Water Quality Impairments Due to Aquatic Life Pesticide Toxicity: Prevention and Mitigation in California, USA.

The management of pesticides to protect water quality remains a significant global challenge. Historically, despite regulatory frameworks intended to prevent, minimize, and manage off-site movement of pesticides, multiple generations of pesticide active ingredients have created a seemingly unending cycle of pesticide water pollution in both agricultural and urban watersheds. In California, the most populous and most agricultural US state, pesticide and water quality regulators realized in the 1990s that working independently of each other was not an effective approach to address pesticide water pollution.

Complex watersheds, collaborative teams: Assessing pollutant presence and effects in the San Francisco Delta.

There is a great diversity of sources of chemical contaminants and stressors over large geographic areas. Chemical contaminant inputs and magnitude can potentially exhibit wide seasonal variation over large geographic areas. Together, these factors make linking exposure to monitored chemical contaminants and effects difficult.

Gastrointestinal and renal excretion of potassium in African-Americans and White Americans.

Objective: Several studies have confirmed the remarkable observation that cumulative urinary potassium (K(+)) excretion is less in African-Americans than White Americans even when identical amounts of potassium are provided in the diet. This study was designed to examine whether this decrease in urinary potassium could be compensatory to an increase in gastrointestinal excretion of potassium in African-Americans.

Methods: Twenty-three young, healthy, normotensive participants of both sexes and races were placed on a fixed diet of 100 mEq per day of K(+) and 180 mEq per day of sodium (Na(+)) for 9 days.

Trihalomethane reactivity of water- and sodium hydroxide-extractable organic carbon fractions from peat soils.

Certain organic carbon moieties in drinking source waters of the Sacramento-San Joaquin Delta can react with chlorine during disinfection to form potentially carcinogenic and mutagenic trihalomethanes. The properties of reactive organic carbon in Delta waters, particularly those of soil origin, have been poorly understood. This study attempts to characterize trihalomethane reactivity of soil organic carbon from three representative Delta peat soils.

Trihalomethane formation potential of filter isolates of electrolyte-extractable soil organic carbon.

Certain organic C moieties of soil origin in drinking source waters of Sacramento-San Joaquin Delta (Delta) can react with chlorine to form trihalomethanes (THMs) during the disinfection process. Isolation and characterization of them and quantitation of their THM formation potential (THMFP) is necessary for developing effective strategies to reduce their influxes in Delta waters and for removing them during drinking water treatment. In this study, organic C from two Delta soils was extracted using deionized H(2)O and four Na- or Ca-based electrolytes of varying electrical conductivity values.

Size and XAD fractionations of trihalomethane precursors from soils.

Soil organic matter is an important source of allochthonous dissolved organic matter inputs to the Sacramento-San Joaquin Delta waterways, which is a drinking water source for 22 million people in California, USA. Knowledge of trihalomethane (THM) formation potential of soil-derived organic carbon is important for developing effective strategies for organic carbon removal in drinking water treatment. In this study, soil organic carbon was extracted with electrolytes (deionized H2O and Na- or Ca-based electrolytes) of electrical conductivity bracketing those found in Delta leaching and runoff conditions.

Filter pore size selection for characterizing dissolved organic carbon and trihalomethane precursors from soils.

Filters with a pore size of 0.45 microm have been arbitrarily used for isolating dissolved organic carbon (DOC) in natural waters. This operationally defined DOC fraction often contains heterogeneous organic carbon compounds that may lead to inconsistent results when evaluating trihalomethane formation potential (THMFP).