Selective predation on mature male Byblis japonicus (amphipoda: Gammaridea) by the barface cardinalfish,Apogon semilineatus

Ontogenetic change of habitat depths of Nautilus pompilius in the Philippines (Tañon Strait) and Fiji is considered by comparing ¹⁸O/¹⁶O ratios in septa and cameral fluid of live-caught specimens and ambient sea-water. ¹⁸O values of cameral liquid become heavier with decreasing volume within a chamber, which may be due to isotopic fractionation during discharge across the siphuncular wall. All of the seven Philippine and Fiji specimens analyzed show a distinct change in ¹⁸O from light values in the first seven septa to heavier values in the succeeding septa. Two different isotopic temperature scales are obtained for the Fiji and Philippine populations, suggesting a differential vital effect of metabolism between them. Sightly light ¹⁸O values in Septa 1 to 7 and hatching at relatively high temperatures in aquaria both suggest that N. pompilius hatch at the shallowest depths within their inhabitable vertical range. Depths of postembryonic animals in the Philippines and Fiji waters estimated from the isotopic temperature-depth diagrams range from 120 to 160 m and from 440 to 520 m, respectively, both of which correlate well with capture records. More than several tens of small-scale ¹⁸O cycles are detected in the sequence of nacreous layers within the single septum of a submature Philippine specimen. This can be interpreted as reflecting daily vertical migration.     

Implications of Land Use Changes on Carbon Dynamics and Sequestration—Evaluation from Forestry Datasets, India

Forests and soils are a major sink of carbon, and land use changes can affect the magnitude of above ground and below ground carbon stores and the net flux of carbon between the land and the atmosphere. Studies on methods for examining the future consequences of changes in patterns of land use change and carbon flux gains importance, as they provide different options for CO₂ mitigation strategies. In this study, a simulation approach combining Markov chain processes and carbon pools for forests and soils has been implemented to study the carbon flows over a period of time. Markov chains have been computed by converting the land use change and forestry data of India from 1997 to 1999 into a matrix of conditional probabilities reflecting the changes from one class at time t to another class time t+1. Results from Markov modeling suggested Indian forests as a potential sink for 0.94 Gt carbon, with an increase in dense forest area of about 75.93 Mha and decrease of about 3.4 Mha and 5.0 Mha in open and scrub forests, if similar land use changes that occurred during 1997–1999 would continue. The limiting probabilities suggested 34.27 percent as dense forest, 6.90 as open forest, 0.4 percent mangrove forest, 0.1 percent scrub and 58 percent as non-forest area. Although Indian forests are found to be a potential carbon sink, analysis of results from transition probabilities for different years till 2050 suggests that, the forests will continue to be a source of about 20.59 MtC to the atmosphere. The implications of these results in the context of increasing anthropogenic pressure on open and scrub forests and their contribution to carbon source from land use change and forestry sector are discussed. Some of the mitigation aspects to reduce greenhouse gas emissions from land use change and forestry sector in India are also reviewed in the study.     

An empirical model of soil chemical properties that regulate methane production in Japanese rice paddy soils

To understand which soil chemical properties are the best predictors of CH4 production in rice paddy soils, a model was developed with empirical data from nine types of rice soils collected around Japan and anaerobically incubated at 30 degrees C for 16 wk in laboratory conditions. After 1, 2, 4, 8, and 16 wk of incubation, CO2, CH4, and Fe(II) were measured to understand soil organic matter decomposition and iron (Fe) reduction. Available N (N ava) was also measured at the end of incubation. The results showed that decomposable C and reducible Fe are two key parameters that regulate soil CH(4) production (P CH4). There was a significant relationship between decomposable C and available N (N ava) (r2 = 0.975**). Except for a sandy soil sample, a significant relationship between total Fe (Fe total) and reducible Fe was found. From this experiment, a simple model of soil CH4 production was developed: P CH4 = 1.593N(ava) - 2.460Fe total/1000 (each unit was mg kg(-1) soil). After simulated CH4 production by two soil chemical properties as above, there was a significant consistency between model simulation and actual measurement (r2 = 0.831**).     

Photochemical decomposition of environmentally persistent short-chain perfluorocarboxylic acids in water mediated by iron(II)/(III) redox reactions

The photochemical decomposition of short-chain (C(3)-C(5)) perfluorocarboxylic acids (PFCAs) was investigated. Direct photolysis in water proceeded slowly with the 220- to 460-nm light emission from a xenon-mercury lamp to form F(-), CO(2), and shorter-chain PFCAs. Addition of a small amount of Fe(3+) to the aqueous solutions of the PFCAs dramatically enhanced their photochemical decomposition under an oxygen atmosphere: when the (initial PFCA)/(initial Fe(3+)) molar ratio was 13.5 (initial PFCA concentration=67.3mM), the pseudo-first-order rate constants for the PFCA decomposition were 3.6-5.3 times those with photolysis alone, and the turnover number for the catalytic PFCA decomposition [i.e., (moles of decomposed PFCA)/(moles of initial Fe(3+))] reached 6.71-8.68 after 24h of irradiation. The catalysis can be explained by photoredox reactions between PFCA, Fe(3+)/Fe(2+) and oxygen via photo-induced complexation of Fe(3+) with the PFCAs.     

