Sample Size Effects on Petrophysical Characterization and Fluid-to-Pore Accessibility of Natural Rocks.

Laboratory-scale analysis of natural rocks provides petrophysical properties such as density, porosity, pore diameter/pore-throat diameter distribution, and fluid accessibility, in addition to the size and shape of framework grains and their contact relationship with the rock matrix. Different types of laboratory approaches for petrophysical characterization involve the use of a range of sample sizes. While the sample sizes selected should aim to be representative of the rock body, there are inherent limitations imposed by the analytical principles and holding capacities of the different experimental apparatuses, with many instruments only able to accept samples at the μm-mm scale.

Dissolution of Mn-bearing dolomite drives elevated Cr(VI) occurrence in a Permian redbed aquifer.

Municipalities in central Oklahoma, U.S.A.

Integrating SANS and fluid-invasion methods to characterize pore structure of typical American shale oil reservoirs.

An integration of small-angle neutron scattering (SANS), low-pressure N physisorption (LPNP), and mercury injection capillary pressure (MICP) methods was employed to study the pore structure of four oil shale samples from leading Niobrara, Wolfcamp, Bakken, and Utica Formations in USA. Porosity values obtained from SANS are higher than those from two fluid-invasion methods, due to the ability of neutrons to probe pore spaces inaccessible to N and mercury. However, SANS and LPNP methods exhibit a similar pore-size distribution, and both methods (in measuring total pore volume) show different results of porosity and pore-size distribution obtained from the MICP method (quantifying pore throats).

Lead adsorption by biochar under the elevated competition of cadmium and aluminum.

Competitive adsorption studies are important to accurately estimate the lead adsorption capacity on biochar in soil. The structure of biochars was evaluated by Fourier-Transform Infrared Spectroscopy and X-ray Diffraction, and the competitive of Cadmium (Cd) and Aluminum (Al) with Lead (Pb) adsorption were determined by kinetic experiments and pH effects. Adsorption kinetics indicated that the adsorption amount (mg g) of Pb by biochar was in the decreasing order of CM400 (90.

An evaluation of water quality in private drinking water wells near natural gas extraction sites in the Barnett Shale formation.

Natural gas has become a leading source of alternative energy with the advent of techniques to economically extract gas reserves from deep shale formations. Here, we present an assessment of private well water quality in aquifers overlying the Barnett Shale formation of North Texas. We evaluated samples from 100 private drinking water wells using analytical chemistry techniques.

Low pore connectivity in natural rock.

As repositories for CO(2) and radioactive waste, as oil and gas reservoirs, and as contaminated sites needing remediation, rock formations play a central role in energy and environmental management. The connectivity of the rock's porespace strongly affects fluid flow and solute transport. This work examines pore connectivity and its implications for fluid flow and chemical transport.

Uranium release from different size fractions of sediments in Hanford 300 area, Washington, USA.

Stirred-flow cell tests were carried out to investigate uranium (U) release from different size fractions of sediments from the U.S. Department of Energy's Hanford 300 Area in Washington, USA.

Quantitative 3-D elemental mapping by LA-ICP-MS of a basaltic clast from the Hanford 300 Area, Washington, USA.

Laser ablation with inductively coupled plasma-mass spectrometry (LA-ICP-MS) was used to measure elemental concentrations at the 100-μm scale in a 3-dimensional manner within a basaltic clast sample collected from the Hanford 300 Area in south-central Washington State, United States. A calibration method was developed to quantify the LA-ICP-MS signal response using a constant-sum mass fraction of eight major elements; the method produced reasonable concentration measurements for both major and trace elements when compared to a standard basalt sample with known concentrations. 3-Dimensional maps (stacked 2-D contour layers, each representing 2100 μm × 2100 μm) show relatively uniform concentration with depth for intrinsic elements such as Si, Na, and Sr.

Using stable lead isotopes to trace heavy metal contamination sources in sediments of Xiangjiang and Lishui Rivers in China.

Lead isotopes and heavy metal concentrations were measured in two sediment cores sampled in estuaries of Xiangjiang and Lishui Rivers in Hunan province, China. The presence of anthropogenic contribution was observed in both sediments, especially in Xiangjiang sediment. In the Xiangjiang sediment, the lower (206)Pb/(207)Pb and higher (208)Pb/(206)Pb ratio, than natural Pb isotope signature (1.

