Copper pyrithione (CuPT) and zinc pyrithiones used as alternatives to organotin antifoulants are toxic to aquatic organisms and are rapidly photolyzed by sunlight. CuPT residues in some sediments but not in seawater have been reported to date. The purpose of this study is to clarify the effect of sediments on the aquatic fate of CuPT. Adsorption and desorption of CuPT between natural marine sediments and artificial seawater was assessed according to the standardized OECD test guideline. Paint particles prepared from a commercial antifouling paint containing CuPT were added to seawater with the sediments. More than 85 % of CuPT in seawater was adsorbed to the marine sediments after a 24 h shaking, and the CuPT adsorption was independent on the ignition loss of the sediments. On the other hand, the CuPT desorption from sediments into seawater was less than 23 %, indicating about 80 % of the CuPT was remained in the sediments. The CuPT concentrations eluted from commercial antifouling paint particles into seawater in the controls were saturated within 5 days, and the ones with sediments were reduced to 38-90 % of the controls depending on the amounts of sediment added, thus suggesting adsorption of CuPT with sediments. The adsorption of CuPT with sediments may be one of the dissipation pathways of CuPT from seawater.

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Long time aging of organochlorine pesticides (OCPs) in agricultural soil was characterized by the sequential solvent extraction using series of shaking with 50% methanol-aq and n-buthanol, and finally soxhlet extracted with dichlorormethane. First, the extractability and the organic carbon normalized adsorption coefficient (Koc) of OCPs by these solvents were calculated to characterize the sequential extraction using 3 type soils. The 50% methanol-aq extractability of OCPs with low n-octanol water partition coefficient (Kow) values in soil with low organic carbon content tended to be high. The Koc of OCPs extracted by 50% methanol-aq tended to be related with Kow.
The exhaustive and the sequential extraction were applied to the paddy soil preserved since 1960s to characterize the long time aging of OCPs in soils. Although OCPs concentrations in paddy soil obtained by the exhaustive extraction have decreased since 1960s, recent decreasing rate is very slow. The half-lives of OCPs for disappearance from the paddy soils were estimated to be ∼5 years from 1960s to 1970s, around 10 years from 1980s to 1990s, respectively. The extractability of α-HCH with the 50% methanol-aq by shaking has been decreased. Additionally, the extractability of α-HCH with the dichlorormethane by soxhlet has been increased gradually. On the other hand, the changes in temporal extractabilities of dieldrin and p,p′-DDT was not found. These results can be indicated that long time aging of α-HCH among OCPs in agricultural soil for a half century can be found by the sequential solvent extraction.

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In this study, the surface property of activated carbons (ACs) was modified by outgassing and ammonia gas treatment to remove the surface acidic functional groups and to introduce the basic sites into the carbon surface, respectively. Then, the nitrate ion adsorption was performed using the prepared ACs to examine the effect of surface charge of the ACs under various solution pH. The competitive adsorption experiment between nitrate ion and nitrogen-containing aromatic compound was also conducted to specify the effective functional groups for the adsorption of nitrate ion. The result showed that low equilibrium pH (pH_e) of the solution enhanced the adsorption of nitrate ion, and the adsorption amount of nitrate ion at the same solution pH_e was promoted according to the increase in the amount of basic sites on the ACs. When the pH_e of the solution was lower than pK_a of the aromatic compounds, the amount of nitrate ion adsorption was increased in the presence of aromatic compounds, and the significant adsorption was observed accompanying the increase in pK_a value. Accordingly, it could be concluded that the basic groups possessing high pK_a value could promote the adsorption of nitrate ion

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A rapid and simple extraction of polychlorinated dibenzo-p-dioxins and dibenzofrurans (PCDD/Fs) derived from the herbicide “Agent Orange” in soil using ultrasonic device was investigated. The results were as follows. The ultrasonic extraction of PCDD/Fs using acetone showed the highest extraction efficiency compared with those of dimethlysulfoxide, methanol, acetone/hexane (1:1) and toluene. PCDD/Fs could be efficiently extracted by an addition of 0.1 mol/L H2SO4 to soil, especially to organic matter-poor soil, and also by an increase of sound pressure. The ultrasonic extraction of PCDD/Fs in soil for 60 min with more than 30 pounds per square inch (psi) showed more than 90% of extraction efficiency as well as soxhlet extraction with toluene. These results suggest that the ultrasonic extraction could be useful for a rapid and simple extraction of PCDD/Fs derived from the herbicide “Agent Orange” in soil.

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