Abandoned Underground Storage Tank Location Using Fluxgate Magnetic Surveying: A Case Study

In 1993, during the removal of a diesel and a gasoline underground storage tank at the municipal garage of the Village of Kohler, Sheboygan County, Wisconsin, soil testing revealed environmental contamination at the site. A site investigation revealed the possibility of a second on-site source of petroleum contamination. Limited historical data and the present usage of structures within the suspected source area precluded the use of most invasive sampling methods and most geophysical techniques. A fluxgate magnetometer survey, followed by confirmatory excavation, was conducted at the site. The fluxgate magnetometer survey identified nine possible magnetic anomalies within the 18 × 25 m area. The subsequent excavation near the anomalies revealed the presence of five paired and two individual 2000 L underground storage tanks. The fluxgate magnetometer survey, although affected by the proximity of buildings, was able to detect the buried tanks within 3 m of the brick structures, using a 1.5 × 1.5 m sampling array.     

Three-Dimensional Numerical Method of Moments for Linear Equilibrium-Adsorbing Solute Transport in Physically and Chemically Nonstationary Formations

A Lagrangian perturbation method is applied to develop a method of moments for reactive solute flux through a three-dimensional, nonstationary flow field. The flow nonstationarity may stem from medium nonstationarity, finite domain boundaries, and/or fluid pumping and injecting. The reactive solute flux is described as a space–time process where time refers to the solute flux breakthrough in a control plane at some distance downstream of the solute source and space refers to the transverse displacement distribution at the control plane. The analytically derived moments equations for solute transport in a nonstationary flow field are too complicated to solve analytically; therefore, a numerical finite difference method is implemented to obtain the solutions. This approach combines the stochastic model with the flexibility of the numerical method to boundary and initial conditions. The approach provides a tool to apply stochastic theory to reactive solute transport in complex subsurface environments. Several case studies have been conducted to investigate the influence of the physical and chemical heterogeneity of a medium on the reactive solute flux prediction in nonstationary flow field. It is found that both physical and chemical heterogeneity significantly affect solute transport behavior in a nonstationary flow field. The developed method is also applied to an environmental project for predicting solute flux in the saturated zone below the Yucca Mountain Project area, demonstrating the applicability of the method in practical environmental projects.     

A gender analysis of quality of life in Saskatoon, Saskatchewan

While many community initiatives have attempted to assess the nature and determinants of their citizens’ quality of life (QOL), these initiatives have produced little about whether the key determinants of life quality differ by gender. Using both quantitative and qualitative data from a recent QOL research project in Saskatoon, Saskatchewan, Canada, this study explores whether factors that predict poor QOL are similar for women and men. The study also examines whether the nature of these gender differences varies across low, medium and high socio-economic status locales. Results showed that men and women were very similar in: (1) their QOL ratings, (2) reports of deterioration in neighborhood QOL, and (3) rating particular aspects of their neighborhood. Few gender differences were also found when analyzing data referring to place characteristics and social cohesion. Multivariate analysis revealed further similarities: (1) being divorced/widowed was a significant predictor of poor QOL, and (2) a negative view of community security issues was associated with deterioration in perceived neighborhood quality of life. For women, however, other variables were important predictors of QOL: being middle aged, being single, and having a poor opinion of the overall quality of their neighborhood. Qualitative analysis revealed that while men and women shared concern about general areas such as safety and neighborhood supports, their perceptions of the details around these issues differed. The multi-method results suggest that urban policy actions should include a gendered discussion of common QOL issues.     

Is the Ogcheon metamorphic belt of Korea the eastward continuation of the Nanhua Basin of China?