Polychlorinated dibenzo-p-dioxins, dibenzofurans, and dioxin-like polychlorinated biphenyls in rice plants: possible contaminated pathways

Uptake of dioxins was confirmed in rice plants. We determined (i) dioxin concentrations and isomer profiles in leaf+stem samples of rice plants grown in three soils with different dioxin concentrations and isomer profiles and (ii) temporal changes in dioxin concentrations and isomer profiles in rice grown in a paddy field on which agricultural chemicals containing dioxin impurities had been used in previous years. Principal-component and chemical mass-balance analyses of the data showed that dioxin concentrations and isomer profiles in the rice grown in the different soils were similar, even though the dioxin concentrations and isomer profiles of the soils were different. However, the dioxin concentrations in the rice were influenced by dioxin levels in the atmospheric gas phase. Changes in dioxin levels during the growing period of the rice were also strongly influenced by adhesion of the soil to plant components during the early stage of growth, but gradually the influence of the atmospheric gas phase became predominant. Calculated dietary uptake estimates indicated that, even in rice grown in Japan on soil contaminated with high concentrations of dioxins, the amount of dioxins ingested by humans from rice is extremely small, and the amount of dioxins ingested by livestock from forage rice is similar to that for other forage crops.     

Humic-like substances global levels and extraction methods in aerosols

Environmental Chemistry Letters - The abundance of humic-like substances in the atmosphere has received considerable attention since these substances play an important role in various atmospheric...     

Influence of dispersants on bioconcentration factors of seven organic compounds with different lipophilicities and structures

Seven compounds with different lipophilicities and structures—1,3,5-trichlorobenzene, pentachlorobenzene, acenaphthylene, 1,4-dimethyl-2-(1-methylphenyl)benzene, 4-ethylbiphenyl, 4,4′-dibromobiphenyl, and 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane—were subjected to bioconcentration tests in carp at concentrations below the water solubilities of the compounds in the presence or absence of a dispersant (either an organic solvent or a surfactant). The bioconcentration factors (BCFs) of the compounds were on the order of 10²–10⁴. The BCF values remained in the range of 15–49% for all the compounds, whether or not a dispersant was present, i.e., the BCF values in the presence of an organic solvent or a surfactant at a concentration below the critical micelle concentration were not significantly smaller than the BCF values in the absence of the solvent or surfactant. This result indicates that the dispersants had no influence on the evaluation of the bioconcentration potential of these test substances.     

Techniques to separate metal from waste printed circuit boards from discarded personal computers

Waste printed circuit boards contain valuable metals such as Au, Pd, Ag, and Cu that can be reutilized and harmful elements such as Pb, Br, and Cr that must be removed from the viewpoint of environmental conservation. In this research, we examined a method that separates the materials from printed circuit boards contained in discarded personal computers. After cutting the printed circuit boards to a size of 20 × 20 mm, they were heated at 873 K under an Ar atmosphere to remove organic resins containing elements such as C, H, and N. After heat treatment, the printed circuit boards were crushed using a planetary ball mill and the pulverized powders were filtered. The fraction with a granularity of greater than 250 μm was separated into magnetic and nonmagnetic materials by a magnetic field. Because the fraction with a granularity of less than 250 μm contained 39 mass% of C, it was heated at 1273 K in an atmosphere of 95% Ar and 5% O₂ to allow carbon combustion to take place, followed by metal reduction processing at the same temperature in an atmosphere of 97% Ar and 3% H₂. The basicity of the resulting powder was adjusted and the powder was heated at 1773 K under an Ar atmosphere. The proposed method separated the slag and metal, and 80% of the valuable metals contained in printed circuit boards could be collected.     

Release of phosphorus from lake sediments

The relationship between the content of various forms of phosphorus in lakesediments and the amount of phosphorus released under aerobic and anaerobic conditions was studied. Total phosphorus content in the sediment of Lake Kasumigaura was highest at the 0–5 cm surface layer and decreased with depth. The constant value below 15 cm was consistent with the decrease of iron-bound phosphorus conent (FeP). The amount of phosphorus released from the sediments was proportional to the decrease of FeP under both aerobic and anaerobic conditions. Under anaerobic conditions, 90% of the FeP initially held in the sediments was released in 55 days. Using dialysis apparatus, maximum growth yield of algae was shown to be linearly dependent on the amount of phosphorus released under aerobic conditions.