Cadmium contamination in orchard soils and fruit trees and its potential health risk in Guangzhou, China

This study examines cadmium (Cd) contamination in orchard soils and fruit trees in Guangzhou, China, and assesses its potential health risk. Soils and tissues samples of three species of fruit trees were collected from three orchards. The average soil Cd concentration was 1.27, 1.84 and 0.68 mg/kg in orchards I, II, and III, respectively. The carambola (Averrhoa carambola) accumulated exceptionally high concentrations of Cd (7.57, 10.84, 9.01 and 2.15 mg/kg dw in root, twig, leaf and fruit, respectively), being 6.0-24 times and 4.0-10 times the corresponding tissue Cd in the longan (Dimocarpus longan) and wampee (Clausena lansium), respectively. Furthermore, all Cd concentrations (0.04-0.25 mg Cd/kg fw) of the fruits exceeded the tolerance limit of cadmium in foods of PR China (0.03 mg/kg fw). Our results indicate that the carambola tree has high Cd accumulation capacity and might be a Cd accumulator; and its fruit, among the three species of fruits studied, also poses the highest potential health risk to local residents.     

Heavy metal and Pb isotopic compositions of aquatic organisms in the Pearl River Estuary, South China

The accumulation of trace metals in aquatic organisms may lead to serious health problems through the food chain. The present research project aims to study the accumulation and potential sources of trace metals in aquatic organisms of the Pearl River Estuary (PRE). Four groups of aquatic organisms, including fish, crab, shrimp, and shellfish, were collected in the PRE for trace metal and Pb isotopic analyses. The trace metal concentrations in the aquatic organism samples ranged from 0.01 to 2.10 mg/kg Cd, 0.02 to 4.33 mg/kg Co, 0.08 to 4.27 mg/kg Cr, 0.15 to 77.8 mg/kg Cu, 0.17 to 31.0 mg/kg Ni, 0.04 to 30.7 mg/kg Pb, and 8.78 to 86.3 mg/kg Zn (wet weight). High concentrations of Cd were found in crab, shrimp and shellfish samples, while high concentration of Pb was found in fish. In comparison with the baseline reference values in other parts of the world, fish in the PRE had the highest elevated trace metals. The results of Pb isotopic compositions indicated that the bioaccumulation of Pb in fish come from a wide variety of food sources and/or exposure pathways, particularly the anthropogenic inputs.     

建设用地土壤污染状况调查监管存在的问题及对策探讨

明确了建设用地土壤污染状况调查监管的对象,分析了我国现阶段调查监管存在的监管力量不足、从业门槛不明确、实时监管措施缺乏等问题.结合国内外调查工作监管经验和近年苏州工业园区调查监管的探索实践,提出了鼓励引导相关利益方参与调查监管、建立健全从业人员和机构监管制度、引入监理机制、推进信息化过程管理等对策建议.     

Simulation of substrate degradation in composting of sewage sludge

To simulate the substrate degradation kinetics of the composting process, this paper develops a mathematical model with a first-order reaction assumption and heat/mass balance equations. A pilot-scale composting test with a mixture of sewage sludge and wheat straw was conducted in an insulated reactor. The BVS (biodegradable volatile solids) degradation process, matrix mass, MC (moisture content), DM (dry matter) and VS (volatile solid) were simulated numerically by the model and experimental data. The numerical simulation offered a method for simulating k (the first-order rate constant) and estimating k₂₀ (the first-order rate constant at 20 °C). After comparison with experimental values, the relative error of the simulation value of the mass of the compost at maturity was 0.22%, MC 2.9%, DM 4.9% and VS 5.2%, which mean that the simulation is a good fit. The k of sewage sludge was simulated, and k₂₀, k_20s (first-order rate coefficient of slow fraction of BVS at 20 °C) of the sewage sludge were estimated as 0.082 and 0.015 d^?1, respectively.     

