Stabilization of arsenic-contaminated mine tailings using natural and calcined oyster shells   总被引：1，自引：0，他引：1  

Deok Hyun Moon  Kyoung-Woong Kim  In-Ho Yoon  Dennis G. Grubb  Dae-Yewn Shin  Kyung Hoon Cheong  Hyung-Il Choi  Yong Sik Ok  Jeong-Hun Park 《Environmental Earth Sciences》2011,64(3):597-605

Natural oyster shells (NOS) and calcined oyster shells (COS) were used to immobilize arsenic (As) from contaminated mine tailings. In addition, a blend of Portland cement (PC)/cement kiln dust (CKD) was used as a stabilizing agent. The Korean Standard Test (KST) method (1 N HCl extraction) was used to evaluate the effectiveness of the treatment. The experimental results showed that COS effectively immobilized As in treated mine tailings. Specifically, an As concentration less than 1 mg L⁻¹ was obtained following COS treatment at 25 and 30 wt%. However, all the samples subjected to NOS treatments failed the Korean warning standard of 1.2 mg L⁻¹ after 28 days of curing. All of the COS-PC treatments were successful meeting the Korean warning standard after 7 days of curing. However, the PC-only treatment failed to meet the Korean warning standard. Similarly, the CKD-only treatment was failed to meet the Korean warning standard after 7 days of curing. However, the COS-CKD treatment showed that when the COS content was greater than 20 wt%, less than 1 mg L⁻¹ of As leachability was obtained. Scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM–EDX) showed needle-like and torpedo-like Ca–As phases in the COS-treated samples suggesting that As was strongly associated with Ca and O. X-ray absorption near edge structure (XANES) analyses confirmed that As(V) was prevalent in the tailings and that there were no changes in As speciation following NOS or COS treatment.  相似文献   

Screened triple-alpha reaction rate to produce carbon in stellar interiors     

A. E. MD. Khairozzaman 《Astrophysics and Space Science》1983,95(1):179-186

Recent experimental data for radiative width and resonance energy are used to find reaction rates and mean lives for triple-alpha reaction affecting screening effect. The reaction rates are found to be drastically altered. Plots of various dimensionless parameters in temperature-density plane are given. The red-giant sttage will be of short duration. The mean lives for gravitationally collapsing stars are insignificantly small. Our results at ?=10⁵ g cm^?3 greatly differ fro those of Burbidgeet al. (1957).  相似文献   

Climate policy: a new era     

Michael Grubb 《Climate Policy》2013,13(3):325-326

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Meeting Report     

Michael Grubb 《Climate Policy》2013,13(4):475-477

Top-down economic approaches theoretically show that placing a price on carbon can reduce emissions. Responses by firms to these policies, however, are less well understood and are critical for understanding the effectiveness of price-based carbon policy. This article provides an analysis of firm-level responses to the carbon tax in British Columbia (BC) through empirical research of grey literature, industry participation, and interviews with executives of major emitting firms in BC. The article highlights the empirical responses to the tax by firms, who experience difficulty in making low-carbon changes in response to fluctuating commodity prices, the low certainty of climate policy over temporal and spatial scales, and the political economy of implementing regional climate policy. It also highlights the importance of understanding firm-level responses as a complementary approach to macro-economic policy making on carbon pricing. The article shows the importance of engaging decision makers in corporations to understand how carbon is governed in light of emerging climate policy.

Policy relevance

This article is relevant to policy makers implementing carbon-pricing initiatives by illustrating the need to complement macroeconomic models with firm-level response analysis. It also demonstrates the key concerns of executives in a resource extractive economy and the ability of a carbon price, and the need for complementary technology funds and policy, to affect change in industrial emissions.  相似文献   

Small steps,big changes     

Sivan Kartha  Michael Grubb 《Climate Policy》2013,13(2):145-146

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RANK-ORDER ANALYSIS FOR ROBUST MULTIRESPONSE,MULTIBLOCK COMPARISONS:EVALUATION OF HERBICIDE INTERACTIONS     

DAVID LEE DUEWER  ROBERT D.CLARK 《地理学报(英文版)》1991,(6)

Studies of interactions among bioactive compounds are often difficult to interpret unambiguously.A priori assumptions about the nature of such interactions can seriously distort analysis of the data.Byapplying a rank order analysis appropriate to the naturally ordinal scale of response to xenobiotic insult,several co-herbicides were successfully identified from among numerous candidates in an experimentinvolving multiple blocks,rates and species.Moreover,underlying herbicide interactions weresubstantiated and identified which were not apparent by more traditional parametric analysis.  相似文献   

Helium plasma: Pycnonuclear triple alpha reaction rates in stars     

A. E. MD. Khairozzaman 《Astrophysics and Space Science》1985,108(2):221-226

The plots of dimensionless parameters, for helium plasma are given, as they are of great importance for the study of physical conditions prevalent in stellar interiors consuming helium. The relevant temperature and density leading to weak and strong screening can be obtained from the plots to compute the effect of screening to enhance the thermonuclear reaction rates. To make a realistic approach, the pycnonuclear triple alpha reaction rates are found for the 7.66 (O⁺) MeV level for pair creation. The equation used here is suitable for white dwarfs satisfying 0<3/1. The rates are enhanced approximately 10⁴² times, which indicates that the mean life will be reduced by the same factor. The extent of the pycnonuclear regime is shown in diagram.  相似文献   

Diversity and distribution of seagrasses in the Union of the Comoros     

CNS Poonian  K Tuharska  MD Hauzer 《African Journal of Marine Science》2016,38(2):263-268

This study represents the first in situ assessment of seagrasses in the Union of the Comoros. The presence of the following 10 species (ranked in order of abundance) was confirmed: Thalassia hemprichii, Thalassodendron ciliatum, Syringodium isoetifolium, Halodule wrightii, Cymodocea rotundata, Cymodocea serrulata, Halodule uninervis, Halophila ovalis, Zostera capensis and Enhalus acoroides. Seagrasses occurred in large, continuous beds in the shallow waters at the northern and southern tips of Grande Comore Island and around the Bimbini Peninsula on western Anjouan Island, but were sparsely distributed throughout the shallow waters surrounding Mohéli Island.  相似文献   

Correction     

Carol Grubb  Anita B. Stanley 《Ground Water Monitoring & Remediation》1998,18(4):196-196

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Durban: the darkest hour?     

Michael Grubb 《Climate Policy》2013,13(6):1269-1271

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