Measurement of Acid Volatile Sulphide and Simultaneously Extracted Metals in Sediment from Lake Albufera (Valencia,Spain)

Lake Albufera (Valencia, Spain) is part of a legally protected wetland of international importance. However, it has deteriorated as a result of urban, industrial, and farming pollution. It is highly eutrophic, and its sediment contains persistent pollutants, such as heavy metals. In anoxic sediments, sulphides represent an important binding phase for heavy metals. In this study, acid volatile sulphide (AVS) and simultaneously extracted metals (SEM) were analyzed in surface sediment extracted from Lake Albufera; organic matter and total metals were also analyzed. Twelve sites were sampled in each of three sampling campaigns conducted in March and September 2007 and September 2008. The results revealed elevated organic matter contents varying between 6.9 and 16.7%. The concentrations of AVS in the lake were high, ranging from 8.5 to 48.5 μmol/g; the lowest concentrations were found in the central sites. The AVS results displayed significant differences between the samples from the winter and summer of 2007 (p < 0.05) but not between the two summer samples. The results obtained for SEM varied from 1.4 to 4.8 μmol/g. The difference SEM-AVS was less than zero for all sampling locations and campaigns, indicating the existence of a sulphide pool able to bind metals.     

食品中重金属的存在形态及其与毒性的关系

简要介绍了近年来有关食品中重金属形态及其毒性关系的研究进展,归纳了食品中重金属的化学形态特征、不同类型食品中重金属的存在形态、食品中重金属形态与生物有效性和毒性的关系,以及该领域中急需研究解决的问题．     

水体沉积物中酸可挥发性硫化物(AVS)研究进展

水体沉积物中酸可挥发性硫化物 (AVS)是总硫含量中活性最高的部分 ,是沉积物中有毒重金属的重要结合形态 ,它的含量在很大程度上影响着沉积物重金属的生物有效性 ,从而作为沉积物中有毒重金属环境污染评价的一个重要指标 ;就十多年来水体沉积物中酸可挥发性硫化物 (AVS)的研究进行了综述。概述了 AVS的测定方法及其影响因素 ;探讨了水体沉积物中 AVS含量时空变化的规律 ;同时就目前“同时可提取重金属”(SEM)与 AVS摩尔浓度比值和水体沉积物重金属生物毒性关系的研究进行了概括和分析。     

东湖沉积物中酸挥发性硫化物的季节、深度分布特征研究

在酸挥发性硫化物AVS存在的情况下,水体沉积物中的重金属的生物有效性将显降低,同步提取金属SEM与AVS的比值SEM/AVS可作为判定重金属生物有效性的良好指标。本通过研究东湖三个不同富营养化水平的站点的AVS的季节、深度变化特征及相关的影响因子,发现AVS的含量夏季要高于冬季,并随深度的加深呈先增高后降低的分布特征,SEM/AVS随深度的变化则呈现出先降低后升高的分布特征。研究结果为正确应用SEM/AYS指标判定沉积物中重金属的生物有效性提供了依据。     

Evaluation of the efficacy of the sequential elution technique,by use of electron microscopy methods

Abstract

In the present study, scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM–EDS) was used in conjunction with the sequential elution technique (SET) to evaluate the efficacy of extraction of Zn from the moss Pseudoscleropodium purum (Hedw.) M. Fleisch. Moss samples were collected from two areas, a contaminated area (with high concentrations of Zn) in the surroundings of a steel works, and an uncontaminated area. Some samples from the uncontaminated area were used as controls, and others were incubated in a solution of ZnCl₂ for subsequent analysis of uptake and location of Zn. The concentrations of Zn in the different cell compartments of the moss were determined by use of the SET, and different points on the surface of the moss and in deposited particles were analysed by SEM–EDS. The results showed that the extracellular fraction obtained by SET includes the Zn bound to cation exchange sites in the moss and Zn bound to particles on the moss surface, which leads to overestimation of extracellular Zn. After extracellular extraction, Zn was not detected on the surface of the moss or in the particles. To avoid problems associated with the presence of particles on the moss surface, a washing procedure should be used to remove such particles before application of the SET. Another possibility is to use the intracellular concentration, as this is not affected by the metal load in the particles and better reflects those contaminants that affect the moss metabolism.     

