Scenarios of major terrestrial ecosystems in China

The spatial pattern and mean-center shift of major terrestrial ecosystems, termed Holdridge Life Zones (HLZ), during the periods from 1961 to 1990 (T1), from 2010 to 2039 (T2), from 2040 to 2069 (T3) and from 2070 to 2099 (T4) were analyzed by combining the zonal patterns of climatic change in China and the climatic change scenarios of HadCM2 and HadCM3. The results showed that nival area would decrease rapidly with temperature increase in the future. HadCM2 and HadCM3 predicted that the nival areas might disappear in 552 years and 204 years, respectively. Using both HadCM2 and HadCM3, the five HLZ types with the largest areal extent are nival zone, cool temperate moist forest, warm temperate moist forest, subtropical moist forest and boreal wet forest, which collectively account for more than 50% of China's land mass. Among these five HLZ types, nival zone, warm temperate moist forest and boreal wet forest would decrease continuously, whereas subtropical moist forest and cool temperate forest would increase continuously during the four periods. HLZ diversity and patch connectivity would increase continuously in the 21st century. The shift distances of mean centers of HLZ types simulated using HadCM3 were markedly greater than those simulated using HadCM2, in general. The results from both HadCM2 and HadCM3 showed that boreal wet forest, subtropical moist forest, tropical dry forest, warm temperate moist forest and subtropical wet forest had bigger shift ranges, indicating that these HLZ types are more sensitive to the climatic change scenarios of HadCM2 and HadCM3.     

珠江河口水体的二氧化碳

本文根据1987年2月至1988年2月每月一次的调查资料,通过测定pH和碱度计算了珠江河口二氧化碳各分量,讨论了ΣCO_2,溶解CO_2与盐度、温度,叶绿素-a 和溶解氧饱和度的关系。     

碳源与底物对不同层次土壤产生N2O能力的影响

底层土壤的反硝化作用是土壤排放N_2O的重要来源,同时也是影响浅层地下水硝酸盐含量的重要因素.通过一系列室内培养试验.研究了一种农用土壤不同土层在碳源和NO_3含量不同情况下产生N_2O的能力。结果表明,试验用土壤的不同土层均具有进行反硝化作用产生N_2O的能力.底层土壤产生N_2O的能力大于根区土壤:单独添加葡萄糖、NO_3或同时添加葡萄糖和NO_3.对土壤N_2O和CO_2释放的影响与土壤层次和观测时间有关;向土壤添加葡萄糖和NO_3,各个土层释放N_2O的能力均显著提高;从产生N_2O和CO_2能力的角度而言,不同层次土壤的微生物区系间存在较大差异。采用短期(24h之内)饱和泥浆好气培养法,可以区分土壤微生物区系在产生N_2O方面的差异。     

[CO2]和温度增加的相互作用对植物生长的影响

ＣＯ2 和温度是影响植物生长、发育和功能的两个关键因子 .在过去一个世纪中 ,[ＣＯ2 ]从 2 80 μｍｏｌ/ｍｏｌ增加到 36 0μｍｏｌ/ｍｏｌ且每年增长速率为 1～ 5 μｍｏｌ/ｍｏｌ,到 2 0世纪末达到更高的浓度[1] .最近的模型预测表明 ,到 2 10 0年 ,全球表面温度可能会增加 1～ 4 .5℃ [2 \〗.ＣＯ2 是光合作用的底物 ,而且还是初级代谢过程 (气孔反应和光合作用 )、光合同化物分配和生长的调节者 .温度几乎影响植物所有的生物学过程 .因此 ,在全球气候变化要素中 ,大气 [ＣＯ2 ]和温度升高对植物的生理过程和生物量及产量具有极为重要的…     

Systemic retention of ingested cantharidin by frogs

Summary Frogs(Rana pipiens) fed on blister beetles (Meloidae) or cantharidin, retain cantharidin systemically. After cessation of feeding, they void the compound relatively quickly. Systemic cantharidin does not protect frogs against ectoparasitic feeding by leeches(Hirudo medicinalis) or predation by snakes(Nerodia sipedon). As suggested by our data, and from reports in the early literature, ingestion of cantharidin-containing frogs can pose a health threat to humans.Paper no. 95 of the seriesDefense Mechanisms of Arthropods; no. 94 is LaMunyon & Eisner, Psyche (in press)     

Hydroquinones from defensive secretion of a giant Pacific millipede, <Emphasis Type="Italic">Acladocricus setigerus</Emphasis> (Diplopoda: Spirobolida)

Summary. The presence of considerable quantities of hydroquinones including hydroquinone, 2-methylhydroquinone, 2,3- dimethoxyhydroquinone, 2-methoxy-3-methylhydroquinone, and 2,3-dimethoxy-5-methylhydroquinone renders the defensive secretion of Acladocricus setigerus (Silvestri, 1897) significantly different from that of other quinone-producing millipedes. In addition, two hitherto undescribed compounds, namely, 2,3-dimethoxy-5-methylhydroquinone and 2-methyl-3,4-methylenedioxyphenol, were characterized from the defensive secretion. However, it is uncertain if the latter compound is formed after the release of the secretion. The two major compounds, 2-methyl-1,4-benzoquinone and 2-methoxy-3-methyl-1,4-benzoquinone, constitute about 75% of the defensive fluid. Furthermore, hydrocarbons, which are typically present in the secretions of most other arthropods that use benzoquinones as repellents, are notably absent in the secretion of A. setigerus.     

