城市土壤不同颗粒中重金属的分布及其对人体吸入重金属的影响

采集了9个不同质地的城市土壤,按颗粒大小分为6个粒级,分别测定了4种重金属(Cu、Cd、Co和Pb)的全量和有效态含量。结果表明,细颗粒中重金属有明显的富集,其中<0.002 mm粒组的重金属含量约为土壤的1.57~13.95倍。有效态重金属占其总量的比例一般是0.250~0.125 mm和0.125~0.050 mm粒组高于其它粒组。质地对重金属在不同颗粒中的分配有很大的影响;虽然重金属含量一般是质地较黏的土壤高于质地不黏的土壤,但砂质土壤中细颗粒组分中的重金属的含量却一般要高于黏质土壤的相应粒组。因此,在相同的重金属含量条件下,砂质土壤对人体的潜在影响要远高于黏质土壤。     

Strongly Basic Anion Exchange Resin Based on a Cross-Linked Polyacrylate for Simultaneous C.I. Acid Green 16, Zn(II), Cu(II), Ni(II) and Phenol Removal

The adsorption ability of Lewatit S5528 (S5528) resin for C.I. Acid Green 16 (AG16), heavy metals (Zn(II), Cu(II) and Ni(II)) and phenol removal from single-component aqueous solutions is presented in this study to assess its suitability for wastewater treatment. Kinetic and equilibrium studies were carried out in order to determine adsorption capacities, taking into account phase contact time, adsorbates’ initial concentration, and auxiliary presence (NaCl, Na₂SO₄, anionic (SDS) and non-ionic (Triton X100) surfactants). The pseudo-second-order kinetic model described experimental data better than pseudo-first-order or intraparticle diffusion models. The adsorption of AG16 (538 mg/g), phenol (14.5 mg/g) and Cu(II) (5.8 mg/g) followed the Langmuir isotherm equation, while the uptake of Zn(II) (0.179 mg^1−1/nL^1/n/g) and Ni(II) (0.048 mg^1−1/nL^1/n/g) was better described by the Freundlich model. The auxiliary’s presence significantly reduced AG16 removal efficiency, whereas in the case of heavy metals the changes were negligible. The column studies proved the good adsorption ability of Lewatit S5528 towards AG16 and Zn(II). The desorption was the most effective for AG16 (>90% of dye was eluted using 1 mol/L HCl + 50% v/v MeOH and 1 mol/L NaCl + 50% v/v MeOH solutions).     

The Utilization of Algae and Seaweed Biomass for Bioremediation of Heavy Metal-Contaminated Wastewater

The presence of heavy metals in water bodies is linked to the increasing number of industries and populations. This has serious consequences for the quality of human health and the environment. In accordance with this issue, water and wastewater treatment technologies including ion exchange, chemical extraction, and hydrolysis should be conducted as a first water purification stage. However, the sequestration of these toxic substances tends to be expensive, especially for large scale treatment methods that require tedious control and have limited efficiency. Therefore, adsorption methods using adsorbents derived from biomass represent a promising alternative due to their great efficiency and abundance. Algal and seaweed biomass has appeared as a sustainable solution for environmentally friendly adsorbent production. This review further discusses recent developments in the use of algal and seaweed biomass as potential sorbent for heavy metal bioremediation. In addition, relevant aspects like metal toxicity, adsorption mechanism, and parameters affecting the completion of adsorption process are also highlighted. Overall, the critical conclusion drawn is that algae and seaweed biomass can be used to sustainably eliminate heavy metals from wastewater.     

Effects of nuclear charge fluctuations on dilepton photoproduction

Fluctuations of dilepton production from two photon interactions γγ→l~+l~- are studied in semicentral and peripheral nuclear collisions.Based on the Weizsacker-Williams approach,electromagnetic(EM) fields generated by moving nuclear charges are approximated as quasi-real photons.As fluctuating EM fields in each collision event are hard to be measured directly in experiments due to its short lifetime,we study the dilepton photoproduction with fluctuating EM fields,which are crucial for the EM fields induced chiral and charged particle evolutions,and calculate the relative standard deviation of the dilepton mass spectrum with the event-by-event fluctuating nuclear charge distributions.This fluctuation effect becomes smaller in more peripheral collisions where the shift of proton positions is implicit for EM fields outside the nucleus.The uncertainty of effective impact parameter △b on the standard deviation is also studied,and its effect is around one-third of the effect of nuclear charge fluctuations when △b is taken as～1 fm.     

Instantaneous work hardening behaviour of two-phase tungsten heavy alloys: a phenomenological approach

ABSTRACT

The present work describes a phenomenological approach to explain the instantaneous behaviour of tungsten heavy alloys (WHAs) in heat-treated and swaged conditions. The strengths and elongation values of heat-treated materials are lower and higher than those of the swaged samples respectively. The heat-treated materials exhibit two slopes in true stress–true plastic strain curves and follow the Ludwigson constitutive equation. On the other hand, swaged materials display a single slope and adhere to typical Swift constitutive equation. The latter reflect the presence of pre-strain in the materials due to swaging deformation. The fracture surfaces in heat-treated materials consist of W-W decohesion along with matrix rupture and W-cleavage, while swaged samples consist of mainly W-cleavage. Both the materials display three typical stages (I, II and III) of work hardening. The second derivatives of true stress–true plastic strain curves of these alloys exhibit a perfect parabola although the nature of true stress–true strain as well as true stress–true plastic strain curves is quite different in heat-treated and swaged materials. This has been observed for the first time in WHAs consisting of matrix and W-grains. The shape of the parabola is simple and easy to fit. The fitting parameters of parabolas have been successfully employed to explain the flow behaviour of a large number of tungsten heavy alloys having two-phase microstructure in different processing conditions.     

