Population health risk due to dietary intake of toxic heavy metals from Spinacia oleracea harvested from soils collected in and around Tshwane,South Africa

In order to assess the possible health risk associated with the consumption of vegetables harvested from waste dump sites, trace metal levels in Spinacia oleracea planted in soils collected from waste dump sites were investigated. Soil samples from different waste dump sites and mining areas were collected and placed in different pots. Seedlings of S. oleracea were introduced into the pots, harvested after 3 months and analysed for trace metal contents using ICP-MS. From the leaves of the plants, the concentration of Fe was found to be significantly higher than all other trace metals (p < 0.05). The trend in trace metal accumulation from the leaves was in the order Fe > Mn > Zn > Pb > Cu > Cr > Ni > Cd. A significantly different concentration of trace metals in the plant was noticed from different soils in different pots used (p < 0.05). Trace metal concentration from plant parts showed roots > leaves > stem. The risk to human health indicated as Hazard Quotient (HQ) was highest for Zn followed by Cu from all the plant parts. The HQ result showed that humans might be at risk if they consume spinach from these waste dump sites. From the study it was concluded that harvesting/consuming spinach from soil around a waste dump site may be extremely dangerous.     

油页岩废渣场的生态恢复

油页岩开采带来一系列的生态与环境问题 ,但对油页岩废渣场进行生态恢复的历史还较短 ,也缺少系统专门的研究报道。国外对油页岩废渣的利用始于 2 0世纪 4 0年代 ,对废渣场生态恢复的研究始于 2 0世纪 6 0年代 ,均早于我国。由于废渣场的基质成分恶劣 ,缺乏一般的土壤结构 ,复垦难度大。一般有 3种常规的复垦方法 :不经处理直接栽种植物 ;常规的物理或化学处理后栽种植物 ;表土覆盖后再进行植被恢复。前 2种方法均难产生显著效果 ,第 3种见效较快 ,但工作量大。近年来 ,一些新技术 ,如生物降解、生物富集和生物强化技术等被发明并用来恢复油页岩废弃地 ,取得了较好的生态恢复与修复效果。我国从 1985年开始 ,在广东茂名进行油页岩废渣场的生态恢复工作 ,先后对面积达 1.4 km2 和 6 .7km2 的 2个大型废渣场 (南排土场和北排土场 )进行了治理 ,主要是采用生物修复技术中的植物修复来进行试验。南排土场经过 19a的复垦演替成了郁郁葱葱的森林 ;北排经过 5 a的实践也取得了很好的恢复效果 ,一些幼林初步形成。然而 ,当前北排土场恢复实践中出现了一些很值得关注的现象 ,如乔木树种矮化、分枝增多等 ,但这些问题还有待进一步研究解决。此外 ,还探讨了油页岩废渣场开展生态恢复的步骤与原则     

油页岩废渣场植物修复的生态效应

对广东茂名页岩油工业固体废物裸露灰渣地植林18a(南排)和3-5a(北排)后的植物生长、凋落物、土壤容重、有机质、pH和植物多样性进行了对比调查和分析。结果表明,南排和北排已形成了森林环境。土壤基质已得到了改善,南排的凋落物现存量增加了1.39倍,土壤有机质增加了52.39%(0-20cm)、50%(20-40cm),土壤pH值提高了0.28个单位。南、北排林地土壤pH值分别比植林前裸地提高了0.99个单位和0.71个单位。这说明植树造林对增加土壤有机质效果明显,对提高土壤pH值则相对较慢。南排自堆放油页岩灰渣后,45a来入侵定居的野生植物有48科118属138种,其中草本植物占总种数的54%,乔木15种;北排堆放28a来,有24科63属66种植物入侵定居,其中草本种类占67%。     

Effects of Pharmaceutical Wastes on Microbial Populations in Surface Waters at the Puerto Rico Dump Site in the Atlantic Ocean

