Estimating net primary production and annual plant carbon inputs, and modelling future changes in soil carbon stocks in arable farmlands of northern Japan

Soil C sequestration in croplands is deemed to be one of the most promising greenhouse gas mitigation options for Japan's agriculture. In this context, changes in soil C stocks in northern Japan's arable farming area over the period of 1971-2010, specifically in the region's typical Andosol (volcanic ash-derived) and non-Andosol soils, were simulated using soil-type-specific versions of the Rothamsted carbon model (RothC). The models were then used to predict the effects, over the period of 2011-2050, of three potential management scenarios: (i) baseline: maintenance of present crop residue returns and green manure crops, as well as composted cattle manure C inputs (24-34 Mg ha⁻¹ yr⁻¹ applied on 3-55% of arable land according to crop), (ii) cattle manure: all arable fields receive 20 Mg ha⁻¹ yr⁻¹ of composted cattle manure, increased C inputs from crop residues and present C inputs from green manure are assumed, and (iii) minimum input: all above-ground crop residues removed, no green manure crop, no cattle manure applied. Above- and below-ground residue biomass C inputs contributed by 8 major crops, and oats employed as a green manure crop, were drawn from yield statistics recorded at the township level and crop-specific allometric relationships (e.g. ratio of above-ground residue biomass to harvested biomass on a dry weight basis). Estimated crop net primary production (NPP) ranged from 1.60 Mg C ha⁻¹ yr⁻¹ for adzuki bean to 8.75 Mg C ha⁻¹ yr⁻¹ for silage corn. For the whole region (143 × 10³ ha), overall NPP was estimated at 952 ± 60 Gg C yr⁻¹ (6.66 ± 0.42 Mg C ha⁻¹ yr⁻¹). Plant C inputs to the soil also varied widely amongst the crops, ranging from 0.50 Mg C ha⁻¹ yr⁻¹ for potato to 3.26 Mg C ha⁻¹ yr⁻¹ for winter wheat. Annual plant C inputs to the soil were estimated at 360 ± 45 Gg C yr⁻¹ (2.52 ± 0.32 Mg C ha⁻¹ yr⁻¹), representing 38% of the cropland NPP. The RothC simulations suggest that the region's soil C stock (0-30 cm horizon), across all soils, has decreased from 13.96 Tg C (107.5 Mg C ha⁻¹ yr⁻¹) in 1970 to 12.46 Tg C (96.0 Mg C ha⁻¹ yr⁻¹) in 2010. For the baseline, cattle manure and minimum input scenarios, soil C stocks of 12.13, 13.27 and 9.82 Tg C, respectively, were projected for 2050. Over the period of 2011-2050, compared to the baseline scenario, soil C was sequestered (+0.219 Mg C ha⁻¹ yr⁻¹) by enhanced cattle manure application, but was lost (−0.445 Mg C ha⁻¹ yr⁻¹) under the minimum input scenario. The effect of variations of input data (monthly mean temperature, monthly precipitation, plant C inputs and cattle manure C inputs) on the uncertainty of model outputs for each scenario was assessed using a Monte Carlo approach. Taking into account the uncertainty (standard deviation as % of the mean) for the model's outputs for 2050 (5.1-6.1%), it is clear that the minimum input scenario would lead to a rapid decrease in soil C stocks for arable farmlands in northern Japan.     

基于ArcGIS区统计的延安市土地生态敏感性评价

在对延安市土地生态环境问题进行调查研究的基础上,采用基于ArcGIS区统计方法进行土地生态敏感性评价,并首次采用了客观确权法--变异系数法确定评价因子权重,与以往叠加评价方法相比,在评价思路、确权方法、评价单元和叠加方法上都有不同程度改进,评价结果更加准确、客观、实用。土地生态敏感性评价结果显示,极敏感和高敏感区占到了全市总面积的40.11%,不敏感和低敏感区占全市总面积的52.06%,地域分异规律上,敏感性程度由北向南逐渐递减,并进行了土地利用生态敏感性评价。最后,针对不同土地生态敏感性分区因地制宜提出用地策略,为本轮土地利用总体规划修编和指导今后土地科学利用服务。     

全国环境统计数据审核软件设计与实现

依托《环境统计数据审核细则》(送审稿)等相关规定,以十一五环境统计软件数据审核功能为基础,设计环境数据访问接口,划分数据审核功能模块,建设环境统计数据审核软件,为确保环境统计数据质量提供信息化手段,减少人工审核的难度,提高工作效率。     

Trends in Rainfall Exceedances in the Observed Record in Selected Areas of the United States1

