Evaluation of 14C abundance in soil respiration using acclerator mass spectrometry

To clarify the behavior of 14C in terrestrial ecosystems, 14C abundance in soil respiration was evaluated in an urban forest with a new method involving a closed chamber technique and 14C measurement by accelerator mass spectrometry (AMS). Soil respiration had a higher Delta14C than the contemporary atmosphere. This indicates that a significant portion of soil respiration is derived from the decomposition of soil organic matter enriched in 14C by atmospheric nuclear weapons tests, with a notable time lag between atmospheric 14C addition and re-emission from soil. On the other hand, delta14C in soil respiration demonstrated that 14C abundance ratio itself in soil-respired CO2 is not always high compared with that in atmospheric CO2 because of the isotope fractionation during plant photosynthesis and microbial decomposition of soil organic matter. The Delta14C in soil respiration was slightly lower in August than in March, suggesting a relatively high contribution of plant root respiration and decomposition of newly accumulated and/or 14C-depleted soil organic matter to the total soil respiration in August.     

High-rate anaerobic digestion of sewage sludge by membrane separation solubilization coupled with UASB process

Journal of Material Cycles and Waste Management - Conventional anaerobic digestion (AD) process was often slow and thus required a large digestion tank. Upflow anaerobic sludge blanket (UASB)...     

Sorption of dissolved lead from shooting range soils using hydroxyapatite amendments synthesized from industrial byproducts as affected by varying pH conditions

For immobilization technologies to be successful, the use of readily available and cost advantageous amendment is important when the remediation targets vast amounts of contaminated soils. The objectives of this study were to investigate whether the byproduct-synthesized hydroxyapatite can be used as an immobilizing amendment for dissolved Pb from a shooting range soil, and to model the kinetic data collected from dissolution experiments. A soil–solution kinetic experiment was conducted under fixed pH conditions as a function of time. A Pb-contaminated soil was reacted with various hydroxyapatite amendments to determine the dissolution rate and mineral products of soil Pb. Three types of amendments used were pure hydroxyapatite (HA), and poorly crystalline hydroxyapatites synthesized from gypsum waste (CHA), and synthesized from incinerated poultry litter (PHA). The dissolved Pb concentration decreased with the addition of amendments at pH 3–7. Both CHA and PHA were more effective than HA for attenuating Pb dissolution at pH 6 and above. According to the thermodynamic calculation at pH 6, the dissolved Pb concentration for CHA and PHA treatments was predicted to be 66% and 50% lower than that of HA treatment, respectively. A better Pb immobilization effect demonstrated by CHA and PHA resulted in their greater solubility at higher pH, which may promote the formation of chloropyromorphite precipitates. Dissolution kinetics of soil Pb was adequately explained by pseudo-first order and pseudo-second order equations in acid pH ranges. According to the ion exchange model, an adequate agreement between the experimental data and regression curves was shown in the initial 40 min of the reaction process, but the accuracy of model predictability decreased thereafter. According to kinetic models and dissolution phenomena, CHA and PHA amendments had better Pb sorption capacity with rapid kinetics than pure hydroxyapatite at weak acid to neutral pH.     

Environmental activisms of firm’s neighboring residents: an empirical study in China

This paper develops an analytical framework based on the reasoned action theory and discusses the environmental activism (EA) of residents living close to the polluting companies. The data was collected by a questionnaire survey conducted in August of 2009 in Suzhou city of Jiangsu Province, China, which successfully obtained a total of 343 valid responses. The survey suggests that the residents are reluctant to act against their neighboring polluters. Nearly 10% respondents have never taken any action against the polluters, and the occasional EA participators account for 66.2% of the total. The items of EA, which require the residents to directly communicate with the governments or polluters, achieve very low ratios of participations (with a range of 5–25%). The path analysis confirms that there are large influences of certain attitudinal components on EA involvement. Understanding of corporate environmental information significantly determines the resident’s intention of EA practices. The residents have an obvious tendency to act collectively against the polluters. An essential message of this study is that the strategy of corporate environmental information disclosure may effectively increase the resident’s readiness of EA participation. The government shall responsively support the residents’ EA efforts since successful environmental protests will greatly convince them to jointly act against their neighboring polluters.     

