Potential Impact of Afforestation on Water Yield in the Subalpine Region of Southwestern China1

Abstract: To combat its growing ecological problems, China has implemented a large‐scale Natural Forest Protection Program (NFPP). Under the umbrella of this program, the Sloping Land Conversion Program (SLCP) was established in 1999 to return cultivated land with slopes of 25° or more to perennial vegetation. However, the regional impacts on water resource management that are incurred by afforestation have not been carefully evaluated, especially in the subalpine region of southwestern China. The purpose of the present study was to provide reference values for the SLCP by evaluating the potential impact of afforestation on water yield under different climatic regimes. Accordingly, evapotranspiration (ET) in cropland (CL), shrubland, and general forest was calculated using a modification of Thornthwaite’s method, and in coniferous forest, broad‐leaved forest (BF), and mixed coniferous and broad‐leaved forest (MF) using the Surface Energy Balance Algorithm for Land (SEBAL) model. The results of both approaches showed that afforestation reduces water yield by 9.6‐24.3% depending on the types of conversion and climatic conditions. Water‐yield reduction is greatest (>143.4 mm, or 24.3%) when CL is converted to BF in dry climate conditions. Compared with the other forest types studied, coniferous plantations prevented water‐yield reduction by as much as 9.6% because of their relatively low levels of ET. It is expected that implementation of the SLCP, together with continuing climate change, will further pressure regional water resources. Thus, the effectiveness of afforestation must be evaluated in a broader context while taking into account its positive ecological aspects, such as soil‐erosion control, the preservation of biodiversity, and the significant carbon sequestration provided by forests.     

陶瓷膜分离技术及其在造纸黑液处理中的应用

主要介绍陶瓷膜的制备工艺进展、动态膜分离技术以及陶瓷膜在造纸黑液中的应用研究进展。陶瓷膜中应用动态膜分离技术具有渗透通量高、反冲效果好、清洗周期长、易化学清洗等优势,研发该技术可行。     

Effect of microbial activity, soil water content and added copper on the temporal distribution patterns of HCB and DDT among different soil organic matter fractions

Temporal changes in the distribution of exogenous HCB and DDT among different soil organic matter fractions were studied under sterile and non-sterile conditions, different soil water contents, and different concentrations of added Cu(2+). The residence time was 311days. Soil organic matter was fractionated into fulvic acid (FA), humic acid (HA), bound-humic acid (BHA), lipid, and insoluble residue (IR) fractions by a methyl isobutyl ketone (MIBK) method. Results revealed that there is a mass transfer tendency of DDT and HCB from FA, HA and BHA to IR and lipid fractions with increasing residence time. Microbial activity accelerated the mass transfer, while the addition of Cu(2+) slowed it down. The HCB and DDT transfer rate decreased as the soil moisture increased from 1.9% to 60%, but increased when soil moisture increased further to 90%. A two-compartment first order kinetic model was used to describe the mass transfer from FA, HA and BHA.     

Metals in sediment/pore water in Chaohu Lake: Distribution, trends and flux

Nine metals, Cd, Cu, Ni, Pb, As, Cr, Zn, Fe, and Mn in sediment and pore water from 57 sampling sites in Chaohu Lake (Anhui Province, China) were analyzed for spatial distribution, temporal trends and diffuse flux in 2010. Metals in the surface sediment were generally the highest in the western lake center and Nanfei-Dianbu River estuary, with another higher area of As, Fe, and Mn occurring in the Qiyang River estuary. Metal contamination assessment using the New York sediment screening criteria showed that the sediment was severely contaminated in 44% of the area with Mn, 20% with Zn, 16% with Fe, 14% with As, and 6% with Cr and Ni. An increasing trend of toxic metals (Cd, Cu, Ni, Pb, As, Cr, Zn) and Mn with depth was shown in the western lake. Compared with metal content data from the sediment survey conducted in 1980s, the metal content of surface sediment in 2010 was 2.0 times that in the 1980s for Cr, Cu, Zn, and As in the western lake, and less than 1.5 times higher for most of the metals in the eastern lake. Among the metals, only Mn and As had a widespread positive diffuse flux from the pore water to overlying water across the whole lake. The estimated flux in the whole lake was on average 3.36 mg/(m². day) for Mn and 0.08 mg/(m². day) for As, which indicated a daily increase of 0.93 μg/L for Mn and 0.02 μg/L for As in surface water. The increasing concentration of metals in the sediment and the flux of metals from pore water to overlying water by diffusion and other physical processes should not be ignored for drinking-water sources.     

