Diffusive boundary layer development above a sediment-water interface.

A model to estimate the entry length to a fully developed diffusive boundary layer above a sediment bed, such as those found in lakes, reservoirs, rivers, and estuaries, is presented. The model is used to determine how the length of a sediment bed in mass-transfer experiments influences the measured vertical diffusive flux at the sediment-water interface. A nondimensional local mass flux is introduced in the form of a Sherwood number (Sh) and expressed as a function of both the distance from the leading edge of the sediment bed (x) and the Schmidt number (Sc). Similarly, a mean Sherwood number (Sh(ave)) for a sediment bed of length (L) is introduced. The diffusive boundary layer grows with distance, and its thickness depends on the Schmidt number (i.e., the diffusive boundary layer gets thicker and develops more quickly as the Schmidt number decreases). For Schmidt numbers greater than or equal to 100, the diffusive boundary layer begins to develop slowly but is fully developed when the nondimensional horizontal coordinate (x+) is approximately 1000. The Sherwood number is largest (i.e., infinity) near the leading edge of the sediment bed (i.e., at x = 0), decreases as the distance from the bed increases, and, finally, approaches a constant value for a fully developed diffusive boundary layer (Sh(infinity)). In this paper, the distance to a fully developed diffusive boundary layer (L99) and the required length of a sediment bed are related explicitly to Sc, sheer velocity (U*), and the relative errors of local or average Sherwood numbers (Sh or Sh(ave), respectively) against the Sherwood number for the fully developed diffusive boundary layer (Sh(infinity)). The lengths L99 and L decrease as the Schmidt number increases and become independent of the Schmidt number when Sc is greater than 1000. A longer sediment bed is needed when the shear velocity or the Schmidt number is small (e.g., L99 and L approximately 1.0 m and 8.0 m, respectively, for Sc = 500, U* = 0.1 cm/s, and a 3% acceptable error). Experimental studies may not be able to meet these requirements and an adjustment of measured mass-transfer rates at a sediment-water interface may be necessary. The magnitude of that adjustment is up to 50%. Its dependence on the Schmidt number, shear velocity, and bed length is given in this paper.     

Effects of deicing salt on the vitality and health of two spruce species,Picea abies Karst., and Picea glehnii Masters planted along roadsides in northern Japan

In northern Japan, the growth of Picea abies Karst., and Picea glehnii Masters, which have been planted along the highways, is often suppressed due to several environmental stresses. To examine the adverse effects of deicing salt, the primary source of stress,we measured needle life span, photosynthetic capacity, and water potential and transpiration rate of the two spruce species at a site with damaged trees, near the roadside and a site with healthy trees, located far from the highway. Results from the analysis showed large amounts of sodium and chlorine in the soil and snow at the damaged site. These elements had accumulated in the needles of the spruce. Moreover, physiological traits of the spruce, at the damaged site were also affected. Therefore, we concluded that poor physiological traits might be attributed to an accumulation of deicing salt in the needles, resulting in the suppression of tree growth.     

The OECD Validation Program of the H295R Steroidogenesis Assay for the Identification of In Vitro Inhibitors and Inducers of Testosterone and Estradiol Production. Phase 2: Inter-Laboratory Pre-Validation Studies (8 pp)

