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Heavy metals in tissues of scorpionfish (Scorpaena porcus) caught from Black Sea (Turkey) and potential risks to human health 全文
2016
Çulha, Saniye Türk | Yabanlı, Murat | Baki, Birol | Yozukmaz, Aykut
Scorpionfish (Scorpaena porcus) is a demersal fish species commercially important for its of which meat is tough and delicious. The aim of this study was to determine heavy metal (Al, Cu, Ni, As, Cd, Hg, Pb, U) concentrations in this fish species which is traditionally consumed in the Black Sea Area and, to compare the concentrations of various toxic elements in different organs of the fish specimens (muscle, liver, gill, and skin). Within this scope, the mineralization was performed using microwave digestion system. Thirty-two scorpionfish caught from Sinop Inland Port during 2010 were analyzed. The heavy metal concentrations were determined with the method of inductively coupled plasma mass spectroscopy (ICP-MS). Verification of the method was demonstrated by analysis of standard reference material (NRCC-TORT-2 lobster hepatopancreas). After evaluation of the results, it was determined that the highest heavy metal accumulation was generally found in the liver. The maximum aluminum level and the minimum uranium level were found in the analyzed tissues. In terms of heavy metals, Al, Cu, Cd, and Hg showed a statistically significant difference between tissues (p < 0.05). It was determined that heavy metal concentrations obtained from the muscle tissues did not exceed the national and international recommended limits; and also it was found that daily intake amounts did not exceed tolerable daily intake amounts. Furthermore, in THQ based risk evaluation, the value 1 which is crucial for children and adults was not surpassed. In terms of public health, it was found out that there was not any risk in consumption of scorpionfish in the study area.
显示更多 [+] 显示较少 [-]Biosorption and degradation of decabromodiphenyl ether by Brevibacillus brevis and the influence of decabromodiphenyl ether on cellular metabolic responses 全文
2016
Wang, Linlin | Tang, Litao | Wang, Ran | Wang, Xiaoya | Ye, Jinshao | Long, Yan
There is global concern about the effects of decabromodiphenyl ether (BDE209) on environmental and public health. The molecular properties, biosorption, degradation, accumulation, and cellular metabolic effects of BDE209 were investigated in this study to identify the mechanisms involved in the aerobic biodegradation of BDE209. BDE209 is initially absorbed by wall teichoic acid and N-acetylglucosamine side chains in peptidoglycan, and then, BDE209 is transported and debrominated through three pathways, giving tri-, hepta-, octa-, and nona-bromodiphenyl ethers. The C–C bond energies decrease as the number of bromine atoms on the diphenyl decreases. Polybrominated diphenyl ethers (PBDEs) inhibit protein expression or accelerate protein degradation and increase membrane permeability and the release of Cl⁻, Na⁺, NH₄⁺, arabinose, proteins, acetic acid, and oxalic acid. However, PBDEs increase the amounts of K⁺, Mg²⁺, PO₄³⁻, SO₄²⁻, and NO₃⁻ assimilated. The biosorption, degradation, accumulation, and removal efficiencies when Brevibacillus brevis (1 g L⁻¹) was exposed to BDE209 (0.5 mg L⁻¹) for 7 days were 7.4, 69.5, 16.3, and 94.6 %, respectively.
显示更多 [+] 显示较少 [-]Heavy Metal Accumulation in Different Rice Cultivars as Influenced by Foliar Application of Nano-silicon 全文
2016
Wang, Shihua | Wang, Fayuan | Gao, Shuangcheng | Wang, Xugang
Silicon (Si) is one of beneficial elements for rice and is considered to enhance plant resistance to toxic metals. Nanofertilizers generally have a smaller particle size and specific characters and behaviors in soil and plants. Thus, nano-Si fertilizers may putatively have an advantage over traditional fertilizers in reducing heavy metal accumulation in rice straws and grains, but their effects still require investigation. Here, using a greenhouse pot culture experiment, we studied the effects of foliar application with organic or inorganic nano-Si on growth and yields, and heavy metal accumulation in six rice cultivars grown in soil artificially polluted with Cd, Pb, Cu, and Zn. Generally, hybrid cultivars had higher biomass and yields than conventional cultivars (P < 0.001), and nano-Si showed positive effects on at least four cultivars (P < 0.001). The average spike weight of six cultivars increased to 25.3 and 24.8 %, respectively, by inorganic and organic nano-Si. Hybrid cultivars generally had higher Cd concentrations in roots, shoots, and grains than conventional cultivars. In most cases, both organic and inorganic nano-Si reduced concentrations (P < 0.01) and bio-concentration factor (BCF) of the heavy metals in grains and decreased the translocation factor (TF) of heavy metals from roots to shoots and/or from shoots to grains, and the most pronounced effects were found on Cd. The average grain Cd concentration decreased to 27.1 and 23.8 %, respectively, by inorganic and organic nano-Si. In general, inorganic nano-Si had more pronounced effect than organic nano-Si on both rice growth and heavy metal accumulation. This present study firstly showed that nano-Si had positive effects on the growth and yields of rice grown in multi-metal-polluted soil and potentially reduced heavy metal accumulation in rice, especially the toxic Cd in grains. However, both rice cultivar and chemical form of Si fertilizers should be taken into account to develop efficient nano-Si fertilizers for preventing heavy metal-contaminated rice grains.
