海南省几种草本植物微量元素的组成

海南省位于我国热带地区，草本植物微量元素组成可反映热带区域生物地球化学特点。海南植物微量元素含量属正常范围值，仅个别植物Ｃｄ、Ｈｇ含量偏高。植物Ｚｎ、Ｃｕ、Ｍｏ含量大多在５ｍｇ／ｋｇ以上，Ｐｂ、Ｃｕ、Ｃｄ含量一般低于２ｍｇ／ｋｇ，Ｈｇ、Ａｓ、Ｎｉ通常不足１ｍｇ／ｋｇ。雀稗（Ｐａｓｐａｌｕｍｃｏｍｍｅｒｓｏｎｉ）、地胆草（Ｅｌｅｐｈａｎｔｏｐｕｓｓｃａｂｅｒ）等微量元素含量普遍较高。红裂稃草（Ｓｃｈｉｚａｃｈｙｒｉｕｍｓａｎｇｕｉｎｅｕｍ）、白茅（Ｉｍｐｅｒａｔａｃｙｌｉｎｄｒｉｃａ）等微量元素含量一般较低。植物微量元素组成与植物种类及其生境条件有关。生物吸收系数反映植物摄取元素的强度，Ｍｏ、Ｃｄ、Ｈｇ、Ｚｎ、Ｃｕ的生物吸收系数通常大于１．０，属强积聚元素，Ｐｂ、Ｃｒ、Ｎｉ、Ａｓ的生物吸收系数大多低于０．３，是弱摄取元素。     

Semi-analytical solution of two-dimensional sharp interface LNAPL transport models

In this paper, we present semi-analytical solutions for two-dimensional equations governing transport of Light Non-Aqueous Phase Liquids (LNAPL) in unconfined aquifers. The proposed model is based on sharp interface displacement and steady groundwater flow assumptions, where both the water–LNAPL interface and the LNAPL–air interface are represented as sharp interfaces. In the case of steady groundwater flow, these equations can be reduced to a two-dimensional nonlinear solute transport equation, with the LNAPL thickness in the free product lens being the primary unknown variable. The linearized form of this solute transport equation falls into the category of two-dimensional transport equation with time-dependent dispersion coefficients. This equation can be solved analytically for an infinite domain region. In this paper, the general form of the analytical solution for the transport equation, as well as the solutions for some specific cases are presented. To demonstrate the utility of the proposed solution, numerical results obtained for two example problems are discussed and presented comparatively with a finite-element solution and other more restrictive solutions available in the literature. Although the solutions discussed in this paper have some simplifying assumptions, such as sharp-interfaces between fluid phases, steady groundwater flow and homogeneous aquifer properties, the semi-analytical solutions presented in this study may be used effectively as bench mark solutions in evaluating LNAPL migration in the subsurface. These solutions are simple and cost effective to implement and may be used in the calibration of other more complex numerical solutions that can be found in the literature.     

Modeling VOC-odor exposure risk in livestock buildings

This paper describes a novel idea of linking models of exposure, internal dosimetry, and health effects. Risk assessment approach that integrates predicted odor caused by volatile organic compounds (VOC-odor) of toluene/xylene concentrations in human tissues leads to predict exposure risks in livestock buildings. First, VOC transport model was developed to calculate airborne toluene/xylene concentrations. Based on a physiologically based pharmacokinetic (PBPK) model, concentrations within five compartments representing lung, liver, fat, slowly perfused tissues, and rapidly perfused tissues could be quantified. By using a pharmacodynamic (PD) Hill model, we can optimally fit data from rat and human experiments to reconstruct dose-response relationships for accounting human health effects from nose poke and eye irritation. Results demonstrated that peak tissue concentration occurring at 5-10h in that fat contains the highest concentration than other tissues at around 4ppm of toluene and 1.8ppm of xylene. The EC(10) values are 114 and 232ppm, whereas expected risks are estimated to be 0.71% and 0.26% of human exposure to toluene and xylene, respectively. Risk analyses indicate that inhalation exposure in livestock buildings poses no significant threat to human health under the present environmental conditions. This method provides a rigorous and effective approach to relate target tissue concentration to human nose poke or eye irritation. We suggest that our probabilistic framework and methods be taken seriously because they produce general conclusions that are more robust and could offer a risk-management framework for discussion of future establishment of limits for respiratory exposure to VOC-odor.     

