Ten-Year Ozone Trends in California and Texas

Ozone trends have been developed for 50 California sites located in six basins and for 15 Texas sites in two regions. All data were obtained directly from state or local monitoring agencies and have been standardized to the current ultraviolet calibration basis. Rigorous standards of data representativeness and statistical validity have been adhered to throughout. The effect of monitoring variance upon apparent trends is reviewed as well as implications of this work for the ozone control strategy. Trends for 1973-82 for three key robust ozone statistics were developed in detail and analyzed. These are: annual average, annual hours >120 ppb and average daily maximum hour (May through October). Summaries for three other statistics including annual maximum hour are also included as well as composite trends for California basins and Texas regions. The statistical significance of all trends is discussed.     

Influences of perfluorooctanoic acid on the aggregation of multi-walled carbon nanotubes

The aggregation of multi-walled carbon nanotubes (MWCNTs) in the aqueous phase not only inhibits their extensive utilization in various aspects but also dominates their environmental fate and transport.The role of surfactants at low concentration in the aggregation of MWCNTs has been studied,however the effect of perfluorinated surfactants at low concentration is uncertain.To understand this interfacial phenomenon,the influences of perfluorooctanoic acid (PFOA),and sodium dodecyl sulfate (SDS) as a control,on MWCNT aggregation in the aqueous phase were examined by the UV absorbency method.Influences of pH and cationic species on the critical coagulation concentration (CCC) value were evaluated.The CCC values were dependent on the concentration of PFOA,however a pronounced effect of SDS concentration on the CCC values was not observed.The CCC values of the MWCNTs were 51.6 mmol/L in NaCl and 0.28 mmol/L in CaCl 2 solutions,which suggested pronounced differences in the effects of Na+ and Ca2+ ions on the aggregation of the MWCNTs.The presence of both PFOA and SDS significantly decreased the CCC values of the MWCNTs in NaCl solution.The aggregation of the MWCNTs took place under acidic conditions and was not notably altered under neutral and alkaline conditions due to the electrostatic repulsion of deprotonated functional groups on the surface of the MWCNTs.     

The World Needs a New Energy Paradigm

During 19–20 October 2009, the Royal Swedish Academy of Sciences arranged the international symposium Energy 2050 in Stockholm. The symposium was held in association with the Swedish EU presidency in autumn 2009. Internationally renowned scientists assessed the energy issue in a broad perspective, with particular emphasis on the possibilities of a fossil-free future. The symposium focused on key topics emanating from the in-depth energy studies carried through by the Academy´s Energy Committee since 2005. The world community is facing a challenge of historic proportions to define a new energy paradigm based on fossil-energy substitutes. This article gives an overview of the current global energy situation (2007) and of the technologies which have the major potential for supplying energy up to year 2050 without jeopardizing the CO₂ emission targets.     

A storm event-based approach to TMDL development

It is vitally important to define the critical condition for a receiving water body in the total maximum daily load (TMDL) development process. One of the major disadvantages of using a continuous simulation approach is that there is no guarantee that the most critical condition will be covered within the subjectively selected representative hydrologic period, which is usually several years depending on the availability of data. Another limitation of the continuous simulation approach, compared to a design storm approach, is the lack of an estimate of the risk involved. Because of the above limitations, a storm event-based critical flow-storm (CFS) approach was previously developed to explicitly address the critical condition as a combination of a prescribed stream flow and a storm event of certain magnitude, both having a certain frequency of occurrence and when combined, would create a critical condition. The CFS approach was tested successfully in a TMDL study for Muddy Creek in Virginia. The present paper reports results of a comparative study on the applicability of the CFS approach in Taiwan. The Dy-yu creek watershed in northern Taiwan differs significantly from Muddy Creek in terms of climate, hydrology, terrain, and other characteristics. Results show that the critical condition for different watersheds might be also different, and that the CFS approach could clearly define that critical condition and should be considered as an alternative method for TMDL development to a continuous simulation approach.     

Treatment Technologies for Hazardous Wastes: Part 1 Treatment Alternatives for Dioxin Wastes

The 1984 Amendments to the Resource Conservation and Recovery Act (RCRA), called the Hazardous and Solid Waste Amendments, (HSWA) direct the EPA to determine if dioxin bearing wastes should be prohibited from landfills. This determination is to made by November 1986. Barring a determination by the Agency that the land disposal of dioxin wastes does not represent a threat to the environment, ot that appropriate alternative treatment technology is not available, a land disposal prohibition would go into effect at that time.¹ The purpose of this paper is to discuss the state of the art for several treatment processes for dioxin wastes that have been proposed to be used instead of land disposal for disposing of solid and liquid wastes containing dioxins.     

