Consumption and waste disposal patterns of household in a tropical urban watershed.

Background/Question/Methods The massive concentration of human activities in urban environments will largely influence the transfer of material and energy throughout urban ecosystems.  Human behaviors associated with cultural traditions, beliefs, knowledge and life styles are likely important drivers of the transfer of matter throughout these urban systems. Recent studies suggest that households are the most appropriate unit  of analysis to understand the effects of human behavior on the transport of materials within urbanized ecosystems.  Within this framework, this study investigated aspects of human consumption, wastewater and, waste-disposal patterns of households across an urban-rural gradient within the Rio Piedras Watershed (RPWS) in the San Juan Metro Area, Puerto Rico. The main goal was an initial characterization of household activities that may influence the movement of materials along the watershed. We randomly sampled 432 households at six sites along the watershed where we conducted  surveys between January-May 2011.  Residents were personally interviewed using a 50 item questionnaire that include open-ended and choice questions with a variety of formats. Questions used in this analysis included data on : source of food consumption (supermarket, corner markets, market squares, and residence yard), connection to the city sewerage system or septic tank, and recycling activities.   

Results/Conclusions Most households along the watershed (~97%) obtain food products from supermarkets.  However, in rural sites more than 60% of residents also consumed food items that were cultivated in their yards.  Less than 30% residents in the more urban sites use the yard as source for food.  Recycling activities were mostly carried out by those residents whose recycled items are collected by the municipality. These residents (78-93%) were mostly located in the high population density areas. In contrast, almost no recycling was conducted at the rural sites due to the lack of recycling collection.  Pathways for septic water disposal can provide mechanistic information about nutrient loading to the ecosystem from households, mostly as excretion.  In rural sites only 4 to 17% of households were connected to the municipality’s sewer system and most households use septic thanks for wastewater disposal.  For these sites, nutrients and pollutants from waste water would eventually migrate from septic tanks into the soils and then into the streams.  Most of the households (~100%) in urban locations responded that they were connected to the sewer system.  Given these initial results we conclude that household dynamics at RPWS can potentially contribute to environmental pollution in this urban ecosystem.