The Ogcheon metamorphic belt in central Korea has been interpreted to be the eastward extension of the Nanhua Basin (aulacogen) of southeast China. In this paper, comparisons are made between the two regions based on stratigraphic, thermal-tectonic and other considerations. From this comparison, correlation of geological events between the Nanhua Basin and Ogcheon metamorphic belt are at best equivocal. The closest similarity is the presence in both regions of two major diamictite units, of glacial origin and Neoproterozoic age (750–690 Ma range) in China but of controversial origin and uncertain age in Korea. Volcanic rocks in both regions appear to have similar petrological and geochemical traits and are interpreted to be rift-related. However, their ages are different, mostly 795–780 Ma in the Nanhua Basin and c. 750 Ma in central Korea, so correlation remains uncertain. More isotopic data from both regions may shed light on this comparison. Correlation between other pre-Carboniferous stratigraphic units in the two regions is hampered by the uncertainty about the stratigraphic age and succession in the Ogcheon metamorphic belt, stemming mainly from the absence of fossils and the strong tectonic–metamorphic overprint. Both regions appear to have undergone deformation and metamorphism during the Middle Triassic (Indosinian, Songrim), in some uncertain way related to the collision between the North and South China plates. In the Ogcheon metamorphic belt, there has been no confirmation of a Mid Palaeozoic event, but in the Nanhua Basin that event is recorded by stratigraphic and palaeogeographic evidence. In the Nanhua Basin, there is no evidence for an Early Permian metamorphic event that appears, on isotopic grounds, to have affected the Ogcheon metamorphic belt. This apparent difference has been interpreted as a result of diachronous deformation during Late Palaeozoic–Early Mesozoic plate collisions that took place earlier in the east, in Korea, than in the west in China.     

Wind and water: Environmental learning in early colonial New Zealand

Abstract:  In the 19th century, pamphlets and handbooks written for intending settlers often depicted New Zealand as environmentally benign. Upon arrival, however, the newcomers experienced episodes of stormy weather and flooding. They also found greater variations across the country, between the seasons, and from year to year, than they had been led to expect. Primarily by experience, but in part guided by Māori informants, rural people learned to recognize the signs of impending storms and flooding in lowland rivers. They also came to appreciate the less predictable features of eastern South Island weather systems, and found ways to reduce their economic and environmental impact.     

Numerical method of moments for solute transport in a nonstationary flow field conditioned on hydraulic conductivity and head measurements

The unconditional stochastic studies on groundwater flow and solute transport in a nonstationary conductivity field show that the standard deviations of the hydraulic head and solute flux are very large in comparison with their mean values (Zhang et al. in Water Resour Res 36:2107–2120, 2000; Wu et al. in J Hydrol 275:208–228, 2003; Hu et al. in Adv Water Resour 26:513–531, 2003). In this study, we develop a numerical method of moments conditioning on measurements of hydraulic conductivity and head to reduce the variances of the head and the solute flux. A Lagrangian perturbation method is applied to develop the framework for solute transport in a nonstationary flow field. Since analytically derived moments equations are too complicated to solve analytically, a numerical finite difference method is implemented to obtain the solutions. Instead of using an unconditional conductivity field as an input to calculate groundwater velocity, we combine a geostatistical method and a method of moment for flow to conditionally simulate the distributions of head and velocity based on the measurements of hydraulic conductivity and head at some points. The developed theory is applied in several case studies to investigate the influences of the measurements of hydraulic conductivity and/or the hydraulic head on the variances of the predictive head and the solute flux in nonstationary flow fields. The study results show that the conditional calculation will significantly reduce the head variance. Since the hydraulic head measurement points are treated as the interior boundary (Dirichlet boundary) conditions, conditioning on both the hydraulic conductivity and the head measurements is much better than conditioning only on conductivity measurements for reduction of head variance. However, for solute flux, variance reduction by the conditional study is not so significant.     

泥质潮滩的海水-地下水交换量化研究——以莱州湾南岸为例

本文目的是利用数值模拟量化研究莱州湾南岸泥质潮滩的海水-地下水交换。选取的典型剖面长约3 800 m,坡度小于1%,沿剖面选取5个监测点,观测地下水的水头和盐度,分析其随时间的变化规律。概化水文地质条件基础上,用SEAWAT-2000建立二维数值模型,模拟水流的流动并将水头模拟值和观测值进行拟合。基于良好的拟合结果,计算出海底地下水排泄(Submarine Groundwater Discharge,SGD)量为17.46 m3/m/d,海水流入量为2.71 m~3/m/d。文章最后提出了观测和模拟过程中存在的问题,需要今后进一步解决。