Fractionation and speciation of arsenic in fresh and combusted coal wastes from Yangquan, northern China.

In this study, the content and speciation of arsenic in coal waste and gas condensates from coal waste fires were investigated, respectively, using the digestion and sequential extraction methods. The fresh and fired-coal waste samples were collected from Yangquan, which is one of the major coal production regions in northern China. High-performance liquid chromatography-inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) was used to determine the concentrations of four major arsenic species [As(III), As(V), monomethylarsonic acid (MMA) and dimethylarsenic acid (DMA)] in the extracts, while ICP-MS was used to measure total As content.

Effects of anion competitive adsorption on arsenic enrichment in groundwater.

Long-term intake of high arsenic groundwater has caused serious endemic disease on people in Datong Basin, northern China. The high arsenic groundwater has medium to high alkalinity with a mean pH value of 8.1; the water generally belongs to HCO(3)-Na type water and contains HPO(4)(2-) in most samples.

Detection of tritium sorption on four soil materials.

In order to measure groundwater age and design nuclear waste disposal sites, it is important to understand the sorption behavior of tritium on soils. In this study, batch tests were carried out using four soils from China: silty clays from An County and Jiangyou County in Sichuan Province, both of which could be considered candidate sites for Very Low Level Waste disposal; silty sand from Beijing; and loess from Yuci County in Shanxi Province, a typical Chinese loess region. The experimental results indicated that in these soil media, the distribution coefficient of tritium is slightly influenced by adsorption time, water/solid ratio, initial tritium specific activity, pH, and the content of humic and fulvic acids.

Arsenate toxicity for wheat and lettuce in six Chinese soils with different properties.

To assess soil arsenic (As, in the form of arsenate) toxicity to plants, 6-d root elongation tests on wheat (Triticum aestivum L.) and lettuce (Lactuca sativa) were conducted in six Chinese soils freshly spiked with As. Plants were treated with 7 or 10 levels of As to establish concentration-effect curves.

Sources of anthropogenic radionuclides in the environment: a review.

Studies of radionuclides in the environment have entered a new era with the renaissance of nuclear energy and associated fuel reprocessing, geological disposal of high-level nuclear wastes, and concerns about national security with respect to nuclear non-proliferation. This work presents an overview on sources of anthropogenic radionuclides in the environment, as well as a brief discussion of salient geochemical behavior of important radionuclides. We first discuss the following major anthropogenic sources and current developments that have lead, or could potentially contribute, to the radionuclide contamination of the environment: (1) nuclear weapons program; (2) nuclear weapons testing; (3) nuclear power plants; (4) uranium mining and milling; (5) commercial fuel reprocessing; (6) geological repository of high-level nuclear wastes that include radionuclides might be released in the future, and (7) nuclear accidents.

Accumulation of polycyclic aromatic hydrocarbons and heavy metals in lettuce grown in the soils contaminated with long-term wastewater irrigation.

Accumulation of polycyclic aromatic hydrocarbons (PAHs) and heavy metals (HMs) by crop plants from contaminated soils may pose health risks. A greenhouse pot experiment using lettuce (Lactuca satuva L.) as a representative vegetable was conducted to assess the concentrations of PAHs and HMs in vegetables grown in wastewater-contaminated soils.

Wheat phytotoxicity from arsenic and cadmium separately and together in solution culture and in a calcareous soil.

The toxicity of two toxic elements, arsenic (As) and cadmium (Cd) (individually or in combination) on root elongation of wheat seedlings (Triticum aestivum, L.) were investigated both in hydroponics and in soils freshly spiked with the toxic elements. Median effective concentration (EC(50)) and non-observed effect concentration (NOEC) were used to investigate the toxic thresholds and potencies of the two elements.

Sorption and transport of iodine species in sediments from the Savannah River and Hanford Sites.

Iodine is an important element in studies of environmental protection and human health, global-scale hydrologic processes and nuclear nonproliferation. Biogeochemical cycling of iodine is complex, because iodine occurs in multiple oxidation states and as inorganic and organic species that may be hydrophilic, atmophilic, and biophilic. In this study, we applied new analytical techniques to study the sorption and transport behavior of iodine species (iodide, iodate, and 4-iodoaniline) in sediments collected at the Savannah River and Hanford Sites, where anthropogenic (129)I from prior nuclear fuel processing activities poses an environmental risk.