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Williams College

Publication Date

Fall 12-1-2014

Program Name

Ecuador: Comparative Ecology and Conservation


Fresh water is an important resource in Puyo, Ecuador, a city named after the Kichwa word for ‘cloudy’ in reference to its overcast weather. However, the Puyo River watershed is the most contaminated in all of Pastaza Province. The objective of this investigation was first to evaluate the health of the Puyo River using macroinvertebrate analyses and measurements of chlorine concentrations, temperature, pH, turbidity, velocity, and flow rate. The second objective was to learn about practices used to whiten clothes in Puyo and perceptions of water quality in order to understand the magnitude of bleach pollution and the population’s awareness of its effects. Lastly, the study investigated alternative stain-removal techniques in the hopes of identifying a biodegradable and nontoxic yet effective substitute for chlorine-based bleach to help improve local water quality. Macroinvertebrates as well as physical and chemical stream data were collected from 11 sites along the Puyo River and its tributaries. Morphospecies richness, exponential Shannon-Weiner diversity, % EPT, % abundance of the dominant taxon, the BMWP/Col Index, and a Principal Component Analysis were used to evaluate the response of aquatic macroinvertebrate communities to pollution and thus to infer the quality of the water. Surveys were conducted (n=37) of both Puyo Residents and visitors along the Paseo Turístico del Río Puyo and in the Parque Central Doce de Mayo. Nine fabric-whitening methods were tested on 6 types of stains and rated based on the completeness of stain removal. Macroinvertebrate diversity, especially in the order Ephemeroptera, and other bioassessment metrics identified three small tributaries of the Puyo River as critically polluted, and confirmed that water quality deteriorates with distance downstream along the Puyo River. Of Puyo residents surveyed, 84% used chlorine-based bleach and 88% disposed of residual whitening or cleaning water down the drain or directly into the river, meaning bleach contributes to water pollution. Chlorine impairs water quality more than other whiteners because it reacts with organic matter in aquatic environments to form toxic disinfection by-products. Blue soap and a mixture of plants and wood ash were more successful than chlorine at removing the assortment of stains. Soap was more time-efficient, while the mixture of plants and ash offered the most environmentally friendly laundry option.


Ecology and Evolutionary Biology | Environmental Education | Environmental Health and Protection | Environmental Indicators and Impact Assessment | Environmental Monitoring | Environmental Sciences | Environmental Studies | Geography | International and Area Studies | Latin American Studies | Social Statistics | Water Resource Management


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