Assessment and Control of Groundwater Contamination Below Waste-Water Irrigated Fields

Laboratory column and field research studies which apply municipal and animal wastewater to cropped land will be conducted to determine, (1) the fate of pathogens, and (2) the chemical transformations that occur as the water moves through the soil, including plant uptake, under various management practices. The research will determine the impact of various management strategies on the potential of these wastewaters to pollute surface water and groundwater. Research on toxic chemicals to be carried out cooperatively with the Animal Metabolism Research,Red River Valley Agricultural Research Center in Fargo, ND. FY00 $225,000 Program Increase per 12/14/99 memo J. Robens, NPL. New Sy.
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<li>What major problem or issue is being resolved and how are you resolving it? Population growth and water shortages will increase the need to use treated wastewater effluent for irrigation, particularly in areas where fresh water resources are limited. However, there are serious concerns about the transmission of zoonotic pathogens and toxic chemicals from municipal and animal wastewater to agricultural land and crops and thus to human food and to groundwater. An increase in foodborne disease in the US has been attributed in part to the transmission of pathogens in the water used for irrigation of edible crops. Furthermore, there is limited knowledge on the long-term effects of irrigation with sewage effluent on soil and underlying groundwater. This research project involves the assessment of microbiological safety of wastewater irrigation of food crops and potential environmental hazards in order to protect the public health and our future groundwater resources. We will use molecular biology techniques to evaluate pathogen survival, regrowth, and transport in vegetative and non-vegetative soil columns, water distribution systems, and field sites with a long history of wastewater application for crop irrigation. Studies will determine the movement of zoonotic pathogens and toxic chemicals through the soil column and whether they are picked up by the crop as well as the factors affecting their survival and transport. This could lead to the development of management strategies that would minimize the introduction of pathogens into the environment and thus reduce the risk to human health.
<li>How serious is the problem? Why does it matter? Municipal wastewater treatment does not always adequately reduce the number of pathogens in human wastewater and can thus contain enough pathogenic microorganisms to threaten human health once released into the environment. Likewise, animals can serve as reservoirs for a variety of pathogenic microorganisms including Cryptosporidium, Giardia, Salmonella, Campylobacter and E. coli O157:H7 which can be transported into the environment through the use of animal wastewater. Recent E.coli outbreaks, with hundreds of hospitalizations and several deaths, were likely caused by contamination of water supplies from animal waste facilities. Land application of wastewater from these facilities has the potential for further contamination of water supplies, as well as contamination of crops. In many areas, municipal sewage effluent from increasing populations represents an increasingly significant water supply for irrigated agriculture. Public health impacts of using this water for crops and the potential degradation of underlying groundwater are largely unknown. Molecular biology methods have the ability to detect low numbers of microorganisms, viable but non culturable (VBNC) bacteria, and target specific pathogens present in wastewater, and thus potentially help reduce the health risks associated with the use of wastewater for irrigation of crops, parks, golf courses, and other public greenways. Appropriate technology for reuse of human and animal wastewater is important in helping to avoid the projected world food crises, while maintaining a healthy natural environment. Use of recycled water for crop irrigation would be a way to reduce groundwater pumping and help conserve water in arid areas where water is a limited resource. Groundwater currently provides for about 37% of agricultural irrigation and it is the largest user of groundwater. In addition, groundwater provides 51% of drinking water for the total population in the US. Thus, efforts to protect and preserve our future water resources would be of great benefit.
<li>How does it relate to the national Program(s) and National Program Component(s) to which it has been assigned? This project falls under National Program 108, Food Safety, Microbial Pathogens Component. The reduction of microbial pathogens in food products also relates to reducing environmental contamination from animal (and human) waste. This project is related to objective 1.6.1.1 "Identify sources and reservoirs of pathogens relative to on-farm and environmental situations. What are the effects of transportation on land and cropping systems" by determining the fate of pathogens in wastewater applied as irrigation to crops. This project also contributes to National Program 201, Water Quality and Management, Irrigation and Drainage in Harmony with the Environment Component. The national program states "Innovations and improvements in American agriculture are needed to sustain our vital national interests in a safe, abundant, and reliable food and fiber supply while enhancing our nation's water quality and sustaining our precious water resources." The research project addresses these issues directly by conducting research on augmenting water supplies through water reuse, and groundwater recharge, and by protecting groundwater quality.
<li>What was your most significant accomplishment this past year? A. Pathogens and organic wastewater contaminants (OWCs) can endure wastewater treatment hence there is a potential threat to human health and the environment when treated wastewater is used for agricultural/urban irrigation or artificial recharge of ground water. A study was conducted using a 1ft diameter x 8 ft long soil column at the U.S. Water Conservation Laboratory to determine if pathogens and wastewater contaminants persist in the soil and reach ground water under a set of likely recharge conditions, with collaboration by the USGS for chemical analyses. The results demonstrated that Legionella and 13 of the original 34 OWCs including two antibiotics (sulfamethanize and sulfamethoxazole) present in the secondarily treated effluent used to recharge the column, persisted throughout the experiment and were detected in samples collected from the bottom of the column (column drainage). This preliminary study helps establish that under a set of likely recharge conditions there is a potential for pathogens, pharmaceuticals and other OWCs to be transported into the ground water and merits the attention of consulting engineers, scientists and regulatory agencies involved in ground water recharge projects. 4B. None 4C. None 4D. This project is being terminated and is replaced by ARIS project 5344-32000-002-00D.
<li>Describe your major accomplishments over the life of the project, including their predicted or actual impact? This project is being terminated and is replaced by ARIS project 5344- 32000-002-00D.
<li>What do you expect to accomplish, year by year, over the next 3 years? Future work in this area will be carried out under new CRIS 5344-32000- 002-00D and will include field-testing the results of this experiment by sampling wells in areas of Arizona where effluent is recharged.</ol>