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Warren D. Brady Matthew J. Eick Paul R. Grossl Patrick V. Brady 《Soil & Sediment Contamination》2003,12(4):541-564
Consideration of monitored natural attenuation (MNA) as a remedy component for metals-contaminated sites can be achieved using a site-specific screening approach, followed by application of one or a series of sequential extraction measurements. Hazardous waste sites contaminated with metals can be screened for the implementation of monitored natural attenuation on the basis of contaminant-specific soil chemical characteristics (i.e., Kd's, solubilities, and nonexchangeable sorbed fraction). Field cases are used to demonstrate the screening approach and to outline the primary considerations involved in accurately applying sequential extraction procedures to support the of MNA for site remediation. The results of these case studies provide strong evidence that site-specific screening and the use of sequential extraction procedures are effective methods for evaluating natural attenuation for metals impacted sites. 相似文献
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Christo Morris Christopher A. Call Thomas A. Monaco Paul R. Grossl Steve A. Dewey 《Plant and Soil》2006,289(1-2):279-288
Although Acroptilon repens (L.) DC. (Russian knapweed) is known to concentrate zinc (Zn) in upper soil layers, the question of whether the elevated Zn has an allelopathic effect on restoration species has not been addressed. Experiments were conducted to investigate whether soils collected from within infestations of A. repens (high-Zn) inhibit the germination or growth and development of desirable restoration species, compared to soils collected adjacent to an A. repens infestation (low-Zn). Four bioassay species [Sporobolus airoides (Torrey) Torrey (alkali sacaton), Pseudoroegneria spicata (Pursh) A. Love (bluebunch wheatgrass), Psathyrostachys juncea (Fischer) Nevski (Russian wildrye) and A. repens] were germinated in a growth chamber and grown in a greenhouse in both soils and received treatments for the alleviation of Zn toxicity (P, Fe, Fe-oxide, and soil mixing) to isolate the effects of elevated soil Zn on plant performance. Percent germination, total plant biomass, tiller and stem number, inflorescence number, and tissue metal levels were compared among soil types and treatments for each species. There was no evidence from any of the indicators measured that high-Zn soils reduced plant performance, compared to low-Zn soils. Tissue Zn levels barely approached the lower range of phytotoxic levels established for native grasses. Older plants with longer exposure times may accumulate higher Zn concentrations. S. airoides and A. repens both had higher biomass in the high-Zn soil, most likely due to increased macronutrient (N and P) availability. As the Zn levels in the soils used in this study were much higher than any levels previously reported in soils associated with A. repens, it is unlikely that the elevation of soil Zn by A. repens will hinder germination or growth and development of desirable grasses during establishment. 相似文献
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In the Xinjiang province of western China, conventional methods of iodine (I) supplementation (i.e, goiter pills and iodinated
salt) used to mitigate I deficiencies were ineffectual. However, the recent addition of KIO3 to irrigation waters has proven effective. This study was conducted to determine the effects of I form and concentration
on rice (Oryza sativa L.) growth, I partitioning within the plant, and ultimately to assist in establishing guidelines for
incorporating I into the human food chain. We compared IO3
− vs. I− in order to determine how these chemical species differ in their biological effects. Rice was grown in 48 L aerated tubs
containing nutrient solution and IO3
− or I− at 0, 1, 10, or 100 μM concentrations (approximately 0, 0.1, 1, and 10 mg kg−1 I). The IO3
− at 1 and 10 μM had no effect on biomass yields, and the 100 μM treatment had a small negative effect. The I− at 10 and 100 μM was detrimental to biomass yields. The IO3
− treatments had more I partitioning to the roots (56%) on average than did the I− treatments (36%), suggesting differences in uptake or translocation between I forms. The data support the theory that IO3
− is electrochemically or biologically reduced to I− prior to plant uptake. None of the treatments provided sufficient I in the seed to meet human dietary requirements. The I
concentration found in straw at 100 μM IO3
− was several times greater than seed, and could provide an indirect source of dietary I via livestock feeding on the straw.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
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Heather?D?SmithEmail author Christopher?P?McKay Andrew?G?Duncan Ronald?C?Sims Anne?J?Anderson Paul?R?Grossl 《Journal of biological engineering》2014,8(1):16
We discuss fluorescence as a method to detect polycyclic aromatic hydrocarbons and other organic molecules, as well as minerals on the surface of Mars. We present an instrument design that is adapted from the ChemCam instrument which is currently on the Mars Science Lander Rover Curiosity and thus most of the primary components are currently flight qualified for Mars surface operations, significantly reducing development costs. The major change compared to ChemCam is the frequency multipliers of the 1064 nm laser to wavelengths suitable for fluorescence excitation (266 nm, 355 nm, and 532 nm). We present fluorescence spectrum for a variety of organics and minerals relevant to the surface of Mars. Preliminary results show minerals already known on Mars, such as perchlorate, fluoresce strongest when excited by 355 nm. Also we demonstrate that polycyclic aromatic hydrocarbons, such as those present in Martian meteorites, are highly fluorescent at wavelengths in the ultraviolet (266 nm, 355 nm), but not as much in the visible (532 nm). We conclude that fluorescence can be an important method for Mars applications and standoff detection of organics and minerals. The instrument approach described in this paper builds on existing hardware and offers high scientific return for minimal cost for future missions. 相似文献
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Aqueous iodine (I2(aq)) is a potent disinfectant that is being evaluated as a soil sanitizer for agricultural fields and a water purification treatment
for the International Space Station. Rice (Oryza sativa L.) plants were grown in solution culture containing different I compounds at approximately 0, 18, or 30 μM total I [I2(aq) + iodide (I−)] consisting of 0, 6, and 20 μM I as I2(aq), respectively. In addition, humic acid (HA) was added to half the treatments. Most I2(aq) was electrochemically reduced to the endpoint metabolite I− within 24 h with HA promoting the response. Plants receiving the highest dose of I2(aq), particularly those in treatments without HA, had the least growth and the greatest biomass I concentrations. Roots from
both I2(aq) treatments without HA were periodically sampled for bacteria. Viable and direct caints of bacterial cell density declined
with increasing I2(aq) concentrations within the first hour after treatment application. However, cell densities recovered within 96 hours and eventually
surpassed the control treatment cell density. Additionally, the resulting high viable: direct count density ratio suggests
that opportunistic species likely dominated the post I2(aq) environment. 相似文献
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