On April 4, 2004, China issued a formal interpretation of the Hong Kong Basic Law. While the interpretation was controversial because it effectively asserted the central government's authority to control the pace of Hong Kong's democratic development, it was also significant for its implication that the Chinese national government had claimed for itself absolute authority to determine the meaning of contested provisions in the Basic Law. This article argues that the interpretation upset the balance established in the Basic Law between Chinese and Hong Kong authorities, improperly aggregating power to the national government and curtailing the autonomy that is guaranteed to Hong Kong under the Basic Law. The article argues that Chinese authorities should adopt a more restrained approach to interpretation - a so-called "cases and controversies" approach - that combines elements of both China's civil law heritage and Hong Kong's common law tradition

For more than 10 years, electron donor has been injected into the Snake River aquifer beneath the Test Area North site of the Idaho National Laboratory for the purpose of stimulating microbial reductive dechlorination of trichloroethene (TCE) in groundwater. This has resulted in significant TCE removal from the source area of the contaminant plume and elevated dissolved CH4 in the groundwater extending 250 m from the injection well. The delta13C of the CH4 increases from 56o/oo in the source area to -13 o/oo with distance from the injection well, whereas the delta13C of dissolved inorganic carbon decreases from 8 o/oo to -13 o/oo, indicating a shift from methanogenesis to methane oxidation. This change in microbial activity along the plume axis is confirmed by PhyloChip microarray analyses of 16S rRNA genes obtained from groundwater microbial communities, which indicate decreasing abundances of reductive dechlorinating microorganisms (e.g., Dehalococcoides ethenogenes) and increasing CH4-oxidizing microorganisms capable of aerobic co-metabolism of TCE (e.g., Methylosinus trichosporium). Incubation experiments with 13C-labeled TCE introduced into microcosms containing basalt and groundwater from the aquifer confirm that TCE co-metabolism is possible. The results of these studies indicate that electron donor amendment designed to stimulate reductive dechlorination of TCE may also stimulate co-metabolism of TCE.

A numerical model was developed to predict the coupled thermal, hydrological, and chemical (THC) processes accompanying the Drift Scale Test (DST) at Yucca Mountain, NV. The DST has been closely monitored through the collection of gas, water, and mineral samples as well as thermal, hydrological, and mechanical measurements. A two-dimensional dual permeability model was developed to evaluate multiphase, multicomponent, reaction-transport processes in the fractured tuff. Comparisons between results using the TOUGHREACT code and measured water (e.g., pH, SiO2(aq), Na+, K+) and gas (CO2) compositions show that the model captures the chemical evolution in the DST. Non-reactive aqueous species (e.g., Cl) show strong dilution in fracture waters, indicating little fracture-matrix interaction. Silica concentrations are higher than in the initial pore water and show a trend of increasing reaction with fracture-lining silicates at higher temperatures. The narrow precipitation zone of predominantly amorphous silica observed above the heaters was also captured.

The Hanford Site in southern Washington contains a large proportion of the 250,000 metric tons of nitrate estimated to reside at DOE sites across the USA. Nitrate concentrations >600 mg/L have been reported for Hanford groundwaters, where nitrate commonly accompanies elevated levels of radionuclide contamination. Much of the Hanford nitrate is stored in the vadose zone, where complicated hydrology and poorly understood chemical and biochemical processes lead to uncertain fate and transport. Analysis of the nitrogen and oxygen isotopic composition of nitrate provides a promising method to identify sources and investigate biochemical degradation of nitrate in the subsurface at Hanford. A preliminary investigation of NO3- fate and transport at the Hanford Site focuses on pore water nitrate, extracted by 1:1 sediment to DI water rinses of vadose zone sediments, in a vertical profile through a radionuclide plume at the TX-TY tank farm, and compares these results with transects across major nitrate plumes in the Hanford unconfined aquifer.Until recently, methods for analyzing d15N and d18O of NO3- in waters were unwieldy for routine analyses of dilute groundwaters and pore water extracts from vadose zone sediments; however, Sigman, et al., 2001 (Anal. Chem) and Casciotti, et al., 2002 (Anal. Chem), developed a method using denitrifying bacteria with a truncated enzymatic pathway to generate N2O for analyzing both isotopes simultaneously from NO3- in dilute samples. Our modifications to this method decrease both culture preparation and sample processing times. Culturing time has been reduced to 2-3 days by increasing the initial inoculation volume to 2mL in 100mL. We grow cultures on a bench top and mix by inversion twice daily, instead of growing on a constant shaking unit. These changes have not been shown to affect the cell yield nor the N2O levels in blanks. Secondly, cell preparation for NO3- reduction has been modified to decrease sample processing time. Intense centrifugation was found to be unnecessary and loose pellet formation at a lower g is more than adequate. We found no detectable background level of N2O in the cultures, and have reduced the sample venting time. Lastly, we have found that samples can be injected, cells lysed, and N2O run in the same day with negligible affects to N2O yield and d15N/d18O values.

Numerical simulations of transport and isotope fractionation provide a method to quantitatively interpret vadose zone pore water stable isotope depth profiles based on soil properties, climatic conditions, and infiltration. We incorporate the temperature-dependent equilibration of stable isotopic species between water and water vapor, and their differing diffusive transport properties into the thermodynamic database of the reactive transport code TOUGHREACT. These simulations are used to illustrate the evolution of stable isotope profiles in semiarid regions where recharge during wet seasons disturbs the drying profile traditionally associated with vadose zone pore waters. Alternating wet and dry seasons lead to annual fluctuations in moisture content, capillary pressure, and stable isotope compositions in the vadose zone. Periodic infiltration models capture the effects of seasonal increases in precipitation and predict stable isotope profiles that are distinct from those observed under drying (zero infiltration) conditions. After infiltration, evaporation causes a shift to higher 18O and D values, which are preserved in the deeper pore waters. The magnitude of the isotopic composition shift preserved in deep vadose zone pore waters varies inversely with the rate of infiltration.