Photocatalytic degradation of chlorophenols using Ru(bpy) 3 2+ /S2O 8 2−

Advanced oxidation processes, such as photocatalysed oxidation, provide an important route for degradation of wastes. In this study, the lowest excited state (³MLCT) of Ru(bpy)₃²⁺ is used to break down chlorophenol pollutant molecules to harmless products. This has the advantage of using visible light and a short-lived catalytically active species. Photolysis of deaerated aqueous solutions of a variety of mono- and poly-substituted chlorophenols has been followed in the presence of Ru(bpy)₃²⁺/S₂O₈²⁻ with near visible light (λ > 350 nm) by UV/visible absorption spectroscopy, luminescence, potentiometry, NMR and HPLC techniques. Upon irradiation, a decrease is observed in the chlorophenol concentration, accompanied by the formation of Cl⁻, H⁺ and SO₄²⁻ ions as the main inorganic products. Benzoquinone, phenol, dihydroxybenzenes and chlorinated compounds were the dominant organic products. As the ruthenium(II) complex is regenerated in the reaction, the scheme corresponds to an overall catalytic process. The kinetics of the rapid chlorophenol photodechlorination has been studied, and are described quite well by pseudo-first order behaviour. Further studies on this were made by following Cl⁻ release with respect to the initial Ru(bpy)₃²⁺ and S₂O₈²⁻ concentrations. A comparison is presented of the photodechlorination reactivity of the mono and polychlorophenols studied at acidic and alkaline pH.     

含TOA微胶囊对Cr2O7^2—萃取的研究

用乙基纤维素作膜材将三辛胺（简称ＴＯＡ）微胶囊化，用于萃取酸性水溶液中的Ｃｒ２Ｏ７＾２－离子。通过搅拌法萃取实验表明，ＴＯＡ被微胶囊化后对铬离子仍具有较高的萃取速度，实验测定渗透系数为６．７８×１０＾－６ｍ／ｍｉｎ，并能有效地防止乳化现象。将微胶囊制备成填充柱对Ｃｒ２Ｏ７＾２－进行萃取实验。对外相水的流速、微胶囊粒径、柱的重复使用次数与萃取容量的关系进行了研究。当粒径为１００－２００μｍ，流速为３     

Mo6+对活性污泥系统反硝化性能的影响

采用对比实验的方法,在不同初始硝酸盐氮和COD质量浓度的条件下,对人工模拟的活性污泥系统投加不同质量浓度的Mo6 ,以此考察Mo6 对活性污泥系统反硝化性能的影响。结果发现,Mo6 的质量浓度小于5mg?L-1以下时能够促进硝酸盐氮的去除,质量浓度为1mg?L-1时促进效果最好。Mo6 的质量浓度在4mg?L-1以下时,可以使COD去除效率增加,质量浓度为2mg?L-1时有最佳促进作用。Mo6 的质量浓度小于1g?L-1时可提高反硝化活性污泥的TTC-脱氢酶活性,过高质量浓度则表现出抑制作用。综合Mo6 的对硝酸盐氮和COD去除的影响规律以及对活性污泥TTC-脱氢酶活性的影响,认为Mo6 在质量浓度为1mg?L-1时对反硝化的促进作用最强。     

可见光下氮掺杂二氧化钛对巯基苯并噻唑的降解

光降解反应中为了有效地利用可见光,以氨水为氮源,采用溶胶凝胶法在温和条件下制备出黄色氮掺杂二氧化钛。分别采用XRD、TEM、XPS和UV-Vis漫反射光谱对样品进行了表征。结果表明,所制备的样品均为锐钛矿相,晶粒随N/Ti配比的增加而增大;氮掺杂进入二氧化钛晶格中使可见光吸收增强。为控制水处理过程中的气味问题,以巯基苯并噻唑为探针,考察了氮掺杂二氧化钛的可见光活性。结果显示氮掺杂二氧化钛在可见光照射下可使巯基苯并噻唑的降解率为商用二氧化钛DegussaP-25的3倍。此外,存在一个最佳N/Ti配比显示出最高的可见光活性。