Delineating a recharge area for a spring using numerical modeling, Monte Carlo techniques, and geochemical investigation

Recharge areas of spring systems can be hard to identify, but they can be critically important for protection of a spring resource. A recharge area for a spring complex in southern Wisconsin was delineated using a variety of complementary techniques. A telescopic mesh refinement (TMR) model was constructed from an existing regional-scale ground water flow model. This TMR model was formally optimized using parameter estimation techniques; the optimized "best fit" to measured heads and fluxes was obtained by using a horizontal hydraulic conductivity 200% larger than the original regional model for the upper bedrock aquifer and 80% smaller for the lower bedrock aquifer. The uncertainty in hydraulic conductivity was formally considered using a stochastic Monte Carlo approach. Two-hundred model runs used uniformly distributed, randomly sampled, horizontal hydraulic conductivity values within the range given by the TMR optimized values and the previously constructed regional model. A probability distribution of particles captured by the spring, or a "probabilistic capture zone," was calculated from the realistic Monte Carlo results (136 runs of 200). In addition to portions of the local surface watershed, the capture zone encompassed areas outside of the watershed--demonstrating that the ground watershed and surface watershed do not coincide. Analysis of water collected from the site identified relatively large contrasts in chemistry, even for springs within 15 m of one another. The differences showed a distinct gradation from Ordovician-carbonate-dominated water in western spring vents to Cambrian-sandstone-influenced water in eastern spring vents. The difference in chemistry was attributed to distinctive bedrock geology as demonstrated by overlaying the capture zone derived from numerical modeling over a bedrock geology map for the area. This finding gives additional confidence to the capture zone calculated by modeling.     

ModfloW在华北平原区地下水库模拟中的应用

通过分析华北平原地下水系统的动态特征及其含水层的分布特点，应用Modflow软件，建立了华北平原地下水系统数学模型。根据对该模型的识别分析结果，得出华北平原由于地下水超采，地下水位降低，增加包气带的厚度，从而腾出了地下水库容。据此提出充分利用含水层的地下空间，修建地下水库，调蓄外来水资源的设想。     

提前调节降水 阻止冰雹形成：论人工防雹新方法

在对称单体雹云中，冰雹形成前对流云进行了长时间的发展，一般为20～40分钟．取决于大气热动力结构。在这一过程中可形成强的上升气流，含水量增大．粒子凝结增长。我们将此过程称作”雹胜生长环境条件的形成阶段”，当雹股形成并开始重力碰冻增长时，出现对流单体的初上台雷达回波，其反射率（15～20dbz）。这时上述阶段将结束。在成熟不对称雹大中，这一阶段在主体引导云中出现，引导云的初始回波与主体云悬挂回波前沿相汇。统计分析表明，在新单体以后的发展过程中产生的液态或固态降水，取决于初要台回波的高度，当初始回波出现在一SC…     

Bioaccumulation of metals by Fucus ceranoides in estuaries of South West England

Fucus ceranoides tolerates abiotic conditions encountered across the full range of estuarine salinities. We examined the bioaccumulation of metals in individuals and metal concentrations in accompanying sediment samples collected at different locations along estuaries of South West England. Intra- and inter-estuarine variations in metal accumulation by F. ceranoides, after correction for particulate contamination using Fe as a proxy, were attributed to variations in the availabilities and concentrations of aqueous metals. Greatest accumulation was observed in estuaries that remain most heavily impacted by historical mining activities and for metals that were mobilised to the greatest extent during these operations (As, Cu, Sn, Zn). Arsenic concentrations displayed a seaward increase in estuaries in which multiple samples were taken, whereas Cd concentrations were always greatest in samples collected from the most landward locations. Ongoing research aims to better understand the mechanisms and kinetics of metal interactions with F. ceranoides and their dependence on salinity.