1990～2015年长江流域县域粮食生产与粮食安全时空格局演变及影响因素分析

长江流域粮食生产与经济发展在全国均占据重要地位,研究近25年长江流域粮食生产与粮食安全时空格局演变及影响因素,可为我国粮食安全及流域可持续发展提供科学依据。基于1990、1995、2000、2005、2010和2015年长江流域县域粮食产量、户籍人口数据、农业化肥使用量和粮食播种面积（740个区县）,运用粮食变化指数、探索性空间数据分析（ESDA）、重心转移模型和空间误差模型(SEM)研究其时空格局演变特征及影响因素。研究结果表明：（1）1990～2015年长江流域粮食产量总体呈增长趋势,东西差异显著,年均增长率为0.5%,上中下游依次为0.6%、0.8%和 -0.7%;上游为劣势区,中游为优势增长区,下游为减弱区。（2）粮食产量冷点聚类一直分布在上游地区,聚类格局在2000年左右由西南边界的“L”型转变为西北倒“L”型;下游江淮地区与太湖平原的热点集聚在2000年后消失,且长期处于减产状态;人均粮食占有量与粮食产量时空格局演变呈较高的空间相似性,2000年为流域粮食生产与粮食安全格局发生变化的转折点。（3）1990～2015年长江流域一般余粮县和重要余粮县重心呈现出“南下西移”态势,缺粮县和供需紧平衡县重心发生了“从南向北、从西向东”迁移变化。（4）粮食播种面积和农业化肥施用量对粮食生产均具显著性正向效益。     

湖北省县域人口迁入与工业集聚的空间关联性研究

基于2000年和2010年湖北省102个县级行政区的规模以上工业总产值和县际迁入人口数据，采用空间自相关分析方法，探讨工业经济和迁入人口的空间格局及变化，以及两者之间的空间关联性；采用面板数据拟合联立方程模型，实证检验人口迁入与工业集聚之间的互动机制。结果表明：湖北省迁入人口和规模以上工业的县际分布之间存在显著的空间正向关联性，武汉市及其邻近县区一直是迁入人口和工业经济的高高集聚区，鄂西地域则是低低集聚区。人口迁入与工业集聚之间存在相互决定的互动关系，地区工业集聚度提高1%，其全部迁入人口和省内迁入人口分别增加 0.544 9% 和 0.602 3%；全部迁入人口或省内迁入人口增加1%，其工业集聚度则分别提高 0.294 0% 和 0.267 8%。社会经济发展水平相对落后的中西部省区应通过推进人口和非农产业协同集聚，培育地区经济增长极，促进地区经济增长和区域协调发展。 关键词： 人口迁入；工业集聚；空间关联性；互动关系；湖北省     

黄土高原水土流失区生态退耕对粮食生产的可能影响

根据黄土高原水土流失区有关各省区制定的退耕规划,分析了生态退耕对粮食生产产生的可能影响。(1)生态退耕将直接减少粮食147.92×104t,由此退耕还林还草可能会带来粮食产量的暂时下降。(2)从生态退耕的正面影响看,退耕节省下来的生产要素的转移可以带来未退耕耕地粮食产量的增加;同时技术进步、中低产田改造等农业基础设施的建设和生态环境的改善,势必也对粮食生产产生促进和推动作用。(3)粮食需求预测表明,2010年黄土高原水土流失区粮食总量将达1 400.71×104t,在人均400kg,425kg和450kg水平下粮食需求分别为1 389.34×104t,470.37×104t和1 563.01×104t。从A方案看,就黄土高原水土流失区整体而言将不会出现粮食短缺;但具体到分区而言,黄土丘陵区必须通过粮食调入才能满足本区需求,而黄土台塬区则有一定盈余。     

省级主体功能区人口分布格局探讨——以宁夏回族自治区为例

人口分布、资源环境和经济布局的空间协调是主体功能区划分和规划的重要基础和依据。合理的区域人口分布格局要实现不同的主体功能区容纳和发展适度规模的人口,这不仅受到人口自身数量的变化规律影响,而且还受到区域资源环境的约束,以及经济发展对生活水平的限制。本文以宁夏为例,在预测县级行政区人口数量的基础上,根据城市经济发展水平、建设用地面积、城市供水量和农村经济发展水平、粮食产量和农村供水量分别计算各县域内城市地区和农村地区的最优人口容量,将人口预测与人口容量进行综合分析,动态研究宁夏的人口分布格局。结果表明,宁夏北部川区人口自然增长的速度较慢,大部分县级行政区人口容量受土地因素的限制比经济发展和水资源的限制大,人口增长和人口容量的对比分析显示,此地区人口容量大,是未来人口集聚的主要地区;相比而言,南部地区人口自然增长速度较快,而人口容量受水资源和经济发展的限制较大,人口容量低,是需要转移人口的重点地区。此结果为主体功能区的划分和区域人口管理政策的制定提供了依据。     