A full-scale sequencing batch reactor system for swine wastewater treatment

A full-scale sequencing batch reactor (SBR) system was evaluated for its ability to remove carbon and nitrogen from swine wastewater. The SBR was operated on four, six-hour cycles each day, with each cycle consisting of 4.5 hours of "React," 0.75 hours of "Settling", 0.75 hours for "Draw" and "Fill." Within each cycle, an amount of wastewater equivalent to about 5% of the reactor volume (5,500 litres) was removed and added. The SBR system was able to remove 82% of biochemical oxygen demand (BOD) and more than 75% of nitrogen. Even though the SBR effluent, with an average effluent BOD5 of about 588 mg L(-1), did not meet the discharge criteria, it enabled a reduction of the land base required for land application of swine wastewater by about 75%. Results indicated that the SBR system was a viable method for the treatment of swine wastewater.     

典型铬渣简易掩埋场铬渣及土壤铬污染特征和处置分析

通过钻孔采样分析,研究了典型铬渣简易掩埋场地下铬渣及土壤铬中Cr6 、总Cr的分布特征和污染状况,结果表明,铬渣简易掩埋场铬污染程度严重,引起了周边和地下深部较大面积的土壤污染,深度达到了地下的基岩.铬含量在土壤层剖面中分布呈现规律性变化,即随土壤深度增加,Cr6 、总Cr含量逐渐下降,但绝大多数超过了危险废物毒性鉴别标准.从铬污染程度上看,总体上存在铬渣>土壤>人工填土.在此基础上,提出了铬渣及污染土壤的处置方式,为铬渣污染治理和资源化利用提供科学依据.     

对璧山县旅游产品策划的再思考

在回顾国内外策划发展史的基础上，提出了璧山县旅游产品策划的概念；结合璧山县旅游产品策划的背景，提出璧山县旅游产品策划的原则，重点对新资源古特色、新功能、全面整合等旅游产品策划方式进行了研究。通过挖掘璧山县旅游资源特色及文化内涵，提出了璧山县旅游产品策划的几个方向。     

广东省杨村华侨柑桔场土壤微量元素含量与分布的研究

采集并分析全场不同母质形成的有代表性的土壤样本142个.研究结果表明，各类土壤全B、Mo、Zn和Mn含量的平均值均低于全国平均值，全量Cu平均值高于全国平均值.有效B、Mo、Zn和Mn含量的平均值均低于临界值，有效Cu的平均值稍高于临界值;但66.7％的土样有效Cu含量低于临界值.硼、钼、锌和锰严重缺乏，铜多数缺乏.全场各类土壤的微量元素含量差异较大，各类土壤微量元素的垂直和水平分布特征不尽相同，尤其是垂直分布差异明显.从土壤微量元素的全量与母质的关系来看，以玄武岩、紫色砂页岩母质形成的土壤全量较高，砂砾岩母质形成的土壤全量中等，砂页岩和冲积物母质形成的土壤全量较低.     

萍乡市农用土壤重金属含量及其分布特征分析

以江西省萍乡地区农用土壤为研究对象,分析研究了萍乡市农用土壤中重金属的含量、分布特征。结果表明:萍乡地区农用土壤中重金属的平均含量均未超过国家土壤环境质量二级标准,但其中锌、镍、铬、铜、镉、砷、铅、锰、汞的含量均超过了江西省土壤重金属相应元素的背景值。从空间分布来看,在全市5个县区布置的29个测点中,有14个测点的重金属含量超标;其中上栗县有8个测点超标,明显多于其他县区,出现了不同的污染特征。     

广西“十二五”主要污染物总量减排现状分析与探讨

实施污染物总量减排是中国环境管理和污染控制的重大举措,“十二五”后期仍是中国环境保护的重点内容,为此科学分析和制定有效的减排对策措施意义重大。通过总结广西“十二五”前三年总量减排工作现状及实施成效,从大气污染物减排、城镇污水处理、畜禽养殖污染防治、机动车氮氧化物控制、环境监管能力建设等方面分析存在问题,提出科学合理的减排对策建议：第一,突出污染减排倒逼作用;第二,严格环境准入;第三,狠抓大气污染物减排;第四,加强环保基层能力建设;第五,加强环境监管能力建设。     

萍乡市土壤中重金属离子含量、空间分布及其变化趋势研究

以江西省萍乡地区土壤为研究对象,分析研究了萍乡市土壤中重金属离子的含量及空间分布特征,并初步估算了重金属离子累积现速率和加速度.结果表明:萍乡市土壤整体环境质量较好,但随着社会经济的快速发展,工农业生产等人为活动对土壤的影响越来越大.从空间分布来看,在全市5个县区布置的52个采样点中,共有24个测点的重金属离子含量超标.其中上栗县有10个测点的重金属离子含量超标,明显多于其他县区,出现了与其他县区不同的污染特征.