Efficient use of resources: urban waste ash and soil fertility on the Jos Plateau, Nigeria

Waste disposal constitutes an acute problem in numerous African cities. One solution could lie in the recycling of the nutrient-rich waste into agriculture taking place in and around cities. Farmers involved in vegetable production around Jos, Nigeria, have developed a sophisticated soil fertility management strategy combining inorganic fertilizers, manure and urban waste ash. This paper: (1) investigates the socio-economic constraints linked to obtaining scarce organic inputs, particularly urban waste ash and the health hazards (particularly heavy metal contamination of soil and crops) caused by using this ash and (2) suggests ways to improve use of this important resource.     

Likely effects of climate change on groundwater availability in a Mediterranean region of Southeastern Spain

Groundwater resources are typically the main fresh water source in arid and semi‐arid regions. Natural recharge of aquifers is mainly based on precipitation; however, only heavy precipitation events (HPEs) are expected to produce appreciable aquifer recharge in these environments. In this work, we used daily precipitation and monthly water level time series from different locations over a Mediterranean region of Southeastern Spain to identify the critical threshold value to define HPEs that lead to appreciable aquifer recharge in this region. Wavelet and trend analyses were used to study the changes in the temporal distribution of the chosen HPEs (≥20 mm day^?1) over the observed period 1953–2012 and its projected evolution by using 18 downscaled climate projections over the projected period 2040–2099. The used precipitation time series were grouped in 10 clusters according to similarities between them assessed by using Pearson correlations. Results showed that the critical HPE threshold for the study area is 20 mm day^?1. Wavelet analysis showed that observed significant seasonal and annual peaks in global wavelet spectrum in the first sub‐period (1953–1982) are no longer significant in the second sub‐period (1983–2012) in the major part of the ten clusters. This change is because of the reduction of the mean HPEs number, which showed a negative trend over the observed period in nine clusters and was significant in five of them. However, the mean size of HPEs showed a positive trend in six clusters. A similar tendency of change is expected over the projected period. The expected reduction of the mean HPEs number is two times higher under the high climate scenario (RCP8.5) than under the moderate scenario (RCP4.5). The mean size of these events is expected to increase under the two scenarios. The groundwater availability will be affected by the reduction of HPE number which will increase the length of no aquifer recharge periods (NARP) accentuating the groundwater drought in the region. Copyright © 2016 John Wiley & Sons, Ltd.     

固体聚合膜电解浓集法测量天然水中低含量氚的化学淬灭效应研究

固体聚合膜电解浓集法是浓缩氚含量较低(1 Bq/m~3)的天然水样的常用方法,但因水样自身含有杂质离子或电解装置聚合膜带入杂质进入浓集液,使浓集液偏酸性,在测量过程中易产生化学淬灭效应,导致氚的测量值偏低。本文研究了水样自身存在的杂质离子和聚合膜上残留的杂质离子、样品溶液的pH值及其电导率所产生的化学淬灭效应的影响,实验表明,为减少化学淬灭效应,提高测量低含量氚的准确性,需保证水样溶液呈中性,电导率≤1μS/cm,同时避免杂质沉积在聚合膜上。如果水样溶液的pH值偏酸性、电导率大于1μS/cm,可采用酸碱混合型离子交换树脂去除水样中自身的杂质;对于聚合膜引入的杂质,可在电解后的水样中加入微量氨水将其pH值调节至中性。     

