Germination,Growth, and Nodulation of Sesbania rostrata Grown in Pb/Zn Mine Tailings

Sesbania rostrata in pure and amended Pb/Zn tailings. About 90% of seeds of S. rostrata germinated in pure Pb/Zn tailings, which contained high concentrations of Pb, Zn, Cu, and Cd. Although seedling growth suffered from the adverse environment of Pb/Zn tailings, they became established on tailings stands, in the greenhouse, as well as on the actual tailings dam, and completed their life cycle in 4 months. Dry matter production and nitrogen accumulation was 3200 kg/ha and 69.4 kg/ha, respectively in the actual tailings dam. Applying inorganic fertilizer to Pb/Zn tailings led to no obvious improvement in growth and nodulation of S. rostrata, while tailings amended by river sediment or domestic refuse rich in organic matter improved the growth and nodulation of the species. Azorhizobium caulinodans survived and formed N-fixing stem and root nodules in S. rostrata grown in pure Pb/Zn tailings with a nodule biomass exceeding 300 mg fresh matter per plant.     

土地整理与可持续发展

本文在分析土地整理产生的客观必要性的基础上．进一步系统阐述推进土地整理是实现可持续发展的必由之路和动力机制，最后提出可持续土地整理的理性思考和对策。     

湖南省洪涝灾害脆弱性评估和减灾对策研究

自然灾害灾情受到灾害系统脆弱性和致灾因子风险性的共同作用，而脆弱性是自然环境变化和人为影响因素在一定的时空条件下耦合的产物。同一致灾强度下，灾情随脆弱性的增强而加重，降低灾害脆弱性可减轻灾害造成的经济损失，因此灾害脆弱性的研究对防灾抗灾具有重要的意义。洪涝灾害是湖南省最严重的自然灾害之一。根据长时间序列的气象资料和经济统计数据，选取7项指标，应用数学模型来综合评估湖南省洪涝灾害的脆弱性．揭示洪涝灾害脆弱性的基本特征。结果表明湖南省洪涝灾害脆弱性总体水平较高，并且具有明显的空间分异规律。通过相关分析，表明这种分异规律与实际洪涝灾害情况具有一致性，说明本研究对该区防洪抗涝决策有一定的借鉴和指导作用。最后针对影响洪涝灾害脆弱性的因素和成灾机制，提出一系列可持续的生态减灾工程体系的建设思路。     

结构风灾经济损失模型在GIS中的应用

在城市抗风防灾研究中，采用GIS技术已成为一种必要的手段，但现有结构风灾经济损失模型参数多，不易采集，造成建立GIS数据库具有一定的困难。因此，简化模型，降低数据采集难度的工作量是十分必要的，本文采用样本计算，制成表格供查询使用，在保证计算精度的前提下，使参数由12个减为2个，大大降低了数据采集和GIS数据库建立的难度。     

改善北京市大气环境质量中居民支付意愿的影响因素分析

本文旨在用统计的方法 ,分析影响北京市居民为改善大气环境质量而付费的支付意愿的主要社会经济因素。分析结果表明 ,对被调查者支付意愿影响最显著的因素是家庭收入 ,其次是年龄、家庭人口数和教育水平。其中 ,收入和教育水平对支付意愿的影响为正 ,年龄和家庭人口数的影响为负。对调查范围内八个行政区被调查者的支付意愿均值比较显示 ,这八个区居民的支付意愿没有显著性差异。本文的结论是 ,提高收入水平和环境意识水平 ,是提高公众为改善环境质量而付费的支付意愿的有效途径     

Identification of weed plants excluding the uptake of heavy metals

Using the field pot-culture and sample-analysis method, 54 weed species belonging to 20 families and 31 weed species belonging to 17 families were systematically examined as to whether they can exclude the uptake of heavy metals. After a systematic identification, it was determined that Oenothera biennis and Commelina communis were Cd-excluders and Taraxacum mongolicum was a Zn-excluder. O. biennis is a potential Cd-excluder, but also a potential Cu-excluder. The research raises the possibility of making a major breakthrough in the application of metal excluders for safe agro-production in the future.     

Incidence rates and risk factors for injury events in high school students in Lijin County, China

PROBLEM: Most investigations of injuries among Chinese populations are focused on urban or better developed areas, fewer on rural or poor areas. METHODS: From September 21 to 27, 2002, an epidemiological investigation of eight kinds of injury-related events was carried out among 1,944 students in 39 classes randomly sampled from middle schools in Lijin County, a rural area. The eight kinds of events were: (a) traffic accidents, (b) poisoning, (c) fall, (d) burn or scald, (e) blunt or sharp tools contact, (f) electrical contact, (g) animal or insect bites, and (h) non-fatal drowning. RESULTS: The total incidence rate of eight kinds of injuries in the previous year was 21.1%. The incidence rate among boys was 24.2%, while that among girls was 17.4%, which was significant (chi-square=13.4, P<0.05). The incidence rate among junior high school students was 23.1%, while that among senior high school students was 15.5%, which was also significant (chi-square=13.2, P<0.05). A case-control study of 410 students with at least one of eight kinds of injury events indicated that students' gender and their mothers' health status were related to their injuries. CONCLUSION: The injury incidence rate in a rural area was less than other results in urban or developed areas. Students' gender and mothers' health status were important factors associated with the occurrence of injury. IMPACT ON INDUSTRY: In order to improve the surroundings of the growing population of adolescents, some preventive measures should be put forward, especially to the high-risk students of injury.     

Methylmercury, total mercury and total selenium in four common freshwater fish species from Ya-Er Lake, China

Snakehead fish (Ophiocephalus argus cantor), silver carp (Hypophthalmichthys molitrtix), crucian carp (Carassius carassius), and common carp (Cyprinus carpio) are four common freshwater fish species in China. In this study, the level of methylmercury (MeHg), total mercury (T-Hg), and total selenium (T-Se) in muscle samples of these four fish species from Ya-Er Lake, China, were analyzed using atomic fluorescence spectrometry coupled with high-performance liquid chromatography, and inductively coupled plasma mass spectrometry. The concentrations of MeHg in all the fish species were significantly correlated with those of T-Hg. Higher T-Hg and MeHg concentrations had accumulated in the snakehead fish, which is a strongly predatory fish, than in the other three species. The concentration ratios of MeHg and T-Hg in the muscles of these four fish species were almost equal. Conversely, there was negative correlation between the concentrations of T-Hg and T-Se, which implies that there is a competition between these two elements with respect to bioaccumulation. It is noteworthy that of all the muscle samples tested, the level of T-Hg exceeded the maximum allowable limit in fish [0.4 mg kg⁻¹ (w/w) recommended by the World Health Organization] in 38.46% of those of the silver carp, 18.18% of those of the crucian carp, and 100% of those of snakehead fish. These results show that the consumption of contaminated fish is a potential threat to human health and that necessary preventive measures to safeguard public health should be emphasized.