复杂岩溶条件下锰矿尾矿库地下水溶质运移特征数值模拟研究

受构造、地层等复杂地质情况综合影响的岩溶地区地下水,其溶质运移及流场模拟向来是水文地质、环境地质研究中的难点。以贵州省松桃县某锰矿尾矿库为例,在充分分析研究区周边水文地质、环境地质条件的基础上,建立地质模型,概化边界条件,利用有限元软件FEFLOW进行流场拟合。在此基础上,模拟特征污染物锰及氨氮的弥散情况。模拟结果表明,在不做任何防渗处理的情况下,特征污染物将在F201断层、地层产状等边界条件的影响下汇入地下暗河,最终流入地表水系及地下水系,流向东部的松江河。因此,必须对锰矿尾矿库采取防渗措施,从而降低其对地下水、地表水的污染风险。     

Modeling Solute Transport in Volcanic Ash Soils with Cation Exchange and Anion Retardation

Groundwater under agricultural lands is often contaminated by nitrate. In southern Japan, aquifers are covered by volcanic ash soils that can leach nitrate to the groundwater. In this study, column experiments using two volcanic ash soils (Kuroboku and Akahoya) were carried out. A mixed solution of KNO₃ and K₂SO₄ was used in the leaching experiments. Based on the experiments, a reactive transport model was developed using the Constrained Interpolation Profile method for ion transport and used to calculate chemical equilibrium for the cation exchange reactions. Anion adsorption was modeled by retardation in the numerical model. The developed simulation model results were compared to results obtained by the reactive transport model PHAST. The developed model was shown to quite well reproduce general characteristics of the experimental results. Also, the developed model results agreed well with results from PHAST. Slight discrepancy between observed and calculated breakthrough curves was probably caused by ignoring the kinetic reaction in the model calculations.     

Evaluation of Numerical Modeling Methods for the Management of Produced Water Discharges in the Coastal Region with a Canadian Case Study

This study aims at evaluating two numerical methods for 3D simulation of marine pollutant dispersion problems: the random walk particle tracking (RWPT) method and an explicit second-order finite difference method (FDM) for assessing produced water discharges from offshore oil platform. Test cases in a steady flow field were used to evaluate the efficiency and accuracy of simulating pollutant concentration profiles obtained using both the FDM and RWPT method in comparison with an analytical solution. Additionally, a field study was conducted to simulate the lead concentration distribution of produced water discharged from an oil platform off Canada’s east coast, based on the Princeton Ocean Model modeling the ocean flow in the study area with field verifications. Results indicate that, with proper configuration of grid resolution and particle resolution, both FDM and RWPT method can provide accurate results with reasonable computational costs for complex field cases. Particularly, the satisfactory 3D simulations of marine pollutant dispersion in the far field by both FDM and RWPT numerical methods enable effective assessment and management of offshore waste discharges.     

近岸海域水色异常遥感监测方法研究

水体颜色是判断水体质量的重要依据,利用遥感技术检测水色异常是进行水质评估和水体污染监测的重要技术手法。基于盐城市废黄河入海口处的GF1-WFV影像数据,利用遥感影像自身光谱特征来构建水色异常判断函数,对研究区域的水色异常进行快速提取和定位,并比较分析了基于单景影像特征和多景影像特征设置判断阈值的提取结果。研究结果表明：该方法完全基于遥感影像光谱特征,可有效提取出未知类型的水色异常信息;与基于单景影像设置的判断阈值相比,基于双景影像设置的判断阈值更合理、更适用,提取速度更快,提取范围更精确,Kappa系数为0.80;另外,采用合适窗口大小进行均值滤波处理能有效防止提取结果细碎和斑块化。     

Development of a Model for Simulation of Solute Transport in a Stream–Aquifer System

A model for simulation of solute transport in a dynamic stream–aquifer system is developed by integrating four existing sub-models. Interface packages are created to link the sub-models. The developed model is successfully used to simulate chloride transport in the stream–aquifer system of the Arkansas River and the Equus Beds Aquifer in Kansas and demonstrates that chloride concentration in the aquifer decreases in the vicinity of the simulated channel over time.     