A series of cruises during 1979 and 1980 to the pharmaceutical dump site located 64 km north of Arecibo, Puerto Rico, in the Atlantic Ocean, was carried out to evaluate effects of wastes on the ecology of the microflora of surface waters of the dump site. In addition to bacteriological monitoring of the waste plume created by the release of wastes from the disposal barge, stations along a series of transects, extending north from coastal waters through and beyond the dump site, were sampled. Largest numbers of culturable bacteria on marine agar were found at stations closest to shore and in the vicinity of the dump site. Bacteria recovered on marine agar were predominantly Vibrio and Aeromonas spp., with the relative abundance of these organisms decreasing as gram-positive organisms (staphylococci, micrococci, and bacilli) became dominant in areas immediately affected by waste dumping. Total numbers of bacteria (determined by acridine orange direct counts [AODC]), which were relatively stable throughout the region, and a direct estimate of viable cells (DVC), i.e., those cells responsive to additions of yeast extract and nalidixic acid, were determined by acridine orange staining and epifluorescence microscopy. Heterotrophic bacterial activity, measured by the uptake (V_max) of ¹⁴C-labeled amino acids, declined relative to distance from land. Increases in specific activity indices (DVC/AODC and V_max/AODC) were observed near the dump site. The composite results of this study, i.e., increased specific activities (determined by two methods), increased numbers of culturable marine bacteria, and marked alteration of the taxonomic composition of the culturable bacterial community in waters within and surrounding the Puerto Rico dump site, indicate demonstrable changes in the marine microbial community in the region used for waste disposal.     

Long term effect of municipal waste disposal on soil properties and productivity of sites used for urban agriculture in Abakaliki,Nigeria

An assessment on the impact of long term (20 years) municipal waste disposal on soil physicochemical properties and soil productivity in municipal waste dump sites was carried out in urban Abakaliki, southeastern Nigeria. Profile pits were dug at selected points and auger and core samples were collected from different soil horizons of dump and non-dump sites using free survey technique to choose observation points. There were differences in particle size distribution between dump and non-dump sites. Similarly, soil bulk density was lower by 9-13% while total porosity and hydraulic conductivity were higher by 9-14% and 240-463%, respectively, in the dump site relative to non-dump sites. Soil organic matter, total nitrogen, cation exchange capacity (CEC) and percent base saturation increased from 701 to 743, 646 to 740, 7% to 10% and 5% to 14%, respectively, in the dump site soil relative to non-dump site soil. These results were confirmed by a high coefficient of alienation (degree of unrelatedness, square root(1 - R2)) in bulk density, 0.65; total porosity, 0.58; hydraulic conductivity, 0.87; organic matter, 0.93; total N, 0.82; pH, 0.85 and cation exchange capacity, 0.97 between dump and non-dump soils. Heavy metals (Pb, Cu, Fe and Zn) increased by between 214% and 2040% in dump site soils relative to non-dump site soil. This may lead to increased uptake of metals by some test crops although their transfer ratios differ from crop to crop. Long term dumping of municipal wastes can influence soil properties and productivity at municipal waste dump sites but still may be used for farming provided that ecotoxological risks associated with its usage are continuously assessed and controlled.     

Thermophilic Iron-Oxidizing Bacteria Found in Copper Leaching Dumps

Rod-shaped bacteria capable of oxidizing ferrous iron at 55°C were cultured from samples of a copper mine leach dump. Yeast extract or cysteine was required by these Thiobacillus-like bacteria for growth, using ferrous iron as an energy source.     

Potential Phytoextraction and Phytostabilization of Perennial Peanut on Copper-Contaminated Vineyard Soils and Copper Mining Waste

This study sought to evaluate the potential of perennial peanut (Arachis pintoi) for copper phytoremediation in vineyard soils (Inceptisol and Mollisol) contaminated with copper and copper mining waste. Our results showed high phytomass production of perennial peanut in both vineyard soils. Macronutrient uptakes were not negatively affected by perennial peanut cultivated in all contaminated soils. Plants cultivated in Mollisol showed high copper concentrations in the roots and shoots of 475 and 52 mg kg⁻¹, respectively. Perennial peanut plants showed low translocation factor values for Cu, although these plants showed high bioaccumulation factor (BCF) for both vineyard soils, Inceptisol and Mollisol, with BCF values of 3.83 and 3.24, respectively, being characterized as a copper hyperaccumulator plant in these soils. Copper phytoextraction from Inceptisol soil was the highest for both roots and entire plant biomass, with more than 800 mg kg⁻¹ of copper in whole plant. The highest potential copper phytoextraction by perennial peanut was in Inceptisol soil with copper removal of 2,500 g ha⁻¹. Also, perennial peanut showed high potential for copper phytoremoval in copper mining waste and Mollisol with 1,700 and 1,500 g of copper per hectare, respectively. In addition, perennial peanuts characterized high potential for phytoextraction and phytostabilization of copper in vineyard soils and copper mining waste.     

