Comparative study of the accumulation and detoxification of Cu (essential metal) and Hg (nonessential metal) in the digestive gland and gills of mussels Mytilus galloprovincialis, using analytical and histochemical techniques

The aim of the present study is the comparative examination of accumulation and detoxification of Cu and Hg in digestive gland and gills of mussels Mytilus galloprovincialis, using atomic absorption spectrophotometry and autometallography. Mussels were exposed to 0.08 mg L⁻¹ Cu, 0.08 mg L⁻¹ Hg, as well as to a mixture of 0.08 mg L⁻¹ Hg and 0.08 mg L⁻¹ Cu for 11 d. After the experimental exposure, animals were kept under laboratory conditions for a detoxification period of 7 d. An antagonistic effect of Cu against to Hg accumulation was noted in the digestive gland of mussels after the experimental exposure, as well as after the detoxification period, supporting the protective role of Cu against to Hg toxicity in this tissue. Digestive gland was suggested as a main organ for Hg accumulation and gills as a target position for Cu accumulation. Additionally, lower time was evaluated for Hg detoxification in the digestive gland and gills of mussels, in relation to those addressed for Cu detoxification in the same tissues. The evaluation of black silver deposits (BSD) extent performed in digestive gland and gills was suggested as a less sensitive approach, in relation to atomic absorption spectrophotometry (AAS), to indentify the concentration of heavy metals in tissues of mussels. The toxic effects of Hg, Cu and a mixture of them on lysosomal system of the digestive cells are also discussed.     

Polycyclic aromatic hydrocarbons and hydroxylated metabolites in the muscle tissue of Eurasian perch (Perca fluviatilis) through dietary exposure during a 56-day period

Eurasian perch (Perca fluviatilis) was exposed trophically to phenanthrene, pyrene and benzo[a]pyrene. Accumulation kinetics in the muscle tissue of parent PAHs and hydroxylated metabolites were established for 56 days at 3 levels of exposure (0, 100 and 500 μg/kg BW). Benzo[a]pyrene and 3-hydroxy-benzo[a]pyrene were not detected in the muscles. During exposure, there was an increase in phenanthrene, pyrene and their hydroxylated metabolites in the muscle tissue. Low transfer to muscle tissue was observed at equilibrium for phenanthrene (4.4 ± 0.6% and 2.7 ± 0.8%) and pyrene (1.0 ± 0.2% and 0.33 ± 0.09%), depending on the concentrations in the spiked feed.     

Eighty-year sedimentary record of heavy metal inputs in the intertidal sediments from the Nanliu River estuary, Beibu Gulf of South China Sea

²¹⁰Pb analysis in the sediment core C11 was used to reconstruct the historical fluxes of Hg, Cu, Pb, Zn, Cd, Cr and As in the Nanliu River estuary during the last ∼81 year. The ²¹⁰Pb_xs-derived sedimentation rates, molar C/N ratios, enrichment factors and excess fluxes indicated that the natural inputs prevailed till the early 1990s. When the erosion related to land-use modifications enhanced, it promoted higher accumulation rates of the sedimentary material. In the recent sediments they were found a moderate enrichment of Cd and Hg (maximum 3.5- and 2.8-fold corresponding to the local background levels, respectively) and a slight enrichment of Cr, Zn, As and Pb (maximum 1.3-, 1.3-, 1.3- and 1.2-fold, respectively). The excess metal fluxes also showed a consistently increasing tread since the early 1990s, which could be associated with the intensive use of phosphate fertilizers and the combustion of fossil fuels derived from human activities.     

Multi-generation cadmium acclimation and tolerance in Daphnia magna Straus

The cladoceran Daphnia magna was acclimated for seven generations to cadmium concentrations ranging from 0 (control) to 250 microg/l Cd (corresponding to a free ion activity of 4.60 nM Cd2+). Acute and chronic cadmium tolerance as well as cadmium accumulation were monitored as a function of acclimation time. After two to three generations of acclimation to concentrations ranging from 0.23 to 1.11 nM Cd2+ increases in acute tolerance were maximal (factor 7.2) and significant. Acclimation for seven generations to the same acclimation concentrations did result in an increased chronic cadmium tolerance (21 days EC50 values increased). Organisms acclimated to 1.93 nM Cd2+ were equally or more sensitive than non-acclimated daphnids in acute and chronic toxicity tests. Cadmium contents in D. magna increased significantly as a function of the acclimation concentration. Maximum body burdens of 236+/-30 microg Cd/g dry weight were measured in organisms exposed to 4.60 nM Cd2+, but detoxification mechanisms were only successful up to 82+/-20 microg Cd/g dry weight as this concentration did not cause major decreases in survival and reproduction in chronic toxicity tests. As the potential positive effect of acclimation on cadmium tolerance disappeared with successive acclimation generations and increasing acclimation concentrations, it is concluded that multi-generation acclimation studies are important for the evaluation of the long-term effects of environmental toxicants.     

旱柳（Salix matsudana Koidz）体内Cu迁移特征的水培模拟研究

为探讨重金属元素Cu在旱柳（Salix matsudana Koidz）植物体内的迁移及形态特征,研究通过水培模拟实验,运用ICP-AES测定了旱柳不同组织中Cu含量,并采用SEM-EDAX技术分析了旱柳不同组织显微结构和Cu存在形态.结果表明：在Cu胁迫下,根、茎、叶中Cu含量随培养液Cu浓度的增加而增加,在450μ...     

