安徽省升金湖湿地土壤有机碳储存及分布

文章研究了安徽省升金湖湿地土壤有机碳储存和分布特征及其与土壤氮素的关系。结果表明,供试湿地土壤全土1m深有机碳密度达10.82±1.90kg.m-2,表层土壤(0—30cm)有机碳密度为5.19±0.68kg.m-2,高于报道的人工湿地——水稻土的碳密度;有机碳(SOC)含量分布随土壤深度(H)的递降符合幂函数方程,湿地土壤有机碳的表层积累强度和积累深度高于稻田;湿地土壤氮素是土壤固碳的有利因子,其氮素对土壤有机碳积累的效应高于水稻土;因湖泊沉积受河流动力学、土壤水分和植物生长条件的影响,湿地土壤有机碳含量存在显著的水平空间变异性。看来,长江中下游淡水湿地在陆地生态系统碳氮储存上具有重要意义。     

苯罐安全储存技术措施

液态苯极易燃烧爆炸,苯类化学事故造成的后果及影响极大,其安全储存涉及多方面技术措施.通过危险预知分析等方法,较详细地介绍了苯罐的安全储存温度和安全储存的技术措施.     

基于粒子群-支持向量机(PSO-SVM)的苯储罐泄漏事故风险预测

将支持向量机(SVM)模型运用于事故前苯储罐泄漏事故风险预测,为使模型性能最优, 用粒子群算法PSO优化SVM模型参数,建立了PSO-SVM风险预测模型。为验证模型风险预测性能,分别采用遗传算法(GA)和网格搜索法(GS)优化SVM参数,并比较测试集与PSO-SVM、GA-SVM、GS-SVM三种模型预测结果的均方误差及相关系数。然后进一步探讨模型中权重调整方式、种群规模对PSO-SVM模型预测性能的影响。研究发现,权重线性递减所建PSO-SVM预测值与测试集相关系数更高、均方误差更小、预测效果更好,种群规模没有影响PSOSVM模型预测值但会影响计算时间,这为危化品泄漏事故的风险预测提供了一种新的方法。     

Spatiotemporal Variability of Modeled Watershed Scale Surface‐Depression Storage and Runoff for the Conterminous United States

This study explores the viability of using simulated monthly runoff as a proxy for landscape‐scale surface‐depression storage processes simulated by the United States Geological Survey’s National Hydrologic Model (NHM) infrastructure across the conterminous United States (CONUS). Two different temporal resolution model codes (daily and monthly) were run in the NHM with the same spatial discretization. Simulated values of daily surface‐depression storage (treated as a decimal fraction of maximum volume) as computed by the daily Precipitation‐Runoff Modeling System (NHM‐PRMS) and normalized runoff (0 to 1) as computed by the Monthly Water Balance Model (NHM‐MWBM) were aggregated to monthly and annual values for each hydrologic response unit (HRU) in the CONUS geospatial fabric (HRU; n = 109,951) and analyzed using Spearman’s rank correlation test. Correlations between simulated runoff and surface‐depression storage aggregated to monthly and annual values were compared to identify where which time scale had relatively higher correlation values across the CONUS. Results show Spearman’s rank values >0.75 (highly correlated) for the monthly time scale in 28,279 HRUs (53.35%) compared to the annual time scale in 41,655 HRUs (78.58%). The geographic distribution of HRUs with highly correlated monthly values show areas where surface‐depression storage features are known to be common (e.g., Prairie Pothole Region, Florida).     

Mitigating Impact of Devils Lake Flooding on the Sheyenne River Sulfate Concentration

Devils Lake is a terminal lake located in northeast North Dakota. Because of its glacial origin and accumulated salts from evaporation, the lake has a high concentration of sulfate compared to the surrounding water bodies. From 1993 to 2011, Devils Lake water levels rose by ~10 m, which flooded surrounding communities and increased the chance of an overspill to the Sheyenne River. To control the flooding, the State of North Dakota constructed two outlets to pump the lake water to the river. However, the pumped water has raised concerns about of water quality degradation and potential flooding risk of the Sheyenne River. To investigate these perceived impacts, a Soil and Water Assessment Tool (SWAT) model was developed for the Sheyenne River and it was linked to a coupled SWAT and CE‐QUAL‐W2 model that was developed for Devils Lake in a previous study. While the current outlet schedule has attempted to maintain the total river discharge within the confines of a two‐year flood (36 m³/s), our simulation from 2012 to 2018 revealed that the diversion increased the Sheyenne River sulfate concentration from an average of 125 to >750 mg/L. Furthermore, a conceptual optimization model was developed with a goal of better preserving the water quality of the Sheyenne River while effectively mitigating the flooding of Devils Lake. The optimal solution provides a “win–win” outlet management that maintains the efficiency of the outlets while reducing the Sheyenne River sulfate concentration to ≤600 mg/L.     

