Assessment of groundwater quality with special reference to arsenic in Nawalparasi district,Nepal using multivariate statistical techniques

Groundwater is a precious resource for humankind not only in Nepal but also across the globe due to its diverse functions. A total of 48 groundwater samples were collected from three villages of Nawalparasi district, Nepal, during pre-monsoon and monsoon to estimate the overall groundwater quality and to identify the sources of contamination with emphasis on arsenic (As). The average concentrations of all tested groundwater quality parameters (temp., pH, EC, ORP, Ca²⁺, Mg²⁺, Na⁺, K⁺, Cl^?, F^?,SO₄ ^2?, PO₄ ^3?, HCO₃ ^?, NO₃ ^?, Cu, Ni, Mn, Cd, Pb, Fe, Zn, Cr, and As) were well within permissible limits of WHO for drinking water, except for Ni, Cd, Pb, Cr, and As. Concentration of As ranged from 60 to 3,100 μg L^?1 and 155 to 1,338 μg L^?1 in pre-monsoon and monsoon, respectively. The Piper diagram of the groundwater chemistry showed groundwater of Nawalparasi belongs to Ca–Mg–HCO₃ and Mg–HCO₃ water type with HCO₃ ^? as dominant ions. As content in the study area was negatively correlated with Fe in pre-monsoon, while it was positively correlated in monsoon. Furthermore, As was negatively correlated with oxidation reduction potential suggesting reducing condition of groundwater. Principal component analysis revealed seven major factors that explained 81.996 and 83.763 % of total variance in water quality in pre-monsoon and monsoon, respectively. The variance of water quality was related mainly with the degree of water–rock interaction, mineralization, and anthropogenic inputs.     

基于MVO优化神经网络的GNSS高程异常拟合方法

针对普通神经网络的梯度消失和易陷入局部极值的问题,提出一种基于多元宇宙优化算法(multi-verse optimizer, MVO)的BP神经网络优化方法(MVO-BP),利用MVO全局寻优的特性求取BP神经网络各层之间可靠的神经元阈值与连接权,从而使神经网络预测模型具备更高的预测精度。建立基于MVO-BP算法的GNSS高程异常拟合预测模型,并采用实际工程中少量高程异常数据进行算法可行性检验。结果表明,相较于常规的BP神经网络法及多面函数法,MVO-BP法精度更高、适用性更强,可为实际工程测量中正常高的求取提供参考。     

水分胁迫对绿洲影响的数值模拟

运用耦合了包含土壤-植被-水文参数化陆面过程的非静力平衡中尺度大气模式MM5,将水平分辨率提高到1km,通过数值模拟的方式,分别从地气间水热交换、对绿洲小气候影响、土壤湿度变化以及径流量的角度,研究了2002年7月下旬我国西北干旱区绿洲环境在不同水量滴灌条件下的变化,从理论上找到了较适宜绿洲小气候维持的滴灌水量。结果表明：1、绿洲下垫面为农田时,从土壤保湿和绿洲小气候维持角度考虑,500m^3／hm^2／10天的滴灌水量对7月下旬黑河流域中游绿洲是一个比较合适的灌溉量。2、500m^3/hm^2／10天的灌溉水量仅为同期大水漫灌定额下限的一半,上限的1／3,间接证明了滴灌是一种高效节水的灌溉方式,可以为干旱区节约大量水资源。     

中国战略性新兴产业集聚度演变与空间布局构想

培育和发展战略性新兴产业,重要任务之一是建成一批产业链完善、创新能力强、特色鲜明的战略性新兴产业集聚区.依据国家统计局编制的《战略性新兴产业分类》(试行),选取了18个战略性新兴产业大类行业,运用地理集中指数方法对中国战略性新兴产业的集聚程度及演变趋势进行分析,并进一步考察其区域分布特征,进而根据测算结论提出中国西部地区战略性新兴产业的布局应以点状模式为主、中部地区应以点轴模式为主、东部沿海地区应以网络模式为主的空间布局模式构想,以及中国战略新兴产业“一带、两区、多点”的空间布局方案构想,以期为中国战略性新兴产业现阶段所面临的区域间同质化竞争和低水平重复建设问题提供突围良策.     

Numerical simulation of the climate effect of high-altitude lakes on the Tibetan Plateau

Lakes regulate the water and heat exchange between the ground and the atmosphere on different temporal and spatial scales. However, studies of the lake effect in the high-altitude Tibetan Plateau(TP) rarely have been performed until recently, and little attention has been paid to modelling of frozen lakes. In this study, the Weather Research and Forecasting Model(WRF v. 3.6.1) is employed to conduct three numerical experiments in the Ngoring Lake Basin(the original experiment, an experiment with a tuned model, and a no-lake experiment) to investigate the influences of parameter optimization on the lake simulation and of the high-altitude lake on the regional climate. After the lake depth, the roughness lengths, and initial surface temperature are corrected in the model, the simulation of the air temperature is distinctly improved. In the experiment using a tuned model, the simulated sensible-heat flux(H) is clearly improved, especially during periods of ice melting(from late spring to early summer) and freezing(late fall). The improvement of latent-heat flux(LE) is mainly manifested by the sharp increase in the correlation coefficient between simulation and observation, whereas the improvement in the average value is small. The optimization of initial surface temperature shows the most prominent effect in the first year and distinctly weakens after a freezing period. After the lakes become grassland in the model, the daytime temperature clearly increases during the freezing and melting periods; but the nocturnal cooling appears in other stages, especially from September to October. The annual mean H increases by 6.4 times in the regions of the Ngoring Lake and the Gyaring Lake, and the LE declines by 56.2%. The sum of H and LE increases from 71.2 W/m2(with lake) to 84.6 W/m2(no lake). For the entire simulation region, the sum of H and LE also increases slightly. After the lakes are removed, the air temperature increases significantly from June to September over the area corresponding to the two lakes, and an abnormal convergence field appears; at the same time, the precipitation clearly increases over the two lakes and surrounding areas.     

