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941.
石门沟钼矿辉钼矿(化)特征为燕山晚期由基性岩浆底侵作用而形成的二长花岗岩体和地表出露的的厚大石英脉体全岩含矿。分析了河南西峡县石门沟钼矿成因机理与成矿模式。认为石门沟辉钼矿化二长花岗岩是下地壳物质部分熔融作用形成的富含Mo元素的花岗质岩浆,由基性向酸性正向演化,后经岩浆结晶分异、同化混染作用,钼(钨)等金属矿物以熔离状态分布在岩浆矿房中;岩浆热液沿构造薄弱带上升到地壳浅部后,富水热流体分离,进入气成热液阶段,形成高中温纵横交错含钼脉体或含钼花岗岩体。石门沟钼矿成因类型为岩浆型、热液充填石英脉型辉钼矿床,与斑岩型有明显区别。 相似文献
942.
通过对比2012、2018、2020年海南文昌沿岸海草床的调查数据,对文昌海草床的现状、退化状况以及退化因素进行分析。结果表明,2020年文昌海域海草有2科6属6种,分别为泰来草(Thalassia hemprichii)、圆叶丝粉草(Cymodocea rotunda)、单脉二药草(Halodule uninervis)、海菖蒲(Enhalus acoroides)、卵叶喜盐草(Halophila ovalis)及针叶草(Syringodium isoetifolium)。文昌海草床的分布呈明显退化的趋势,海草床面积由2012年的31.8 km2减少到2018年的24.2 km2,2020年进一步降低至18.8 km2。分析数据显示, Cu、Cd、Cr等重金属离子与调查区海草床的盖度显著负相关,表明在低营养负载时文昌周边虾塘养殖废水排放带来的重金属污染也会导致文昌海草床的退化。 相似文献
943.
The use of kaolinite‐based clay minerals as a low‐cost natural adsorbent for the removal of Cu(II) from electroplating waste leachate was studied. Batch experiments were conducted to determine the effects of varying adsorbent loading, initial pH, adsorbent dosage, and contact time. Box–Behnken design with three variables like initial pH, adsorbent dosage, and contact time at three different levels was studied to identify a significant correlation between the effects of these variables to the amount of Cu(II) adsorbed. The methodology identifies the principal experimental variables, which have the greatest effect on the adsorption process. After optimizing the input variables by using Simplex algorithm, the adsorption of Cu(II) was maximal (99.9% with a maximum (positive) standard deviation of 9.4) at pH 6.24, adsorbent dosage of 0.83 g L?1, and contact time of 97 min, respectively. Furthermore, the experimental values are in good agreement with predicted values, the correlation coefficient and adjusted correlation coefficients were found to be 0.96 and 0.87, respectively. 相似文献
944.
In this study, a modified method was used to increase the adsorption of lead ions from aqueous solutions by using modified clay mineral on the laboratory scale. Adsorption experiments have been carried out on the use of both thermal activated sepiolite (TAS) and their glutamate/sepiolite modification (GS) as adsorbents. The experimental data was analyzed using adsorption kinetic models (pseudo first‐ and second‐order equations). The pseudo second‐order kinetic model fitted well to the kinetic data (R2 ≥ 0.99). Then, the Freundlich and Langmuir models were applied to describe the uptake of Pb(II) on GS and the Langmuir isotherm model agrees well with the equilibrium experimental data (R2 ≥ 0.97). The maximum adsorption capacity was observed to be 128.205 mg/g by GS according to the Langmuir equation. Desorption efficiency of the GS was studied by the batch method using EDTA, HCl, and HNO3 solutions. Desorption of 69.18, 74.55, and 80% of Pb(II) from GS was achieved with 0.1 M EDTA, 0.1 M HCl, and 0.1 M HNO3 solutions, respectively. FTIR analysis suggests the importance of functional groups such as amino, hydroxyl, and carboxyl during Pb(II) removal. SEM observations demonstrated that an important interaction at the lead‐modified sepiolite interface occurred during the adsorption process. In addition, the thermodynamic constants was calculated that the values of the Gibbs free energy (ΔG*), enthalpy (ΔH*), and entropy (ΔS*) of modification were 86.79 kJ/mol, ?18.91 kJ/mol, and ?354.70 J/mol/K, respectively. The negative value of ΔH* shows exothermic nature of adsorption. 相似文献
945.
