农林复合经营研究──桉树人工林间种西瓜对林木和土壤的效应

本文调查研究了雷州林业局纪家、河头林场桉树人工林间种西瓜对林木和土壤的影响．结果表明，利用造林前空隙种一造西瓜或在桉树林地间种西瓜，均有利于桉树生长．单位面积林木蓄积量和年生长量均比对照林分显著增加，经济效益显著；土壤养分也有增加。作为农林复合经营的有益尝试，值得在有条件的地区推广。     

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.     

向海湿地河道上下游土壤重金属污染程度分析

以向海湿地河道上、下游土壤沉积物为研究对象，以Al元素作为标准化元素，通过对重金属元素富集因子的分析，研究了Cu、Ni、Mn、Fe、Ba、Cr等6种重金属元素的人为污染状况及分级。结果表明，该区土壤沉积物中重金属元素均受到不同程度的人为污染影响，部分层面Ni、Ba等重金属元素污染程度达到显著水平，造成这种现象的主要原因是富含重金属的霍林河上游矿源物质的沉积及人类对湿地开发活动的历史变迁过程；此外，径流淹没频率不同造成了两断面土壤沉积类型和沉积效果的不同，使得受水文影响较大的上游断面的人为污染程度大于受影响较小的下游断面，说明向海湿地对人为污染具有一定的缓冲能力，或向海湿地具有较强的净化和过滤功能。     

高浑浊河流悬沙质量浓度的地面遥感监测方法

以金沙江中下游一级支流龙川江为例，通过探讨河流地面反射光谱与河流悬沙质量浓度的关系，初步开发了河流悬沙质量浓度的地面遥感预测技术。研究发现，基于R800/R550的经验模型，仅能够预测浓度范围在400g．m^-3以下的悬沙质量浓度值，对于较低悬沙质量浓度的河流或其他水域有较大运用价值。光学拟合技术能够预测龙川江在其整个变化范围的河流悬沙质量浓度，最高预测浓度可以达到13000g.m^-3。通过直接运用两种方法，或者进一步将它们提升成为卫星遥感运用技术后，对于中国西南众多的江河湖库有着重要的理论和现实意义。     

广东省水资源问题及可持续利用对策

论述了广东省的水资源状况和水资源利用中存在的主要问题，提出了水资源可持续利用的对策。认为水质性缺水、水利工程老化失修、水资源浪费严重、管理体制不健全是水资源利用中存在的主要问题；应加强水污染的防治，健全防洪防旱体系，建立健全水资源统一管理运作饥制，提高全民节水观念，发展节水农业，走兴林治水之路，使水资源可持续利用。     

畜禽养殖区磷流失对水环境的影响及其防治措施

概述了畜禽养殖废物中磷的流失对水环境的影响,分析养殖废物中磷的来源和流失途径,并从保护水资源的角度提出减少畜禽粪便中磷流失的管理和控制措施。     

铝离子与聚硅酸的相互作用

本文应用核磁共振技术及化学分析方法研究了铝离子与聚硅酸之间的相互作用情况;借助于微电泳技术测定了含铝离子的聚硅酸絮凝剂在不同pH值条件下水解沉淀物的表面ζ电位变化情况;借助于透射电镜手段及静置观察方法考察了铝离子含量对聚硅酸胶凝作用的影响。实验结果表明,聚硅酸对铝离子具有一定的螯合(络合)和吸附作用,但二者之间不存在定量的作用关系,而是聚硅酸对铝离子的作用量随着铝离子含量的增加而增加。铝离子影响聚硅酸的胶凝时间,适量的铝离子的存在可延长聚硅酸的胶凝时间。聚硅酸的存在影响铝离子在不同pH值下的水解沉淀物的ζ电位值,使得达到零电位状态时的pH值向低pH值方向移动。     

γ-辐照对水中腐殖酸去除的研究

以腐殖酸作为消毒副产物前驱物的代表,研究了γ-辐照对其去除效果.结果表明,γ-辐照对水中腐殖酸具有较好的去除作用.腐殖酸初始浓度为10mg·l-1时,在1.0kGy的辐照剂量下,腐殖酸去除率为88.6%,总有机碳减少62.8%,色度去除率为76%.随着辐照剂量的增加,氧化还原电位先增大后减小,而电导率则相反.在相同的辐照剂量下,初始浓度较低的腐殖酸去除率较高.碳酸盐对辐照去除腐殖酸具有抑制作用,中性条件有利于γ-辐照对腐殖酸的去除.辐照去除腐殖酸的过程可用一级动力学描述.     

Purification and some properties of β-N-acetyl-D-glucosaminidase from prawn (<Emphasis Type="Italic">Penaeus vannamei</Emphasis>)

The -N-acetyl-D-glucosaminidase (NAGase, EC 3.2.1.52) from prawn (Penaeus vannamei) was purified by extraction with 30% ethanol solution and ammonium sulfate fractionation, then chromatographed on Sephadex G-100 followed by DEAE-cellulose (DE-32) columns. The purified enzyme determined to be homogeneous by polyacrylamide gel electrophoresis (PAGE) and SDS-PAGE. The specific activity of the purified enzyme was 1,560 U mg^–1. Enzyme molecular weight was determined to be 105,000 Da; it contained two subunits of the same mass (45,000 Da). The pI value was calculated to be 4.8 by isoelectric focusing. The optimum pH and optimum temperature of the enzyme for the hydrolysis of pNP--D-GlcNAc (enzyme substrate) were determined to be pH 5.2 and 45°C, respectively. The behavior of the enzyme during hydrolysis of pNP--D-GlcNAc followed Michaelis–Menten kinetics, with K_m=0.254 mM and V_m=9.438 M min^–1, at pH 5.2 and 37°C. The stability of the enzyme was investigated, and the results showed that the enzyme was stable in a pH range from 4.2 to 10.0 and at temperatures <40°C. The effects of metal ions on the enzyme were also studied. Li⁺, Na⁺ and K⁺ had no influence on enzyme activity. Mg²⁺, Ca²⁺ and Mn²⁺ activated the enzyme, while Ba²⁺, Zn²⁺, Co²⁺, Cd²⁺, Hg²⁺, Pb²⁺ Cu²⁺, Fe³⁺ and Al³⁺ showed various degrees of inhibitory effects on the enzyme.Communicated by O. Kinne, Oldendorf/Luhe     

水处理无机混凝剂的研究进展

概略评述了国内外无机混凝剂的研究进展。无机混凝剂可分为铝盐类、铁盐类、铁铝复合类、活化硅酸等,聚合氯化铝（简称ＰＡＣ）是目前水处理中广泛应用的无机高分子混凝剂。无机复合类混凝剂是近来年发展十分迅速的水处理剂,聚硅酸铝盐类是其中的代表。文中对无机混凝剂今后的研究工作提出了建议,认为在无机混凝剂的研制开发中,要加强应用基础性研究,产品多样化、专门化,要降低生产成本,提高产品质量,进行优化研究。