Background, Goals and Scope In response to concerns that have been raised about chemical substances that may alter the function of endocrine systems and result in adverse effects on human health, an OECD initiative was undertaken to develop and validate in vitro and in vivo assays to identify chemicals that may interfere with endocrine systems of vertebrates. Here we report on studies that were conducted to develop and standardize a cell-based screening assay using the H295R cell line to prioritize chemicals that may act on steroidogenic processes in humans and wildlife. These studies are currently ongoing as part of the ‘Special Activity on the Testing and Assessment of Endocrine Disruptors’ within the OECD Test Guidelines Program to review, develop, standardize, and validate a number of in vitro and in vivo toxicological assays for testing and assessment of chemicals concerning their potential to interact with the endocrine system of vertebrates. Study Design Six laboratories from five countries participated in the pre-validation studies. Each laboratory tested the effects of three model chemicals on the production of testosterone (T) and estradiol (E2) using the H295R Steroidogenesis Assay. Chemicals tested were well described inducers or inhibitors of steroidogenic pathways (forskolin, prochloraz and fadrozole). All experiments were conducted in 24 well plates following standard protocols. Six different doses per compound were analyzed in triplicate per plate. A quality control (QC) plate was run in conjunction with the chemical exposure plate to account for inter-assay variation. Each chemical exposure was conducted two or three times. Results All laboratories successfully detected increases and/or decreases in hormone production by H295R cells after exposure to the different model compounds and there was good agreement in the pattern of response for all groups. Forskolin increased both T and E2 while fadrozole and prochloraz decreased production of both hormones. All chemicals affected hormone production in a dose-dependent manner with the exception of fadrozole which caused maximum inhibition of E2 at the two least concentrations tested. Some inter-laboratory differences were noted in the alteration of hormone production measured in chemically exposed cells. However, with the exception of the production of T measured at one laboratory in cells exposed to forskolin, the EC₅₀s calculated were comparable (coefficients of variation 34–49%) for all hormones. Discussion and Perspectives The results indicated that the H295R Steroidogenesis Assay protocol was robust, transferable and reproducible among all laboratories. However, in several instances that were primarily related to one laboratory there were unexplained minor uncertainties related to the inter-laboratory hormone production variation. Based on the findings from this Phase 2 prevalidation study, the H295R Steroidogenesis Assay protocol is currently being refined. The next phase of the OECD validation program will test the refined protocol among the same group of laboratories using an extended set of chemicals (∼30) that will include positive and negative chemical controls as well as a broad spectrum of different potential inducers and inhibitors of steroidogenic pathways. Submission Editor: Dr. Carsten Brühl (bruehl@uni-landau.de)     

Decolorization of Orange II using an anaerobic sequencing batch reactor with and without co-substrates

We investigated the decolorization of Orange II with and without the addition of co-substrates and nutrients under an anaerobic sequencing batch reactor (ASBR). The increase in COD concentrations from 900 to 1750 to 3730 mg/L in the system treating 100 mg/L of Orange II-containing wastewater enhanced color removal from 27% to 81% to 89%, respectively. In the absence of co-substrates and nutrients, more than 95% of decolorization was achieved by the acclimatized anaerobic microbes in the bioreactor treating 600 mg/L of Orange II. The decrease in mixed liquor suspended solids concentration by endogenous lysis of biomass preserved a high reducing environment in the ASBR, which was important for the reduction of the Orange II azo bond that caused decolorization. The maximum decolorization rate in the ASBR was approximately 0.17 g/hr in the absence of co-substrates and nutrients.     

关于资源技术与工程学科建设若干问题的讨论

资源技术与工程是现阶段资源科学学科建设的主要方向之一,是研究资源直接利用、间接利用、循环利用的理论、方法和实践的学科,其研究对象为物质实体。目前国内外资源技术与工程学科建设的进展仍处于纵向分异的阶段,单项资源(水、土、气、生物、矿产、能源等)利用的技术与工程研究仍是其主要特征。资源技术与工程的基本学科定位应为工学,其学科体系可分为3个二级学科和12个三级学科。在开展资源技术与工程学科建设时,理科院校应侧重于新型资源、替代资源的开发利用技术与工程研究,而工科、农科院校则应注重单项资源以及多项资源之间的再生利用、循环利用、保护利用、协同利用和综合利用技术与工程研究。     

Degradation of Reactive Yellow 86 with photo-Fenton process driven by solar light

The decolorization of Reactive Yellow 86(RY 86),one of reactive azo dyes,was investigated in the presence of Fenton reagent under solar light irradiation.The decolorization rate was strongly influenced by pH,initial concentrations of H 2 O 2 and Fe(II),and so on.An initial concentration of 40 mg/L was decolored more than 90% after 20 min under optimum conditions.The activation energy of the solar photo-Fenton reaction was 1.50 kJ/mol for RY 86 in the temperature range of 10-60°C.In the kinetic study,the rate constant of RY 86 with OH· radicals could be estimated to be 1.7 × 10 10 L/(mol·sec).The decolorization efficiency of RY 86 under solar light irradiation was comparable to the artificial light irradiation.The decrease of TOC as a result of mineralization of RY 86 was observed during photo-Fenton process.The rate of RY 86 mineralization was about 83% under UV irradiation after 24 hr.The formation of chloride,sulfate,nitrate and ammonium ions as end-products was observed during the photocatalytic process.The decomposition of RY 86 gave two kinds of intermediate products.The degradation mechanism of RY 86 was proposed on the base of the identified intermediates.     