Nickel Tolerance and Accumulation by Filamentous Fungi From Sludge of Metal Finishing Industry

Industrialization, urbanization and increased vehicular traffic have resulted in increased contamination of our environment by heavy metals. The long persistence of heavy metals in nature has in turn resulted in development of metal resistant microbial strains. These strains are minimizing heavy metals toxicity, either by metal complexation or precipitation and other mechanisms. Characterization of fungal diversity was done in contaminated soil of the Wazirpur industrial area throughout the year. In this area highly acidic hazardous solid waste produced high concentration of heavy metals (Ni, Cu, Cr, Fe, Mn). Nickel toxicity is a major environmental concern. Due to long persistence of this waste in the environment without any treatment, many fungal isolates from the surrounding environment settle on the upper surface of waste. Few of them are capable of growing in the toxic conditions. More than 20 strains were isolated, most of them belonging to species of Aspergillus, Penicillium, Fusarium and Mucor genera. Seasonal variation in fungal diversity was significant. Four filamentous fungal isolates were found to be resistant for nickel (II) and a strain of Papulaspora sepedonoides reported first time for bioremediation of Ni (II) in this investigation, which is absorbing 62.33 μmol Ni gr^?1. These fungal isolates showed a high level (100–10000 mg kg^?1) of resistance for Ni (II) salt and removing Ni (II) from solution. Metal uptake varied with fungi. The toxicity also was influenced by different factors like pH and composition of growth medium.     

Population Fluctuation of Three Parasitic Nematodes in Florida Citrus

In Florida, Tylenchulus semipenetrans on citrus has two high and two low population levels each year. High levels occur in April-May and November-December, and low levels, in February-March and August-September. Population increases occur about 4-5 weeks after the spring and fall flush of root growth. Populations of Pratylenchus coffeae on citrus varied widely, and were not related to season. Populations of P. brachyurus showed seasonal variation with a high in June-July and a low in March-May. Males of T. semipenetrans and P. coffeae were found throughout the year, whereas males of P. brachyurus were rare and were found only during November and December.     

Seasonal variation of metal accumulation and translocation in yellow pond-lily (Nuphar lutea)

Abstract

Heavy metal bioaccumulation and translocation properties of aquatic plants are interesting because of their potential use in phytoextraction. However, there is not enough knowledge about the seasonal changes of the metal distribution properties of aquatic plants. Our study focused on seasonal variation of some heavy metals in relation to their bioaccumulation and translocation in Nuphar lutea, a floating leaved, widespread plant that is important to wildlife. In this study, N. lutea, corresponding sediment and water samples were collected at different seasons from Lake Abant (Turkey) and analysed for their heavy metal content (Pb, Cr, Cu, Mn, Ni, Zn and Cd). Accumulation and translocation of heavy metal ratios were calculated seasonally. It was found that Cr and Zn were actively transported from sediment to the root, where they accumulated especially in summer; it was also shown that Cu, Mn and Zn were not only taken up from the sediment but also from the surrounding water. The investigations suggested that translocation ratios for leaf/root of Pb, Cr, Mn and Zn reached their highest levels in spring. It was found that the bioaccumulation and translocation of heavy metals at different parts of N. lutea changes with respect to season and the type of heavy metal.     

Seasonal Variations of Chemical Composition of Water and Bottom Sediments in the Wetland of Wadi Gaza,Gaza Strip

Water and sediment samples were collected from 18 sampling stations in Wadi Gaza for two successive years in order to: (1) Establish a baseline condition of the geochemistry of surface water and sediments; (2) assess the impact of seasonal variation on distribution of heavy metals and major ions; and (3) identify possible natural and anthropogenic sources of pollution. The heavy metal concentrations in the sediments of the lake (downstream) were higher than those of the eastern eight stations(upstream) where the water was shallower. Shallower areas showed greater temporal variation than deeper areas. Several elements (P, Fe, Mn and As) showed the greatest temporal variability. For example, in the winter rainy season these elements decreased 2–10 times compared to their values in summer. Moreover, Ca, Na, Cl, PO₄, and NO₃ decreased3, 3, 5, 2, 4 times, respectively. Some of the trace metals were more abundant in these waters compared to the domestic wastewaters of the study area. The averages of Cd and Co were 6 and 43 μg/l, respectively and they were 50 times higher than the domestic wastewater results. The discharge of olive oil mill wastewater was recorded in the Ca, Na, Mg, K and P concentrations in sediments of one of the sampling stations.     

