Well and Interstitial Water Crop Protection Chemicals Study on the Salina Fan Delta Aquifer
2002 - 2004
Critical Water Problems
This project examines the groundwater and interstitial water quality, toxic substances and nonpoint contamination in the Jobos Basin Estuarine Reserve. The Jobos Bay is located between the Salinas and Guayama municipalities in the south coast of Puerto Rico and comprises more than 2,500 acres, including a forest and a mangrove. The Jobos Estuaries Ecosystem has been severely stressed since the late 80's by land and water channels alterations which have changed the water flow patters of the zone. One of the key issues that needs to be addressed in Puerto Rico and worldwide is the pesticide and phthalate esters movement in soil and groundwater and their effects over sensitive environmental zones, including flora, fish and wildlife. Non-managed application of pesticides and other compounds that reach non target sites may result in leaving residues where crops will later be planted or where they may reach surface and ground water resources. No intensive research in Puerto Rico related to organic pollution in the Jobos mangrove zone has been carried out. The proposed field and laboratory research will be the first one that will help provide a more comprehensive view of water quality in the zone and will be complementary to another research project related to nitrate levels currently underway in the zone.
Results or Benefits
The expected benefits of the research proposed will be the development and advancement of new scientific information related to pesticide and organic toxic residues in the groundwater and interstitial water in the Salinas and Guayama municipalities. Agriculture is expected to continue in the zone, and water sampling for the presence of crop protection chemicals is necessary to ensure human health and the protection and conservation of the environment. The project will also provide data for risk/benefit decisions concerning chemical usage. Data for the year 2002-2003 will be analyzed, interpreted and results, findings and conclusions will be submitted for either technical papers on referred journals, oral presentations and posters during the following year. There will be one or two publications associated with the completion of the research.
Nature, Scope and Objectives of the Research
Before the late 1970's, ground water contamination from field applied pesticides were virtually unexpected. It was assumed that pesticides in the natural environment would break down or be adsorbed into the soil, sand, gravel, and rock formations. Currently human activities such as organic compounds applied for crop protection can clearly lead to contamination of surface and groundwater and thus indirectly affecting estuaries and associated wetlands interstitial water and soil quality (Panke, 2000; Snedaker, 1981). The water quality and humidity content of soil will affect first the microbial population of the zone, influencing nutritional chain, and many other biological and biochemical processes, including plant absorption, metabolism and microbial degradation of organic matter and other natural and anthropogenic chemicals. Therefore, pesticides and other toxic anthropogenic source compounds in water-soil environment are a public and environmental concern problems that deserve further investigation in this region. The south coastal plains of Puerto Rico were used as agricultural lands for sugarcane cultivation until the mid 70's: After a diversification program established by the Puerto Rico Department of Agriculture, bananas and plantains, legumes, vegetables and tropical fruits production has intensified in the last twenty-five years. Groundwater in the Salinas municipality is used for potable water and agricultural purposes, extracting close to three million gallons per day (Molina, 1998) Some pesticides currently used in the zone are very soluble in water suggesting a high potential to move by runoff and leaching to reach surface and groundwater, hence affecting its quality and eventually reaching estuaries, wetlands and marine ecosystems. The Salinas Fan Delta is the major aquifer in the Guayama, Salinas and Santa Isabel zone and is recharging the water in the Jobos Estuarine Natural Reserve (Gomez, 1990; Gonzalez, 1999). Although intensive agricultural practices have been carried out in this zone, no comprehensive study has conducted to assess to the presence, runoff, leaching, degradation and fate of agrochemicals, and other anthropogenic source compounds.
The project's objective is to determine the presence, levels and seasonal variability of agrochemicals in groundwater in the zone near the Jobos Basin. The magnitude of adsorption of the detected pesticides on the main agricultural soils and wetland soils found in the zone. This will serve as an index for selection of more adequate soils and agricultural management practices to avoid pesticide contamination and further disruption of the Jobos Estuaries Ecosystem. This research will help address pesticide groundwater contamination in Puerto Rico and pinpoint management practices, to save and protect Jobos Basin. The specific objectives of the research are: 1) Survey water wells and interstitial water in the Jobos Basin zone to identify and quantify the major pesticides and phthalates esters, and the levels of nitrate-nitrite, phosphates, dissolved oxygen and other types of compounds from anthropogenic sources. 2) Determine the microbial mass present in the Jobos estuaries zone and its relationship to the mangrove health, organic and inorganic compounds present in interstitial water and dissolved oxygen (DO).