浙江省耕地变化与粮食安全的分析及预测

运用回归分析方法、预测理论、最小人均耕地面积和耕地压力指数模型及Excel软件,在分析浙江省改革开放以来耕地、人口、粮食动态变化的基础上,分析了最小人均耕地面积和耕地压力指数的变化特点,运用预测理论对未来15年耕地、人口、粮食、最小人均耕地面积和耕地压力指数进行了预测。研究结果显示：1978～2004年,浙江省耕地面积、粮食产量呈下降趋势,人口数量逐年增加,从而造成最小人均耕地面积和耕地压力指数呈现增大趋势。这表明此期粮食供需差距越来越大。在未来15年,人口数量进一步增加,耕地和人均耕地面积降低明显,最小人均耕地面积和耕地压力指数却呈降低趋势,这依赖于耕地生产力水平的提高,但耕地仍严重超载,粮食安全问题仍将十分突出,形势比较严峻。据此提出降低耕地压力、保证粮食生产安全、促进可持续发展的对策。     

改革开放以来北京市人口空间分布的变动特征——基于1982-2010年四次人口普查资料的分析

本文使用了1982年、1990年、2000年和2010年的北京市第三次、第四次、第五次和第六次共四次人口普查资料的相关数据,综合利用人口重心研究方法和标准离差椭圆分析方法,借助于Arcgis软件分析工具,分析了北京市人口空间分布的集中和离散的变化趋势,揭示了改革开放以来北京市人口空间分布的基本演变态势。研究结论表明,近30年间,北京市人口空间分布的总体格局呈现为人口增长速度提高、人口规模总量不断膨胀的基本态势,城市功能拓展区和城市发展新区的人口增长速度领先,全市人口重心位于城市中心区的北部位置,位移距离变化较小,基本保持稳定;北京全市域人口密度由内到外呈现较为显著的阶梯状递减特征,中心城区人口密度与近郊区人口密度梯度差异逐渐变小,近郊区与远郊区的人口密度的梯度差异逐渐扩大,以中心城区和近郊区分布为主的首都功能核心区和城市功能拓展区人口集聚趋势依然明显,反映了北京市人口空间分布结构具有较强的稳定性特点;北京市人口标准离差椭圆长短轴均呈缩短趋势,长短轴之比亦呈变小趋势,反映了在北京市人口规模整体扩张的基本态势上,北京市人口空间分布呈现出更强烈的向心极化趋势和同心圆集聚趋势。总之,北京市仍然表现为人口增量型的城市化发展阶段,相对稳定的人口重心变化和较小的标准离差椭圆变化表明了北京市人口增加趋势呈现出城市化中后期趋于相对稳定的发展阶段,质量型城市化将进一步成为北京市未来城镇化过程中的主要挑战。     

湖北省"两圈"生物资源生态足迹动态分析

本文对1998-2008年湖北省武汉城市圈和鄂西生态文化旅游圈的生物资源生态足迹及其组成、人均生物资源生态足迹、生物资源生态承载量和生物资源生态赤字(盈余)进行了动态分析.研究表明,武汉城市圈生物资源生态足迹组成以耕地为主,其他生态生产性用地的足迹比例较小,各市州生物资源生态足迹整体呈现逐年增加的趋势,人均生物资源生态足迹小于省均值,生物资源生态承载量先升高后降低,各市州生物资源生态承载量由大到小排序为:黄冈、孝感、武汉、咸宁、天门、黄石、仙桃、鄂州、潜江,生态赤字呈增大趋势;鄂西生态圈除神农架外其他各市州的生物资源生态足迹均较大,林地足迹占主要地位,其总量对全省的贡献较大;人均生物资源生态足迹大于省均值,生物资源生态承载量呈增高趋势,各市州由大到小排序为:宜昌、十堰、襄樊、荆州、恩施、随州、荆门、神农架,该圈一直保持很高的生物资源生态盈余,但盈余值有减小的趋势.     