Phytoremediation of coal mine spoil dump through integrated biotechnological approach

Field experiment was conducted on mine spoil dump on an area of 10 ha, to restore the fertility and productivity of the coal mine spoil dump using integrated biotechnological approach. The approach involves use of effluent treatment plant sludge (ETP sludge), as an organic amendment, biofertilizers and mycorrihzal fungi along with suitable plant species. The results of the study indicated that amendment with effluent treatment plant sludge (ETP sludge), @ 50 ton/ha improved the physico-chemical properties of coal mine spoil. Due to biofertilizer inoculation different microbial groups such as Rhizobium, Azotobacter and VAM spores, which were practically absent in mine spoil improved greatly. Inoculation of biofertilizer and application of ETP sludge helped in reducing the toxicity of heavy metals such as chromium, zinc, copper, iron, manganese lead, nickel and cadmium, which were significantly reduced to 41%, 43%, 37%, 37%, 34%, 39%, 37% and 40%, respectively, due to the increased organic matter content in the ETP sludge and its alkaline pH (8.10-8.28), at which the metals gets immobilized and translocation of metals is arrested. Thus, amendment and biofertilizer application provided better supportive material for anchorage and growth of the plant on coal mine spoil dump.     

Effect of Water Potential on Growth and Iron Oxidation by Thiobacillus ferrooxidans

The effect of water potential on the growth of two strains of Thiobacillus ferroxidans was determined by adding defined amounts of sodium chloride or glycerol to the culture medium. The two strains differed slightly, and the most tolerant strain had a minimum water potential for growth of -15 to -32 bars when sodium chloride was used and -6 bars when glycerol was used. In another approach, the limiting water potential was determined by equilibrating small amounts of culture medium with atmospheres of relative humidities equivalent to specific water potentials, and the ability of the organism to grow and oxidize ferrous iron was determined. Under these conditions, which are analogous to those which might control water potential in a coal refuse pile or copper leaching dump, the lower limit at which iron oxidation occurred was -23 bars. The water potential of some coal refuse materials in which T. ferrooxidans was present were determined, and it was found that the water potentials at which the organism was active in these habitats were similar to those at which it was able to grow in culture. However, marked variation in water potential of coal refuse materials was found, presumably due to differences in clays and organic materials, and some coal refuse materials would probably never have water potentials at which the organism could grow. Some literature on the water potentials in copper leach dumps is reviewed, and it is concluded that control of water potential is essential to maximize the success of leaching operations. Because adequate drainage is necessary in a leach dump to ensure sufficient aeration, in many cases water availability in leach dumps may restrict the development of the bacterium necessary for the process.     

露天煤矿排土场边坡植被组成特征及其群落稳定性评价

研究植被恢复过程中植物群落组成、结构及稳定性的变化,可进一步了解到植物群落的演替过程及规律。采用空间代时间的方法对内蒙古锡林郭勒盟北电胜利露天煤矿4个排土场边坡人工恢复植被进行群落调查,在此基础上采用多样性指数与优化后的M.Godron稳定性指数对植物物种组成、物种多样性及其群落稳定性进行分析,探究不同恢复年限排土场边坡植被在恢复过程中群落特征及稳定性变化特征。结果表明：（1）排土场边坡植物物种组成共有16科44属56种,植物群落组成较简单,其中禾本科种类最多,生长型以草本植物为主。（2）随着恢复年限的增加,植物生活型由一、二年生转变为多年生,坡面优势种由人工种植植物转变为本土植物。（3）整体看,随着恢复年限增加,物种多样性呈下降趋势,群落稳定性整体呈上升趋势。（4）由于不同坡向土壤微环境差异,北坡恢复效果及稳定性好于南坡。本研究在一定程度上可为露天煤矿排土场边坡人工修复过程中植物物种及合理配置模式的选择提供科学依据。     

