有机磷农药化学结构与色谱保留值定量关系研究（Research on the Relation between Chemical Structures of Organophosphorus Pesticide Residues and Their Chromatography Retention）

利用开放源代码软件CDK(Chemistry Development Kit)描述符和GC-MS以及GC-FPD测定值,对人参根部101种残留有机磷农药进行结构表征,分别以多元线性回归和偏最小二乘回归法建立定量结构色谱保留值关系模型.逐步线性回归模型的相关系数为R=0.942(R2=0.893),交互检验的复相关系数为R=0.912(R2cv=0.832).偏最小二乘模型的相关系数为R2=0.720,交互检验的复相关系数Q2=0.552.结果表明,原子极化率和电荷偏面积等分子属性具有表征能力强等优点,所建模型具有良好的稳定性和估计能力.     

Model of stomatal ammonia compensation point (STAMP) in relation to the plant nitrogen and carbon metabolisms and environmental conditions

Agricultural crops can be either a source or a sink of ammonia (NH₃). Most NH₃ exchange models developed so far do not account for the plants nitrogen (N) metabolism and use prescribed compensation points. We present here a leaf-scale simplified NH₃ stomatal compensation point model related to the plants N and carbon (C) metabolisms, for C₃ plants. Five compartments are considered: xylem, cytoplasm, apoplasm, vacuole and sub-stomatal cavity. The main processes accounted for are the transport of ammonium (NH₄⁺), NH₃ and nitrate (NO₃⁻) between the different compartments, NH₄⁺ production through photorespiration and NO₃⁻ reduction, NH₄⁺ assimilation, chemical and thermodynamic equilibriums in all the compartments, and stomatal transfer of NH₃.The simulated compensation point is sensitive to paramaters related to the apoplastic compartment: pH, volume and active transport rate. Determining factors are leaf temperature, stomatal conductance and NH₄⁺ flux to the leaf. Atmospheric NH₃ concentration seem to have very little effect on the compensation point in conditions of high N fertilization. Comparison of model outputs to experimental results show that the model underestimates the NH₃ compensation point for high N fertilization and that a better parametrisation of sensitive parameters especially active trasport rate of NH₄⁺ may be required.     

Origins and scales of hypoxia on the Louisiana shelf: Importance of seasonal plankton dynamics and river nutrients and discharge

Management plans for the Mississippi River Basin call for reductions in nutrient concentrations up to 40% or more to reduce hypoxia in the Gulf of Mexico (GOM), while at the same time the government is considering new farm subsidies to promote development of biofuels from corn. Thus there are possibilities of both increasing and decreasing river nutrients depending on national priorities. River flow rates which also influence the extent of hypoxia on the shelf may be altered by global climate change. We have therefore developed a series of simulations to forecast ecosystem response to alterations in nutrient loading and river flow. We simulate ecosystem response and hypoxia events using a linked model consisting of multiple phytoplankton groups competing for nitrogen, phosphorus and light, zooplankton grazing that is influenced by prey edibility and stoichiometry, sub-pycnocline water-column metabolism that is influenced by sinking fecal pellets and algal cells, and multi-element sediment diagenesis. This model formulation depicts four areas of increasing salinity moving westward away from the Mississippi River point of discharge, where the surface mixed layer, four bottom layers and underlying sediments are represented in each area. The model supports the contention that a 40% decrease in river nutrient will substantially reduce the duration and areal extent of hypoxia on the shelf. But it also suggests that in low and middle salinity areas the hypoxia response is saturated with respect to nutrients, and that in high salinity regions small increases in nutrient and river flow will have disproportionally large effects on GOM hypoxia. The model simulations also suggest that river discharge is a stronger factor influencing hypoxia than river nutrients in the Mississippi River plume. Finally, the model simulations suggest that primary production in the low salinity regions is light limited while primary production in the higher salinity zones is phosphate limited during the May to October period when hypoxia is prevalent in the Mississippi River plume.     