青岛市前海一线海域水质评价与水质改善措施研究

系统调查了青岛市前海一线水质状况,采用单因子污染指数、富营齐化指数、有机评价指数法进行了水质评价.对污染成因进行了分析,提出了进一步改善海域水质的对策建议.     

PLS and PCR Methods in the Assessment of Coastal Water Quality

Partial least squares regression analysis (PLS) and principal component regression analysis (PCR) were examined asmethodological procedures for assessing the quality of coastalwaters in a tourist area. Four variables related to the trophicstate of waters, namely nitrate, nitrite, ammonia and phosphate were analyzed. The models resulting from PLS and PCR were verysimilar. Both defined three groups of water masses characterizedby different nutrient loadings. These groups were in accordancewith those obtained by numerical classification. The PLS methodwas selected as the optimal model, on the basis of its lowerprediction errors (lower Press and Rmsd values). For managementpurposes, this statistical model allows mesotrophic conditions,reflecting some nutrient enrichment over background conditions,to be characterized and the successful diagnosis of additionalsamples within this context.     

Comparison and Verification of Bacterial Water Quality Indicator Measurement Methods Using Ambient Coastal Water Samples

During the summers of 2002 and 2004, in-stream integrated flow and concentration measurements for the total dissolved solids in the Cheyenne River, South Dakota, USA was conducted in order to compare the obtained actual field measurements with the predictions values made by the Bureau of Reclamation in the Environmental Impact Statement. In comparison to the actual field measurements conducted in this study, The Bureau of Reclamation extension of a small database used in the analysis for the impact of operations at the Angostura Unit over the past 50 years and into the future to predict the annual total dissolved solid loadings doesn't represent the actual loading values and various conditions in the study area. Additional integrated flow and concentration sampling is required to characterize the impact of the current Angostura Dam operations and Angostura Irrigation District return flows on the Cheyenne River in different seasons of the year.     

近岸海域水质目标考核评价方法研究

为满足《水污染防治行动计划》近岸海域水质考核要求,根据目前近岸海域环境监测工作的实际情况,在考核范围、评价方法、目标分解、计分方法等方面进行了比较,在保证公平、公正的前提下,以一致性、可比性和适应性为原则,提出的考核评价方法以单因子评价法和点位评价法为基础,在未达标情况下,按照水质目标完成比例计分;达标情况下,在达标分值基础上按水质的保持和改善给予不同程度的加分,通过实例研究分析能够适应近岸海域水质状况变化的考核工作要求。     

A Numerical Model for the Transport of Chromium and Fine Sediments

A mathematical model which represents the transport processes of heavy metals and fine sediments in a fluvial stream was developed. The model consists of a three-equation system: the first one for total chromium concentration in the water column, C _Tw, the second one for total suspended sediment concentration, S _w, and the third one for chromium concentration in bed sediments, r. The third equation represents the chromium exchange between the water column and bed sediments by two processes: diffusion of soluble chromium and erosion/deposition of chromium sorbed to sediments. The basic assumption of the model is the instantaneous equilibrium. The main parameters are the partition coefficients in the water column and bed sediments, the depth of the active bed sediment layer, and the mass transfer coefficient between the water column and sediment pore water. The numerical model approximates the equations of advection–dispersion for chromium in water and suspended sediments by using a Eulerian third-order scheme. Numerical vs. analytical solutions were considered satisfactory for different initial, boundary, and sedimentological conditions. In order to estimate the impact of a chromium side discharge, the model was implemented for the Salado River in a reach of 65.6-km long (Santa Fe, Argentina). The results showed the effect of chromium discharge on almost the whole reach, then the vulnerability of the water quality in the Salado River when the flow was low was evidenced. When comparing the computed and measured results, the former showed a reasonable representation of the presence of chromium in water and bed sediments.     