Growth and metal accumulation response of <Emphasis Type="Italic">Vigna radiata</Emphasis> L. var PDM 54 (mung bean) grown on fly ash-amended soil: effect on dietary intake

Plants of Vigna radiata L. var. PDM 54 (mung bean) were grown in soil amended with different amounts (10 and 25%) of fly ash (FA). Although total metal content increased with increasing FA amendment, DTPA-extractable metals were higher for 10% FA. Accumulation of metals by the plants increased with increasing FA amendment and was greater in shoots than in roots (except for Mn and Cu) and seeds (except Mn). The total daily intake (TDI) of all the tested metals in seeds was within the recommended dietary allowance (RDA)/provisional tolerable daily intake (PTDI) for adults, except for Cd, which was higher than recommended values. Principal-components analysis (PCA) based on studies of physicochemical properties, DTPA-extractable metals, and metal accumulation in the different parts of V. radiata showed that physicochemical properties such as cation-exchange capacity, organic carbon, and organic matter had significant positive effects on accumulation of Cd, Co, Ni, and Pb by the plant, whereas EC had a significant negative effect. Although addition of fly ash (10%) initially increased the rate of growth, toxic symptoms were observed for 25% FA. Results from analysis of antioxidants (carotenoids, ascorbic acid, non-protein thiol, and free proline) revealed that these increased more in plants grown in 10% FA than in those grown in garden soil. Cysteine and malondialdehyde (MDA) content increased with increasing FA amendment. PCA also showed that all the antioxidants studied behaved similarly except cysteine, for which there was a close relationship with MDA content. Thus, the results obtained during this study revealed that V. radiata L. var. PDM 54 may be grown in 10% FA and/or contaminated agricultural soil.     

零价纳米铁对青梗菜吸收土壤铬的抑制效果探讨

通过盆栽实验探讨不同铬污染水平农田土壤施加零价纳米铁对不同时期青梗菜吸收土壤铬的抑制效果。结果表明,零价纳米铁能够有效抑制青梗菜对铬的富集,且在施加铬铁质量比例为1∶20和1∶40时效果较好,与对照相比,青梗菜根、茎、叶铬含量最高减少量分别为66%、79%、78%。同一污染土壤,不同采集时期青梗菜体内铬含量无显著差异。青梗菜体内富集的铬含量与土壤总铬含量呈正相关,青梗菜对铬富集量呈现根部茎部叶部。     

Characteristics of cesium accumulation in the filamentous soil bacterium Streptomyces sp. K202

A filamentous soil bacterium, strain K202, was isolated from soil where an edible mushroom (Boletopsis leucomelas) was growing and identified as belonging to the genus Streptomyces on the basis of its morphological characteristics and the presence of LL-2, 6-diaminopimelic acid. We studied the existence states of Cs and its migration from extracellular to intracellular fluid in the mycelia of Streptomyces sp. K202. The results indicated that Cs accumulated in the cells through at least 2 steps: in the first step, Cs⁺ was immediately and non-specifically adsorbed on the negatively charged cell surface, and in the second step, this adsorbed Cs⁺ was taken up into the cytoplasm, and a part of the Cs entering the cytoplasm was taken up by an energy-dependent transport system(s). Further, we confirmed that a part of the Cs⁺ was taken up into the mycelia competitively with K⁺, because K⁺ uptake into the intact mycelia of the strain was significantly inhibited by the presence of Cs⁺ in the culture media. This suggested that part of the Cs is transported by the potassium transport system. Moreover, ¹³³Cs-NMR spectra and SEM-EDX spectra of the mycelia that accumulated Cs showed the presence of at least 2 intracellular Cs states: Cs⁺ trapped by intercellular materials such as polyphosphate and Cs⁺ present in a cytoplasmic pool.     

Effects of nano-TiO(2) in combination with ambient UV-irradiation on a leaf shredding amphipod

Production and use of engineered nanoparticles, such as titanium dioxide nanoparticles (nTiO₂), is increasing worldwide, enhancing their probability to enter aquatic environments. However, direct effects of nTiO₂ as well as ecotoxicological consequences due to the interactions of nTiO₂ with environmental factors like ultraviolet (UV) irradiation on representatives of detrital food webs have not been assessed so far. Hence, the present study displayed for the first time adverse sublethal effects of nTiO₂ at concentrations as low as 0.2 mg L⁻¹ on the leaf shredding amphipod Gammarus fossarum both in presence and absence of ambient UV-irradiation following a 7-d exposure. In absence of UV-irradiation, however, the effects seemed to be driven by accumulation of nTiO₂ at the bottom of the test vessels to which the gammarids were potentially exposed. The adverse sublethal and lethal effects on gammarids caused by the combined application of nTiO₂ and ambient UV-irradiation are suggested to be driven by the formation of reactive oxygen species. In conclusion, both the accumulation of nTiO₂ at the bottom of the test vessel and the UV induced formation of reactive oxygen species clearly affected its ecotoxicity, which is recommended for consideration in the environmental risk assessment of nanoparticles.     

Comparison of the use of mussels and semipermeable membrane devices for monitoring and assessment of accumulation of mutagenic pollutants in marine environment in combination with a novel microbiological mutagenicity assay

A novel microbiological mutagenicity assay, based on bioluminescence of a marine bacterium Vibrio harveyi mutant strain, potentially suitable for monitoring and assessment of mutagenic pollution of marine environment, has been described recently. Here, we tested the use of this assay, in combination with either mussels (Mytilus sp.) or semipermeable membrane devices (SPMDs), in assessment of accumulation of mutagens in marine water (samples of Baltic Sea water were tested). Either similar results were obtained in both systems or higher signals in the SPMD-based system were detected, depending on the tested water samples. We conclude that the use of both mussels and SPMDs in combination with the V. harveyi bioluminescence mutagenicity assay is a method suitable for monitoring and assessment of accumulation of mutagenic pollutants in marine environment, but in some cases the SPMD-based system may provide a more sensitive test.