基于标准化降水蒸发指数(SPEI)的东北干旱时空特征

东北地区是我国重要的粮食作物和经济作物的生产基地,易受异常降水和干旱的影响。随着全球气候变暖,东北地区温度增高、降水量减少,干旱事件发生频繁。但是目前国内对东北地区干旱的研究较少、结果存在分歧,且主要关注干旱的时空变化特征和干旱的影响,较少研究关注干旱的区划研究。依据1961─2013年东北地区月平均气温和降水资料,运用标准化降水蒸发指数（SPEI）分析了东北地区的干旱趋势,并根据主成分分析和聚类分析研究东北地区干旱的时空特征,研究结果表明：东北地区在1961─2012年期间干旱发生频率呈现波动增加的趋势;在1961─1999年期间,东北地区干旱发生频率低、持续时间短,干旱危害较小;而2000年以后,东北地区干旱事件频发,干旱持续时间长、强度大,出现了2000─2002和2007─2008年2个连续干旱期。从空间分布来看,2000─2010年是东北地区干旱发生频率和影响范围最大的时期,尤其是东北地区的中部和西部,其干旱频率分别达到42.86%和33.34%。根据主成分析和聚类分析的结果将东北划分为8个干旱相似区。研究结果对于实现东北干旱监测、评估,为减轻该区域干旱损失,指导区域水资源管理和农业生产具有重要的现实意义。     

试论我国自然资源立法的几个基本问题

本文从自然资源产权、国家管理和资源定价几个方面，简要讨论了我国自然资源立法的基本问题，提出建立多样化产权制度、合理界定国家管理界限和理清税费的一些原则建议     

Linking Landscape Characteristics and High Stream Nitrogen in the Oregon Coast Range: Red Alder Complicates Use of Nutrient Criteria

Red alder (Alnus rubra), a nitrogen(N)‐fixing deciduous broadleaf tree, can strongly influence N concentrations in western Oregon and Washington. We compiled a database of stream N and GIS‐derived landscape characteristics in order to examine geographic variation in N across the Oregon Coast Range. Basal area of alder, expressed as a percent of watershed area, accounted for 37% and 38% of the variation in summer nitrate and total N (TN) concentrations, respectively. Relationships between alder and nitrate were strongest in winter when streamflow and landscape connections are highest. Distance to the coast and latitude, potential surrogates for sea salt inputs, and watershed area were also related to nitrate concentrations in an all‐subsets regression analysis, which accounted for 46% of the variation in summer nitrate concentrations. The model with the lowest Akaike's Information Criterion did not include developed or agricultural land cover, probably because few watersheds in our database had substantial levels of these land cover classes. Our results provide evidence, at a regional scale, that background sources and processes cause many Coast Range streams to exceed proposed nutrient criteria, and that the prevalence of a single tree species (N‐fixing red alder) exerts a dominant control over stream N concentrations across this region.     

南方稻区季节性干旱农户适应行为及其影响因素实证分析

气候异常给我国粮食生产带来的影响成为当前社会各界关注的焦点。受全球气候变暖影响,大范围持续性干旱成为农业生产的最严重威胁,特别是近年来南方稻区季节性干旱问题日趋严重,已严重危害到我国经济社会的和谐健康发展。因此,如何适应季节性干旱已成为当前全社会普遍关注的话题,农户作为农业生产的微观决策主体,其适应季节性干旱行为选择如何,其影响因素有哪些?此问题的解决是实现科学减灾的前提和基础。因此,论文利用南方稻区江西省41个县755份农户调查样本数据,从理论与实证上分析了季节性干旱农户适应行为及其影响因素,统计结果表明：面对季节性干旱时,68.6%的农户会采取相应的适应行为,并且补种（苗）、改种其他作物、调整播种和收获日期是农户最优先考虑采用的适应措施,而资金和劳力是农户采取适应行为措施最主要的限制因素。利用Probit回归模型、Poisson回归模型和Tobit回归模型实证分析了季节性干旱农户适应行为措施选择、采用规模和采用强度的影响因素,计量结果表明：社区资本、干旱发生频率、防灾信息的可获性等因素对农户适应行为采用意愿、规模和强度有正向影响,而所在村距最近公路远近和所处的地形特征对农户适应行为采用意愿、规模和强度有负向影响。因此,需要进一步丰富社区资本、加强农户防灾信息可获性以及加强交通基础设施建设等方面以促进农户采纳适应措施的积极性。     

