System Dynamics to Sustainable Water Resources Management in the Eastern Snake Plain Aquifer Under Water Supply Uncertainty1

Abstract: Water supply uncertainty continues to threaten the reliability of regional water resources in the western United States. Climate variability and water dispute potentials induce water managers to develop proactive adaptive management strategies to mitigate future hydroclimate impacts. The Eastern Snake Plain Aquifer in the state of Idaho is also facing these challenges in the sense that population growth and economic development strongly depend on reliable water resources from underground storage. Drought and subsequent water conflict often drive scientific research and political agendas because water resources availability and aquifer management for a sustainable rural economy are of great interest. In this study, a system dynamics approach is applied to address dynamically complex problems with management of the aquifer and associated surface‐water and groundwater interactions. Recharge and discharge dynamics within the aquifer system are coded in an environmental modeling framework to identify long‐term behavior of aquifer responses to uncertain future hydrological variability. The research shows that the system dynamics approach is a promising modeling tool to develop sustainable water resources planning and management in a collaborative decision‐making framework and also to provide useful insights and alternative opportunities for operational management, policy support, and participatory strategic planning to mitigate future hydroclimate impacts in human dimensions.     

Editorial: Statistical ecology and forest biometry

Environmental and Ecological Statistics -     

Composition and distribution of polycyclic aromatic hydrocarbons in the surface sediments from the Susquehanna River

Polycyclic aromatic hydrocarbon (PAH) concentrations in 34 surface sediments along the Susquehanna River were investigated in 2000. The total concentrations of PAHs in the surface sediments of Lake Clarke, Lake Aldred, the upper Conowingo Reservoir, and the lower Conowingo Reservoir were 3.3+/-1.5 microg g-1 (n=9), 1.6+/-1.3 microg g-1 (n=4), 9.8+/-5.5 microg g-1 (n=7), and 4.0+/-1.2 microg g-1 (n=14), respectively. These represent the first comprehensive measurement of PAHs in Susquehanna River surface sediments. Overall, total PAH concentrations were relatively lower in Lake Aldred, which is more shallow and sloped, and significantly higher in the upper Conowingo Reservoir. The sediment PAH levels were related to river flow rates, which are indirectly correlated with the particle size of the surface sediments. Total PAH levels in all the studied sites were below the effects range median (ERM) of 44.8 microg g-1 with 38% (13 of the 34 sampling sites) exceeding the effects range low (ERL) of 4.02 microg g-1. Principal component analysis indicated that variations in the PAH compound patterns of each reservoir decreased from upstream to downstream, indicating that the surface sediments were mixed along the Susquehanna River. The PAH patterns in the lower Conowingo Reservoir sediments were a combination of those upstream sources. Source analysis using isomer ratios as indicators suggested that PAHs in the Susquehanna River surface sediment are derived from the combustion of fossil fuels such as coal and gasoline with coal as the major source of contaminants.     

Removal of arsenic in tailings by soil flushing and the remediation process monitoring

In order to investigate the optimum conditions for the application of soil flushing of arsenic, a batch test was carried out using EDTA at various concentration and pH levels. Based on the optimum condition derived from the batch test, a column test was conducted to examine the feasibility of the soil-flushing technology under field-equivalent conditions. In this column test, a low flushing solution flow rate showed a significantly higher As removal efficiency (71.6%) than a high flow rate (56.3%). TCLP (toxicity characteristic leaching procedure) and a seed germination test were carried out to monitor the toxicity both during and after the treatment. The finally treated tailings were shown to be significantly remediated, having a reduced toxicity by both the TCLP and seed germination tests.     

Radium isotopes in the Ulsan Bay

In order to estimate the fluxes of Ra isotopes, we measured 224Ra, 226Ra, and 228Ra activities in the Ulsan Bay mixing zone. The convex upwards curvature of the plot of Ra isotope activities versus salinity for the mixing zone suggests that Ra isotopes are supplied from particles entering the mixing zone from both the river and bottom sediments. This addition increases the estuarine flux of 226Ra and 228Ra to the outer sea by factors of 15 and 95 over the flux attributable to Ra dissolved in the riverine water alone. In order to estimate the residence time of the water in Ulsan Bay, we applied a mass balance model to the distribution of 224Ra and 226Ra activities in the Ulsan Bay mixing zone with the inflow from the Taehwa River. The obtained residence times of the waters in the Ulsan Bay were estimated to be 6.8-11.4 d. The waters in the upper part of the estuary have long residence times whereas those in the lower part, in contact with the open sea, have shorter residence times. The mean residence time of the water in the Ulsan Bay was estimated to be 9.1 d.     

A taxonomy of performance influencing factors for human reliability analysis of emergency tasks

This paper introduces the process for, and the result of, the selection of performance influencing factors (PIFs) for the use in human reliability analysis (HRA) of emergency tasks in nuclear power plants. The approach taken in this study largely consists of three steps. First, a full-set PIF system is constructed from the collection and review of existing PIF taxonomies. Secondly, PIF candidates are selected from the full-set PIF system, considering the major characteristics of emergency situations and the basic criteria of PIF for use in HRA. Finally, a set of PIFs is established by structuring representative PIFs and their detailed subitems from the candidates. As a result, a set of PIFs comprised of the 11 representative PIFs and 39 subitems was developed.     

Reductive dissolution and sequestration of arsenic by microbial iron and thiosulfate reduction

Environmental Geochemistry and Health - Iron oxide and oxy-hydroxide are commonly used for remediation and rehabilitation of arsenic (As)-contaminated soil and water. However, the stability of As...     

Colloid mobilization and heavy metal transport in the sampling of soil solution from Duckum soil in South Korea

Environmental Geochemistry and Health - Colloid mobilization is a significant process governing colloid-associated transport of heavy metals in subsurface environments. It has been studied for the...     

不同好氧预处理方式对餐厨垃圾产甲烷的影响

为了研究不同好氧预处理方式对餐厨垃圾厌氧消化产甲烷的影响,通过建立3个模拟厌氧生物反应器,研究了传统厌氧生物反应器C1、上层好氧预处理-厌氧生物反应器C2和底部好氧预处理-厌氧生物反应器C3 3种不同操作条件下的产甲烷过程.结果表明,挥发性有机酸的累积使C1始终处于产甲烷滞后阶段;而C2、C3的好氧预处理通过加快易水解酸化组分和过量挥发性有机酸的好氧降解,有效缓解了酸性抑制,产甲烷滞后时间明显缩短至10 d内.第32天C2停止上层曝气后,在27 d内甲烷浓度达到了50％以上,同时,产甲烷速率迅速上升,并在第81天可达到峰值773 mL/(kg·d).C3在第11天停止底部曝气后,虽然经过22 d的时间甲烷浓度即上升至50％,但之后产甲烷速率经历回落阶段后再次逐渐上升,在实验结束时仅达到517 mL/(kg·d).上层曝气的好氧预处理方式所需曝气时间相对较长,但其产甲烷启动快,与底部曝气相比,其后期的甲烷化过程更稳定并可达到较高的产甲烷速率.