Temporal and spatial trends in heavy metal concentrations in the marine mussel Mytilus edulis from the Western Scheldt estuary (The Netherlands)

Since the first North Sea Conference (1984, Bremen), all countries bordering the North Sea made commitments to reduce discharge of hazardous substances into the North Sea. From Belgium and The Netherlands, large reductions (upto 90) in heavy metal emissions from land-based sources have been reported between 1985 and 2000. Recently, some studies in the Western Scheldt estuary (WS) have shown that total metal concentration in the water, sediments and suspended particles have decreased compared to levels in the 70s. However, data on aquatic organisms is still very limited and it is therefore difficult to confirm whether the reductions in pollution input and generally improving water quality in the WS have a corresponding impact on the levels of heavy metals in aquatic organisms. The current study measured metal concentrations in the soft tissues of mussels, Mytilus edulis (known to be good indicators of environmental metal pollution) during the period 1996–2002. Spatial (salinity and pollution gradients), temporal and seasonal variations were also studied. Results showed a down-stream decreasing trend for the metals studied (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb and Zn) during all sampling campaigns. There was also a significant seasonal effect on tissue metal concentrations, with a peak observed around spring in both WS and the nearby less polluted Eastern Scheldt (ES). On temporal trends, a clear drop of metals in mussels was observed in the early 80s coinciding with the start of the efforts to reduce chemical pollution input into the North Sea. Since those early reductions, metal concentrations in mussels generally remained unchanged upto mid 90s. However, in recent times metal concentration in mussels have increased significantly, for example Cd in 2002 was almost 10 times the values in 1983 and similar to levels seen during the peak in the 70s. Other metals also increased in the 90s also reaching levels seen in the 70s. As there is no indication of recent increase in metal input into the estuary, we suggest that increased metal concentrations observed in mussels in recent years especially in the upper estuary are most likely a result of changes in physical and chemical speciation and metal bioavailability. Such changes may be caused by changes in some water quality parameters in the estuary (i.e. increased dissolved oxygen, concentration of organic matter), resulting in conditions that favour releases of sediment-bound metals into the water column. The relationship between metal content and season showed very similar annual profiles in the polluted WS and less polluted ES. Thus, seasonal variations in metal concentrations appear to be largely controlled by biological processes, while total body burdens are dependent on environmental levels and bioavailability.     

Seasonal accumulation of metals by red alga Gracilaria verrucosa (Huds.) Papens. from Thermaikos Gulf, Greece

Concentrations of Fe, Pb, Cu, Zn and Cd were determined during one season in the red alga Gracilaria verrucosa, sediment and seawater from the Thermaikos Gulf, Greece. This region has been subject to change due to increases in industrial and domestic activities. The relative abundance of metals in G. verrucosa and seawater decreased in the order: Fe>Zn>Pb>Cu>Cd and in the sediment: Pb>Fe>Zn>Cu>Cd. Cadmium concentration in the alga correlated positively with that in seawater. There was positive correlation between Fe concentrations in the alga and those of the Zn and Cu. The concentrations of metals in the alga showed no significant differences between the stations. Lead, Zn and Cu concentrations in the alga were slightly higher at Biamyl, whereas Cd was higher at Perea and Fe at Nea Krini. Seasonal variation of metal concentrations in the alga was significant for Cd and Fe. Copper and Fe increased from winter to summer, whereas Cd was the opposite. Zinc concentrations were minimum and Pb concentrations were maximum during spring. These variations are discussed in relation to tissue age, life cycle, ambient concentrations of metals and other environmental conditions. Cd and Pb concentrations inG. verrucosa in the Thermaikos Gulf were higher and those of Cu and Zn were lower than in other species of the genus. This revised version was published online in August 2006 with corrections to the Cover Date.     

Equivalent uptake of organic and inorganic zinc by monkey kidney fibroblasts, human intestinal epithelial cells, or perfused mouse intestine

Zinc (Zn) is recognized as an essential nutrient, and is added as a supplement to animal and human diets. There are claims that zinc methionine (ZnMet) forms a stable complex that is preferentially transported into tissues, and this has contributed to uncertainty about conflicting reports on the bioavailability of various Zn compounds. This study evaluated the cellular and intestinal uptake of inorganic and organic forms of Zn. Steady-state uptake of⁶⁵Zn by human intestine epithelial cells, and monkey kidney fibroblasts was not significantly different with zinc chloride (ZnCl₂), ZnMet, or zinc propionate (ZnProp) (P > 0.05). Uptake of⁶⁵Zn from zinc chelated with EDTA was significantly lower (P < 0.01). In live mice,⁶⁵Zn uptake by perfused intestine and deposition in intestine and liver showed no significant difference between ZnCl₂ and ZnMet. Equimolar [⁶⁵Zn]methionine and zinc[³⁵S]methionine were prepared according to a patented method that yields “ complexed” Zn. Cellular uptake of the radiolabeled methionine was <0.1% of the radiolabeled Zn from these complexes, indicating separate uptake of the Zn and methionine. Gel filtration did not distinguish between⁶⁵Zn in ZnCl₂, ZnProp, or reagent ZnMet, though feed-grade ZnMet containing >10% protein did give a higher-mol-wt form of⁶⁵Zn. Results of this study show equivalent uptake of Zn from inorganic and organic compounds, and support recent feed trials on Zn bioavailability.     