10a生连香树人工群落生物量研究

对１０年（ａ）生连香树人工群落生物量的分布与模型及凋落物进行了研究,主要结果为：①建立了连香树各器官与地（胸）径或树高的回归模型６８个．②群落总生物量（Ｗｔ／ｔｈｍ－２）为１２６．３２６,其中,地上和地下部分生物量（Ｗ／ｔｈｍ－２）分别为７６．０６８和４７．８１０,凋落物Ｗ为２．４４８．③群落、根系和吸收根的生产力（Ｐ／ｔｈｍ－２ａ－１）分别是１２．３８８～１５．２４８、４．７８１和０．６１１．④群落光能和有效光能利用率分别为０．７５％和１．８８％．⑤９７．４８％的根集中于０～２０ｃｍ土层,６９．９３％的根分布于距干基４０ｃｍ的水平范围;９２．０７％的叶分布于３～６ｍ的垂直范围,８３．８０％的叶分布于距干基１ｍ的水平范围;８４．０５％的干枝分布于距干基０．５ｍ的水平范围．⑥１０～１２月凋落量占全年的８１．２６％．⑦凋落物对元素生物循环的影响大小顺序为Ｐ＞Ｎ＞Ｋ＞Ｃａ＞Ｍｇ＞Ｆｅ＞Ａｌ＞Ｍｎ．⑧提出了生物循环功能系数、凋落物分解率和保存率的算法及含义     

Retaining natural vegetation to safeguard biodiversity and humanity

Global efforts to deliver internationally agreed goals to reduce carbon emissions, halt biodiversity loss, and retain essential ecosystem services have been poorly integrated. These goals rely in part on preserving natural (e.g., native, largely unmodified) and seminatural (e.g., low intensity or sustainable human use) forests, woodlands, and grasslands. To show how to unify these goals, we empirically derived spatially explicit, quantitative, area-based targets for the retention of natural and seminatural (e.g., native) terrestrial vegetation worldwide. We used a 250-m-resolution map of natural and seminatural vegetation cover and, from this, selected areas identified under different international agreements as being important for achieving global biodiversity, carbon, soil, and water targets. At least 67 million km² of Earth's terrestrial vegetation (∼79% of the area of vegetation remaining) required retention to contribute to biodiversity, climate, soil, and freshwater conservation objectives under 4 United Nations’ resolutions. This equates to retaining natural and seminatural vegetation across at least 50% of the total terrestrial (excluding Antarctica) surface of Earth. Retention efforts could contribute to multiple goals simultaneously, especially where natural and seminatural vegetation can be managed to achieve cobenefits for biodiversity, carbon storage, and ecosystem service provision. Such management can and should co-occur and be driven by people who live in and rely on places where natural and sustainably managed vegetation remains in situ and must be complemented by restoration and appropriate management of more human-modified environments if global goals are to be realized.     

ABR-SBR法处理草浆造纸中段废水试验研究

针对草浆造纸中段废水 ,进行了ABR、SBR及ABR SBR组合处理工艺的研究 ,结果表明 :ABR的HRT为 6h时 ,废水可生化性由 0 2— 0 2 5增加到 0 4— 0 5 ;SBR最佳HRT为 8h ,单独运行 ,COD去除率 6 5 %左右 ;ABR SBR组合工艺中SBR处理效果明显提高 ,COD去除率达 80 %左右 ,且组合工艺处理效果好 ,COD和BOD5去除率达 90 %左右 ,抗冲击负荷能力强。     