Biotechnology in hydrometallurgical processes

The presence of microorganisms in metal sulfide leaching operations has been found to be beneficial in catalysing the dissolution process. Currently this technology is applied on a commercial scale in the recovery of copper and uranium in heap, dump and in-situ leach techniques. However, the biotechnological principles are not limited to the extraction of these two elements. Cobalt, nickel and zinc could be solubilized from their respective sulfides, and coal, silver and gold resources purified from pyrite and arsenopyrite inclusions.     

Soil quality around a solid waste dumpsite in Port Harcourt, Nigeria

The levels of soil parameters and selected heavy metals around a solid waste dumpsite receiving untreated wastes from all sources and a control site within Port Harcourt, Nigeria have been examined. Top soil (0–15 cm) and sediment samples were collected and analysed for pH value, particle size, total nitrogen, potassium, available phosphorus, organic matter, effective cation exchange capacity, cadmium, nickel and lead using standard methods. The results showed that the waste dump contributed to the high levels of nutrients and heavy metals. The dry season mean concentrations were: organic matter (5.28 ± 1.34% or 132,422.4 kg ha^?1), K (1.60 ± 0.52 meq per 100 g), N (0.09 ± 0.06% or 2257.2 kg ha^?1), Av.P (15.11 ± 7.57 μg g^?1), Cd (1.34 ± 0.72 μg g^?1), Ni (4.10 ± 1.63 μg g^?1) and Pb (38.85 ± 22.18 μg g^?1) while the wet season mean concentrations were organic matter (5.46 ± 1.39% or 136,936.8 kg ha^?1), K (2.79 ± 0.81 meq per 100 g), N (0.10 ± 0.05% or 2508 kg ha^?1), Av.P (9.22 ± 2.69 μg g^?1), Cd (1.72 ± 1.22 μg g^?1), Ni (14.95 ± 14.94 μg g^?1) and Pb (53.50 ± 40.09 μg g^?1). There was efficient mineralization process in the area. The texture of soil on the main dumpsite was loamy sand, which suggests that the ground water in the area is susceptible to contamination by surface pollutants. The texture of soil at the control site is sandy loam while sediment has the textural class of sand. Decomposed organic materials and agricultural activities influenced the texture of soils. The soils from the main dump and sediment were slightly alkaline while the control soil was moderately acidic. In both seasons, a significant variation exists (P < 0.05) between the metal concentrations in soil at the main dump and those in the sediments with a positive correlation (r = 0.572149) in the wet season and (r = 0.956647) in the dry season. The presence of liming materials and activities of microorganisms on the waste dump increased the pH of the soils. The accumulation of nutrients results in the luxuriant growth of plants/crops on the waste dump.     

A tundra of sickness: the uneasy relationship between toxic waste, TEK, and cultural survival

In 1992 an abandoned federal radioactive waste dump was discovered in Arctic Alaska. The discovery of this site, a byproduct of the Atomic Energy Commission program known as Project Chariot, sent shockwaves throughout I?upiaq communities and ignited a heated controversy over the health effects of subsisting on a "tundra of sickness." Drawing on thirty months of ethnographic research in Arctic Alaska, this paper explores a host of environmental, social, and moral uncertainties sparked by toxic waste. Anthropological claims regarding the extent to which "traditional ecological knowledge" will empower local communities and foster self-determination are challenged. Ultimately the paper argues that TEK has been conceived in such restrictive terms that it misrepresents the dynamic, emerging, and at times contradictory responses to toxic waste in the Arctic today. Moreover, there is dire need for a more materialist, as opposed to discourse-based, approach that acknowledges the very real threat of toxic waste to physical, and therefore, cultural reproduction.     