基于毒理基因组学的PBDE-209和镉联合毒性效应研究

多污染物引发的联合毒性是环境污染物风险评价中的重要问题之一,然而此类研究相对不足.多溴联苯醚和重金属镉可在多种环境介质中共存,虽对其各自单独暴露所产生的毒性已有相对明确的认识,但对二者联合毒性效应及其分子机制的探索仍十分有限.生物信息学的发展为污染物的健康效应研究提供了一种新的思路.为此,本研究基于比较毒理基因组学数据库(CTD)分析了十溴联苯醚和镉在单独或共同暴露下所影响的基因和相关疾病,推测两种污染物对胎儿红系造血过程产生的潜在影响,并进一步整合外源红系细胞基因表达数据库中的基因芯片确证二者共同影响的基因集合.同时,通过对这些基因集合进行生物学过程和信号通路富集分析,筛选出潜在的靶基因JAK3和AKT2,并在无显著细胞毒性的暴露条件下,通过体外细胞实验验证了十溴联苯醚和镉对这两个靶基因表达的干扰.本研究结果可为预防多溴联苯醚和重金属的联合暴露风险提供一定的科学依据,同时,CTD数据库和外源特定疾病发生发展相关基因表达数据库联合使用,并结合传统毒理学研究手段的评价模式,可为污染物的共同暴露与特定疾病的相关性及分子机理的探索在研究思路和技术手段上提供参考.     

韦布尔分布的环境因子

在试验样本较少时,需要对不同实验条件下的数据和信息进行转换和综合,这就要求人们必须对实验的环境因子进行确定.本文主要介绍了用韦布尔分布参数的估计值来确定环境因子的方法.本文首先给出了韦布尔分布的性质,然后对韦布尔分布环境因子进行了理论分析.根据环境因子的二因子法得出了韦布尔分布的环境因子并给出了其估计量.在此基础上提出了用环境因子进行数据转换和综合的步骤.     

北京市大气中NMHC的来源特征研究

对2006年北京气象塔每周大气中非甲烷烃(NMHC)数据进行了分析和研究,烷烃和芳香烃是大气中最丰富的组分,总NMHC浓度夏秋两季最高,春季最低。正矩阵因数分解(PMF)模型解析出5个非甲烷烃可能来源,分别是汽车尾气、汽油挥发、工业排放、燃烧源和植物排放。PMF解析的NMHC浓度与实测值有很好的一致性。和交通源相关的汽车尾气和汽油挥发是主要的排放源,贡献率分别为36.0%、26.3%,其他排放源为工业排放(23.1%)、燃烧源(10.1%)、植物排放(4.6%)。由于源、汇以及气象条件的影响,PMF解析出的各排放源贡献也表现出明显的季节变化。     

反硝化除磷系统中PHB红外光谱解析及其与磷去除率的相关性

为快速、准确测定生物除磷系统中微生物细胞内w(PHB)(PHB为poly-β-hydroxy butyrate,聚-β-羟基丁酸酯)并及时预测PO₄3--P去除率,采用红外光谱法对微生物细胞内PHB的转化规律进行解析,并结合气相色谱法建立w(PHB)的快速测定模型,研究w(PHB)减少量与PO₄3--P去除率的相关性. 结果表明:反硝化除磷系统中微生物细胞内PHB的特征峰位于波数1 730 cm-1处,PHB特征峰的吸光度与w(PHB)的增减趋势相同. 采用PLS(partial least squares,偏最小二乘法)对反硝化除磷系统中微生物细胞内PHB特征峰吸光度与w(PHB)建立PLS模型,对w(PHB)的校正和预测时的相关系数(R2)分别达到0.963 0、0.951 4,其均方根误差分别为0.031 0、0.037 9. 根据预测结果,进一步建立了反硝化除磷缺氧段w(PHB)减少量与PO₄3--P去除率的相关关系,相关系数为0.979 0. 研究表明,利用PLS模型对反硝化除磷系统中PHB红外光谱解析能够快速、准确地表征反硝化除磷系统中微生物细胞内w(PHB)的变化,并能进一步预测PO₄3--P去除率.      

脱水污泥/松木锯末水蒸气共气化研究

以城市污水处理厂机械脱水后的污泥(含水率约为80％)和松木锯末的混合物为原料,进行了共气化制取富氢燃气的研究.同时,采用热重分析(TGA)研究了混合样品的热失重特性,并在固定床反应器上考察了不同掺混比对燃气成分、燃气产量和碳转化率的影响.TGA结果表明,随着锯末掺混比的增加,样品的失重量、最大失重率及挥发分析出特性指数增大.在固定床反应器中,脱水污泥中的水分在高温条件下形成蒸气气氛,与产生的半焦发生了蒸气气化反应.实验结果表明,最佳掺混比为40％ ～ 60％,此时氢气含量、燃气产量、碳转化率分别为40％、0.70 m3· kg-1、64.1％.此外,借助BET和SEM对残余半焦的比表面积及表面形貌特征进行了分析.     

中国废荧光灯管理现状分析与政策建议研究

废荧光灯舍有汞,如不分类收集与处理,其所含的汞将分散或集中进入环境,影响人体健康.中国目前仍有大量工业、商业、大型公建与居民产生的废荧光灯未纳入正规管理渠道.本文从中国大陆废荧光灯的产生情况、含汞量水平以及荧光灯中汞对环境与人体的潜在危害等方面分析,评估了中国废荧光灯管理的必要性.结合中国废荧光灯管理的现状,提出了短期与长期管理政策建议.