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The article attempts to determine trihalomethane reactivity of soil organic carbon from three representative Delta peat soils. Reactive organic carbon's isolation and concentration may be done by fractionation of the bulk soil organic carbon into relatively more molecularly homogeneous isolates such as humic acids and fulvic acids. Delta source waters' organic carbon levels are so elevated that removal of organic carbon is often needed before disinfection can proceed. Research studies have shown that a huge section of organic carbon in Delta source waters evolves from Delta island peat soils through drainage returns or wetlands where soil organic carbon is in direct touch with the water. It has been found that not all organic carbon of soil origin chemically reacts with chlorine in the same way and degree. Aromatic organic carbon moieties are considered by earlier research to be the reactive organic carbon. Current studies indicated that organic carbon aromaticity alone cannot fully explain or predict disinfection by-product reactivity.

This article focuses on a study which states that certain organic carbon moieties of soil origin in drinking source waters of Sacramento-San Joaquin Delta (Delta) in California, can react with chlorine to form trihalomethanes during the disinfection process. Organic carbon from soils may be collected from lysimeters and piezometers, or from drainage ditches and canals adjacent to the soils. At each sampling site, subsamples were collected from the surface layer between 0 and 0.3 m using an auger. Subsamples were then mixed and cleaned of rocks, undecomposed roots, and crop residue before being composited into 1-L mason jars. Increases in electrical conductivity of extractants generally decreased the quantity of extractable organic carbon. Two soils of contrasting texture and organic carbon contents were extracted using five extractants including deionized water and four sodium and calcium-based electrolytes. The extractable organic carbon was then separated into particulate, colloidal, fine colloidal, and soluble organic carbon to determine trihalomethane formation potential.

Determines whether oxalate can be used as an extractant for estimating the available phosphorus pool in soils. Availability of oxalate extractable phosphorus in soils; Estimation of oxalate extractable phosphorus versus the available phosphorus using the Hedley method; Phosphorus content of slightly weathered soils.

Demonstrates a supercritical fluid extraction procedure for quantitative recovery of polar and nonpolar chemicals from soils. Use of (ethylenedinitrilo)-tetraacetic acid tetrasodium salt (Na4EDTA) in pretreatment procedure; Effect of Na4EDTA on extraction efficiency; Effect of soil moisture on polar analytes recovery; Extraction of carboxylic acids and phenols.

The environmental impact of copper sulfate (CuSO4#lb5H2O) must be evaluated before the chemical can be registered as a pesticide to control the apple snail (Pomacea canaliculata) in Hawaii's wetlands. To help achieve this goal, we investigated the sorption‐desorption reactions of CuSO4#lb5H2O with six wetland‐taro soils (Tropaquepts) of Hawaii. Our results indicated that: (i) copper (Cu) was sorbed rapidly: 98.0–99.9% of the added Cu was removed from solution within one hour when the loading rate was less than or equal to 300 mg Cu kg‐1 [initial Cu concentration = 30.0 mg Cu L‐1 or 12 kg (ha‐cm)‐1 as CuSO4#lb5H2O which is 10 times the maximum recommended rate of pesticide applications, (ii) Cu sorption increased as soil pH increased from 5.0 to 8.0, and (iii) sorption capacity varied from 210 mg Cu kg‐1 in a Tropaquept from Kauai Island to 500 mg Cu kg‐1 in another Tropaquept from Maui Island, after seven days of incubation at soil‐solution pH 6.0 and total solution Cu concentration of 0.10 mg Cu L‐1, a Cu level deemed toxic to some living organisms. It appears that more Cu was sorbed (less Cu remained in solution) if the soil contained high organic carbon (C) and low indigenous Cu. Also, there was an inverse relationship between Cu sorption and desorption by the soils tested: the more Cu a soil can sorb, the tighter it holds Cu, and the less Cu it releases. Since soil pH increases by 1 to 1.5 units upon flooding and Cu sorption increases with increasing pH, the recommended practice of flooding the soil for at least 48 hours between CuSO4#lb5H2O application and crop planting should be followed. [ABSTRACT FROM PUBLISHER]

Iron (Fe)‐impregnated filter paper strips (Pi) have been proposed as a method for measuring available soil phosphorus (P). A well‐defined Pi method has not yet been developed and Pi strips are often prepared with different filter papers and procedures. A study aimed at arriving at a consistent Pi method is thus needed. Four types of Pi strips, prepared with the two most widely used papers, Whatman No. 50 and 541, following a procedure that incorporates improvements both proposed in the literature and made in our laboratory, were evaluated for P extraction capacity and error. Two of the best strips, which are significantly different in P extraction capacity, along with the Mehlich 1 (0.05M HCl and 0.0125M H2SO4) and the Olsen method (0.5M NaHCO3, pH 8.5) were further evaluated in a greenhouse experiment involving eight soils planted with corn (Zea mays L.). Results indicated that strips prepared with both Whatman No. 50 and 541 were appropriate for P extractions as long as strips were washed with deionized water after treatment with ammonium hydroxide (NH4OH). At room temperatures the strips probably contain both hydrous Fe hydroxides and oxides in both crystalline and amorphous forms. Pi P was well correlated with Olsen P and P uptake in all soils, indicating that Pi is generally applicable in diverse soils. No obvious advantage was found for the Pi with respect to the Olsen method. Both the Pi and the Olsen method were better extractants with respect to the Mehlich 1, which was ineffective for extracting P in calcareous soils. Extractable P by Mehlich 1, Olsen, and Pi all correlated highly with accumulated plant available P estimated by eight sequential crops in the greenhouse. However, none of the methods could account for all the variation in plant P removal. [ABSTRACT FROM PUBLISHER]

Background: Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a group of manmade chemicals containing at least one fully fluorinated carbon atom. The widespread use, large number, and diverse chemical structures of PFAS pose challenges to any sufficiently protective regulation, emissions reduction, and remediation at contaminated sites. Regulating only a subset of PFAS has led to their replacement with other members of the class with similar hazards, that is, regrettable substitutions. Regulations that focus solely on perfluoroalkyl acids (PFAAs) are ineffective, given that nearly all other PFAS can generate PFAAs in the environment. Objectives: In this commentary, we present the rationale adopted by the State of California's Department of Toxic Substances Control (DTSC) for regulating PFAS as a class in certain consumer products. Discussion: We at the California DTSC propose regulating certain consumer products if they contain any member of the class of PFAS because: a) all PFAS, or their degradation, reaction, or metabolism products, display at least one common hazard trait according to the California Code of Regulations, namely environmental persistence; and b) certain key PFAS that are the degradation, reaction or metabolism products, or impurities of nearly all other PFAS display additional hazard traits, including toxicity; are widespread in the environment, humans, and biota; and will continue to cause adverse impacts for as long as any PFAS continue to be used. Regulating PFAS as a class is thus logical, necessary, and forward-thinking. This technical position may be helpful to other regulatory agencies in comprehensively addressing this large class of chemicals with common hazard traits. https://doi.org/10.1289/EHP7431, Introduction The PFAS Class The term perfluoroalkyl and polyfluoroalkyl substances (PFASs) was first introduced by Buck et al. (2011) to describe certain manmade chemicals containing at least one fully fluorinated [...]