Nucleon effective mass splitting and density-dependent symmetry energy effects on elliptic flow in heavy ion collisions at E_(lab)= 0.09 ～ 1.5 GeV/nucleon

By incorporating an iso spin-dependent form of the momentum-dependent potential in the ultra-relativistic quantum molecular dynamics(UrQMD) model,we systematically investigate effects of the neutron-proton effective mass splitting m*_(n-p)=m*_n-m*_p/m and the density-dependent nuclear symmetry energy E_(sym)(ρ) on the elliptic flow v_2 in~(197)Au+~(197) Au collisions at beam energies from 0.09 to 1.5 GeV/nucleon.It is found that at higher beam energies(≥0.25 GeV/nucleon) with the approximately 75 MeV difference in slopes of the two different E_(sym)(ρ),and the variation of m*_(n-p) ranging from-0.03 to 0.03 at saturation density with isospin asymmetry δ=(ρ_n-ρ_p)/ρ-0.2,the E_(sym)(ρ) has a stronger influence on the difference in v_2 between neutrons and protons,i.e.,v_2~n-v_2~p,than m*_(n-p) has.Meanwhile,at lower beam energies(≤0.25 GeV/nucleon),v_2~n-v_2~p is sensitive to both the E_(sym)(ρ) and the m*_(n-p).Moreover,the influence of m*_(n-p) on v_2~n-v_2~p is more evident with the parameters of this study when using the soft,rather than stiff,symmetry energy.     

Probe chiral magnetic effect with signed balance function

In this paper a pair of observables are proposed as alternative ways,by examining the fluctuation of net momentum-ordering of charged pairs,to study the charge separation induced by the Chiral Magnetic Effect(CME)in relativistic heavy ion collisions.They are,the out-of-plane to in-plane ratio of fluctuation of the difference between signed balance functions measured in pair’s rest frame,and the ratio of it to similar measurement made in the laboratory frame.Both observables have been studied with simulations including flow-related backgrounds,and for the first time,backgrounds that are related to resonance's global spin alignment.The two observables have similar positive responses to signal,and opposite,limited responses to identifiable backgrounds arising from resonance flow and spin alignment.Both observables have also been tested with two realistic models,namely,a multi-phase transport(AMPT)model and the anomalous-viscous fluid dynamics(AVFD)model.These two observables,when cross examined,will provide useful insights in the study of CME-induced charge separation.     

洛阳市郊区叶菜中重金属含量抽样分析及评价

为了研究洛阳市郊区蔬菜中重金属污染状况,采用火焰原子吸收法对郊区李楼乡和孙旗屯乡抽取的叶菜样品中重金属Cu、Zn、Pb、Cd含量进行了测定。结果表明,8个蔬菜样品中Cu含量在0.393 9～0.970 7 mg/kg之间,Zn含量在1.395 0～10.080 0 mg/kg之间,均未超过国家蔬菜卫生限量标准;Pb含量在0.100 0～0.248 6 mg/kg之间,其中有3个样品Pb含量超出国家蔬菜卫生限量标准;Cd含量有5个样品未检出,其余3个样品也不超国标。经用单因子和综合因子污染指数评价,洛阳市郊区叶菜类蔬菜重金属污染大部分已处于警戒级到轻度污染,因此,应加强蔬菜中重金属污染的预防与治理工作。     

土壤重金属污染来源及其解析研究进展

土壤重金属污染问题是环境和土壤科学研究者关注的热点问题。对土壤重金属污染物来源的鉴别是准确、有效控制和治理污染源的前提。根据近年来国内外对土壤重金属污染的相关研究报道,综述了土壤中污染物的工业、农业和交通因子三大主要来源,重点阐述了目前解析土壤重金属污染来源所运用的化学形态研究、剖面分布、同位素示踪、空间分析和多元统计等方法,并就存在的问题和今后的研究重点进行了总结。     

柚子皮衍生类蜂窝状碳材料在同步检测重金属离子中的应用

不含金属的碳材料通过廉价且易获得的柚子皮经KOH活化和高温热解获得,该碳材料具有高比表面积(1 055 m~2·g~(-1))和高石墨化程度的类蜂窝状结构。将多孔碳(PAC)材料修饰后的电极作为工作电极,采用阳极溶出伏安法(SWASV)同步检测Cd~(2+)、Pb~(2+)和Cu~(2+)离子,表现出较高的灵敏度、可重复性、稳定性和较低的检测限。研究认为PAC的微孔和中孔可以充当有效的离子传递通道,从而加速离子的扩散并显著提高交换效率,而高的石墨化程度提高了材料的导电性,加速了电子传输。