Effects Of Cadmium Contamination Research Articles

Effects of cadmium contamination on bacterial and fungal communities in Panax ginseng-growing soil

BackgroundCadmium (Cd) contamination in soil poses a serious safety risk for the development of medicine and food with ginseng as the raw material. Microorganisms are key players in the functioning and service of soil ecosystems, but the effects of Cd-contaminated ginseng growth on these microorganisms is still poorly understood. To study this hypothesis, we evaluated the effects of microorganisms and Cd (0, 0.25, 0.5, 1.0, 2.0, 5.0, and 10.0 mg kg-1 of Cd) exposure on the soil microbial community using Illumina HiSeq high-throughput sequencing.ResultsOur results indicated that Cd-contaminated soil affected the soil microbial diversity and composition, and bacterial diversity was affected more than fungal diversity in Cd-contaminated soil, especially according to Shannon indices. The abundance of the soil microbial community decreased and the composition changed according to the relative abundances at the phylum level, including those of Saccharibacteria and Gemmatimonadetes in bacteria and Mortierellomycota in fungi. The LEfSe algorithm was used to identify active biomarkers, and 45 differentially abundant bacterial taxonomic clades and 16 differentially abundant fungal taxonomic clades were identified with LDA scores higher than 4.0. Finally, a heatmap of Spearman's rank correlation coefficients and canonical discriminant analysis (CDA) indicated that some key biomarkers, Arenimonas, Xanthomonadales, Nitrosomonadaceae, Methylophilales, Caulobacterales, Aeromicrobium, Chitinophagaceae, Acidimicrobiales, Nocardioidaceae, Propionibacteriales, Frankiales, and Gemmatimonadaceae, were positively correlated with the total and available Cd (p<0.05) but negatively correlated with AK, AP, and pH (p<0.05) in the bacterial community. Similarly, in the fungal community, Tubaria, Mortierellaceae, and Rhizophagus were positively correlated with the total and available Cd but negatively correlated with AK, AP, TK, and pH.ConclusionCd contamination significantly affected microbial diversity and composition in ginseng-growing soil. Our findings provide new insight into the effects of Cd contamination on the microbial communities in ginseng-growing soil.

Effect of cadmium contamination on the eutrophic secondary pollution of aquatic macrophytes by litter decomposition

The objective of this study was to identify the effect of cadmium (Cd) contamination on the decomposition of aquatic macrophyte litter and its eutrophic secondary pollution. A laboratory experiment was conducted with three treatments: water Cd contamination (Cd-w), litter Cd contamination (Cd-l) and control (CK). The results showed that CK and Cd-w exhibited the typical decomposition dynamics of litter, i.e., early rapid decomposition followed by slow decomposition, while the litter biomass loss (BL) in Cd-l exhibited an approximately linear relationship with time over the 64-day experimental period. The BL in Cd-l was only 10.8% in the initial 4 days, while that in CK and Cd-w was 59.0% and 54.8%, respectively. Cd inhibited the fluctuation of the water chemical oxygen demand (COD) by reducing both the early increase and the subsequent decrease. The increases in water total nitrogen (TN) and total phosphorus (TP) were inhibited by Cd contamination throughout most of the decomposition period. The alterations of litter quality during the plant growth period and of the bacterial community during the litter decomposition period by Cd contamination could explain the variations in litter decomposition rate and its eutrophic secondary pollution during the early and late decomposition stages, respectively. The Cd inhibition of the eutrophic secondary pollution of aquatic macrophytes has great significance for the improved evaluation of Cd contamination.

Spent NiMH batteries: Characterization and metal recovery through mechanical processing

The growing concern about the environment, associated with the continuous increase in the production of electronic equipment, such as computers, cell phones, mobile devices and consequently batteries, has induced research to develop new technologies to recycle the huge numbers of spent batteries generated in the last few years. The amount of spent NiMH batteries will tend to grow continually over the next few years. These batteries have in their chemical composition, valuable metals such as Ni, Co and rare earths. In the first stage of this work a characterization of NiMH batteries was done. Batteries from different brands and models were disembled and their components were characterized in relation to their chemical composition and main phases. In a second stage of this work, a sample of spent NiMH batteries was milled and the polymeric and metallic fractions were magnetically separated. The results obtained demonstrate that the recycling study, aimed at the recovery of Ni, Co and rare earths, is viable due to the great amount of these metals that are present batteries. It also demonstrates that magnetic separation is a very efficient process to recovery nickel alloys. However the effects of cadmium contamination (originating from fake batteries) will cause the recycling processes to be re-evaluated.