鄱阳湖典型洲滩湿地土壤质地与水分特征参数研究

频繁干湿交替增强了鄱阳湖洲滩土壤水对湿地系统的动态调节作用。以鄱阳湖吴城国家自然保护区的一个典型洲滩湿地为研究区,调查分析了土壤质地沿高程梯度的分布特征,确定了不同土壤质地的水分特征参数,并阐述了土壤质地与其水分特征参数的空间异质性。结果发现:该洲滩湿地主要分布砂土、粉壤土和粘土三种类型。水平断面方向上,粒径较粗的砂土和粉壤土主要分布在高位滩地,而粒径相对较细的粘土主要分布在近湖区开阔水面的低位滩地;土壤剖面方向上,土壤质地呈现出固有分层特性。van Genuchten模型应用于鄱阳湖洲滩湿地土壤水分特征曲线拟合,证实了该模型在鄱阳湖洲滩湿地的适用性。模型结果表明土壤残余含水率θr变化约9%~19%,饱和含水率θs变化约42%~57%,土壤进气值的倒数α约0.01 cm~(–1),水分特征曲线形状参数n介于1.11~4.65之间。土壤含水率变化对van Genuchten模型中参数α和n较为敏感,而对θr和θs的敏感性相对较弱。研究成果可为后续该区域以及全湖区湿地生态水文模型的构建和发展提供背景信息和参数资料。     

不同泥龄MBR中溶解性微生物代谢产物对膜污染的影响

通过4套平行运行的小试膜生物反应器(membrane bioreactor,MBR)研究了不同泥龄下溶解性微生物代谢产物(soluble microbial products,SMP)对膜污染的影响.以多糖、蛋白质表征SMP的含量,并通过三维荧光光谱(EEM)、分子量分布(MW)、红外光谱(FTIR)及扫面电镜-能谱分析(SEM-EDX)技术分析了不同泥龄下SMP的变化.结果表明,各泥龄MBR对氨氮和COD均有较好的去除效果,但SMP的含量以及膜污染程度均随着泥龄的升高而降低.泥龄越低,膜阻力越大,小分子量物质(＜1 000)积累程度越大,低泥龄MBR中蛋白质以及腐殖酸类物质含量较高;扫描电镜-能谱分析(SEM-DEX)结果表明,金属元素更容易在低泥龄MBR中的膜表面堆积.     

Historical nitrogen content of bryophyte tissue as an indicator of increased nitrogen deposition in the Cape Metropolitan Area, South Africa

Information on changes in precipitation chemistry in the rapidly expanding Cape Metropolitan Area (CMA) of South Africa is scarce. To obtain a long-term record of N deposition we investigated changes in moss foliar N, C:N ratios and nitrogen isotope values that might reflect precipitation chemistry. Tissue from 9 species was obtained from herbarium specimens collected between 1875 and 2000 while field samples were collected in 2001/2002. There is a strong trend of increasing foliar N content in all mosses collected over the past century (1.32-1.69 %N). Differences exist between ectohydric mosses which have higher foliar N than the mixohydric group. C:N ratios declined while foliar δ¹⁵N values showed no distinct pattern. From relationships between moss tissue N and N deposition rates we estimated an increase of 6-13 kg N ha⁻¹ a⁻¹ since 1950. Enhanced N deposition rates of this magnitude could lead to biodiversity losses in native ecosystems.     

Nitrous oxide emissions from an intensively managed greenhouse vegetable cropping system in Northern China

Nitrous oxide (N₂O) emissions from a typical greenhouse vegetable system in Northern China were measured from February 2004 to January 2006 using a close chamber method. Four nitrogen management levels (NN, MN, CN, and SN) were used. N₂O emissions occurred intermittently in the growing season, strongly correlating with N fertilization and irrigation. No peak emissions were observed after fertilization in the late Autumn season due to low soil temperature. 57-94% of the seasonal N₂O emissions came from the initial growth stage, corresponding to the rewetting process in the soil. The annual N₂O emissions ranged from 2.6 to 8.8 kg N ha⁻¹ yr⁻¹, accounting for 0.27-0.30% of the annual nitrogen input. Compared with conventional N management, site-specific N management reduced N fertilization rate by 69% in 2004 and by 76% in 2005, and consequently reduced N₂O emissions by 51% in 2004 and 27% in 2005, respectively.