Seasonal variation in plasma lipids and lipases in young healthy humans

Although intermediate metabolism is known to follow circadian rhythms, little information is available on the variation in lipase activities (lipoprotein and hepatic lipase, LPL and HL, respectively) and lipids throughout the year.

In a cross-sectional study, we collected and analysed blood from 245 healthy students (110 men and 135 women) between 18 and 25 years old from the University of Barcelona throughout the annual campaign (March, May, October and December) of the blood bank. All subjects gave their written informed consent to participate. All blood samples were taken after breakfast at 8:00 and 11:00 am.

Plasma glucose, total plasma protein, triacylglycerides (TAG), free fatty acids (FFA), free cholesterol and esterified cholesterol (FC and TC, respectively), cholesterol in low-density lipoproteins (cLDL), cholesterol in high-density lipoproteins (cHDL), phospholipids (PL) and lipase activities (LPL and HL) were determined. Cosinor analysis was used to evaluate the presence (significance of fit cosine curve to data and variance explained by rhythm) and characteristics of possible 12-month rhythms (acrophase, MESOR and amplitude).

Statistically significant seasonal rhythms were detected for all the variables studied except proteins, with most of them peaking in the winter season. The lowest value for cLDL and the HL occurs in summer, while for cHDL and the LPL it is in winter.

These findings demonstrate for the first time that in physiological conditions, plasma LPL and HL activities and lipids follow seasonal rhythms. The metabolic significance of this pattern is discussed.     

Spatial and seasonal characteristics of dissolved heavy metals in the aquaculture areas of Beibu Gulf,South China

Abstract

To study the contamination of heavy metals in the aquaculture area of Beibu Gulf, the concentrations of seven metals in seawater were investigated. The results showed that significant seasonal and spatial distributions of heavy metals were observed in the four aquaculture areas. Generally, the heavy-metal concentrations in the Maowei Sea were higher than the other three aquaculture areas, which may be related to local industrialization and urbanization development. The concentrations of some metals were obviously higher in wet seasons than in dry seasons, which may be attributed to the seasonal river discharge, rainfall and seawater intrusion. Compared to other regions, some metal levels revealed relatively high contamination. Remarkably, the concentrations of Hg, Cu and Cd were much higher than concentrations found in the past 20?years in the seawater of the Guangxi Beibu Gulf, suggesting that there were increasing anthropogenic inputs of those metals in the aquaculture areas. The assessment of ecological risk index (ERI) indicated that the highest ERI value was found in the Maowei Sea, followed by Pearl Bay, Lianzhou Bay and Hongsha. Hg is the main ecological risk factor, and the heavy-metal contamination in the aquaculture areas must not be ignored.     

Studying the effects of heavy metal on chlorophyll and sugar in one year-old seedlings organs of Acer velutinum specie

Pollution is one of the most important factors inhibiting growth in the environment; therefore the effects of zinc pollution were studied in Acer velutinum specie. Two years old seedlings of Acer velutinum specie were prepared from nursery, the concentrations of zero and one hundred and thirty mg per liter of zinc chloride solution were added to the soil of seedlings pots after calculating and after passing a three-month period of seedling growth, the plant organs were removed, then the amount of zinc concentration in the samples was determined and data were analyzed. The results of the analysis showed that the highest amount of accumulation on the stem, root and soil in treatment concentrations is 87.75, 65.68 and 24.78 mg per kg and accumulation of zinc in total chlorophyll and sugar in treatment concentrations is 4.61 and 0.6028 mg per g, respectively, and accordingly Acer velutinum specie is suitable for refinement of soils contaminated with zinc.     

白腐菌的研究进展及其在重金属修复中的展望

白腐菌是一类特殊的丝状真菌,能降解多种污染物质,具有广谱、彻底、高效、无专一性的 特点,在生物修复中有广阔的应用前景。综述了白腐菌的分类、酶系、降解机理以及应用于有机 物污染的研究现状,特别介绍了白腐菌在重金属污染的生物修复的应用进展情况,包括白腐菌吸 附重金属的原理、在重金属污染的废水中的研究应用现状及在修复重金属污染土壤中需考虑的 因素。同时展望了白腐菌在重金属污染及复合污染的生物修复中的应用前景。