钦州湾近岸海域水质状况及富营养化分析

2012年5月钦州湾近岸海域水质监测结果表明,钦州湾近岸水温、盐度、pH、溶解氧等基本环境参数均有利于亚热带海洋生物的生长繁殖;溶解无机氮(DIN)和活性硅酸盐(SiO2-3-Si)均显示过剩,但溶解无机磷(DIP)具有低磷特征,高的氮磷比值使PO3-4-P可能成为浮游植物生长的潜在限制因子,且COD部分站位出现超标现象。污染指数(A)和单因子污染指数(Pi)结果显示,近期整个钦州湾近岸水域污染程度达到2级,属于开始受到污染,水质受到化学耗氧有机物不同程度的污染,超标率达到30%。富营养状态指数结果表明,钦州湾近岸海域总体尚未达到富营养化,但局部区域已出现富营养化状况。COD对富营养化的贡献率平均值及范围为72.46%(67.36%~83.96%),COD已成为影响钦州湾近岸海域富营养化的重要因素。     

Selection and Calibration of Numerical Modeling in Flow and Water Quality

Numerical modeling is frequently used in coastal engineering research and application. One possible issue associated with using this method however, is that initial outcomes might differ from expectation. Modeling manipulation addresses this issue by changing the initial parameters which in turn affects the final output results.The advancement of modeling techniques in recent years has seen a gradual but steady accruement of knowledge regarding the relationship between input parameters and possible outputs, which has resulted in improved accuracy and efficiency methods. The advancements within this field have predominantly occurred on an individual basis and as such lack standardisation. An expert numerical modeler may use this knowledge subconsciously, yet may not know how to convey it to the model users. This paper has been written to introduce a systematic intelligent coding schema designed to organise current coastal engineering modeling manipulation knowledge into a standardised format. This system is relevant to the development of appropriate strategies for improved accuracy and efficiency as well as model modification to simulate specific real phenomena in prototype application cases.     

Numerical Analyses of Soft Bottom Macroinvertebrates to Diagnose the Pollution in Tropical Coastal Waters

Soft bottom benthic organisms especially polychaetes are known to adapt as r or k selected strategies to different gradients of pollution. This will result in changes of benthic community structure from that of normal structure. There are a number of techniques to assess the impact of pollution on benthic community structure. Hence, to test this hypotheses some of the univariate and multivariate techniques were applied to soft bottom macro-invertebrates data of coastal waters of Mangalore, central west coast of India, a hot-spot area. Univariate techniques such as Pearson Rosenberg Model (PRM), abundance biomass comparison curve (ABC), geometrical class distribution, dominance-diversity curve, benthic community structure indices and multivariate techniques such as cluster classification, multidimensional scaling (MDS) and principal component analysis (PCA) were used to discriminate and diagnose the disturbance among the sites. Effectiveness and applicability of some of the above techniques are highlighted and discussed with the present set of data for environmental impact assessment studies.     

Selection and Calibration of Numerical Modeling in Flow and Water Quality

Numerical modeling is frequently used in coastal engineering research and application. One possible issue associated with using this method however, is that initial outcomes might differ from expectation. Modeling manipulation addresses this issue by changing the initial parameters which in turn affects the final output results. The advancement of modeling techniques in recent years has seen a gradual but steady accruement of knowledge regarding the relationship between input parameters and possible outputs, which has resulted in improved accuracy and efficiency methods. The advancements within this field have predominantly occurred on an individual basis and as such lack standardisation. An expert numerical modeler may use this knowledge subconsciously, yet may not know how to convey it to the model users. This paper has been written to introduce a systematic intelligent coding schema designed to organise current coastal engineering modeling manipulation knowledge into a standardised format. This system is relevant to the development of appropriate strategies for improved accuracy and efficiency as well as model modification to simulate specific real phenomena in prototype application cases.     

Performance Evaluation of Multiple Groundwater Flow and Nitrate Mass Transport Numerical Models

Environmental Modeling & Assessment - Benchmarking of different numerical models simulating groundwater flow and contaminant mass transport is the aim of the present study, in order to...     