Jung Eun Lim Mahtab Ahmad Sang Soo Lee Christopher L. Shope Yohey Hashimoto Kwon‐Rae Kim Adel R. A. Usman Jae E. Yang Yong Sik Ok 《洁净——土壤、空气、水》2013,41(12):1235-1241
Low cost lime‐based waste materials have recently been used to immobilize metals in contaminated soils. This study was conducted to evaluate the effects of oyster shells and eggshells as lime‐based waste materials on immobilization of cadmium (Cd) and lead (Pb) in contaminated soil, as well as their effects on metal availability to maize plants (Zea mays L.). Oyster shells and eggshells were applied to soils at 1 and 5% w/w, after which they were subject to 420 days of incubation. The toxicity characteristic leaching procedure (TCLP) test was employed to determine the mobility of Cd and Pb in soils. The results showed that the addition of waste materials effectively reduced the metal mobility as indicated by the decrease in the concentration of TCLP‐extractable Cd and Pb, and this was mainly due to significant increases in soil pH (from 6.74 in untreated soil to 7.85–8.13 in treated soil). A sequential extraction indicated that the addition of such alkaline wastes induced a significant decline in the concentration of Cd in the exchangeable fraction (from 23.64% in untreated soil to 1.90–3.81% in treated soil), but it increased the concentration of Cd in the carbonate fraction (from 19.59% in untreated soil to 36.66–46.36% in treated soil). In the case of Pb, the exchangeable fraction was also reduced (from 0.67% in untreated soil to 0.00–0.01% in treated soil), and the fraction of Pb bound to carbonate was slightly increased (from 16.61% in untreated soil to 16.41–18.25% in treated soil). Phytoavailability tests indicated that the metal concentrations in the shoots of maize plant were reduced by 63.39–77.29% for Cd and by 47.34–75.95% for Pb in the amended soils, with no significant differences being observed for the amendment types and the application rates. Overall, these results indicate that oyster shells and eggshells can be used as low cost lime‐based amendments for immobilizing Cd and Pb in contaminated soils. 相似文献
946.
The present paper evaluates the temporal and spatial impact of heavy metal containing (Cr, Zn, Cu, Ni, Cd and Fe) effluents of brass, electroplating and tannery industries on chemical and microbiological characteristics of affected soil and groundwater. Therefore, samples were drawn from three sites, S1, S2 and S3, with a longitudinally distant from effluent drain of 20, 200 and 700 m, respectively. In general, the metals concentration exceeded the standard limits not only in the discharged effluents but also in the soil and groundwater. The significant reduction of microbial biomass C and N, soil respiration and microbial coefficient with increasing metal content from S3 to S1 was recorded, the effect being more pronounced in summer. However, the Cmic/Nmic ratio decreased whilst the metabolic quotient ($q_{{\rm CO}_{{\rm 2}} } $ ) increased with increasing metal concentration in soil. The content of Zn (11.5 mg/L) and Bacillus sp. was at maximum in groundwater of brass and electroplating industry site, whereas that of tannery site contained maximum Cr (2.34 mg/L) and Enterobacter sp. The toxic metals adversely polluted the groundwater which made it to harbours Escherichia coli beyond the prescribed limit. To check the soil and groundwater pollution, eco‐friendly measures involving improved effluent treatment technology and site‐specific application of treated effluent are recommended. 相似文献
947.
Chicgoua Noubactep 《洁净——土壤、空气、水》2013,41(5):493-502
Metallic iron (Fe0) is often reported as a reducing agent for environmental remediation. There is still controversy as to whether Fe0 plays any significant direct role in the process of contaminant reductive transformation. The view that Fe0 is mostly a generator of reducing agents (e.g. H, H2 and FeII) and Fe oxyhydroxides has been either severely refuted or just tolerated. The tolerance is based on the simplification that, without Fe0, no secondary reducing agents could be available. Accordingly, Fe0 serves as the original source of electron donors (including H, H2 and FeII). The objective of this communication is to refute the named simplification and establish that quantitative reduction results from secondary reducing agents. For this purpose, reports on aqueous contaminant removal by Al0, Fe0 and Zn0 are comparatively discussed. Results indicated that reduction may be quantitative in aqueous systems containing Fe0 and Zn0 while no significant reduction is observed in Al0/H2O systems. Given that Al0 is a stronger reducing agent than Fe0 and Zn0, it is concluded that contaminant reduction in Fe0/H2O systems results from synergic interactions between H/H2 and FeII within porous Fe oxyhydroxides. This conclusion corroborates the operating mode of Fe0 bimetallics as H/H2 producing systems for indirect contaminant reduction. 相似文献
948.
949.
In this study,the ability of macroalgae Gracilaria sp.of removing eutrophication factors and toxic heavy metals Al,Cr,and Zn in a closed cultivation system is reported.The results show that the concentration of the three heavy metals decreased significantly during the experimental period in an algal biomass dependent manner.The biofiltration capacity of the alga for Al,Cr,and Zn is 10.1%-72.6%,52.5%-83.4% and 36.5%-91.7%,respectively.Using more materials resulted in stronger heavy metal removal.Additionally... 相似文献
950.
北京城市广场及校园表土(灰尘)中重金属水平与健康风险 总被引:24,自引:4,他引:20
通过对北京市城市广场和学校表层土壤与相应的地表灰尘中重金属含量调查,探讨土壤与灰尘之间元素分布的差异及来源,评估青少年在校期间通过灰尘摄入重金属的健康风险。研究表明:城市广场和校园土壤中Cu、Pb和Zn、灰尘中As、Cu、Pb、Zn和Cd显著高于北京市土壤重金属背景值,土壤(灰尘)中As、Ni、Cu、Pb、Zn和Cd超过背景值的样本比率分别为67%(27%)、13%(63%)、83%(100%)、73%(100%)、83%(100%)和53%(100%)。土壤中Cu、Pb和Zn存在一定积累,灰尘中Cd、Cu、Pb和Zn积累较重。灰尘中Cu、Pb和Zn显著高于土壤。校园土壤中Ni显著高于城市广场土壤,其他元素两者之间差异不大;校园灰尘中Ni、Pb和Zn显著高于城市广场。中学生通过校园灰尘摄入没有导致明显的健康风险。 相似文献