Cd~(2+)对BY-2细胞的毒性机制及水杨酸的缓解作用

镉对生态环境的危害表现出对植物这种定生生物的毒害性。以绿色荧光蛋白(GFP)膜泡标记的烟草BY-2细胞为实验材料,分别在荧光显微镜和激光共聚焦显微镜下观察了Cd2+对植物细胞的毒害作用和机制,并研究了水杨酸(SA)处理对Cd2+植物细胞毒害的缓解作用。研究发现激光共聚焦显微镜可以观察到Cd2+处理3 h后细胞荧光亮度减弱,6 h时细胞皱缩和液泡缩小,9 h细胞大多死亡。在Cd2+胁迫同时加入SA,可显著提高细胞成活时间,荧光亮度增强、液泡化程度加大,同时能够观察到荧光标记的细胞膜包裹Cd2+的高荧光颗粒。SA处理的细胞还通过高度液泡化来缓解重金属Cd2+的毒性。结果表明具有生物活性的SA诱导细胞的液泡化,并通过膜成分对重金属的包裹和结合进一步降低了重金属对植物细胞的毒害。因此水杨酸缓解重金属对植物细胞的毒性,是通过诱导细胞的液泡化和膜对重金属离子的包裹束缚而实现的。     

Cadmium adsorption in montmorillonite as affected by glyphosate

Behaviors of soil heavy metals are often affected by coexisting herbicides due to their physical and chemical interaction. Effect of glyphosate, an herbicide containing -PO~3- and -COOH groups, on cadmium adsorption in montmorillonite was studied in detail. The results showed that the cadmium adsorption quantity in montmorillonite increased with increasing soil solution pH and cadmium concentration as usual, but decreased with glyphosate, which is due to the formation of a low affinity complex of Cd and glyphosate and decreasing solution pH induced by glyphosate addition. When the equilibrium solution pH was below 6.7, glyphosate has little effect on cadmium adsorption, but when the equilibrium solution pH was above 6.7, glyphosate significantly decreased cadmium adsorption quantity in montmorillonite. In addition, the adding order of Cd and glyphosate also influenced Ccl adsorption quantity in montmorillonite.     

无机硅叶面肥及土壤调理剂对水稻铅、镉吸收的影响

喷施叶面阻控剂和施用土壤调理剂是目前污染稻田治理的主要措施,针对不同污染类型、污染程度稻田研发效果较好的叶面阻控剂及土壤调理剂是研究重点。文章通过2019年的田间试验研究无机硅叶面肥及土壤调理剂对中重度铅镉复合污染稻田水稻铅镉阻控效果。共设3个处理:常规施肥处理(CK)、常规施肥+喷施无机硅叶面肥处理(L-Si)、常规施肥+施用无机硅土壤调理剂处理(S-Si)。结果表明:L-Si处理土壤中铅质量分数较对照(116.00±4.35)mg·kg-1高18.97%;S-Si处理较对照(5.51±0.06)能够显著提高稻田土壤pH值0.73,土壤中铅和镉分别较对照(116.00±4.35)、(1.89±0.03)mg·kg-1高12.07%和14.81%。L-Si处理下铅在根、叶片、稻米中富集较对照分别减少11.69%、12.40%和38.46%;镉在叶片、稻壳、稻米中较对照显著减少了18.10%、5.84%和40.84%。而S-Si处理中铅在根、茎、叶、稻壳、稻米中富集量较对照显著减少11.69%、36.93%、15.16%、23.47%和51.28%;镉在根、茎、叶、稻壳、稻米中富集量显著降低12.93%、42.28%、61.75%、59.85%和49.21%。L-Si及S-Si处理水稻产量较对照(7052.27±95.07)kg·hm^-2分别提高3.24%和4.09%。综上所述,无机硅经叶面吸收后,在减少叶片中铅富集的同时减少了根系对土壤铅的吸收,将经根系吸收的铅富集于茎和稻壳中;而在减少叶片中镉富集的同时并未减少根系对镉吸收,将经根系吸收的镉富集于根和茎中。无机硅土壤调理剂在将土壤中铅和镉固定于土壤中的同时阻隔了水稻根系对铅和镉下吸收,因此水稻根、茎、叶、稻壳、稻米中铅和镉的含量均显著降低。     

Removing cadmium from aqueous solutions utilizing agricultural wastes

The purpose of this study was to determine the cadmium (Cd) biosorption capacities of several agricultural wastes from aqueous solutions. Samples were tested unaltered and after hydrochloric acid treatment. Additional parameters tested include sample dose, contact time, particle size, mixing temperature, and the concentrations and pH of the Cd solutions. Desorption studies were performed to determine if the removed Cd could be recovered. In addition, tests were conducted to determine if the agricultural waste samples (AWS) could be reused for additional Cd biosorption cycles. The results of this study demonstrate a wide range of Cd biosorption proficiencies ranging from 33 to 100% removal. The parameters that resulted in higher Cd removal include higher sample dose, higher pH, and lower Cd solution concentration. Desorption results showed a 36–56% Cd recovery rate. Reused AWS were effective at removing Cd during subsequent trials. Therefore, all AWS types tested in this study can be reused for additional Cd biosorption cycles. Hence, it is possible that using AWS for metal treatment could reduce hazardous waste disposal inefficiencies and costs by avoiding disposing of spent AWS following each Cd biosorption cycle.     