Biogeochemical cycling of selenium in the San Joaquin Valley,California, USA

Subsurface agricultural drainage waters from western San Joaquin Valley, California, were found to contain elevated concentrations of the element selenium in the form of selenate. In 1978, these drainage waters began to replace previous input to Kesterson Reservoir, a pond system within Kesterson National Wildlife Refuge; this substitution was completed by 1982. In the 1983 nesting season, unusual rates of deformity and death in embryos and hatchlings of wild aquatic birds (up to 64% of eared grebe and American coot nests) occurred at the refuge and were attributed to selenium toxicosis. Features necessary for contamination to have taken place included geologic setting, climate, soil type, availability of imported irrigation water, type of irrigation, and the unique chemical properties of selenium. The mechanisms of biogeochemical cycling raise questions about other ecosystems and human exposure.     

Photodegradation of the herbicide EPTC and the safener dichlormid, alone and in combination

Photodegradation of the herbicide EPTC (S-ethyl-N, N-dipropylthiocarbamate), and the safener dichlormid (2,2-dichloro-N, N-diallylacetamide) has been examined in methanol and in water solutions. Irradiation of EPTC and dichlormid with UV light at 254 nm caused rapid degradation in both media. Remarkable and gradual changes in color of EPTC irradiated solution was observed from clear to yellow then to intense orange. EPTC half-life of elimination in water was 14.0, and 18.5 min, and in methanol 37.2 and 32.2 min, when irradiated with and without dichlormid, respectively. There was significant difference between rate of EPTC degradation in water and methanol in the presence or in the absence of dichlormid. Negligible degradation of EPTC or dichlormid at > 290 nm was observed. Photoproducts were separated and identified using GC or/and thin-layer chromatography then identified using mass spectrometry. It appeared that some products have high molecular weight that formed as a result of dimerization. This is possibly a result of the coupling of radicals that formed through EPTC degradation. The cleavage of C-S and C-N bonds accounted for the formation of these radicals. Gradual dealkylation of the acid chains of EPTC has also occurred. EPTC-sulfoxide, EPTC-sulfone, Propylamine and dipropylamine were detected as photoproducts of EPTC at 254 nm. Dichlormid pathways of degradation at 254 nm were characterized as dechlorination, dealkylation, and hydrolysis both in water and methanol. The findings showed that dichlormid did not significantly affect EPTC photodegradation either at 254 nm or at > 290 nm. The biological/toxicological properties of the photoproducts need further study, particularly the dimer compounds.     

New Technology for Conducting Radiation Hazard Assessments: The Application of the Underwater Radiation Spectral Identification System (URSIS) at the Massachusetts Bay Industrial Waste (U.S.A.)

The Underwater Radiation Spectral Identification System (URSIS) is a portable spectrometer used for the in situ detection of radioactivity in the marine environment. This paper reports on the first time application of this technology to assess, in a preliminary manner, the potential radiation threat to the public and environment at an aquatic disposal site – the Massachusetts Bay Industrial Waste Site (IWS). Utilizing the meneuvering capabilities of ROV and manned submersible vehicles, the URSIS was successfully positioned close (5–10 cm) to waste containers for a period sufficient to detect, in real time, the presence of radioactive materials. Spectral data from 45 individual targets indicated that the radionuclides present in sediments which draped or partially buried waste containers were consistent with natural background concentrations. No man-made radionuclides were detected at any of the target or background measurement locations. These data support the conclusion that low-level radiation does not pose an imminent and widespread human health or ecological threat in Massachusetts Bay.     

Sorption of chlorpyrifos and fonofos on four soils and turfgrass thatch using membrane filters

Abstract

Chemical transport in soil is a major factor influencing soil and water contamination. Four soils and turfgrass thatch, representing a wide range of organic carbon OC content were studied to determine sorption K_d and K_f parameters for the insecticides chlorpyrifos and fonofos. The batch equilibrium method was used. The concentration of insecticide was measured in the solution as well as in the solid phase to determine the most accurate sorption data. Four soils and thatch were equilibrated for 24 h at 22 ± 1^OC with aqueous insecticide solutions. Four concentrations of the insecticides, each <50% of their respective water solubilities, were selected for the experiments. After extraction with an organic solvent, the concentration of insecticides in the aqueous solution was determined by gas liquid chromatography using electron capture detection for chlorpyrifos, and nitrogen/phosphorus detection for fonofos. Data obtained were fitted to the log and simple linear form of the Freundlich equation. Mass balance Freundlich isotherm exponents n ranged between 0.82 and 0.93 for chlorpyrifos. 0.82 and 1.21 for fonofos, with r² ≥ 0.97. K_oc (percent of organic carbon %OC normalized Sorption coefficient) values were calculated by using experimentally developed K_d and K_f coefficients in relation to OC levels from 0.29 to 34.85%. K_d and K_f coefficients of both insecticides were positively correlated with OC (r² ≥ 0.96). organic matter OM (r² ≥ 0.96), and cation exchange capacity CEC (r² ≥ 0.90).