Colloid-Associated Groundwater Contaminant Transport in Homogeneous Saturated Porous Media: Mathematical and Numerical Modeling

During the past two decades, significant efforts have been made to study contaminant transport in the presence of colloids. Several researchers reported that colloidal particles could enhance the migration of contaminants in groundwater by reducing retardation factor. When the colloidal particles are present in the aquifer, the subsurface system can be considered as a three-phase system with two solid phases and an aqueous phase. The interaction between contaminants, colloids, and solid matrix should be considered in assessing the fate and transport of the contaminant in the groundwater flow system. In this study, a one-dimensional numerical model is developed by employing a fully implicit finite difference method. This model is based on mass balance equations and mass partition mechanisms between the carriers and solid matrix, as well as between the carriers and contaminants in a saturated homogeneous porous medium. This phenomenon is presented by two approaches: equilibrium approach and fully kinetic first-order approach. The formulation of the model can be simplified by employing equilibrium partitioning of particles. However, contaminant transport can be predicted more accurately in realistic situations by kinetic modeling. To test the sensitivity of the model, the effect of the various chemical and physical coefficients on the migration of contaminant was investigated. The results of numerical modeling matched favorably with experimental data reported in the literature.     

近岸海域水质自动监测质量保证和质量控制

根据实际工作经验,阐述了近岸海域水质自动监测系统运行过程中的质量保证与质量控制措施,包括建立规章制度、实验室条件、设备维护和校准、数据检查和审核、记录等方面的要求,通过实例介绍了设备维护和校准周期的确定、设备维护效果的影响和数据有效性的判别等,为近岸海域连续自动监测系统的有效管理提供依据。     

凝聚法处理水中腐植质的初步研究

通过凝聚试验确定ＡＩ盐，Ｆｅ盐处理腐植持的最佳ｐＨ值，最佳投加量，并从机理入手探讨产生影响的原因，为改进对策提供理论依据。     

Quality of Shallow Groundwater and Drainage Water in Irrigated Agricultural Lands in A Mediterranean Coastal Region of Turkey

Spatial and seasonal differences in water quality of drainage water and unconfined shallow groundwater were related to irrigation in Samandağ, a Mediterranean coastal region. Eighteen wells, seven drainage points and Orontes River were monitored bimonthly for one year for analyses of electrical conductivity (EC), total dissolved solids (TDS), sodium adsorption ratio (SAR), cations (Na, K, Ca + Mg) and anions (CO₃, HCO₃, Cl and SO₄). Agricultural irrigation using saline groundwater decreased water quality of Orontes River during the irrigation season (May to September) more than during the non-irrigation season (October to April). Seasonal fluctuations in water quality of shallow groundwater were greater during the irrigation season than the non-irrigation season in the study area. Excessive use of groundwater resulted in a decline in the water table levels in the irrigation season. Water table level rose up to the soil surface in areas where there was a lack of drainage or poor drainage, due to the impact of precipitation in the winter. SAR and pH values of drainage water increased in the irrigation season, while the other properties of drainage water decreased. Irrigation water quality of Orontes River was classified as C₃S₁ in both seasons. Irrigation water quality of shallow groundwater and drainage water varied from C₂S₁ to C₄S₂ in one year. Drainage and well waters were found to be different on yearly basis in terms of Na, SAR (p<0.01) and Ca + Mg concentrations (p<0.001). Ca + Mg concentrations for both sources were different for all sampling dates (p<0.001).     

中国沿海三省主要饮用水源有机物监测

采用固相萃取、吹扫捕集和气相色谱-质谱联用仪(GC-MS)对江苏、浙江、山东省的21个主要地表饮用水源、126份水样中的25种VOCs、38种SVOCs进行定量检测。结果有19种VOCs、10种SVOCs至少在一个水源地多次被检出,其中挥发性氯代烃、苯系物、氯代苯类、酚类、硝基苯类、酞酸酯类、农药为中国或美国环境保护局提出的"水中优先控制污染物",最高检出量为27.79μg/L。三省主要地表水受到有机物轻度污染,水体中VOCs、SVOCs含量尚未超过《地表水环境质量标准》(GB 3838-2002)和《生活饮用水卫生标准》(GB 5749-2006)限值,工业废水排放及农田雨水径流是地表水有机物的重要来源。