Study on the dynamic response of polyurea coated steel tank subjected to blast loadings

Steel tanks are widely used in the storage of various chemical liquids, and the blast resistance of the tanks is very important because of the explosiveness of these liquids. To explore a feasible method to improve the blast resistance of steel tanks, the effect of polyurea coating on the blast resistance of steel storage tank is investigated in this paper. The responses of monolithic steel tanks and polyurea coated tanks under blast loads are studied by field blast experiments using TNT explosive, and the results shows that the polyurea layers are effective in reducing the maximum and residual displacements of the tank. Numerical simulations are performed and validated, and the deformation process and stress and strain distribution of the tanks are analyzed accordingly. The increase on the bending moment of the plastic hinge lines of the tanks and the increase of the area density of the cylindrical shell induced by the polyurea layers are believed to be the two main factors contributing to the displacement reduction effect of polyurea in this paper. The validated numerical model is used to study the influence of polyurea layer's thickness on the deflection of the tank, and a nearly inversely proportional relationship between the thickness and the maximum displacement is found. Three deformation modes of the tanks are identified when subjected to blast load with varying intensity and it is found that the displacement reduction effect of polyurea varies in different deformation modes.     

基于超效率DEA模型的三峡库区生态效率评价及空间演化格局分析

本文基于2010—2017年的统计数据,首先采用超效率DEA模型对三峡库区26个区县的生态效率进行测算,然后运用空间自相关分析方法对三峡库区生态效率的演化格局进行了实证分析,探索三峡库区生态效率的时空动态演变特征。研究表明:2010—2017年三峡库区生态效率平均水平处于0.5601～1.1920,整体呈现波动性变化趋势,生态效率在一定程度上有所改善,但是整体水平仍然较低;从区域层面看,各个区县间生态效率水平不平衡,空间分布上呈现"西高东低"的非均衡性特征。局部空间自相关分析表明,三峡库区2010—2017年集聚性呈逐渐减弱态势,空间异质性逐渐增加,整体的生态效率差异变大。最后依据实证研究分析结果,本文对如何提升三峡库区生态效率提出了相应的政策建议。     

Photosynthesis and related metabolic mechanism of promoted rice (Oryza sativa L.) growth by TiO2 nanoparticles

• The rice growth was promoted by nano-TiO₂ of 0.1–100 mg/L. • Nano-TiO₂ enhanced the energy storage in photosynthesis. • Nano-TiO₂ reduced energy consumption in carbohydrate metabolism and TCA cycle. Titanium dioxide nanoparticle (nano-TiO₂), as an excellent UV absorbent and photo-catalyst, has been widely applied in modern industry, thus inevitably discharged into environment. We proposed that nano-TiO₂ in soil can promote crop yield through photosynthetic and metabolic disturbance, therefore, we investigated the effects of nano-TiO₂ exposure on related physiologic-biochemical properties of rice (Oryza sativa L.). Results showed that rice biomass was increased >30% at every applied dosage (0.1–100 mg/L) of nano-TiO₂. The actual photosynthetic rate (Y(II)) significantly increased by 10.0% and 17.2% in the treatments of 10 and 100 mg/L respectively, indicating an increased energy production from photosynthesis. Besides, non-photochemical quenching (Y(NPQ)) significantly decreased by 19.8%–26.0% of the control in all treatments respectively, representing a decline in heat dissipation. Detailed metabolism fingerprinting further revealed that a fortified transformation of monosaccharides (D-fructose, D-galactose, and D-talose) to disaccharides (D-cellobiose, and D-lactose) was accompanied with a weakened citric acid cycle, confirming the decrease of energy consumption in metabolism. All these results elucidated that nano-TiO₂ promoted rice growth through the upregulation of energy storage in photosynthesis and the downregulation of energy consumption in metabolism. This study provides a mechanistic understanding of the stress-response hormesis of rice after exposure to nano-TiO₂, and provides worthy information on the potential application and risk of nanomaterials in agricultural production.     

官厅水库入库断面水质多指标评价与演变特征分析

水体质量状况及其污染特征是流域水污染防治规划和治理措施制定的前提和基础。采用主成分分析和层次聚类分析等多元统计分析方法,选取溶解氧、高锰酸盐指数、化学需氧量等10个不同类型的监测指标,综合评价了官厅水库入库断面八号桥2006—2017年丰水期和枯水期水质年际变化特征,识别了不同阶段关键污染指标。结果表明:各年份丰水期(9月)大多数水质指标均优于枯水期(5月),特别是粪大肠菌群和氨氮,但总磷和高锰酸盐指数的差异较小。根据水质指标年际变化情况,可将研究期分为污染严重阶段(2006—2007年)、污染改善阶段(2008—2015年)和污染全面好转阶段(2016—2017年)。大部分水质指标呈现逐年好转的趋势,特别是粪大肠菌群、氨氮和五日生化需氧量,但总磷仍是官厅水库入库河流的重要污染指标。     

水库抗旱调度分期特征确定方法研究

为在一定程度上减轻流域干旱损失,国家防汛抗旱总指挥部提出旱限水位的概念,并开展水库抗旱调度,降低干旱影响程度。旱限水位是水库低水位运行的控制性水位,其合理设置对提高区域水资源利用率意义重大,而水文气象特征在年内的阶段性变化要求基于旱限水位的水库管理应适应其变化特征。此次研究提出水库抗旱调度分期的确定方法,采用核主成分分析法提取指标的非线性特征,结合熵权法赋予指标权重后利用Fisher最优分割法对干旱的年内阶段性变化进行划分。以黄河流域刘家峡和小浪底水库为例,分期结果刘家峡水库分3期为:7月至9月,10月至3月,4月至6月;小浪底水库分3期为:7月至10月,11月至3月,4月至6月。