Influence of velocity field on driftwood accumulation at a bridge with a single pier

Environmental Fluid Mechanics - Transport of driftwood during heavy rainfall events can intensify the flood hazard. Driftwood accumulates at a bridge and backwater rises. Accumulated logs sink...     

Material flow analysis of used personal computers in Japan

Most personal computers (PCs) are discarded by consumers after the data files have been moved to a new PC. Therefore, a used PC collection scheme should be created that does not depend on the distribution route of new PCs. In Japan, manufacturers’ voluntary take-back recycling schemes were established in 2001 (for business PCs) and 2003 (for household PCs). At the same time, the export of used PCs from Japan increased, affecting the domestic PC reuse market. These regulatory and economic conditions would have changed the flow of used PCs.In this paper, we developed a method of minimizing the errors in estimating the material flow of used PCs. The method’s features include utilization of both input and output flow data and elimination of subjective estimation as much as possible. Flow rate data from existing surveys were used for estimating the flow of used PCs in Japan for fiscal years (FY) 2000, 2001, and 2004. The results show that 3.92 million and 4.88 million used PCs were discarded in FY 2000 and 2001, respectively. Approximately two-thirds of the discarded PCs were disposed of or recycled within the country, one-fourth was reused within the country, and 8% were exported. In FY 2004, 7.47 million used PCs were discarded. The ratio of domestic disposal and recycling decreased to 37% in FY 2004, whereas the domestic reuse and export ratios increased to 37% and 26%, respectively. Flows from businesses to retailers in FY 2004 increased dramatically, which led to increased domestic reuse. An increase in the flow of used PCs from lease and rental companies to secondhand shops has led to increased exports. Results of interviews with members of PC reuse companies were and trade statistics were used to verify the results of our estimation of domestic reuse and export of used PCs.     

Radiocarbon and stable carbon isotope compositions of chemically fractionated soil organic matter in a temperate-zone forest

To better understand the role of soil organic matter in terrestrial carbon cycle, carbon isotope compositions in soil samples from a temperate-zone forest were measured for bulk, acid-insoluble and base-insoluble organic matter fractions separated by a chemical fractionation method. The measurements also made it possible to estimate indirectly radiocarbon ((14)C) abundances of acid- and base-soluble organic matter fractions, through a mass balance of carbon among the fractions. The depth profiles of (14)C abundances showed that (1) bomb-derived (14)C has penetrated the first 16cm mineral soil at least; (2) Delta(14)C values of acid-soluble organic matter fraction are considerably higher than those of other fractions; and (3) a significant amount of the bomb-derived (14)C has been preserved as the base-soluble organic matter around litter-mineral soil boundary. In contrast, no or little bomb-derived (14)C was observed for the base-insoluble fraction in all sampling depths, indicating that this recalcitrant fraction, accounting for approximately 15% of total carbon in this temperate-zone forest soil, plays a role as a long-term sink in the carbon cycle. These results suggest that bulk soil organic matter cannot provide a representative indicator as a source or a sink of carbon in soil, particularly on annual to decadal timescales.     

Formation of estrogenic products from environmental phthalate esters under light exposure

Phthalate esters (PEs) have been suspected to be environmental endocrine disruptors and the detailed mechanism remains unclear. The activities of these chemicals can be enhanced through chemical modification under the environmental conditions. We demonstrate that PEs acquire unequivocal estrogenic activity by light exposure. Through UV exposure of an aqueous PE solution, one active photoproduct, identified as 4-hydroxyPE (PE-4OH) based on its characteristic UV and mass spectra, was detected in an estrogen receptor alpha-dependent transactivation assay. PE-4OH was effectively generated by UV 290 nm. The PE-4OH production accompanied H2O2 generation in a UV dose-dependent manner. Both PE and UV irradiation were indispensable in the generation of H2O2. Addition of H2O2 to the PE solution increased PE-4OH production under UV irradiation. The PE-4OH production was also observed in the PE reaction with the Fenton reagent generating hydroxyl radical without UV irradiation. The proposed mechanism for PE-4OH production based on these results is such that by PE-mediated photosensitization H2O2 is generated from O2 and H+ and decomposed to hydroxyl radical, thus oxidizing the PE benzene ring. The PEs-4OH are remarkably active estrogenic products of PEs and would be involved in ER-mediated endocrine disruption.