粤北土地资源人口承载能力及其现实意义

本文从粮食生产潜力的角度,提出了广东省粤北(韶关市和清远市)的土地资源人口承载能力,并以我国2000年人口平均粮食需要量和第四次全国人口普查结果,预测了韶关市和清远市人口承载能力临界值出现的时间。这对宏观指导农业生产和控制人口增长,有重要的现实意义。     

示波极谱法对酚类化合物的分析

用示波极谱法对酚类化合物进行分析，方法的线性范围在３．０×１０￣（－５）～８．０×１０￣（－３）ｍｇ／Ｌ之间，最低检出限为６．０×１０￣（－６）ｍｇ／Ｌ，浓度为０．２６×１０￣（－２）～０．５２ｍｇ／Ｌ时的相对标准偏差为１．８％～４．０％，浓度为０．３×１０￣（－２）～０．５１ｍｇ／Ｌ时的回收率为９５．０％～１０２．１％，其结果与４－氨基胺替比林分光光度法相一致。     

后起之“绿”——沈阳

几年前，一提起沈阳人，人们自然就会把她与世界10大污染最严重的城市联系在一起。然而，近年来，沈阳市面貌有了翻天覆地的变化：城市干净了，河流清澈了，空气清新了。由于在环境方面的突出表现，沈阳市今年2月获得了中华环境奖，沈阳市环保局宣教中心还在今年“地球日”获得了“地球奖”的称号。     

铬酸钠共存对铝酸钠溶液种分的影响

研究了铬酸纳共存时对铝酸钠溶液种分的影响，结果表明，含有铬酸钠的铝酸钠溶液中，铝铬比大于３．６时，铬酸钠的存在对铝酸钠种分没有明显影响；铝铬比小于１．８时，铬酸钠的存在对铝酸钠种分有明显影响，本文还试验了选择一定组成的实际铝酸钠溶液，经种分，使铬酸钠与铝酸钠完全有得到了有效分离。     

经济发展与环境保护并重:机遇与挑战--访亚洲开发银行驻中国代表处首席代表涩市彻先生

中国快速增长的经济以及由此带来的诸如能源紧张、环境污染等问题已是众所周知，甚至是有点“老生常谈”的话题了。除了中国政府及早采取了经济“点刹”的方式外，各种各样的论坛、会议、研究都是“你方唱罢我登场”，媒体对此话题的报道也是“铺天盖地”。那么对于那些与中国经济发展有着密切关系的国际或区域金融组织的专家们有什么样的观点？他们又都采取了什么措施呢？近日。本刊记者对亚洲开发银行驻中国代表处首席代表涩市彻先生就有关经济发展和环境保护的话题进行了独家专访。[编者按]     

Forecasting of dissolved oxygen in the Guanting reservoir using an optimized NGBM (1,1) model

An optimized nonlinear grey Bernoulli model was proposed by using a particle swarm optimization algorithm to solve the parameter optimization problem. In addition, each item in the first-order accumulated generating sequence was set in turn as an initial condition to determine which alternative would yield the highest forecasting accuracy. To test the forecasting performance, the optimized models with different initial conditions were then used to simulate dissolved oxygen concentrations in the Guanting reservoir inlet and outlet(China). The empirical results show that the optimized model can remarkably improve forecasting accuracy, and the particle swarm optimization technique is a good tool to solve parameter optimization problems. What's more, the optimized model with an initial condition that performs well in in-sample simulation may not do as well as in out-of-sample forecasting.     

Effects of elevated atmospheric CO2 concentration and temperature on the soil profile methane distribution and diffusion in rice-wheat rotation system

The aim of this experiment was to determine the impacts of climate change on soil profile concentrations and diffusion effluxes of methane in a rice–wheat annual rotation ecosystem in Southeastern China. We initiated a field experiment with four treatments:ambient conditions(CKs), CO_2 concentration elevated to ~ 500 μmol/mol(FACE),temperature elevated by ca. 2°C(T) and combined elevation of CO_2 concentration and temperature(FACE + T). A multilevel sampling probe was designed to collect the soil gas at four different depths, namely, 7 cm, 15 cm, 30 cm and 50 cm. Methane concentrations were higher during the rice season and decreased with depth, while lower during the wheat season and increased with depth. Compared to CK, mean methane concentration was increased by 42%, 57% and 71% under the FACE, FACE + T and T treatments, respectively, at the 7 cm depth during the rice season(p 0.05). Mean methane diffusion effluxes to the 7 cm depth were positive in the rice season and negative in the wheat season, resulting in the paddy field being a source and weak sink, respectively. Moreover, mean methane diffusion effluxes in the rice season were 0.94, 1.19 and 1.42 mg C/(m~2·hr) in the FACE,FACE + T and T treatments, respectively, being clearly higher than that in the CK. The results indicated that elevated atmospheric CO_2 concentration and temperature could significantly increase soil profile methane concentrations and their effluxes from a rice–wheat field annual rotation ecosystem(p 0.05).     

三维粒子电极填充方式对焦化废水深度处理能耗的影响

采用钌钛网(Ti/Ru O2)为阳极、钛网(Ti)为阴极、活性炭颗粒为三维粒子电极的电催化氧化装置深度处理焦化废水,通过分析处理效果和能耗研究了三维粒子电极填充方式的影响。结果显示三维悬挂电极填充方式的处理效果和能耗与传统三维电极填充方式相近,但所需材料质量及反应器容积分别为后者的34%与67%。新的填充方式在电流密度2.5 m A/cm2、悬挂电极总质量49.4g、流速100 m L/min的条件下处理120 min后,焦化废水ρ(COD)由99 mg/L降至53 mg/L,COD去除率为46.5%,单位COD处理能耗为68.5 k W·h/kg,吨水能耗为3.15 k W·h/t。     

河流中碳、硫稳定同位素的研究进展

河流系统是全球生物地球化学循环的关键环节,是将陆地侵蚀物质输入海洋的主要通道.自然风化是河流水物源的主要营力,人为活动的影响使河流污染物的来源更加复杂,仅仅依靠主要离子组成不能很好的区分河流中物质的不同来源,而稳定碳、硫同位素可以示踪河流中物质的来源.本文综述了当代河流系统中碳、硫同位素的研究现状和分析方法,并对未来河流研究中碳-硫耦合循环研究进行了展望.