Liver Metallothionein Level and Metal Content in Fish of Chung-Kung Stream,Taiwan-Tilapia and Liza Macrolepsis

A survey of Chung-Kung sttream fish was undertaken on six occasions from March 1994 to August 1995. Tilapia (Oreochromis hybrid) and Liza macrolepsis were the major species found downstream and were chosen as the target species for metallothionein (MT) analysis of liver tissue. in total MT of 77 tilapia and 48 Liza macrolepsis liver samples were analyzed. Significantly higher values (p >0.05) were found for the August 1995 samples than for samples taken earlier at site B (6 km from the sea) for tilapia and at site A (estuary) for Liza macrolepsis. Liver zinc, copper and cadmium were analyzed for the 1995 samples. for tilapia, liver MT concentration was found to correlate well with zinc concentration (r = 0.84, p > 0.001). for Liza macrolepsis, good correlation was found for MT with both zinc (r = 0.89, p > 0.001) and copper (r = 0.90, p > 0.001). These results indicate that in the Chung-Kung stream, zinc and copper may be the major inducers of fish liver MT. Since these two species are ubiquitous in tropical areas, they would provide a good biomarker for evaluation of integrated metal exposure in the tropical aquatic environment.     

Influence of some parameters on adsorption rate and toxicity of cadmium in activated sludge

The influence of pH, competitor ions (NaNO₃) and aerobic and anaerobic stabilization of activated sludge on the cadmium uptake by activated sludge solids was investigated. Above 0.08 mg L^‐1 cadmium in solution, biosorption was found to follow the Freundlich isotherm. Active cellular uptake of soluble cadmium does not appear to be a significant mechanism of the biosorption. In addition, the cadmium uptake is not completely reversible. The adsorption of cadmium by activated sludge seems to involve a physico‐chemical mechanism with especially weak electrostatic interactions with ion‐exchange reaction. The optimum adsorption pH was 7.5. Adsorption is influenced by sodium ion concentrations up to an equivalent conductivity of 10 000 μS cm^‐1. Aerobic and anaerobic stabilization of activated sludge increase systematically the initial adsorption capacities. Respirometric measurements were done to evaluate the inhibitive effects of cadmium on activated sludge. Monod's equation and the equation of non‐competitive inhibition were used to describe the toxicity related to cadmium uptake. These two equations appear to be complementary.     

Multivariate optimization of Cd(II) biosorption onto Ulmus tree leaves from aqueous waste

Ulmus tree leaves were successfully used as a novel and efficient biosorbent for removing cadmium, (Cd(II)), from aqueous solutions in a batch system. A multivariate strategy for optimization of removal efficiency conditions of Cd(II) was carried out. A 2³ full factorial design with three center points (9 runs) was performed for screening the main variables and reducing the large number of experimental runs. Initial concentration of metal ion (C _m), amount of sorbent (m), and pH were considered as the three main variables at two different levels. The maximum removal efficiency of Cd(II) was achieved within 1 h contact time. It was found that all the main factors and their interactions were significant at p < 0.05. Doehlert response surface methodology was utilized (13 runs) for finding a suitable mathematical model. The analysis of variance and some statistical tests such as lack-of-fit, coefficient of determination (R ²), and residual distribution plot confirmed the validity of the model. The optimum conditions for maximum removal of Cd(II) by Ulmus tree leaves were found as pH = 3.4, m (amount of sorbent) = 0.128 g, C _m (initial concentration of metal ion) = 12.1 mg L^?1.     

