RESUMEN
Ceramic pot filters (CPFs) are an effective means of household water treatment, but the characterization of CPF lifetimes is ongoing. This paper describes a lifetime field study in Guatemala which was made possible by a collaboration between researchers, CPF-using households, and local non-governmental organizations (NGOs). Disinfection data were collected periodically for two years using field coliform enumeration kits as were flow rate data with the assistance of NGO staff. Consumer acceptance was characterized by surveying householders in the four subject villages at the beginning and end of the study. Flow rate data showed that average CPF flow rates decreased below the recommended minimum of 1 L h-1 after 10 months of use; however, the survey results indicated that the consumers were tolerant of the lower flow rates, and it is reasonable to assume that the daily volume of treated water can be readily increased by refilling the CPFs more frequently. Of greater concern was the finding that disinfection efficacy decreased below the recommended bacterial reduction after 14 months of use because it would not be obvious to users that effectiveness had declined. Finally, the follow-up visits by the researchers and the NGO staff appeared to increase consumer acceptance of the CPFs.
Asunto(s)
Cerámica/análisis , Desinfección/métodos , Agua Potable/análisis , Filtración/métodos , Purificación del Agua/métodos , Desinfección/instrumentación , Filtración/instrumentación , Guatemala , Purificación del Agua/instrumentaciónRESUMEN
Historical mining activity (1850-1970) in the now inactive Tri-State Mining District provided an ongoing source of lead and zinc to the environment including the US Environmental Protection Agency Superfund site located in Cherokee County, southeast Kansas, USA. The resultant contamination adversely affected biota and caused human health problems and risks. Remediation in the Superfund site requires an understanding of the magnitude and extent of contamination. To provide some of the required information, a series of sediment and soil investigations were conducted in and near the Superfund site to characterize lead and zinc contamination in the aquatic and floodplain environments along the main-stem Spring River and its major tributaries. In the Superfund site, the most pronounced lead and zinc contamination, with concentrations that far exceed sediment quality guidelines associated with potential adverse biological effects, was measured for streambed sediments and floodplain soils located within or downstream from the most intensive mining-affected areas. Tributary streambeds and floodplains in affected areas are heavily contaminated with some sites having lead and zinc concentrations that are an order of magnitude (or more) greater than the sediment quality guidelines. For the main-stem Spring River, the streambed is contaminated but the floodplain is mostly uncontaminated. Measured lead and zinc concentrations in streambed sediments, lakebed sediments, and floodplain soils documented a persistence of the post-mining contamination on a decadal timescale. These results provide a basis for the prioritization, development, and implementation of plans to remediate contamination in the affected aquatic and floodplain environments within the Superfund site.
Asunto(s)
Monitoreo del Ambiente/métodos , Restauración y Remediación Ambiental/métodos , Sedimentos Geológicos/química , Minería , Contaminantes del Suelo/análisis , Contaminantes Químicos del Agua/análisis , Ecosistema , Humanos , Kansas , Plomo/análisis , Ríos/química , Suelo/química , Zinc/análisisRESUMEN
2-(Thiocyanomethylthio)benzothiazole (TCMTB) is a biocide used in the leather, pulp and paper, and water-treatment industries. TCMTB may enter aquatic ecosystems during its manufacture and use. TCMTB is environmentally unstable; therefore, it is important to evaluate the toxicity of the more persistent degradation products. This study compared the toxicity of TCMTB with its degradation products 2-mercaptobenzothiazole (2-MBT), 2-(methylthio)benzothiazole (MTBT), benzothiazole (BT), and 2-hydroxybenzothiazole (HOBT). Toxicity was determined using Ceriodaphnia dubia 48-hour acute and 7-day chronic test protocols. TCMTB was the most toxic compound evaluated in both the acute and chronic tests with EC50s of 15.3 and 9.64 microg/L, respectively. 2-MBT, the first degradation product, was the second most toxic compound with acute and chronic EC50s of 4.19 and 1.25 mg/L, respectively. The toxicity of MTBT and HOBT were similar with acute EC50s of 12.7 and 15.1 mg/L and chronic EC50s of 6.36 and 8.31 mg/L, respectively. The least toxic compound was BT with acute and chronic EC50s of 24.6 and 54.9 mg/L, respectively. TCMTB was orders of magnitude more toxic than its degradation products. Toxicity data on these benzothiazole degradation products is important because of concerns regarding their release, degradation, persistence, and non-target organism effects in aquatic ecosystems.
Asunto(s)
Cladóceros/efectos de los fármacos , Tiazoles/toxicidad , Tiocianatos/toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Benzotiazoles , Cladóceros/fisiología , Dosificación Letal Mediana , Nivel sin Efectos Adversos Observados , Tiazoles/química , Tiocianatos/química , Pruebas de Toxicidad Aguda , Pruebas de Toxicidad CrónicaRESUMEN
Diazolidinyl urea (Germall II) is a new preservative recommended for use in certain consumer products. Although 2 reports document the human sensitization rates of this preservative, no publications quantify its sensitization potential in controlled animal experiments. Diazolidinyl urea induced mild sensitization (grade 2) under maximization test conditions. Further, there was evidence of cross-reactions with both imidazolidinyl urea (Germall 115) and formaldehyde in diazolidinyl-urea-sensitized animals. Rechallenge of diazolidinyl-urea-sensitized animals with diazolidinyl urea 4 weeks following the primary challenge only elicited a weak response (0.5) from 1 animal out of 8.