CORS系统在二调中的可靠性研究

针对CORS系统精度能否满足二调城镇地籍控制测量要求的问题,结合当前国内外CORS的研究状况,就其定位精度的可靠性进行了研究,详细阐述了其可靠性控制方法理论,并依托桂林市二调地籍控制测量项目,论证了CORS系统的内符合与外符合精度。实践证明,CORS系统应用于二调地籍图根控制测量是完全可靠的。     

山岳旅游地生态服务价值时空分异及其与环境因子关系——以武夷山风景名胜区为例

以山岳型旅游地武夷山风景名胜区为例,估算了风景区景观生态服务价值,分析1986年、1997年、2009年风景区景观生态服务价值时空变化特征,并运用相关分析和逐步回归分析方法对生态服务价值与环境因子的关系进行了探讨,以期揭示风景区景观生态服务价值与环境因子间的作用规律。结果表明:1.武夷山风景名胜区景观类型单位面积生态服务价值最高为水体(9 3707元/(hm2.a)),最低为裸地(354元/(hm2.a)),建设用地价值(12 000元/(hm2.a))仅高于裸地、农田、灌草等景观类型,杉木林、马尾松林、竹林、阔叶林等森林景观服务价值相差不大;2.风景区内景观生态服务价值在1986—1997年间服务价值有较大损失,在1997—2009年间得到一定程度弥补,但1986-2009年间景观生态服务价值变化呈亏损趋势,植被景观类型向建设用地的转变导致景观生态服务价值的降低;3.风景区内景观类型生态服务价值与环境因子(坡向除外)间呈现中等相关性,其中,郁闭度与生态服务价值相关系数最高(0.7**),环境因子中蓄积量与郁闭度相关系数最高(0.86**);4.植被景观生态服务价拟合结果(R2=0.7524,p<0.0001)值优于非植被景观(R2=0.5370,p<0.0001),拟合效果能较好地揭示景观类型生态服务价值与环境因子间的数量关系。     

乡村文化记忆的场域认知、依恋与传承关系 ——以苏州金庭镇为例

以苏州金庭镇居民为研究对象,利用问卷及访谈数据,通过结构方程模型甄别场域认知、地方依恋和传承途径的维度差异,验证彼此的影响路径和作用关系.研究表明:1)居民对乡村文化记忆的场域认知包括纪念性场地、村落型场地、自然型场地和软记忆场等维度,其中,前三者对软记忆场有着正向显著影响;2)乡村文化记忆场域认知是居民地方依恋构建的...     

省级国土空间生态修复规划编制的思路与方法

省级国土空间生态修复规划是新时期各省深入推进生态文明建设的行动指南和纲领性文件,迫切需要多学科交叉的理论与方法支撑。文章从探析国土空间生态修复的科学内涵与理论基础出发,以人地关系地域系统理论框架为指导,融合景观生态学以及基于自然的解决方案,结合广东省国土空间生态修复规划地方实践,聚焦省级国土空间生态修复规划的目标指标、重大格局、分区布局、工程体系等规划重点、难点,提出了省级国土空间生态修复规划的思路与方法,具体概括为：按照“六步走”的整体思路,围绕“四个维度”目标体系,聚焦生态、城镇、农业“三大空间”,推进“重大格局—分区布局—重大工程”3个层次空间布局,形成“格局尺度重大工程、单元尺度重点项目、场地尺度工程措施”3个尺度工程体系布局。     

基于不同空间尺度的上海市装备制造业创新网络演化分析

利用国家重点产业专利信息服务平台,对1986~2012年上海市装备制造业合作发明专利数据进行检索,描绘了城市、区域和国家3个尺度上海市装备制造业的网络空间结构及其演变特征。研究发现,上海市装备制造业创新网络的演化具有明显的阶段性特征,不同因素在不同空间尺度对创新网络的结构演化影响不同。在国家尺度,城市创新能级是主体结网行为的主要影响因素,且随着时间的推进,其重要性越发明显,而地理距离在这之中并不起作用;在区域尺度,主体创新能级的重要性贯穿整个网络发展阶段,而地理邻近的重要性在后期才开始显现;在本地尺度,合作主体间的平均距离急剧缩减,地理邻近的重要性极为突出。最后,针对上海推动产业升级、建设科创中心提出了一些建议。