Wednesday, November 7, 2007
247-2

Stream Water Quality along a Coffee Production Subbasin of Puerto Rico.

Gustavo Martinez and Francisco Monroig. University of Puerto Rico, Univ. of Puerto Rico, South Botanical Garden, 1193 Guayacan St, San Juan, PR 00926-1118

The effect of coffee production and processing activities on the nutritional status of nearby stream was ascertained. Water samples (grab) were collected at five points along a river line traversing the basin. Sampling points were located upstream and downstream of different coffee processing plants. An additional sampling station was established at the closing point of a nearby reference basin (no anthropogenic presence) for comparison purposes. Samples were collected during the coffee processing period (September- February) and during the processing off season (March-July) for two years. Samples were analyzed for total phosphorus (TP), dissolved phosphorus (DP), nitrate (NO3), and dissolved organic carbon (DOC). In addition, analyses of the biologic oxygen demand (BOD) of the coffee processing water generated at two of the processing plants are being conducted.

Except for nitrate, nutrient concentrations (i.e., TKN, TP, DP, DOC) at the different sampling stations were similar to those at the reference site. For TP, average concentrations ranged from 26 ppb to 44 ppb along the coffee subbasin compared to 36 ppb at the reference site. However, in the case of nitrate elevated concentrations (avg. 1.67 mg/L NO3-N) were observed at the highest elevation point being sampled. Nitrate concentrations at this point were 3 to 5 times higher that average concentrations observed at the other stations along the basin and approximately 11 times higher than the average concentration of the reference site. An attempt to identify the specific contamination source has initially identified a nearby landfill that has been closed for over ten years. More analyses are been conducted to certify this. The results will be presented.