Assessment of cadmium,chromium, and copper levels in market fruit samples in Meerut,North India

The levels of cadmium (Cd), chromium (Cr), and copper (Cu) were assessed in 24 fruit species in Meerut, North India using atomic absorption spectrometry. Data showed that Cd concentrations in fruits except banana, pomegranate, papaya, orange, and cherry were above the recommended maximum allowable limit of Food and Agriculture Organization (FAO)/World Health Organization (WHO) (0.2 µg/g). Average Cr concentrations in all analyzed fruit samples were also found higher than the safe limit of FAO/WHO (2.3 µg/g). In contrast, fruits viz. banana, lychees, papaya, Indian apple, Asian apple, and tiger nut showed concentration of Cu below the recommended safe limit (40 µg/g). Our study demonstrated that concentration of studied heavy metals in all tested samples varied according to fruit species and respective contaminants. Data suggest that more strict rules/standards need to be applied by National/International regulatory agencies in order to make these important fruit items free from heavy metals contamination and protect the consumer.     

Effect of calcium and magnesium on copper,cadmium, and some essential elements of Indian major carps Labeo rohita (Hamilton) and Catla catla (Hamilton) treated with copper and cadmium

The effect of calcium and magnesium either singly or in combination on accumulation of cadmium and copper in Labeo rohita (rohu) and Catla catla (catla) was investigated in this study under laboratory conditions. The investigation showed that copper accumulation in rohu exposed to 0.25 mg L^?1 of copper for 14 days reduced from 31.0 ± 0.4 mg kg^?1 at no calcium/magnesium treatment to 3.5 ± 0.2 and 2.2 ± 0.1 mg kg^?1, respectively, at 75 mg L^?1 calcium or magnesium treatment. The copper level in catla exposed to 0.20 mg L^?1 of copper for 14 days reduced from 5.7 ± 0.1 mg kg^?1 at no calcium/magnesium treatment to 3.4 ± 0.2 and 3.3 ± 0.1 mg kg^?1, respectively, at 300 mg L^?1 calcium or magnesium treatment. The cadmium accumulation in rohu exposed to 0.20 mg L^?1 of cadmium for 14 days reduced from 1.7 ± 0.1 mg kg^?1 at no magnesium treatment to 1.4 ± 0.1 mg kg^?1 at 120 mg L^?1 magnesium treatment. The cadmium accumulation in catla exposed to 0.20 mg L^?1 of cadmium for 14 days reduced from 0.8 ± 0.2 mg kg^?1 at no magnesium treatment to 0.6 ± 0.2 mg kg^?1 at 80 mg L^?1 magnesium treatment. Copper and cadmium treatments also reduced some essential microelements of rohu and catla. Both the fishes restored these elements at different levels of calcium and magnesium.     

Effect of cadmium in the soil on growth,secondary metabolites and metal uptake in Salvia miltiorrhiza

We investigated the effect of Cd with different concentrations in soil (control, 0.5, 1.0, 1.5, and 2.0 mg kg^?1) on Salvia miltiorrhiza. The growth of S. miltiorrhiza was examined at 90 and 120 d, while active components were tested at 0, 30, 60, 90, and 120 d; Cd uptake was measured at days 0, 90, and 120. The biomass data indicated that high Cd concentration can stimulate the accumulation of biomass after a long treatment. The Cd content in the above- and below-ground parts strongly corresponds to the bioavailable Cd extracted by ethylene diamine tetraacetic acid (EDTA) and acetic acid. The Cd content in the below-ground parts of control approached the Cd standards given by World Health Organization after 120 d. The Cd content in the below-ground parts of S. miltiorrhiza at a Cd concentration of 0.5 mg kg^?1 exceeded the Cd standards after being grown for 90 and 120 days. The accumulation of hydrosoluble components in the above-ground parts appeared later than that in the below-ground parts. With longer treatment time, high Cd treatment promoted an accumulation of hydrosoluble and liposoluble components. The Cd content in the below-ground plant parts indicated that there was still a risk of exceeding the Cd limit for S. miltiorrhiza grown in the soil contaminated by low-concentration Cd after a long time.     