Why did the project fail to achieve its objectives in some villages? The experience of the Upland Settlement Project (USP) in Bangladesh

By sampling an upland settlement project (USP) village, this study examined why the project failed to achieve the planned objectives in some villages, and what livelihood strategies villagers (planters) have adopted to sustain their livelihoods. The paper uses data obtained by qualitative and quantitative methods. The USP was formulated with the objectives of settling 50 landless and marginal tribal families in a project village and introducing agroforestry and rubber plantations for short- and long-term socioeconomic development of planters, in a participatory manner. There are now only 15 planters in the project village and, although agroforestry has progressed well, only 30 to 40% of poor quality rubber trees remain. Planter participation in project activities was limited to wage labour, indicating that the USP failed to adequately achieve all its proposed objectives. In the face of project failure, planters have adopted diversified strategies to maintain their livelihoods. Several shortcomings caused failure of the project, such as the inability of project staff members to organize planters, failure to create awareness among planters about project benefits, lack of regular project money disbursement, sociocultural ignorance, and lack of social capital among planters. Recommendations are made for securing effective participation of local people to assure successful and sustainable project outcomes. Lessons learned will be helpful in formulating future development programmes in this country and elsewhere.     

Developing joint educational programs in sustainability science across different universities: a case study from Japan

The challenge for sustainability educational programs lies in how to imbue students with the strong motivation necessary to move the world in a more sustainable direction. Five universities in Japan have mutually collaborated in the design and development of a unique curriculum and education system for sustainability science since 2008. Specifically, they have developed a common and remote lecture system called the “Frontier of sustainability science” (FSS). This paper discusses the concepts and challenges of FSS and how it was organized to teach students to actively learn how to work with people of various disciplines to realize interdisciplinarity.     

Restoration of cadmium-contaminated paddy soils by washing with ferric chloride: Cd extraction mechanism and bench-scale verification

The ability of FeCl3 to extract Cd from three paddy soils was compared with that of various irons, manganese, and zinc salts to elucidate the extraction mechanism. Manganese, zinc and iron salts (including FeCl3) extracted 4-41%, 8-44% and 24-66% of total Cd, respectively. This difference reflected the pH of the extraction solution, indicating that the primary mechanism of Cd extraction by FeCl3 is proton release coupled with hydroxide generation, as iron hydroxides are insoluble. Washing with FeCl3 led to the formation of Cd-chloride complexes, enhancing Cd extraction from the soils. FeCl3 effectively extracted Cd from all of the three soils compared to HCl that is a conventional washing chemical, when the concentrations of the two washing chemicals were between 15 and 60mM(c) (at above extraction pH 2.4), while the corresponding extraction pH of FeCl3 was slightly higher than HCl. As HCl is the strong acid of complete dissociation, if excess amount of HCl was added to soil, it is possible to give the dissolution of clay minerals in soils. In contrast, proton release from FeCl3 is controlled by the chemical equilibrium of hydroxide formation. While soil fertility properties were affected by a bench-scale soil washing with 45mM(c) FeCl3, adverse effects were not crucial and could be corrected. The bench-scale test confirmed the effectiveness of FeCl3 for removal of soil Cd. The washing had no negative effect on rice yield and lowered the Cd concentration of rice grain and rice straw in a pot experiment.     

Photodegradation of hexachlorobenzene and theoretical prediction of its degradation pathways using quantum chemical calculation

Experimentally determined photodegradation pathways of hexachlorobenzene (HCB), a chlorinated aromatic compound, in hexane, 2-propanol (IPA), and methanol were compared with those predicted by quantum chemical calculation based on density functional theory (DFT), and the adequacy of the prediction method was evaluated. The experimental main degradation pathways of HCB were virtually the same for the three solvents and also agreed with the predicted main degradation pathways. In the DFT method, the main degradation product was the dechlorinated benzene at the position where the C-Cl bond was predicted to have the lowest bond dissociation energy. This result suggested that the photodechlorination pathways of chlorinated aromatic compounds could be predicted by comparing the bond dissociation energies calculated with the DFT method.