显示更多 [+] 显示较少 [-]Uptake and Release of Sequestered Nutrient in Subtropical Monsoon Ecological Ditch Plant Species 全文
2016
Kumwimba, Mathieu Nsenga | Dzakpasu, Mawuli | Zhu, Bo | Muyembe, Diana Kavidia
Ecological ditches have demonstrated the ability to filter and control nutrient transport to rivers. Few studies, however, have examined the internal loading of nitrogen (N) and phosphorus (P) in these systems due to vegetation decomposition. Most often, this concept is overlooked during evaluation of the nutrient removal rate of the ditches. Thus, the litter bag technique was used to analyze nutrient release to surface water during these processes. Mesocosm and field experiments were conducted to assess the growth characteristics and consequent nutrient accumulation by six ditch plant species. Of the six, Canna indica had the highest aboveground accumulation of N and P. About 85–95 % increase in the aboveground biomass was recorded at the end of the experimental period. The removal efficiencies of TN, TP, and NH₄-N from the sewage reached up to 72–99.4, 64–98.7, and 75 %–100, respectively. Complete removal of all NO₃-N was achieved. The amounts of N and P uptake by plant species were closely related to the biomass of plants. During the decaying process, N and P concentrations in the aboveground biomass decreased. These lost nutrients were eventually shifted to the system, which led to a deterioration of the water quality. Therefore, harvesting of aboveground biomass from inside the ditch is an appropriate intervention to prevent the release of N and P in the dormant season. The finding is important for planning an efficient eco-ditch system and predicting the influence of nutrient loading in the eco-ditches upon senescence of ditch plants.
显示更多 [+] 显示较少 [-]Electrokinetic Removal of As from Soil Washing Residue 全文
2016
Shin, Su-Yeon | Park, Sang-Min | Baek, Kitae
In this study, electrokinetic remediation (EKR) was carried out to remove arsenic (As) from soil washing residue. We screened various processing fluids and found that oxalic acid was most effective for As removal because it reductively dissolved Fe and As from the soil. In EKR, however, NaOH was a more effective agent for removing As, implying that the main removal mechanism of As was ion exchange between OH– and oxyanionic As. Oxalic and citric acid, both of which were efficient agents for removing As in the screening tests, did not effectively remove As by EKR, probably due to the relatively high pH and low soil-to-agent ratio. In EKR, As was mainly removed by electromigration toward the anode, even under high amounts of accumulated electro-osmotic flow. Therefore, strategies that increase electromigration have potential for enhancing As removal.
显示更多 [+] 显示较少 [-]Assessment of a Natural Iron-Based Sand for the Removal of Nitrate from Water 全文
2016
Zorgani, E Abdulmutaleb | Cibati, Alessio | Trois, Cristina
This research investigated the efficiency of South African sands and a type of zero-valent iron (ZVI) to remove nitrate from contaminated water. Batch experiments were carried out using soils widely available in the region of Kwazulu-Natal in South Africa (Berea red Sand (BRS) and Umgeni Sand (US), a type of ZVI and two mixes of BRS-ZVI (75–25 and 50–50 % w/w). The experiments were conducted in semi-anoxic conditions to investigate the nitrate removal potentials of the substrates. Batch tests revealed 100 % of nitrate removal by ZVI at lower concentrations (10–25 mg/L), while at higher concentrations (up to 100 mg/L), the removal efficiency decreased. The BRS, as sole material, showed the highest removal (70 %) at 25-mg/L nitrate solution, while at higher concentrations (50 and 100 mg/L), the nitrate removal was 36.7 and 42.9 %, respectively. The ZVI-BRS 50 % mix showed the best performance in terms of both rates and percentage of removal for most of the nitrate concentrations investigated indicating that a higher amount of BRS in the mixes improves the adsorption capacity. Both Langmuir and Freundlich isotherm models were applied to experimental data, and Langmuir described better the nitrate removal process. According with our findings, the BRS could represent a viable alternative to the ZVI to reduce the cost of the treatment and to increase the nitrate removal capacity.
显示更多 [+] 显示较少 [-]Field-scale study of the influence of differing remediation strategies on trace metal geochemistry in metal mine tailings from the Irish Midlands 全文
2016
Perkins, William T. | Bird, Graham | Jacobs, Suzanne R. | Devoy, Cora
Mine tailings represent a globally significant source of potentially harmful elements (PHEs) to the environment. The management of large volumes of mine tailings represents a major challenge to the mining industry and environmental managers. This field-scale study evaluates the impact of two highly contrasting remediation approaches to the management and stabilisation of mine tailings. The geochemistry of the tailings, overlying amendment layers and vegetation are examined in the light of the different management approaches. Pseudo-total As, Cd and Pb concentrations and solid-state partitioning (speciation), determined via sequential extraction, were established for two Tailings Management Facilities (TMFs) in Ireland subjected to the following: (1) a ‘walk-away’ approach (Silvermines) and (2) application of an amendment layer (Galmoy). PHE concentrations in roots and herbage of grasses growing on the TMFs were also determined. Results identify very different PHE concentration profiles with depth through the TMFs and the impact of remediation approach on concentrations and their potential bioavailability in the rooting zone of grass species. Data also highlight the importance of choice of grass species in remediation approaches and the benefits of relatively shallow-rooting Agrostis capillaris and Festuca rubra varieties. In addition, data from the Galmoy TMF indicate the importance of regional soil geochemistry for interpreting the influence of the PHE geochemistry of capping and amendment layers applied to mine tailings.
