchloroethylene PCE) was believed to be due to

mobilization of numerous point sources from spills or leaks at dry cleaners or other businesses, or possibly, from leaky sewer lines that hold small amounts of PCE (5).

Although these common chemicals are detected in very low or trace amounts, the possible cumulative or synergistic effects of these chemicals on plants, animals, and humans is currently unknown. Additional data from the USGS is forthcoming. There are no potential adverse health effects of these chemicals at such low documented concentrations.

If treatment or remediation is deemed appropri- ate, advanced oxidation, enhanced bioremediation, or improved water polishing/filtering could be added to exist- ing wastewater treatment plants to reduce contaminants of these types from entering the environment. More lim- ited pretreatment for septic systems could also help to reduce these chemicals in the environment. For individual water users, small point-of-use treatment systems could be used to remove trace amounts of contaminants (3).

This is a chemical society: Chemicals are widely used on a daily basis at a personal level in the household (personal care products, gasoline, solvents, pesticides, etc), and for a better quality of life in industry and agriculture (wide variety of chemicals). Anthropogenic impacts on the environment, which were largely uncontrolled until the last thirty years, are still unavoidable even with the current best standards of practice. Further, society is still continuing to understand the environmental impacts of past chemical handling and disposal practices as laboratory and investigative analytical tools improve. With population increasing at the current rate, projections are for increased demands on water supply, increased stress of the existing water supply and hydrologic systems, and shortages in dry years, unless steps are taken to increase water supplies and reliability through strategies including water conservation, recycling, desalination, conjunctive use, and artificial recharge. No doubt there will continue to be more ‘‘new’’ chemicals found to be present in our hydrologic system in the future that we did not know about before, but may have been present for some time. This will require planned adaptive management approaches and practices to assess the potential affects on humans and ecosystems, to develop alternative management strategies and remediation if appropriate, and to have on-going educational programs beginning at the elementary school level to edify society as to the information and risks so that society can make informed decisions as to how these challenges should be managed in the future.

BIBLIOGRAPHY

1. Kolpin, D.W. et al. (2002). Pharmaceuticals, hormones, and other organic wastewater contaminants in U.S. streams, 1999–2000: A national reconnaissance, USGS. Environ. Sci. Technol. 36(6): 1202–1211.

2. Barnes, K.K., Kolpin, D.W., Meyer, M.T., Thurman, E.M., Fur- long, E.T., Zaugg, S.D., and Barber, L.B. (2002). Water-Quality Data for Pharmaceuticals, hormones, and Other Organic Waste Water Contaminants in U.S. Streams, 1999–2000. USGS Open File Report 0-2-94, Iowa City, IA.

3. Jacobs, J.A. and Parker, T. (2002). Low Concentrations of Organic Contaminants in the Hydrologic System. Groundwater