Bonnin, Geoffrey M., Kazungu Maitaria, and Michael Yekta, 2011. Trends in Rainfall Exceedances in the Observed Record in Selected Areas of the United States. Journal of the American Water Resources Association (JAWRA) 47(6): 1173–1182. DOI: 10.1111/j.1752‐1688.2011.00603.x Abstract: Semantic differences have led to a gap in the understanding of the impacts of climate change on precipitation frequency estimates. There is popular perception that heavy rainfalls have become more frequent, and that this trend will increase with global warming. Most of the literature examines this question from the point of view of climatology using definitions of “heavy,”“very heavy,” or “extreme” rainfall, which are different from those commonly used by civil engineers. This article identifies the differences in meaning used by the climate and civil engineering communities and examines trends in the observed record in the frequency of exceedances (not trends in magnitudes). Using concepts recognized as the basis for design of the Nation’s civil infrastructure, we look at trends in the number of exceedances of thresholds for a variety of precipitation frequencies and event durations used by civil engineers. We found that the estimated trends in exceedances at one‐day and multiday durations were statistically significant and increasing for the Ohio River Basin and surrounding states but the reverse was true for the Semiarid Southwest (i.e., not significant and decreasing trends). In addition, we found the magnitude of the trends was small for all but the more frequent events and also small with respect to the uncertainty associated with the precipitation frequency estimates themselves.     

煤矿应急管理外部扰动可测状态控制方案

为提高煤矿应急管理能力,在发生事故时进行迅速、正确的应急决策,采用状态空间表达式描述煤矿安全管理系统,对其进行稳定性分析,初步判定其在李雅普诺夫意义下稳定;根据鲁棒性能分析,判定该不确定系统是Q—稳定的。定义煤矿突发事故为系统控制过程的一种外在扰动,建立添加外部扰动参数的外扰系统模型,根据控制论原理,采用状态反馈加扰动顺馈的控制方法,可找到一种外扰可测状态下的控制律。从计算所得控制律及校正系统方程的系数矩阵可以得出系统输出不受外扰影响的控制方案。结果表明,瓦斯抽放、煤层注水、加大通风量等措施为瓦斯爆炸后可使煤矿恢复正常运作应采取的应急管理策略。     

石油钻井工业事故统计分析

石油钻井工业每年发生大量的事故,造成人员伤亡,环境污染和经济损失。本文通过对中东某采油区13年间3008起各类事故进行统计分析,找出不同因素影响下钻井事故发生的分布规律,为安全管理提供依据。统计结果表明,在炎热的季节,事故发生较为集中,在气候宜人的季节,事故相对较少;斋月所在的月份,事故数量明显增多,与斋月相邻的两个月事故数量明显减少;各类事故按其严重程度呈现金字塔形分布;手脚受伤在LTI中占据相当高的比例;HSE管理质量和承包商的变更对事故的分布有显著的影响。     

克拉玛依市大气降水化学的统计学分析

运用相关分析、因子分析和聚类分析等统计学分析方法,对2009—2010年新疆克拉玛依市的大气降水化学组成和分布特征进行分析。结果表明,SO4^2-、Cl^-、Ca^2＋和Na^＋是降水中主要离子。降水的pH值、电导率、降水量和各离子组份均呈现明显的正偏态分布,降水样品以低离子含量的样本为主,因子分析和聚类分析2种分类方法分析降水中水溶性离子主要分为3类。SO4^2-、Cl^-、Mg^2＋、F^-主要来自人为活动的贡献,K^＋、Ca^2＋主要来源于土壤和沙尘等地壳,H^＋与其他阴、阳离子间并未表现出明显的相关关系,表明研究区域的降水酸度是所有致酸离子和各种离子综合作用的结果,而不是降水中某个单一的离子组份确定的。     

1960-2011 年东北地区热量资源时空变化特征

基于1961-2011 年东北地区88 个气象站逐日气温资料,采用Kendall-Theil 线性趋势估计等方法探讨了该地区热量资源的时空变化特征。结果表明,近50 多年东北地区稳定≥0 ℃积温以25～95 ℃·d/10 a 的趋势显著增加,三江平原的增加趋势明显大于东部山区。稳定≥0 ℃气温的起始期在东北北部和中部显著提前,终止期在北部基本显著延后,日平均气温稳定≥0℃的日数在北部和中部地区基本以2～4 d/10 a 的趋势显著增加。东北地区大部分站点终霜冻日期明显提前,初霜冻日期明显延后,无霜冻期基本以3～5 d/10 a 的趋势显著增加。稳定≥10 ℃积温以30～110 ℃·d/10 a 的趋势显著增加,稳定≥10 ℃气温的起始期北部地区显著提前,终止期南部地区显著延后,作物有效生长期在中部和北部地区基本以2～4 d/10 a 的趋势显著增加。     

天津市工业污染源污染状况分析

为了掌握天津市工业污染源污染状况,对2010年天津市各区县工业污染源进行调查统计。结果表明,2010年天津市各区县工业废水入河量共计6556.79万t,COD入河量共计9656.67t,氨氮入河量共计1939.87t。大沽排污河中污染物COD和氨氮的排入量最大,分别为5783.56t和1274.87t。滨海新区COD等标污染负荷值和氨氮等标污染负荷比均最高,分别为50.49%和56.34%;东丽区、西青区、蓟县、宁河县的COD和氨氮等标污染负荷比也较高。因此在进行水环境管理时,应对这些区县作为核心管理对象。