高寒地区煤矿排土场植被恢复研究——以内蒙古扎哈淖尔煤矿为例

高寒煤矿排土场植被恢复是制约我国矿区绿色可持续发展亟待解决问题，内蒙古扎哈淖尔煤矿通过不同的生态措施对排土场进行人工植被恢复的实践。本研究在2020年和2021年对该高寒煤矿排土场75个样地进行野外连续监测，对不同生态恢复措施影响高寒地区内蒙古扎哈淖尔露天煤矿排土场植物恢复过程中的群落组成、盖度、物种多样性进行分析，阐明不同恢复措施在高寒地区煤矿排土场植被恢复中的作用。研究结果表明：从2020年到2021年排土场的植物群落物种数、植被盖度和群落多样性存在显著的季节变化规律；周边原生草原的非人工种植植物随恢复时间增加而不断进入排土场，导致群落物种数显著增加；植物群落多样性在平面、坡面与田字格地形存在显著差异，田字格上Shannon-Wiener多样性指数最低；坡度显著影响群落多样性，同时受到季节变化影响；喷播加灌木种植方式与其他4种播种方式相比显著增加群落香浓维纳多样性指数；但不同坡向、土壤施肥方式和水分灌溉方式对植物群落多样性没有显著影响。本研究结果可为完善草原露天煤矿植被恢复技术提供科学依据。     

Degradation of Chrysanthemum (Dendranthema grandiflora) wastes by Pleurotus ostreatus for the production of reducing sugars

In Colombia, a great amount of waste is generated during the cut-off and harvest stages in flowers culture. This study examines the possibility of degrading Chrysanthemum wastes by using Pleurotus ostreatus, Trametes versicolor, and Phanerochaete chrysosporium cultures; this has not been studied previously. The initial effect of fungi on the degradation of Chrysanthemum wastes were studied individually and in co-cultures. The highest degradation was by P. ostreatus. After that, the influence of pH and waste, copper, and manganese concentrations on reducing sugars concentration were determined in a submerged culture in 100 mL Erlenmeyer flasks. There was a significant effect of manganese and waste concentrations on sugar concentration, while the effect of copper concentration and pH were not significant. Following, the process was carried out in a 1.5 L reactor at the optimal values of the variables studied in Erlenmeyer flask but varying air injection from 0 to 2 vvm. The highest concentration of sugars was 21.2 g/L with 78% of glucose content at 6.3% w/v of waste, 7.5 mM of Mn and Cu and 2 vvm of air injection. Finally, laccase, Manganese peroxidase, endo-1,4-β-glucanase, exo-1,4-β-glucanase and 1,4-β-glucosidase were detected in the extract obtained under these conditions. The highest activities were obtained for laccase (4,694 U/L) and 1,4-β-glucosidase (9,513 U/L).     

The Bactericidal Effect of Dendritic Copper Microparticles,Contained in an Alginate Matrix,on Escherichia coli

Although the bactericidal effect of copper has been known for centuries, there is a current resurgence of interest in the use of this element as an antimicrobial agent. During this study the use of dendritic copper microparticles embedded in an alginate matrix as a rapid method for the deactivation of Escherichia coli ATCC 11775 was investigated. The copper/alginate produced a decrease in the minimum inhibitory concentration from free copper powder dispersed in the media from 0.25 to 0.065 mg/ml. Beads loaded with 4% Cu deactivated 99.97% of bacteria after 90 minutes, compared to a 44.2% reduction in viability in the equivalent free copper powder treatment. There was no observed loss in the efficacy of this method with increasing bacterial loading up to 10⁶ cells/ml, however only 88.2% of E. coli were deactivated after 90 minutes at a loading of 10⁸ cells/ml. The efficacy of this method was highly dependent on the oxygen content of the media, with a 4.01% increase in viable bacteria observed under anoxic conditions compared to a >99% reduction in bacterial viability in oxygen tensions above 50% of saturation. Scanning electron micrographs (SEM) of the beads indicated that the dendritic copper particles sit as discrete clusters within a layered alginate matrix, and that the external surface of the beads has a scale-like appearance with dendritic copper particles extruding. E. coli cells visualised using SEM indicated a loss of cellular integrity upon Cu bead treatment with obvious visible blebbing. This study indicates the use of microscale dendritic particles of Cu embedded in an alginate matrix to effectively deactivate E. coli cells and opens the possibility of their application within effective water treatment processes, especially in high particulate waste streams where conventional methods, such as UV treatment or chlorination, are ineffective or inappropriate.     