萃取净化废水中镉的动力学研究简

采用恒界面池研究了二壬基萘磺酸（简称DNNSA或HD）-煤油体系萃取废水中镉离子的动力学。考察了搅拌转速、二壬基萘磺酸浓度、镉离子浓度和温度对萃取速率的影响,并得到了DNNSA萃取废水中镉离子的萃取动力学方程。实验结果表明,镉离子的萃取速率在200 r/min时出现与搅拌强度无关的化学反应动力学“坪区”,FT-IR结果表明,反应产物为磺酸盐;在动力学“坪区”,镉离子萃取速率随着萃取剂浓度、水相中的镉离子浓度增加而增加;随着温度升高,萃取速率增加,萃取活化能为11.8 kJ/mol。     

内循环泡沫浮选塔间歇分离含镉废水

为强化气液传质,提出了泡沫塔对泡沫分离性能影响的研究,并为此设计了在泡沫塔内加内循环套筒的泡沫分离塔。结果表明,与没有加内循环套管的常规塔相比,通过FT-IR检测分析,内循环塔性能明显优于常规塔。在间歇分离条件下,研究在内循环塔内处理含镉废水,探讨pH、LAS、停留时间、气泡大小等因素对镉去除率的影响。确定最佳处理条件为:pH=4.0,LAS=65 mg/L,塔内停留时间大于20 min,气体流量为250 mL/min,在此最佳实验条件下,镉的去除率可达99.9%以上,此时的镉质量浓度为10 mg/L。表面活性剂协同效应实验结果表明,在加入阳离子表面活性剂十二烷基二甲基苄基溴化铵时,会形成一个二元表面活性剂协同效应区。     

Impact of spiked concentrations of Cd,Pb, As and Zn in growth medium on elemental uptake of Nasturtium officinale (Watercress)

This study is aimed at investigating the impact of water quality on the uptake and distribution of three non-essential and toxic elements, namely, As, Cd and Pb in the watercress plant to assess for metal toxicity. The plant was hydroponically cultivated under greenhouse conditions, with the growth medium being spiked with varying concentrations of As, Cd and Pb. Plants that were harvested weekly for elemental analysis showed physiological and morphological symptoms of toxicity on exposure to high concentrations of Cd and Pb. Plants exposed to high concentrations of As did not survive and the threshold for As uptake in watercress was established at 5 ppm. Translocation factors were low in all cases as the toxic elements accumulated more in the roots of the plant than the edible leaves. The impact of Zn on the uptake of toxic elements was also evaluated and Zn was found to have an antagonistic effect on uptake of both Cd and Pb with no notable effect on uptake of As. The findings indicate that phytotoxicity or death of the watercress plant would prevent it from being a route of human exposure to high concentrations of As, Cd and Pb in the environment.     

利用体外实验方法评估稻米中镉的生物可给性和健康风险

为了研究稻米中镉(Cd)的生物可给性与稻米理化性质之间的相互关系以及稻米摄入而导致的Cd健康风险,从湖南某些地区采集了16个稻米样品,利用in vitro方法研究了这些稻米中Cd的生物可给性及其人体健康风险。结果表明:在16个样品中,有13个样品的Cd含量超过稻米中Cd的限量标准(0.2 mg·kg-1)。稻米中Cd的溶解态含量及其生物可给性变化较大,胃阶段和肠阶段Cd的溶解态含量范围分别为0.102~1.70 mg·kg-1和0.015~0.249 mg·kg-1,平均值分别为0.698 mg·kg-1和0.103 mg·kg-1,胃阶段和肠阶段Cd的生物可给性的范围分别为56.8%~82.0%和6.62%~15.9%,平均值分别为70.9%和11.1%。模拟肠液中Cd的溶解态含量与稻米的纤维含量之间有显著的相关性。如果不考虑稻米中Cd的生物可给性,所采集的所有稻米样品的摄入都将导致成人和儿童健康风险。如果我们考虑了稻米中的生物可给性,只有31%的稻米样品会对成人产生健康风险,将有50%的稻米样品会对儿童产生健康风险。     

用粉煤灰吸附废水中的金属离子

研究了在粉煤灰对金属离子的吸附反应中溶液pH及共存离子对金属离子去除率的影响,分析了粉煤灰对金属离子的吸附动力学,并考察了粉煤灰对实际废水的处理效果。实验结果表明,随pH的增大,金属离子的去除率增大。吸附等温线符合Fretmdlich模型,但在pH为4．5时表现为单一线性段、在pH为6时表现为两个线性段。粉煤灰对金属离子的吸附明显受到其他共存离子的影响。对钢铁厂生产废水的吸附实验结果表明,在pH为8、粉煤灰加入量为20g/L时,废水中Cd^2＋,Cu^2＋,Pb^2＋,Zn^2＋的去除率分别为70％,100％,100％,100％。     

微波活化制备加拿大一枝黄花活性炭及对Cd（Ⅱ）的吸附

以入侵植物加拿大一枝黄花为原料,在400℃氮气保护下,直接碳化90 min后,以KOH为活化剂,微波活化的方法制备了高比表面积微孔活性炭SCAC。结果显示活性炭SCAC的表面面积为1 888 m2/g,总孔容量为0.804 cm3/g,微孔容量为0.741 cm3/g,平均孔径0.567 nm,微孔平均孔径0.488 nm。通过静态吸附实验研究了活性炭添加量、溶液初始浓度、初始pH及吸附时间对SCAC吸附Cd(Ⅱ)的影响,通过动力学方程拟合探讨了活性炭对Cd(Ⅱ)的吸附机理。结果表明,吸附平衡时间、最佳pH及活性炭添加量分别为120 min、pH>7.5及0.05 g/50 mL,活性炭SCAC吸附动力学过程符合准二级方程模型。