上扬子会泽地区早三叠世飞仙关组砂岩物源特征:来自重矿物铬尖晶石和碎屑锆石的限定

上扬子会泽地区早三叠世飞仙关组主要为河流相的紫红色砂岩,物源主要来自于西部和西北部。碎屑重矿物组合表明物源主要来自于岩浆岩,且重矿物中发现大量碎屑铬尖晶石和锆石。本文运用电子探针微区成分分析和碎屑锆石U-Pb测年方法,对上扬子早三叠世飞仙关组砂岩中铬尖晶石和碎屑锆石进行分析。铬尖晶石电子探针化学成分分析显示,其具有高铬、低Fe~(3+)和高TiO_2含量的特征,源岩分析指示这些铬尖晶石来源于与洋岛/板内、岛弧以及大火成岩省相关的火成岩。同时,碎屑锆石LA-ICP-MS U-Pb年龄测定表明,飞仙关组的物源主要来自于248~272Ma和715~997Ma的岩浆岩。铬尖晶石和碎屑锆石综合分析表明,248~272Ma的物源岩石具有大火成岩省玄武岩特征,主要为峨眉山玄武岩及同期基性侵入岩;715~997M的物源为洋岛/板内玄武岩类,主要为研究区周缘与新元古代苏雄组及其同期的岩浆岩;铬尖晶石指示的岛弧性质物源则可能源自1000~1100Ma的岩浆岩。同时,碎屑锆石还指示古元古代和早寒武世发育岩浆作用,且存在古老的新太古代结晶基底。这些资料为上扬子地区构造演化提供了沉积学的证据。     

The Upstream “Strong Signals” of the Water Vapor Transport over the Tibetan Plateau during a Heavy Rainfall Event in the Yangtze River Basin

A heavy rainfall event that occurred over the middle and lower reaches of the Yangtze River Basin(YRB) during July11–13 2000 is explored in this study. The potential/stream function is used to analyze the upstream "strong signals" of the water vapor transport in the Tibetan Plateau(TP). The studied time period covers from 2000 LST 5 July to 2000 LST 15 July(temporal resolution: 6 hours). By analyzing the three-dimensional structure of the water vapor flux, vorticity and divergence prior to and during the heavy rainfall event, the upstream "strong signals" related to this heavy rainfall event are revealed. A strong correlation exists between the heavy rainfall event in the YRB and the convective clouds over the TP. The "convergence zone" of the water vapor transport is also identified, based on correlation analysis of the water vapor flux two days and one day prior to, and on the day of, the heavy rainfall. And this "convergence zone" coincides with the migration of the maximum rainfall over the YRB. This specific coupled structure actually plays a key role in generating heavy rainfall over the YRB. The eastward movement of the coupled system with a divergence/convergence center of the potential function at the upper/lower level resembles the spatiotemporal evolution of the heavy rainfall event over the YRB. These upstream "strong signals" are clearly traced in this study through analyzing the three-dimensional structure of the potential/stream function of upstream water vapor transport.     

Logistic判别模型在强降水预报中的应用

利用Logistiv判别模型进行强降水预报,并设计3种方案进行对比分析。方案1直接使用14个影响因子进行判别预报,受因子共线性作用及噪音信号影响,虽然拟合效果较好,但预报效果明显下降。方案2对14个影响因子进行主成分分析,利用前6个主成分建模,虽然拟合效果较方案1降低,但由于消除了因子共线性作用以及噪音信号影响,预报效果较方案1提高。方案3运用Bootstrap抽样技术得到符干样本并建模计算模型参数,打乱了原有时间序列中的波动,仪保留平稳信息,拟合自由度进一步降低,导致拟合效果较方案案2下降,但预报效果却是3种方案中最好且最稳定的。在上述研究基础上,利用欧洲中心数值预报模式的预报场资料,建立基于Logistic判别模型的强降水客观预报系统,并在中央气象台业务运行。2013和2014年连续两年汛期预报检验结果表明,概模型对强降水预报的TS评分高于数值模式本身,具有一定的业务参考价值。     

中国东部7类暴雨异常环流型

近年来的研究发现,瞬变扰动天气图上的扰动场天气系统对区域暴雨的落区指示能力强于传统天气图上的总场天气系统。为供预报员在业务预报中参考,本文划分1998年发生在中国东部地区的41日次区域暴雨为7类扰动场天气系统。与区域暴雨相联系的7类异常环流型分别是:华南切变线、华南涡旋、华南倒槽、长江切变线与槽、沿江涡旋、华北涡旋和东北涡旋。无论是在对流层的垂直剖面上,还是在850 hPa水平分布上,扰动天气图上位势高度低值和风扰动辐合处并配合大的水汽扰动对应有区域暴雨,而传统天气图上的低值系统和高水汽区与暴雨之间存在位置上的偏移。由此建议,用实况大气变量和中期数值模式产品绘制扰动天气图有助于预报员确定区域暴雨落区。     