显示更多 [+] 显示较少 [-]Challenges of diatom-based biological monitoring and assessment of streams in developing countries 全文
2016
Bere, Taurai
Stream biomonitoring tools are largely lacking for many developing countries, resulting in adoption of tools developed from other countries/regions. In many instances, however, the applicability of adopted tools to the new system has not been explicitly evaluated. The objective of this study was to test the applicability of foreign diatom-based water quality assessment indices to streams in Zimbabwe, with the view to highlight challenges being faced in diatom-based biological monitoring in this developing country. The study evaluated the relationship between measured water quality variables and diatom index scores and observed some degree of concordance between water quality variables and diatom index scores emphasising the importance of diatom indices in characterisation and monitoring of stream ecological conditions in developing countries. However, ecological requirements of some diatom species need to be clarified and incorporated in a diatom-based water quality assessment protocol unique to these regions. Resources should be channelled towards tackling challenges associated with diatom-based biological monitoring, principally taxonomic studies, training of skilled labour and acquiring and maintaining the necessary infrastructure. Meanwhile, simpler coarse taxonomy-based rapid bioassessment protocol, which is less time and resource consuming and requires less specialised manpower, can be developed for the country.
显示更多 [+] 显示较少 [-]Comparative Evaluation of Genotoxic Effects Induced by CuO Bulk and Nano-Particles in Nile Tilapia, Oreochromis niloticus 全文
2016
Abdel-Khalek, Amr A.
Metal oxide nano-particles have definitely unique toxicological properties than currently investigated oxides. Therefore, this study was aimed to comparatively evaluate the genotoxicity of nano-CuO and bulk CuO particles on a model fish species Oreochromis niloticus. Fish were exposed to two selected concentrations (¹/₁₀ and ¹/₂₀ of the LC50/96 h) of both nano-CuO and bulk CuO for 30 days. Genotoxic effects associated with DNA ladder formation and chromosomal damage were investigated using DNA fragmentation and micronucleus techniques. Based on DNA fragmentation of fish hepatocytes, the two selected concentrations of bulk and nano-CuO were found to induce DNA damage. Analysis of the DNA fragments initiated by bulk CuO on agarose gel revealed DNA ladder pattern, which is commonly considered as a hallmark of apoptosis, while fish exposed to nano-CuO particles showed a molecular hallmark of necrosis which is the fragmentation of the nuclear DNA into a smear-like pattern. Also, DNA damage was further confirmed quantitatively using the image analysis software Image J. In this context, nano-CuO-treated groups exhibited a maximum DNA damage especially at the lower concentration (¹/₂₀ LC50/96 h). To ensure CuO genotoxicity, micronucleus and other nine nuclear abnormalities were studied in peripheral erythrocytes and significant (p < 0.05) elevation was observed in nano-CuO-exposed groups at the lower concentration followed by a decrease in extent of chromosomal damage at the higher concentration, while fish groups treated with bulk CuO showed a more or less dose-dependent effect.
显示更多 [+] 显示较少 [-]Effects of Modified Excess Sludge on the Growth of Artemisia ordosica and Transformation of Heavy Metals 全文
2016
Xiang, Yulin | Xiang, Yuxiu | Wang, Lipeng | Zhang, Zhifang
A greenhouse experiment was accomplished to investigate the feasibility of excess sludge modified by coal fly ash pretreatment and γ-ray irradiation in soil application for cultivation of Artemisia ordosica. The results showed that modified excess sludge provided a positive effect on the growth of Artemisia ordosica. The modified excess sludge and aeolian sandy soil at the volume ratio of 1:2 was optimal, and nutrient concentrations of Artemisia ordosica reached the highest. In the aeolian sandy soil, the bio-concentration factor values of most heavy metals were less than 1.0 except for Cu, Zn, and Ni. The average bio-concentration factor values of heavy metals in Artemisia ordosica increased in a sequence of Mo < Cd < Fe < V < Cr < Co < Mn < Pb < Cu < Zn < Ni for all samples. Artemisia ordosica could be used to decrease the bioavailability and eco-toxicity of Ni, V, and Mo in all cultivation experiments of artificial soil, and Artemisia ordosica could also reduce the bioavailability and eco-toxicity of Cu, Cd, Cr, and Mn in the artificial soil of modified excess sludge and aeolian sandy soil at the volume ratio of 1:2.
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