Phytoremediation of Sb,As, Cu,and Zn from Contaminated Water by the Aquatic Macrophyte Eleocharis acicularis

Sb, As, Cu, and Zn toxicity and contamination have become a growing concern in recent years. Phytoremediation, a plant based and cost effective technology, may be an effective approach in the cleanup of water contaminated by these metals. In this study, the aquatic macrophyte Eleocharis acicularis was used in laboratory and field experiments to assess its capability to accumulate Sb, As, Cu, and Zn, and thereby investigate its potential application in phytoremediation. The results showed that E. acicularis adapted well to water contaminated by these metals. The removal rates of Sb, As, Cu, and Zn in the laboratory experiment were 3.04, 2.75, 0.417, and 1.49 μg/L/day, respectively. The highest concentrations of these metals accumulated in E. acicularis after 10 days of the laboratory experiment were 6.29, 6.44, 20.5, and 73.5 mg/kg dry weight, respectively. Only 8% of As, 12% of Sb, 87% of Cu and 93% of Zn removed from the water were used by E. acicularis. The highest concentrations of Sb, As, Cu, and Zn accumulated in E. acicularis after 10 wk of the field experiment were 76.0, 22.4, 33.9, and 266 mg/kg dry weight, respectively. The results indicate that E. acicularis has the ability to accumulate Sb, As, Cu, and Zn from contaminated water.     

Zn(II) Ion Biosorption onto Surface of Eucalyptus Leaf Biomass: Isotherm,Kinetic, and Mechanistic Modeling

Bioremediation of Zn(II) by biosorption across aqueous phase on to surface of eucalyptus leaf powder has been investigated in present research work. The adsorptive potential of eucalyptus leaf powder was evaluated as function of pH, temperature, contact time, agitation rate and particle size. Maximum metal ion uptake and percentage removal capacity of eucalyptus leaf powder were 23.5 mg g⁻¹ and 94%, respectively, at optimized pH 5, 20 ± 1°C, contact time 6 h, particle size 0.5 mm and agitation rate 200 rpm. The biomass surface analysis revealed the fact that the biomass surface was heterogeneous and porous in nature. The functional groups like amine, amide, carboxyl, hydroxyl, and methyl groups, significantly important for metal ion binding were present on biomass surface in tremendous amount. Additionally, the Fourier transformation IR spectrum analysis of acid and base activated eucalyptus leaf biomass ruled out all the possibilities of the presence of surface functional groups mentioned above. The reaction rate was studied by applying two rate limiting models pseudo first and pseudo second order. Pseudo second order model was found to be more suitable (R² = 0.998) in comparison to pseudo first order (R² = 0.724). Adsorption equilibrium of batch stirred reaction data fitting shows the dominance of Langmuir isotherm (R² = 0.99) against Freundlich isotherm (R² = 0.887) model with equipartitional involvement of both film and intra particle diffusion as rate limiting steps at differential status of contact time.     

Two pulses of mineralization and genesis of the Zhaxikang Sb–Pb–Zn–Ag deposit in southern Tibet: Constraints from Fe–Zn isotopes

