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Rice generally contains higher levels of arsenic than most terrestrial-based foods. Studies related to dietary intake of arsenic from rice must take into account arsenic speciation due to toxicity differences in arsenic species. In this study, microwave-assisted extraction with trifluoroacetic acid was used to prepare rice samples for arsenic speciation analysis by high-performance liquid chromatography-inductively coupled plasma mass spectrometry. Fifty-three samples collected directly from the fields in four major rice-producing states in 1980 and 1981 were analysed for total and speciated arsenic and the results were compared with each other and with results for several more recently collected samples from local markets. The average content of total arsenic was 210 ± 190 ng As g(-1). This study demonstrates that US rice samples with higher levels of total arsenic have higher levels of dimethylarsinic acid; however, inorganic arsenic levels, regardless of the total arsenic content, rarely exceed 150 ng As g(-1) dry weight. These data are consistent with more recent findings, thus establishing trends that arsenic content in US-grown rice has been relatively constant throughout the last 30 years. To the authors' knowledge, the presented data are unique in that they provide a historical reference point for arsenic distribution in US-produced rice. These data would be invaluable for several applications including long-term arsenic exposure studies, environmental clean-up assessments, and to establish models for future trends in arsenic contribution in total diet studies.

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Evaporation of trichloroethylene (TCE) is a viable option in the remediation of TCE contaminated water. In this study, laboratory batch experiments were conducted to understand the evaporation kinetics of TCE in surface water, with further extension of this knowledge to field application. Experiments were set up for 15, 30, 60, and 90 min time intervals in open glass containers with initial concentration of 10 mgl −1 TCE in 100 ml water. The containers were either exposed to wind or were placed on an orbital shaker to produce constant water motion. A reference study carried out in absence of wind and water-motion showed much slower rate of TCE evaporation, compared to other studies done with wind or orbital shaker. Experiments with water turbulence at 150 rpm yielded a higher volatilization coefficient, K v =4.36 h −1 for TCE. The wind at a flow rate of 0.7 m/s also gave rise to 2.24 h −1 coefficient for TCE evaporation. The volatilization coefficient for the reference study yielded a smaller value of 0.23 h − 1 , with corresponding half-life of 3 h, indicating the importance of wind and water motion in TCE evaporation. Experiments conducted at 150rpm and 0.7 m/s wind velocity showed consistent evaporation trend, and were in better agreement with the extrapolated rate of evaporation obtained through the first order rate equation.