Semi-analytical solution of two-dimensional sharp interface LNAPL transport models

In this paper, we present semi-analytical solutions for two-dimensional equations governing transport of Light Non-Aqueous Phase Liquids (LNAPL) in unconfined aquifers. The proposed model is based on sharp interface displacement and steady groundwater flow assumptions, where both the water–LNAPL interface and the LNAPL–air interface are represented as sharp interfaces. In the case of steady groundwater flow, these equations can be reduced to a two-dimensional nonlinear solute transport equation, with the LNAPL thickness in the free product lens being the primary unknown variable. The linearized form of this solute transport equation falls into the category of two-dimensional transport equation with time-dependent dispersion coefficients. This equation can be solved analytically for an infinite domain region. In this paper, the general form of the analytical solution for the transport equation, as well as the solutions for some specific cases are presented. To demonstrate the utility of the proposed solution, numerical results obtained for two example problems are discussed and presented comparatively with a finite-element solution and other more restrictive solutions available in the literature. Although the solutions discussed in this paper have some simplifying assumptions, such as sharp-interfaces between fluid phases, steady groundwater flow and homogeneous aquifer properties, the semi-analytical solutions presented in this study may be used effectively as bench mark solutions in evaluating LNAPL migration in the subsurface. These solutions are simple and cost effective to implement and may be used in the calibration of other more complex numerical solutions that can be found in the literature.     

甲苯降解菌的分离、鉴定及其对甲苯的降解特性

从重庆钢铁集团焦化厂脱酚池车间污泥中分离纯化得到一株能以甲苯为惟一碳源和能源的革兰氏阴性菌。根据生理生化实验结果、菌落特征、菌体形态,初步鉴定为假单孢菌属。菌株的最佳生长条件为：pH7、温度35℃、加入量100mL培养基中加入60μL甲苯、接种量5．0％。考察了菌株对甲苯的降解特性,在甲苯质量浓度为150mg/L时,比降解速率达到0．211h^-1。     

Heavy metal characteristics in porewater profiles,their benthic fluxes,and toxicity in cascade reservoirs of the Lancang River,China

Environmental Science and Pollution Research - The construction of cascade reservoirs on the Lancang River (the upper Mekong) has an important influence on the distribution and accumulation of...     

Temporal dynamics of microcystins in two reservoirs with different trophic status during the early growth stage of cyanobacteria

Environmental Science and Pollution Research - Harmful cyanobacterial blooms are increasing in frequency and severity, which makes their toxic secondary metabolites of microcystins (MCs) have been...     

光照条件对跑道池光生物反应器内蛋白核小球藻生长特性的影响

本文采用多孔曝气管的曝气方式,以蠕动泵为藻液循环的动力,研究了气体流量、光照强度、光照周期等因素对跑道池光生物反应器内蛋白核小球藻生长与代谢特性的影响,并利用傅里叶红外光谱半定量法对不同光照条件下藻细胞内蛋白质、油脂以及多糖含量变化进行了分析。研究结果表明,适当的气体流量、光照强度和光照周期有利于跑道池内蛋白核小球藻细胞的生长和代谢。在本实验条件下,在最佳气体流量2 000 mL/min条件下,光照强度为3 500 μW/cm2,光照周期为16:8时最有利于蛋白核小球藻的生长;光照强度为2 000 μW/cm2和光照周期为16:8的条件均有利于藻细胞内油脂的积累。     

广东省耕地资源的动态变化特征

耕地资源问题已成为制约广东省农业以至社会经济发展的主要因素之一。本文通过分析该省耕地资源数量、质量变化特征及各地区耕地资源的流失、净增减情况,得出耕地资源动态变化特征,并简要地阐述了产生这些变化的机制和原因,最后提出了保护耕地资源的基本对策     

高邮人的筑台与古今防汛

高邮人有筑台御水的传统。据明隆庆《高邮州老·建置志》记载:“秦并楚、(高邮)又居秦,始建台,置邮亭,名秦邮。”说明秦朝在建高邮亭时曾先筑高台,又因邮亭是建在高高的土台上,便被形象地称为“高邮亭”,且邮亭系秦所建,故后人又称高邮为“秦邮”。秦代建高邮亭时为什么要先筑高台呢?这是因为高邮地处里下河地区,地势低洼,不筑台就不能抵御洪水。高邮     

雨凇环境影响因子研究与应用——以湖南省为例

运用概率论和数理统计方法,基于湖南气象观测资料、NCEP资料及地理信息资料,分析了气象因子、地理因子对雨凇天气形成的影响,揭示了各影响因子的临界影响点。进而分析了主要影响因子位于不同影响点时其它因子对雨淞天气形成的作用,在此基础上,研制了基于气象要素因子、地理因子的雨凇日数学模型。选取平均连续雨凇日数、年平均雨凇日数、雨凇最长持续时间等3项与雨凇日数有关的气候指标对模型模拟结果进行了检验,结果表明模型模拟结果与实际观测结果相关性高,均值差异小。雨凇日模型已被用于精细化的雨凇气候区划。     

改进的灰色关联分析在滑坡危险性评价中的应用——以广东省滑坡危险性评价为例

利用改进的灰色关联分析方法,采用“中心化”无量纲的处理方法,对广东滑坡灾害危险性的影响因素进行灰色关联度分析。通过地形地貌条件、地层岩性特征、地质构造特征、岩土体结构特性、水文地质条件、植被覆盖率、降雨分布、地震、人类经济工程活动等9个评价因素与滑坡危险性的关联度计算,得出各影响因素与滑坡危险性评价的关系,具有一定的客观性、科学性和合理性。     

TEPA调控AMP-DGDE水溶液相变吸收CO2性能及机理

相变吸收剂在降低CO₂捕集能耗方面具有较大优势,但现有吸收剂普遍存在再生性能差的问题。基于2-氨基-2-甲基-1-丙醇 (AMP) 的吸收剂再生性能优异,但通常难以发生相变。利用四乙烯五胺 (TEPA) 作为相变调控剂引入AMP-二乙二醇二甲醚 (DGDE) 水溶液,构建了具有良好再生性能的新型相变吸收剂AMP-DGDE-TEPA。在最佳配比下,AMP-DGDE-TEPA的吸收负荷可达0.88 mol∙mol⁻¹,其中97.6%的CO₂富集于溶液下层,下层体积仅占总体积51%。经7次吸收-解吸循环,吸收剂的吸收负荷仍能保持0.63 mol∙mol⁻¹,再生效率为71.6%。¹³C核磁共振结果表明,AMP与CO₂反应生成易于分解的碳酸氢盐,因而吸收剂具有良好的再生性能;而TEPA的引入可使系统中生成稳定的质子化TEPA和氨基甲酸盐。质子化TEPA和氨基甲酸盐具有高极性,可打破吸收剂原有的均相状态,促使吸收剂发生液-液相变。相比于DGDE,H₂O和极性反应产物之间具有更强的相互作用力,这些物质聚集形成CO₂富相,而DGDE则单独形成CO₂贫相。此外,AMP-DGDE-TEPA的再生显热和潜热仅为0.33和0.43 GJ∙t⁻¹ CO₂,具有良好的节能潜力。该研究结果可为高效低能耗碳捕集材料的制备提供参考。