Speciation studies on simulated gastro‐intestinal digests of foodstuffs†

The factors affecting the solubilisation of metals during digestion of food have been examined in a two‐stage model system comprising simulated gastric and intestinal juices. The solubilisation of iron, copper and zinc was examined in digests of white and wholemeal bread. Zinc solubility was principally governed by pH and the simulated digestion had little additional effect. In contrast both iron and copper solubility were markedly affected by digestion of the bread. In the case of copper the enzymolysis increased solubility appreciably at neutral pH. All of the cadmium in a simulated gastric digest of canned crab meat was associated with soluble low molecular weight species of less than 1000 daltons. Cadmium solubility resulted from the acidic conditions of the digest rather than enzymatic solubilisation of binding proteins. Ninety percent of the cadmium in the digest became rebound to the insoluble fraction on adjustment to pH7.0. Subsequent simulated intestinal digestion increased the level of soluble cadmium to 20%; 1.0–1.5% was associated with soluble species in the range 26,000–37,000 daltons and 15.0–20.0% with soluble species of less than 3,000 daltons.     

氯化镉暴露对斑马鱼幼鱼神经行为毒性作用

为探索低剂量镉持续暴露对斑马鱼胚胎和幼鱼神经发育的影响,将受精后36h(36hpf)的斑马鱼胚胎暴露于不同浓度氯化镉受试液中持续至受精后6d(6dpf)。在一般毒性观察的基础上,采用高通量视频跟踪技术检测了48孔板中幼鱼的自发运动能力和对外界刺激产生的惊恐反应及恢复能力。结果显示:在不引起外观形态明显改变的暴露剂量下幼鱼自发运动表现异常。其中,0.1～0.5μmol·L-1暴露组幼鱼自发运动增多、轨迹紊乱、刻板式转向运动增加、触壁活动减少;1.0μmol·L-1暴露组幼鱼出现运动抑制、静止和原地震颤等状态,幼鱼的自发运动距离与氯化镉浓度关系呈现剂量依赖性倒"U"型,这种行为毒性效应与乙醇急性暴露引起的运动效应相似。光照惊恐反射实验中,暴露组幼鱼对突发的光暗变化表现敏感或迟钝。在撤除光源后暗适应减慢或加快。以上结果说明,斑马鱼胚胎和幼鱼对氯化镉的神经发育毒性作用敏感,并且高通量的幼鱼神经行为学方法在外源性化学物的毒性评价中能够提高检测效率,具有良好的应用前景。     

镉对小鼠骨生物力学及成骨细胞MG-63的影响

为了探讨镉对骨的影响及机制,选取7周龄C57BL/6J小鼠给予氯化镉2 mg.kg-1腹腔注射,每周2次,染毒4周后进行了骨力学参数的测量.结果显示,暴露组股骨的最大弯曲应力及弹性模量降低,骨灰干重比下降.体外结果显示,氯化镉(CdCl2)的暴露影响人成骨肉瘤细胞MG-63的细胞形态、活力及增殖,并且呈剂量依赖性.因此,氯化镉暴露可导致小鼠骨量下降和骨力学性能下降,并对成骨细胞有明显的毒性.     

城市污泥中重金属镉对苏云金杆菌发酵的影响机制

为揭示苏云金杆菌（Bacillus thuringiensis,简称Bt）富集重金属的可行性,考察重金属对Bt发酵的影响,以生物毒性较大的重金属镉（Cd）为研究对象,以城市污泥为培养基,研究了添加Cd（II）对Bt生长和晶体蛋白合成的影响,分析了Bt发酵过程中Cd有效态质量浓度的变化,利用傅立叶红外光谱（FTIR）和X线光电子能谱（XPS）初步探讨了Cd（II）在Bt表面吸附的作用机制。结果表明：培养基中外加Cd（II）对Bt生长的影响主要取决于Cd有效态质量浓度,污泥培养基在支持Bt生长和降低重金属有效态质量浓度上均明显优于常规培养基;Bt对Cd（II）有较好的耐受性,当Cd有效态质量浓度在20 mg.L-1以下时,Bt能较好地完成生长代谢过程;光谱学分析表明Bt对Cd（II）有少量吸附,吸附位点主要为羟基,少量C=O基团也可与吸附反应,可有效降低重金属的生物有效性。