基于生态足迹和生态承载力的湖北省利川市可持续发展研究

本文以湖北省利川市2010~2014年统计年鉴为基础,利用生态足迹研究方法,对利川市的可持续发展状态进行分析。研究结果表明:利川市2010~2014年平均人均生态足迹为1.805hm2,平均人均生态承载力为0.303hm2,平均人均生态赤字为1.502hm2。其中,耕地和草地的人均生态足迹所占的比重最大,另外,耕地和林地的人均生态承载力在2010~2014年之间总体呈现出下降趋势而草地和水域人均生态承载力变化不大。人均生态盈余呈现递减趋势,由2010年的-1.338hm2/人下降到2014年的-2.421hm2/人。其中,6个消费项目中人均生态盈余最高的是草地。这些数据在一定程度上表明:利川市的经济发展是建立在对资源过度开发的基础上。此外,本文还提出通过创建生态市来改善利川生态环境,减缓区域生态压力提升区域的可持续发展能力的政策建议。     

基于敏感度分析的江苏省粮食生产与耕地数量变化动态响应研究

江苏省作为我国重要的粮食生产基地,其耕地资源变化不仅影响区域的可持续发展,更关系国家的粮食安全。以江苏省55个县域为研究单元,结合数理统计和GIS空间分析,研究2000～2015年江苏省耕地与粮食生产的时空演变及粮食生产对耕地资源变化的敏感程度。结果表明:(1)江苏省耕地总体呈减少趋势,其中耕地相对稀疏区主要分布在苏锡常地区,而集聚区主要分布在苏北;粮食生产的空间格局与耕地分布基本一致,但总量呈增加趋势,2015年江苏省粮食产量达到3561×10~4 t,为2000年的1.15倍。(2)耕地重心与粮食产量重心的移动方位大致相同,均表现为向北偏西方向移动。(3)对比2000～2009年和2009～2015年两个时期,江苏省粮食产量对耕地资源变化的敏感性逐渐减弱。随着农业技术的发展,区域粮食生产对耕地面积的依赖程度逐渐降低,保护耕地与保障粮食安全亟需因地制宜,针对不同敏感性地区合理布局粮食生产。     

城镇化对粮食生产环境技术效率影响研究

我国粮食生产在实现了"十一连增"之后正面临着城镇化所带来的资源约束和环境挑战,如何实现城镇化与粮食生产的协调发展,是我国当前需要高度关注的一个重大问题。本文以1994-2012年我国29个省(市、区)为研究对象,利用方向距离函数将环境因素纳入到粮食生产技术效率测算框架,对我国粮食生产环境技术效率值进行了测算,并对不同阶段各粮食生产功能区粮食生产环境技术效率的演变特征进行了分析,在此基础上将城镇化细分并设置了人口城镇化指标、土地城镇化指标、产业发展城镇化指标和生态环境压力城镇化指标,利用所构建面板数据模型探讨了城镇化对粮食生产环境技术效率的影响。研究结果表明:11994-2012年城镇化加速期,我国粮食主产区和主销区的粮食生产与环境的协调度要优于粮食平衡区,但是粮食主产区和主销区的粮食生产环境在逐步恶化,粮食平衡区则在逐步好转;2人口城镇化有利于粮食主销区和平衡区粮食生产环境技术效率提升,对粮食主产区则相反。土地城镇化、产业发展城镇化和生态环境压力城镇化不利于全国及各粮食生产功能区粮食生产环境技术效率的提升;3城镇化对粮食生产环境技术效率的影响存在功能区差异性。     

Present status of Rn in groundwater in Extremadura

Radon-222 was measured in groundwater sources of Extremadura (Spain), analyzing 350 samples from private and public springs, wells, and spas by liquid scintillation counting (LSC) and gamma spectrometry. The ²²²Rn activity concentrations ranged from 0.24 to 1168 Bq L⁻¹. The statistical analysis showed a log-normal distribution with a mean of (111 ± 7) Bq L⁻¹ and a median of (36 ± 3) Bq L⁻¹. A hydrogeological study revealed correlations between the activity concentration and the aquifer material's characteristics. A map of ²²²Rn in groundwater was elaborated and compared with the natural gamma radiation map for this region. About 35% of the samples showed ²²²Rn activity concentrations above the Euratom recommended limit of 100 Bq L⁻¹. Three uranium series radionuclides (²³⁸U, ²³⁴U, and ²²⁶Ra) were also assayed by alpha-particle spectrometry, estimating the annual effective dose due to the presence of these natural radionuclides in drinking water.     