2007年夏季江淮强降水过程中10~30d低频变化及其与对流层上层波包活动的联系

利用NCEP/NCAR再分析和全国740站逐日降水资料,运用一点滞后相关等方法,对2007年夏季江淮流域强降水期间低频振荡的波动活动特征及其与降水低频变化的联系进行了分析。结果表明,在2007年夏季降水中,降水低频分量起着重要作用。降水的低频振荡主周期为10~30d,降水距平时间序列与10~30d低频分量具有较好的对应关系。低频扰动在对流层上层和低层都呈现波列状分布,且在降水活跃位相时,低频环流在高、低层具有斜压结构。在对流层上层,低频扰动有缓慢的东移倾向,相速度为每天2~3个经度。西风带中存在多次移动性波列向下游的传播,且在120°E以西以每天14经度的群速度向下游频散能量,表明10~30d低频波动具有明显的下游发展特征。在强降水开始5d前,低频波动与能量可起源于高纬的乌拉尔山附近,沿着西北-东南向的路径向下游传播。下游发展的低频波动为江淮流域带来了能量,为强降水的发生提供了条件。这些结果加深了人们对低频波动在江淮流域强降水过程中所起作用的认识,可为寻找江淮流域强降水过程预报线索提供科学依据。     

胶州湾沉积物重金属形态不同浸取方法的比较与污染讯息指示作用初探

海洋沉积物中重金属的活性形态对于指示沉积物污染状况具有重要作用;为探寻简洁且能够有效提取重金属活性形态的浸提方法;实验研究了0.1 mol/L和1 mol/L盐酸的单级提取和欧共体标准局（European Community Bureau of Reference）提出的BCR分级提取法对胶州湾表层沉积物中重金属（Cr、Cu、Ni、Pb、Zn）和Al、Fe、Mn的浸取效果。结果显示;3种提取方法提取的金属含量呈显著正相关关系;两种浓度的稀盐酸对BCR方法中的酸可提取态和可还原态金属均具有较好浸提效果;但对可氧化态金属浸提能力相对较弱。不同提取方法的人为信号指数（ASI）计算结果表明;BCR浸取法提取结果的金属ASI值最大;表明其对沉积物中金属活性形态提取效率较高;1 mol/L HCl提取结果的金属ASI值最低;可能是较高浓度强酸使沉积物较大颗粒内层中“惰性”金属被浸取出来;“增加”了金属活性组分的污染讯息信号;对沉积物中Cu、Pb和Zn而言;0.1 mol/L HCl提取结果的ASI值与BCR方法接近。经过Al归一化后;0.1 mol/L HCl浸提的重金属含量的空间分布与胶州湾的实际污染状况相吻合;表明0.1 mol/L的HCl在一定程度上能够代替复杂的BCR浸取法;此方法可简化重金属活性形态的提取步骤;适合大范围沉积物重金属污染评价。     

长岛县南五岛土壤地球化学特征及环境质量评价

以长岛县南五岛土壤为研究对象,对区内土壤元素的含量特征进行分析,并对土壤环境质量进行评价。结果表明：研究区土壤平均含量与烟台市、山东省以及全国土壤平均水平相比,除CaO,Na2O,Hg,S,Se,P,F元素含量差异较明显,其他大部分元素含量相对稳定,元素含量的高低不仅与研究区背景条件有关,也与人类活动密切相关。研究区土壤环境质量整体较好,大部分区域属于清洁区和尚清洁区,仅城区局部受到一定程度的Cd,Hg,Zn污染。