Zhaxikang is one large Sb–Pb–Zn–Ag deposit located in the North Himalaya of southern Tibet. To date, the genesis of this deposit still remains controversial. Here, we present new pyrite Fe and sphalerite Zn isotopic data for the first three stages of mineralization, Fe–Zn isotopic data for Mn–Fe carbonate that formed during the first two stages of mineralization, and Zn isotopic data for the slate wall rocks of the Jurassic Ridang Formation to discuss the genesis of the Zhaxikang deposit. The overall δ⁵⁶Fe and δ⁶⁶Zn values range from −0.80‰ to 0.43‰ and from −0.03‰ to 0.38‰, respectively. The δ⁵⁶Fe values of Mn–Fe carbonates are lighter than those of associated pyrite in six mineral pairs, indicating that the iron carbonates are preferentially enriched in light Fe isotopes relative to pyrite. The sphalerite has lighter δ⁶⁶Zn values than associated Mn–Fe carbonates in three mineral pairs.The δ⁵⁶Fe values of pyrite that formed during the first three stages of mineralization gradually increase from stage 1 (−0.33‰ to −0.09‰) through stage 2 (−0.30‰ to 0.19‰) to stage 3 (0.16‰–0.43‰). In comparison, the sphalerite that formed during these stages has δ⁶⁶Zn values that gradually decrease from stage 1 (0.16‰–0.35‰) through stage 2 (0.09‰–0.23‰) to stage 3 (−0.03‰ to 0.22‰). These data, in conjunction with the observations of hand specimens and thin sections, suggest that the deposit was overprinted by a second pulse of mineralization. This overprint would account for these Fe–Zn isotopic variations as well as the kinetic Rayleigh fractionation that occurred during mineralization. The temporally increasing δ⁵⁶Fe and decreasing δ⁶⁶Zn values recorded in the deposit are also coincident with an increase in alteration, again supporting the existence of two pulses of mineralization. The δ⁵⁶Fe values of the first pulse of ore-forming fluid were calculated using theoretical equations, yielding values of −0.54‰ to −0.34‰ that overlap with those of submarine hydrothermal solutions (−1‰ to 0‰). However, the δ⁵⁶Fe values of the stage 3 pyrite are heavier than those of typical submarine hydrothermal solutions, which suggests that the second pulse of mineralization was probably derived from a magmatic hydrothermal fluid. In addition, the second pulse of ore-forming fluid has brought some Fe and taken away parts of Zn, which results the lighter δ⁶⁶Zn values of sphalerite and heavier δ⁵⁶Fe values of pyrite from the second pulse of mineralization. Overall, the Zhaxikang deposit records two pulses of mineralization, and the overprint by the second pulse of mineralization causes the lighter δ⁶⁶Zn values and heavier δ⁵⁶Fe values of modified samples.     

粉煤灰、粘土、膨润土等对Zn2+的吸附试验研究

研究了粉煤灰、粘土、膨润土等从溶液中去除有毒金属离子Zn2+的吸附过程。动态试验显示吸附过程是快速的。吸附试验结果表明,粉煤灰、膨润土对Zn2+的吸附能力相当,但远大于粘土、粉质粘土。平衡吸附模型充分说明,在高浓度下Zn2+在粉煤灰、粘土、粉质粘土上的吸附符合Langmuir等温线。试验结果亦表明,随着吸附剂中Zn2+含量的增加,粉煤灰等吸附剂对Zn2+吸附的百分率均呈减小的趋势。     

岩溶区与非岩溶区不同土地利用方式下土壤Zn元素形态分析

本文采用连续提取法,对岩溶区与非岩溶区农田和林地两种土地利用形式下土壤中Zn元素形态进行了分级提取。测定结果表明,土壤中Zn元素主要以残渣态(占总量68. 5%～ 85. 0% )存在。此外,岩溶区农田、林地石灰土中Zn元素相对活泼态,即离子交换态(包括水溶态)、碳酸盐结合态、腐殖酸结合态(松结有机结合态)的含量均比非岩溶区对应的要低,而相对稳定态,即铁锰氧化物结合态、强有机结合态(包括部分硫化物态)的含量均比非岩溶区相对应的要高,残渣态含量与相对稳定态具有相同的趋势。这意味着岩溶土壤地球化学环境对土壤Zn的迁移、富集、形态转换具有明显的影响。长期耕种下岩溶区和非岩溶区土壤均会出现缺Zn状况,岩溶区情况更为严重。而适宜的土壤改良措施,可望提高土壤有效Zn形态的含量。      

The Forming Conditions of and Ore- searching Direction for B, Mg, Pb, Zn and Au Deposits in the Liaoji Proterozoic Rift

The Liaoji Proterozoic rift is an inter- intracontinenatl rift developed from Archean granite- greenstone tectonic regime and contains many important mineral deposits of U, B, magnesite, Pb - Zn, Au, Ag, Co and P. These deposits were formed as the result of late mobilization, transportation and concentration of the previously enriched ore - forming materials in several ore- bearing formations formed during the rift stage. So the metallogeny of these deposits in the rift shows both inheritance and new generation of the ore - forming materials. In future ore - searching practice, attentions should be paid on the studies of the ore - bearing formations in the rift, on the multiple stages of metallogeny and and on multiple derivations of the ore - forming materials.     