Bioaccumulation of mercury,arsenic, cadmium,and lead in plants grown on coal mine soil

Mercury (Hg), arsenic (As), cadmium (Cd), and lead (Pb) are the major toxic metals released by coal mining activities in the surrounding environment. These metals get accumulated in the soils. The plants grown on the contaminated soil uptake these toxic metals in their roots and aerial parts. This study monitored the bioaccumulation of Hg and other three toxic metals in coal mine soil. The pot study of Hg accumulation in Brassica juncea showed that the extent of Hg uptake by roots and shoots of the plants grown on was high in the mature plant and Hg content in root was higher than the shoot. In the soil of unreclaimed overburden (OB) dump, the toxic metal content was higher than that of reclaimed OB dump which posed high ecological risk in the soil of unreclaimed OB dump. Bioaccumulation coefficient (BAC) value showed that Hg was not accumulated in the leaves of Dalbergia sissoo L., Gmelina arborea, Peltaphorum inerme L., Cassia seamea L, and Acacia mangium L grown on coal mine soil.     

Are Phytochelatins Involved in Differential Metal Tolerance or Do They Merely Reflect Metal-Imposed Strain?

Plants from nontolerant and copper-tolerant populations of Silene vulgaris both produce phytochelatins upon exposure to copper. The threshold copper concentration for induction of phytochelatin and the copper concentration at which maximum phytochelatin contents occurs increase proportionally with the level of tolerance to copper. When exposed to their own highest no-effect concentration or 50%-effect concentration of copper for root growth, tolerant and nontolerant plants exhibit equal phytochelatin contents in the root apex, which is the primary copper target. This also holds for distinctly tolerant nonsegregating F₃ families, derived from a single cross of a nontolerant plant to a tolerant one. Therefore, the phytochelatin content of the root apex can be used as a quantitative tolerance-independent measure of the degree of toxicity experienced by the plant. Differential copper tolerance in S. vulgaris does not appear to rely on differential phytochelatin production.     

On the role of the cell wall in the phenomenon of copper tolerance in Silene paradoxa L.

The potential role of the cell wall in the phenomenon of copper tolerance in Silene paradoxa was investigated. Plants from Fenice Capanne (FC, copper tolerant population) mine waste and Colle Val D’Elsa (CVD, sensitive population) uncontaminated soil were grown in hydroponics and exposed to different CuSO₄ treatment to evaluate tolerance, accumulation and pectin concentration of the root cell wall. Physiological mechanisms relying both on avoidance and tolerance at the cellular level seemed to characterise the copper tolerance phenomenon showed by the metallicolous population of S. paradoxa. Avoidance was realised at both the symplast and the apoplast levels in the roots. Data suggested that in the tolerant population the presence of copper in the culture medium could decrease root cell wall pectin concentration and increase pectin methylation degree. Results proposed that a low cell wall ability to bind copper can probably combine to generate the tolerant/excluder phenotype of the S. paradoxa copper tolerant population.     

Root exudation pattern of Typha latifolia L. plants after copper exposure

Aims

Typha latifolia L. is an aquatic plant that has been widely exploited for the aims of phytoremediation. The main reason why we have chosen this plant species for the current study is its capacity to accumulate and detoxify heavy metals. The main topic of the investigation focused on the root uptake of copper (II) nitrate and copper (II) sulfate and the impact of different chemical copper species on the excreted organic acids.

Methods

Oxalic, malic, acetic and lactic acids were determined using capillary electrophoresis; a comparison between the concentration and the time course during 7 days of treatment was performed.

Results

There is a correlation between the total copper (II) sulfate concentration in the roots and the total amount of the excreted organic acids. In addition to that organic acids are involved in the detoxification mechanisms of Typha latifolia for copper (II) nitrate and copper (II) sulfate.

Conclusions

Different from so far investigated plant species the highest amounts of organic acids are excreted from T. latifolia roots not in the first hours after treatment, but up to 7 days later.