我国南方地区50 a冬季降水和相对湿度特征分析

根据中国地面气候日值数据集资料,利用气候趋势系数、气候倾向率等方法,研究了我国南方地区冬季50 a降水和湿度的时空变化特征,并运用基尼系数对降水均匀性的空间分布进行了分析。结果表明：降水和相对湿度分布皆自西北向东南递增,最大中心位于长江以南附近内陆区域,最小值基本位于高原。降水强度整体呈现增加趋势,在沿长江附近区域以及云南部分地区增强明显,最大气候倾向率为1.0 mm/d/10 a左右,有明显的突变时间,为1979年;降水量呈微弱的增加趋势,其中云贵和川渝局部区域降水量呈减少趋势,为-3 mm/10 a左右,没有明显的突变时间;降水日数在长江以南局部区域及云贵区域显著减少,其中云南的西南地区为最小气候倾向率-10 d/10 a,明显突变时间为1980年;相对湿度表现出一定的局地增减趋势,长江以北（南）主要呈微弱增加（减少）趋势,云南南部减小趋势显著;相对湿度和降水呈明显的正相关,其中与降水量和降水日数相关系数高达0.784、0.753。降水量基尼系数的空间分布与降水分布相似,只是降水分布的大（小）值中心为基尼系数小（大）值中心,不同年代及冬季不同月份的降水量基尼系数大（小）值区域范围有所增减。总的来看,我国南方冬季中部和东部大部分区域为降水均匀区,西南高原区域为不均匀区。 关键词： 南方地区;冬季;降水;相对湿度     

Kinetics of dissolution of Chernobyl fuel particles in soil in natural conditions

Kinetic of fuel particles dissolution under natural environmental conditions has been investigated using the data on (90)Sr speciation in soils collected from 1995 to 1997 within the Chernobyl nuclear power plant 50 km zone. The dependency of fuel particles dissolution constants on the soil acidity (pH = 4-7) has been obtained on the basis of large and statistically reliable experimental data. Results show that between 2 and 21% of (90)Sr activity is associated with weathering resistant fuel particles. Therefore, these particles would not influence the radiological situation in the near future. The map of the main agrochemical characteristics and the map of the fuel particles dissolution constants have been created for the 30-km zone territory. According to the prognosis of dynamics of fuel particles dissolution in the investigated zone, a radiological situation along the fuel paths of radioactive fallout in present time reached a stable state. An increasing in absolute contents of (90)Sr mobile forms in neutral soils will be observed in the next 10-20 yr. However, the difference between the maximum level of mobile forms contents and their existing contents will not exceed 20%.     

Concentration and characterization of plutonium in soils of Hubei in central China

To study the Pu concentration and isotope ratio distributions present in China, the ^239+240Pu total activities and ²⁴⁰Pu/²³⁹Pu atom ratios in core soil samples from Hubei Province in central China were investigated using Accelerator Mass Spectrometry (AMS). The activities ranged from 0.019 to 0.502 mBq g⁻¹ and the ^239+240Pu inventories of 45 and ∼55 Bq m⁻² agree well with that expected from global fallout. The ²⁴⁰Pu/²³⁹Pu atom ratios in the soil ranged from 0.172 to 0.220. The ratios are similar to typical global fallout values. Hence, any close-in fallout contribution from the Chinese nuclear weapons tests, mainly conducted in the 1970s, must have either been negligible or had a similar ²⁴⁰Pu/²³⁹Pu ratio to that of global fallout. The top 10 cm layer of the soil contributes ∼90% of the total inventory and the maximum concentrations appeared in the 2-4 cm or 4-6 cm layers. It is suggested that climatic conditions and organic content are the two main factors that affect the vertical migration of plutonium in soil.     

Diffusion of Lead-free Soldering in Electronics Industry in China

The EU directives on e-waste management (WEEE and RoHS) have drawn the attention of electronics producers around the world to the environmental benign technologies in recent years. One of the technological challenges to the electronics manufacturers is the adoption of the lead-free soldering system. This article studies the diffusion of lead-free soldering technology among the electronics producers in China, and finds out the relevance of clusters for the diffusion of environmental benign technological innovation among firms. Four agents, as key promoters, were identified within the production network –leading global brand-name companies, the OEM companies who provide integrated manufacturing service, the suppliers of lead-free components, and specialized consultant companies. The conclusion is that industrial cluster facilitates communications among all agents for the diffusion of innovation, whereas, the incentives for firms within the cluster, to collaborate for innovation, comes from outside.     