铜陵地区的镶嵌构造及其控矿意义

铜陵地区是我国著名的铁铜矿区。海西—印支期,环太平洋波浪引起了北东向展布的褶皱群,其背斜是波峰带,向斜是波谷带。印支期,古地中海地壳波浪使本区形成了北西向断裂。北东向构造和北西向构造的交织,形成了区内镶嵌构造格局。北西向断裂控制着铜铁矿床的分布,铅锌矿床则沿北东向的背斜翼部分布,构造的等间距性决定着矿田分布的等间距性。     

Multiple Foliations Defined by Different Sillimanite Crystal Habits, Partial Melting and the Late Metamorphic Development of the Cannington Ag-Pb-Zn Deposit, Northeast Australia

A succession of foliations defined by different sillimanite-bearing structural fabrics suggests that the macroscopic, isoclinal synform that dominates the geometry of the Cannington Ag-Pb-Zn deposit, northwest Queensland, Australia formed during D₂. The five foliations in this succession, S₁ to S₅, are defined by aligned sillimanite with habits ranging from individual crystals in S₁ through S₄ to clusters of fibrolite in S₅ in both the matrix and as inclusion trails within garnet and gahnite (Zn-rich spinel) porphyroblasts. S₁, S₃ and S₅ formed as sub-horizontal foliations, whereas S_1a, S₂ and S₄ formed sub-vertically. Foliation intersection/inflexion axes (FIAs) within garnet and gahnite porphyroblasts preserve a succession of trends that shifts from W-E to N-S. This succession indicates that this region experienced N-S followed by W-E bulk crustal shortening. N-S shortening occurred during D₁and D_1a, and W-E shortening occurred from D₂ to D₅. Prismatic and rhombic sillimanite produced during D₁-D₄ accompanied prograde metamorphism to ca. 634 62°C and 4.8 1.3 kbar. The coexistence of fibrous, prismatic and rhombic sillimanite resulted from post peak metamorphic reactivation of the early foliations during D₅. The synformal D₂ fold was intensified during D₄ by W-E bulk shortening. Local partial melting occurred after D₁ in the appropriate bulk rock compositions, based on calculation of P-T pseudosections in the chemical systems KFMASH, KFMASHTO, NCKFMASH and MnNCKFMASH. Zn mineralization related to gahnite growth occurred during D₃ through D₄, and was redistributed by partial melting into structural and rheological sites during D₄ and D₅shearing.     

Climate shifts vs. edaphic humidity and the difficulty of palaeoreconstructions – a malacological study on stable isotopes in Quaternary dune sequences of Fuerteventura

Dune palaeosurface sequences on the Eastern Canary Islands were investigated for stable isotope records in gastropod shells of the genus Theba. Due to the ecology of the taxon and the special oceanic insularity of the study site, we assume that δ¹⁸O_shell signals in our case mainly reflect shifts in δ¹⁸O signals of sea surface water. We found that a rapid decrease in δ¹⁸O_shell signals is associated with significant changes in gastropod associations. We suggest that these faunal changes were caused by strong (hot) winds at the end of glacial phases, that were described previously by Moreno et al. In addition, we assume that rapid declines in δ¹⁸O_shell signals due to marine transgressions were followed by geomorphologically stable phases, dominated by dust enrichment. Such palaeosurfaces correlate with maxima of gastropod biodiversity and with more negative δ¹³C_shell signals indicating a higher proportion of C3 plants. Based on our results, we also assume that these silty palaeosurfaces were associated with increased soil moisture conditions due to a higher water storage capacity of the finer substrate, independent of climatic moisture conditions.     

河套灌区耕地-荒地-海子系统间不同类型水分运移转化

为了探明耕地-荒地-海子系统中不同类型水分的运移转化规律,在2018-2019年典型时期对系统内具有代表性的采样点进行水样采集,分析了不同时期内不同水体的δ¹⁸O变化特征,并利用二端元混合模型和土壤水动力学方法计算了不同类型水分转化贡献率。结果发现：①在灌溉期,82%的灌溉水储存于1 m土体中,18%的灌溉水通过渗漏补给了耕地地下水,渠系灌溉水通过地下侧向径流给耕地地下水贡献了76%。②灌溉水和降雨对耕地地下水平均贡献率为94%和6%;耕地地下水和降雨对荒地地下水的平均贡献率为71%和29%;荒地地下水和降雨对海子的平均贡献率为43%和57%。③渠系灌溉水通过侧向径流贡献给耕地地下水的水量基本全部迁移给了荒地地下水,地下水迁移转化是由渠系水侧向径流触发的。④灌后5 d,耕荒地交界土层0~40 cm存在饱和-非饱和侧向补给;灌后15 d和30 d,耕地和耕荒地交界处的地下水向根区40~60 cm、土层80 cm以及100 cm补给水分;灌后30 d,耕地中的灌溉水水分消失。⑤在非灌溉期,荒地地下水和海子耗水较多,应给海子补给水分。