Determination and potential importance of diterpene (kaur-16-ene) emitted from dominant coniferous trees in Japan

Reactive volatile organic compounds (VOCs) are known to affect atmospheric chemistry. Biogenic VOCs (BVOCs) have a significant impact on regional air quality due to their large emission rates and high reactivities. Diterpenes (most particularly, kaur-16-ene) were detected in all of the 205 enclosure air samples collected over multiple seasons at two different sites from Cryptomeria japonica and Chamaecyparis obtusa trees, the dominant coniferous trees in Japan,. The emission rate of kaur-16-ene, was determined to be from 0.01 to 7.1 μg dwg⁻¹ h⁻¹ (average: 0.61 μg dwg⁻¹ h⁻¹) employing branch enclosure measurements using adsorbent sampling followed by solid phase-liquid extraction techniques. The emission rate was comparable to that of monoterpenes, which is known major BVOC emissions, collected from the same branches. In addition, total emission of kaur-16-ene at 30 °C was estimated to exceed that of total anthropogenic VOC emissions.     

Extraction of raw sewage sludge containing iron phosphate for phosphorus recovery

The objective of the present study was to establish an alkali extraction technology for FePO₄-containing sewage sludge obtained from a wastewater treatment system that includes phosphorous removal by iron electrolysis. By clarifying the extraction properties of phosphorous, organic matter, and inorganic matter, conditions for alkali extraction were optimized. As a result, it was suggested that unheated phosphorous extraction would be superior for FePO₄-containing sewage sludge. And, extraction methods and sewage sludge properties were also compared, and the noteworthy result that extraction of metals can be suppressed to extremely low amounts with alkali extraction as compared with acid extraction was obtained. A new insight was also gained that, as compared with the use of incinerated ash reported in previous studies, alkali extraction was more efficient when raw sewage sludge was used.     

Studies on the accumulation and transformation of arsenic in freshwater organisms I. Accumulation, transformation and toxicity of arsenic compounds on the Japanese medaka, Oryzias latipes

Accumulation, transformation and toxicity of arsenic compounds to Japanese Medaka, Oryzias latipes were investigated. For sodium arsenite [As(II)] and disodium arsenate [As(V)], the mean value for 7-day lethal concentration LC50 for O. latipes were 14.6 and 30.3 mg As/l, respectively. Direct accumulation of arsenic in O. latipes increased as a function of As(III) concentration in water. A small proportion of accumulated arsenic was transformed to methylated arsenic. As much as 70% of the total arsenic accumulated in tissue was depurated. Accumulation and transformation of As(III) by O. latipes in a simple freshwater food chain were also investigated. The transformation of As(III) to As(V) by organisms was more prevalent than biomethylation of accumulated arsenic in organisms of the three steps of the food chain.     

Removal of Cr(VI) from contaminated soil by electrokinetic remediation

A new process for the removal of hexavalent chromium [Cr(VI)] contaminated soil is described. The process provides for an efficient removal of anionic chemicals from contaminated soils. Chromate anions were removed from the soil to the anodic reservoir by the moving force of electromigration. In this process, the chromate anions that accumulate in the anodic reservoir are simultaneously eliminated by using a column packed adsorbent. The adsorbent (immobilized tannin) used was chemically incorporated into cellulose. Cr(VI) was found to be adsorbed to this adsorbent efficiently. In the electrokinetic process, the pH of the aqueous solution in the anodic reservoir was decreased by the electrolysis of water. In the present study, the pH of the solution in the anodic reservoir is maintained at pH 6 by the addition of an aqueous alkaline solution during the electrokinetic process. The advantage of pH control is that it promotes the release of Cr(VI) from the soil by electromigration, thus permitting the maximum adsorption of Cr(VI) on the immobilized tannin. Simultaneous collection of Cr(VI) from the anodic reservoir leads to the protection from secondary contamination with Cr(VI).     

Tree-ring strontium-90 and cesium-137 as potential indicators of radioactive pollution

To examine whether tree rings can be used to detect or assess local historical 90Sr or 137Cs fallout, such as that resulting from the Hiroshima atomic bomb, radial distribution of 90Sr and 137Cs in trees was examined. We studied a gymnosperm [Japanese cedar, Cryptomeria japonica (L. f.) D. Don] and an angiosperm (Japanese persimmon, Diospyros kaki Thunb.) tree species from the vicinity of the atomic bomb hypocenter, and from other locations in Japan. A significant amount of 137Cs was detected in tree rings formed before 1945, indicating lateral migration of Cs. In contrast, the specific activity of 90Sr in the Hiroshima Japanese cedar showed the highest level in 1945, due to relatively immobile characteristics of Sr compared with Cs. Strontium-90 and Sr analyses in tree rings helped identify and distinguish between residual 90Sr activity from the Hiroshima atomic bomb and the atmospheric nuclear testing. This indicates the possibility of detecting or assessing previous local 90Sr pollution through with treering analysis.