东北典型黑土区讷谟尔河流域土地利用变化对沟蚀影响研究

论文以东北典型黑土区中的黑龙江省讷谟尔河流域作为研究区,以1965年的Corona 和2005年的SPOT5影像做为数据源,获取研究区1965和2005年的侵蚀沟分布数据;以地形图、Landsat/MSS影像和TM影像作为数据源,获取1954、1975、1995和2005年的土地利用数据,据此就研究区沟蚀动态和土地利用变化对沟蚀发展的影响进行分析。结果表明：40 a间侵蚀沟密度>250 m/km²的区域由1965年的0 km²增加到4 077.17 km²,占总侵蚀区面积的37.57%;侵蚀沟密度以北东—南西向为轴线从剧烈增加区逐渐过渡到微度增加区;耕地上沟蚀状况最严重,草地和沼泽地次之,林地侵蚀沟密度较小;耕地和草地之间的互相转换,侵蚀沟密度增加最大,分别为600.60和456.08 m/km²;其次是林地转变为耕地,侵蚀沟密度增加346.91 m/km²;各沟蚀变化区耕地的增加比例在29.21%~46.54%之间,草地减少的比例在27.10%~41.50%之间,沼泽地减少的比例在5.86%~12.50%之间。     

中国典型城市水环境中邻苯二甲酸酯类污染水平与生态风险评价

邻苯二甲酸酯类(PAEs)作为一类重要的环境激素类化学物质,被广泛应用于塑料的增塑剂中。随着工业的发展,中国PAEs的需求量迅速增加,PAEs已成为中国城市水环境的重要风险因子,因此需要对其进行生态风险评价。本研究首先针对我国典型城市水环境中PAEs的污染现状进行文献综述,总结归纳得到我国典型城市水环境中PAEs的污染分布特征;其次运用熵值法计算了我国典型水环境中PAEs对于藻类、水蚤和鱼类种群的生态风险,并依据生态风险等级划分标准将PAEs生态风险划分为4个水平。文献综述结果表明我国城市水环境中的PAEs浓度多数都高于8.00μg·L~(-1),超过了我国地表水环境质量标准(PRC-NS 2002)和饮用水质量标准(PRC-NS 2006)中的规定限值,且在大城市或PAEs工业区周围的污染水平要显著高于其他区域。将我国与国外典型城市水环境中PAEs的污染水平进行比较,结果表明我国水环境中的PAEs污染水平明显高于其他国家。此外,我国城市水环境中PAEs的污染不仅出现在地表水环境中,而且在广东东莞等地的地下水环境中也出现了PAEs污染,PAEs浓度范围为0.0~6.7μg·L~(-1)。生态风险评价的结果表明,邻苯二甲酸二丁酯(DBP)、邻苯二甲酸二异辛酯(DEHP)和邻苯二甲酸丁苄酯(BBP)是我国城市水环境中最主要的风险因子。PAEs污染分布特征和生态风险评价的结果表明我国城市水环境中的PAEs生态风险值总体处于10≤风险熵(RQ)100到RQ≥100水平,尤其是在大城市或者PAEs工业密集区域,因此,亟需对我国城市水环境中PAEs的生态风险进行早期预警和风险管理。     