Effect of cadmium contamination with sewage sludge and phosphate fertiliser amendments on soil enzyme activities, microbial structure and available cadmium

The effect of Cd pollution (50 mg kg -1), with and without sewage sludge (Sw) and PO4 3- fertiliser (P) addition, on soil biochemical activity and available Cd was assessed in a 112-day soil incubation experiment. The availability of Cd decreased with incubation time and was reduced by the Sw and P additions resulting in the following order of treatments: Cd>P+Cd>Sw+Cd. With the exception of urease and N-acetylglucosaminid- ase activities, all enzyme activities were negatively cor- related with available Cd. The total culturable bacterial population was significantly higher with the addition of Sw alone than in the control during the incubation period (P<0.05). The number of fluorescent pseudomonads de- creased with time, but was significantly increased by the addition of Sw. The total fungal populations decreased with time in all treatments, whilst the addition of Sw and PO4 3- fertilisers relatively increased the fungal popula- tion. Addition of Sw in the presence of Cd increased the fungal populations in relation to the addition of Cd alone. The results support the view that Cd contamina- tion has a large detrimental effect on nutrient cycling and microbial activity and that the effects of Cd are reduced by P and Sw additions.

The effects of cadmium contamination on the discriminative stimulus properties of cocaine and related drugs.

Rats were exposed to a diet containing 100 ppm cadmium chloride or a control diet. At 52 days of exposure, rats were trained to discriminate between saline and 5 mg/kg cocaine injections. After acquisition training, successive substitution tests were conducted using cocaine, the indirect dopamine agonist d-amphetamine, the mixed D1-D2 agonist apomorphine, SKF 38393 and SKF 82958 (both preferential D1 agonists), quinpirole (a preferential D2 agonist), GBR 12909 (a dopamine reuptake inhibitor), procaine (a local anesthetic), and morphine (an opiate). The results showed that cadmium-exposed rats were slower to acquire the saline-cocaine discrimination than controls. Moreover, cadmium contamination reduced substitution when apomorphine, SKF 82958, and GBR 12909 were presented during generalization testing. Also, cadmium exposure blocked tolerance to cocaine that was evident in control rats following 14 days of exposure to 60 mg/kg/day cocaine.

The effects of cadmium contamination on the discriminative stimulus properties of cocaine and related drugs.

The effects of cadmium contamination on the discriminative stimulus properties of cocaine and related drugs.

Effects of cadmium contamination on ethanol-induced changes in locomotor activity and rota-rod performance.

Effects of cadmium contamination on ethanol-induced changes in locomotor activity and rota-rod performance.

Effects of cadmium contamination on ethanol-induced changes in locomotor activity and rota-rod performance.

Effects of cadmium contamination on ethanol-induced changes in locomotor activity and rota-rod performance.

Involvement of metallothionein in cadmium accumulation and elimination in the clam Ruditapes decussata

Cadmium is one of the most toxic pollutants in seawater because of its persistence, toxicity and potential for bioaccumulation. It is included on the [open quotes]black list[close quotes] of several international agreements established to regulate the input of pollutants into the marine environment. The deleterious effects of cadmium contamination in marine organisms result from its accumulation within specific tissues. However, most of these organisms have developed subcellular detoxification processes, including the synthesis of metallothioneins, low-molecular weight, metal-binding proteins. Bivalves have the ability to accumulate and concentrate cadmium to levels several orders of magnitude above those found in their environment. The present study was designed to examine the involvement of metallothionein synthesis in cadmium accumulation and elimination in the bivalve Ruditapes decussata when exposed to a sublethal cadmium concentration (100 [mu]g/l) and to a mixture of cadmium (100 [mu]g/1), copper (50 [mu]g/l) and zinc (50 [mu]g/1). 15 refs., 2 figs., 1 tab.

Effect of cadmium contamination on denitrification processes in Brookston clay and Fox sandy loam

The effect of cadmium on the kinetics of denitrification processes in Brookston clay and Fox sandy loam was determined using a gas-flow system whereby anaerobic soil columns were continuously purged by argon carrier gas. Rates of removal of NO 3 −, formation and removal of NO 2 −, and net steady-state rates of NO and N 2O production were measured. Cadmium, at levels up to ∼60 μg Cd g −1 dry soil added to these soils as Cd(NO 3) 2, decreased the rate of NO 2 − loss resulting in temporary accumulation of this potentially hazardous ion. In the clay soil maximum NO 2 − concentrations of 0·95 ± 0·04 and 0·67 ± 0·03 μg N g −1 (dry wet) were observed in the soil amended to 3 contain 61·7 μg Cd g −1 and in unamended soil which contained 1·8 μg Cd g −1 respectively. In sandy soil the effect was much more pronounced with corresponding NO 2 − concentration of 1·75 ± 0·05 and 0·40 ± 0·01 μg N g −1 in soil containing 54·1 μg Cd g −1 and 1·1 μg Cd g −1 respectively. Addition of Cd had no apparent effect on removal of NO 3 −, on loss of NO or on formation and loss of N 2O. Cadmium therefore appears to be an effective and specific inhibitor of the biological reduction of NO 2 − to NO.

Cadmium Contamination May Modify Response of Tomato to Atmospheric Ozone

The combined effects of cadmium contamination and ozone exposure on tomato plants were studied to determine synergistic effects. It was found that Cd and O/sub 3/ acted synergistically at certain O/sub 3/ concentrations and specific environmental conditions.