Environmentally Friendly Polyurethane Composites: Preparation, Characterization and Mechanical Properties

The waterborne polyurethane (PU) prepolymer was prepared based on isophorone diisocyanate (IPDI), polyester polyol (N220), dimethylol propionic acid (DMPA) and hydroxyethyl methyl acrylate (HEMA). The modified waterborne polyurethane–acrylate (PUA) emulsions were obtained with different proportions of acrylate (butyl acrylate and methyl methacrylate) and initiating agent by in situ dispersion technique. The structures and thermal properties of prepared PU and PUA were analyzed and characterized with FT-IR, UV–Vis spectroscopy and DSC. The PUA hybrid samples had lower glass transition temperature of hard segment and higher decomposition temperatures than PU sample. Performances of the emulsion and film were studied by means of apparent viscidity, particle size and polydispersity, surface tension and mechanical properties. The results indicated that the particle sizes of the PUA dispersions were larger than those of the pure PU and the solvent resistance, mechanical properties of PUA films was improved compare with the unmodified polyurethane film. The film had the biggest hardness and the least water absorption when the BA/MMA mass ratio 5:5 modified PU. The obtained PUA have great potential application such as coatings, leather finishing, adhesives, sealants, plastic coatings and wood finishes.     

Design and risk assessment tool for vegetative treatment areas receiving agricultural wastewater: Preliminary results

Vegetative treatment areas (VTAs) are commonly being used as an alternative method of agricultural process wastewater treatment. However, it is also apparent that to completely prevent discharge of pollutants to the surrounding environment, settling of particulates and bound constituents from overland flow through VTAs is not sufficient. For effective remediation of dissolved agricultural pollutants, VTAs must infiltrate incoming wastewater. A simple water balance model for predicting VTA soil saturation and surface discharge in landscapes characterized by sloping terrain and a shallow restrictive layer is presented and discussed. The model accounts for the cumulative effect of successive rainfall events and wastewater input on soil moisture status and depth to water table. Nash–Sutcliffe efficiencies ranged from 0.65 to 0.81 for modeled and observed water table elevations after calibration of saturated hydraulic conductivity. Precipitation data from relatively low, average, and high annual rainfall years were used with soil, site, and contributing area data from an example VTA for simulations and comparisons. Model sensitivity to VTA width and contributing area (i.e. barnyard, feedlot, silage bunker, etc.) curve number was also investigated. Results of this analysis indicate that VTAs should be located on steeper slopes with deeper, more-permeable soils, which effectively lowers the shallow water table. In sloping landscapes (>2%), this model provides practitioners an easy-to-use VTA design and/or risk assessment tool that is more hydrological process-based than current methods.     

Inexact fuzzy-stochastic constraint-softened programming – A case study for waste management

In this study, an inexact fuzzy-stochastic constraint-softened programming method is developed for municipal solid waste (MSW) management under uncertainty. The developed method can deal with multiple uncertainties presented in terms of fuzzy sets, interval values and random variables. Moreover, a number of violation levels for the system constraints are allowed. This is realized through introduction of violation variables to soften system constraints, such that the model’s decision space can be expanded under demanding conditions. This can help generate a range of decision alternatives under various conditions, allowing in-depth analyses of tradeoffs among economic objective, satisfaction degree, and constraint-violation risk. The developed method is applied to a case study of planning a MSW management system. The uncertain and dynamic information can be incorporated within a multi-layer scenario tree; revised decisions are permitted in each time period based on the realized values of uncertain events. Solutions associated with different satisfaction degree levels have been generated, corresponding to different constraint-violation risks. They are useful for supporting decisions of waste flow allocation and system-capacity expansion within a multistage context.     

Using fuzzy method to evaluate safety condition of big diesel engine

Big diesel engine is one of the most important equipments in industry, and its safety condition plays a great role in oil production. This paper presents a fuzzy method to monitor the safety state of the big diesel. Six useful diagnostic characteristic parameters have been selected to diagnose safety condition of the big diesel engine. The standard fuzzy vector was obtained by using statistical method, so the status of big diesel's safety condition can be determined by calculating the fuzzy distance between the fuzzy vector and standard fuzzy vector. This fuzzy method has been successfully used on PZ12V190 diesel engine.     

实时气体分析在控制炼钢过程中的应用

电弧炉二次燃烧和转炉煤气回收是炼钢过程中2个最重要的节能降耗手段.而这2个过程中都需要对气体浓度进行实时分析来反馈控制工艺过程.分析了这两个过程中的气体实时分析的重要性,并对正在开发的激光气体分析系统进行了简要介绍.