Predictions of in situ solid/liquid distribution of radiocaesium in soils

Previous work has demonstrated that plant uptake of radiocaesium (RCs) is related to the activity concentration of RCs in soil solution, which is linked to the soil/soil solution distribution coefficient, K(D). The solid-liquid distribution of RCs is generally studied in soil suspensions in the laboratory and there are few reported measurements for in situ soil solutions. From a data set of 53 different soils (contaminated with either 134CsCl or 137CsCl) used in pot trials to investigate grass uptake of RCs, we analysed the variation of in situ K(D) with measured soil properties. The soils differed widely in % clay (0.5-58%), organic matter content (1.9-96%) and pH (2.4-7.0, CaCl2). The K(D) varied between 29 and 375,000 L kg-' (median 1460 L kg(-1)). Stepwise multiple regression analysis showed a significant correlation between the log K(D) and pH (p < 0.001), log %clay (p < 0.01) and log exchangeable K (p < 0.001) (overall R2 = 0.70). The in situ K(D) values were further compared to K(D)S predicted using an existing model, which assumes that RCs sorption occurs on specific sites and regular ion-exchange sites on the soil solid phase. Sorption of RCs on specific sites was quantified from the radiocaesium interception potential (RIP) measured for each soil and the soil solution concentrations of K+ and NH4+. The in situ log K(D) correlated well with the predicted K(D) (R2 = 0.85 before plant growth, R2 = 0.83 after plant growth). However, the observations were fivefold to eightfold higher than the predictions, particularly for the mineral soils. We attribute the under-prediction to the long contact times (minimum 4 weeks) between the RCs tracers and our experimental soils relative to the short (24 h) contact times used in RIP measurements. We conclude that our data confirmed the model but that ageing of RCs in soil is a factor that needs to be considered to better predict in situ KD values.     

Evaluation of Urban Sustainability in Specific Sectors in Latvia

In Latvia, the concept of sustainability is only slowly gaining recognition. An analysis of Development Plans prepared by the four largest cities of Latvia indicates that sustainability is presented as one of the guiding principles. However, a comparison of Development Plan policies against the urban sustainability issues reveals a great deal of ambiguity and contradiction.At the municipal level, planners and politicians lack indicators to gauge whether the long-term goals of Development Plans and the principles of sustainable development are being achieved. As a consequence, the broad public is deprived of the opportunity to assess for itself the process of development in relation to Development Plan policies, thus limiting accountability in development decision-making. Relevant statistical data collected on a regular basis are required to create sustainability indicators reflecting sustainability issues, to supplement and replace existing statistical compilations pertaining almost exclusively to economic growth and consumption. Development and utilisation of sustainability indicators can be an effective instrument for promoting the values of sustainable development amongst politicians, planners and the broad public and for enhancing accountability in decision-making.     

Reuse of mining wastewater in agricultural activities in Jordan

A pilot study was completed in the Al-Abyad area near phosphate mining activity in Jordan. Six plots of 50 m² each were planted with two types of plant species (Zea mays spp. and Medicago lupulina spp.) and irrigated using three types of water (fresh groundwater, mine wastewater, and hydride water consisting of 50% fresh and 50% mine wastewater) to investigate the suitability of utilizing mine wastewater for food production in the area. Water, soil and plant sampling was completed for each plot over different time intervals and analyzed for heavy metal (Cr⁺⁶, Ni⁺², Zn⁺² and Pb⁺²) in addition to major ionic composition of the water used for irrigation. Crop yield was estimated at the end of the experiment. Plots irrigated with mine wastewater showed slightly higher heavy metals concentrations and soil salinity during the experiment period was higher for plots irrigated with mine wastewater compared to plots irrigated with fresh water, and it was uniform through the upper 45 cm of the soil profile due to the high amount of irrigation water used during the experiment. Crop yield was inversely proportional to salinity as an increase of salinity by 2-folds resulted in reducing yield by almost 50%. However, no risk of heavy metals contamination was found in plants and soil. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

Seasonal changes in radon concentrations in buildings in the region of northeastern Poland

In this study, seasonal observations of radon concentration changes inside buildings carried out in the northeastern region of Poland is presented. One-year measurements of radon concentrations were performed in chosen buildings. The integral method of Cr-39 trace detectors in diffusive chambers was used. Mean values of radon concentrations were determined in monthly, 2-, 3-, 6-month, and annual observations. The fraction of a mean annual concentration of the value obtained in a shorter observation was calculated. Monthly concentration values were from about 0.2 to 14.9 of the annual mean. All buildings revealed seasonal fluctuation of radon concentration. Negative correlation of indoor radon concentration in the buildings and the mean temperature outside was observed in most examined buildings. The lowest coefficient range, determining which part of the annual mean value would be obtained in the 6-month observation, was gained for exposure begun in April or October.