中国水路运输业能源消耗与废气排放测算

采用基于运输周转量的自下而上方法建立了中国水路运输业能源消耗和废气排放测算模型.根据GDP增长预测得到未来一段时间内中国内河、沿海和远洋货运周转量,结合IMO(International Maritime Organization)温室气体研究采用的废气排放因子,测算得到2001~2030年中国水路运输业的能源消耗和废气排放.研究结果表明:2001年,中国水路运输业燃油消耗量及NO_x、CO、NMVOC(非甲烷挥发性有机物)、CO₂、SO₂和PM排放量分别为790.9,63.6,5.9,1.9,2483.2,37.2,4.6万t,到2030年,将分别为5951.8,405.1,16.5,18.3,18743.2,15.5,6.1万t;2001~2030年,中国水路运输业燃油消耗及CO₂和NO_x排放呈逐年增长趋势,年均增长率分别为7.2%、7.2%和6.6%;受国际公约的限制,与硫含量密切相关的SO₂和PM排放量自2020年之后显著下降;2001年,中国水路运输业CO₂排放量占世界航运排放量的比重在3.2%左右,此后呈逐渐上升趋势,到2020和2030年,将分别增长至11.5%和15.3%.     

Evaluation of the ecological status with benthic indices in the coastal system： the case of Bohai Bay （China）

Based on biologic and environmental materials collected from coastal areas of Bohai Bay （China） in April, 2008, three biotic indices （AZTI＇s Marine Biotic Index （AMBI）, Shannon-Wiener Index and W-statistic） were applied together to evaluate the ecological status of the sampling area. The results showed a clear spatial gradient from a worse ecological status in the near-shore areas （especially around Haihe and Jiyun River Estuaries） to a better status in the offshore areas. While all the three indices could assist decision makers in visualizing spatial changes of organic pollutants in Bohai Bay, two indices, i. e., AMBI and Shannon-Wiener index, were effective in distinguishing sites from Haihe River Estuary, Jiyun River Estuary and other area. However, W-statistic can＇t tell the differences between estuaries and other area. It would be explained that organic pollutants and/or other environ- mental stresses in Bohai Bay were not strong enough to reduce the size ofmacrozoobenthos, which may cause both of the abundance and biomass curves crossed. To our knowledge, this is the first time that several benthic indices were used to assess the benthic ecological status in Bohai Bay, which gave the similar results. Furthermore, there is indication that the ecological status is related to excess input of wastewater along main rivers and outlets. In a word, AMBI, Shannon-Wiener Index and W-statistic could be able to assess the benthic ecological status of Bohai Bay under the organic pollutants pressure.     

Assessing the potential of crop residue recycling in China and technology options based on a bottom-up model

Crop residues are an important biomass, and are significant in the sustainable development of China. This paper uses the Grey-Markov modeling approach, the cost-benefit analysis method, and the constraint optimiza- tion method to establish the potential of crop residue recycling in China （CRRC） using a bottom-up analysis. Taking 2010 as the baseline year, the CRRC model is used to determine the quantity trends of crop residue resources, simulating the recycling potential and selecting key crop residue recycling technologies for operation between 2010 and 2030. The results illustrate that the total residue output from different crops will gradually increase to 1062 million tons in 2030. The proportion of crop residue for field burning is expected to decrease as a result of guidance and support from the government. Market mechanisms are also improving the development of the crop residue recycling industry. The economic benefit of crop residue recycling is expected to be worth 132 billion CNY in 2030 according to technology structure options. Key crop residue recycling technologies preferred such as liquefaction, amination, silo, co-firing straw power and composting will account for more than 85% of the total benefits.     

Moving towards sustainable development: rhetoric,policy and reality of ecological agriculture in China

Past decades have witnessed the rise of sustainable agriculture movements throughout the world. In parallel with this international trend, ecological agriculture (with essential goals of food security, rural employment, poverty alleviation, natural resource management and environmental protection) has been advocated as a workable approach for the realization of sustainable agriculture in China. Two decades of ecological agricultural development have shown that it not only gained legitimacy at the senior policy level but also became a focus of scientific research in fields such as ecological economics, ecology, and agricultural and environmental sciences. However, this endeavour is hardly known in the West and little attention has been paid so far to examining the broader politico-economic and sociocultural contexts within which it has evolved. This paper attempts to provide a general review of the emerging background, development history, policy initiatives and recent tendencies of ecological agriculture. In addition, the extant problems and potential contributions of this alternative practice to China's sustainable agricultural development are discussed. The purpose of this study is to identify the gap between the policy rhetoric and practical implementation of Chinese ecological agriculture and therefore to facilitate its moving towards sustainable development.