Aspects of trace metal contamination in the coastal rivers of Israel

Nine trace elements of biological concern: Cr, Co, Cu, Cd, Ni, Pb, Hg, Zn and Ag were investigated in the sediments of the most important coastal steams in Israel. All of these are subjected to some degree of domestic and/or industrial sewage input with the consequent liability of contamination by trace metals. The Ayyalon, Gadura, Qishon and locally the Hadera rivers contain sediments exhibiting severe pollution effects. There is a danger of infiltration through the soils into the groundwaters as well as exposing nearshore fauna to sediments contaminated by possibly toxic trace metals. The other rivers bear smaller levels of trace metals; however, an increase of the Pb and the Zn levels occurs near major highways.     

Aquatic insects as environmental monitors of trace metal contamination: Red River,New Mexico

Discontinuous sampling of water for toxic chemicals is unreliable in lotic ecosystems or in systems subjected to sporadic discharges. Such sampling either fails to detect the contaminants or seriously underestimates their concentrations. This study explored the use of resident aquatic insects as biomonitors of trace metal contamination in a river subjected to episodic spills of Mo mill tailings. Aquatic insects at sites downstream from the mill accumulated more Mo and Cu than upstream insects. Due to a prolonged shutdown at the mine, no tailings spills were recorded during this study and Mo and Cu levels in water and bottom sediments declined to near background levels. However, concentrations of these metals in insects declined only slightly. This study indicates that aquatic insects are useful biomonitors of trace metal contamination in an intermittently impacted system. Reduction of elevated trace metal concentrations from the insects occurred at a slower rate than from the non-living components of the river ecosystem thereby facilitating detection of the spills.     

Biologically induced accumulations of CaCO3 in orthox soils of Biga,Ivory Coast

Biologically induced accumulations of calcium carbonate have been found inside orthox soils, under and around the native iroko tree Milicia excelsa (Moraceae) in Biga (Ivory Coast). The nature of these accumulations and their origin were studied in two soil profiles, directly under the tree and at a distance of 30 cm from the trunk. Microscale forms of CaCO₃ include: (1) wood pseudomorphic structures such as parenchyma cells, cellulose fibers, and calcitic vessel infillings; (2) three types of rhombohedra; and (3) needle fiber calcite (NFC). In addition, large scale blocks exhibit three types of textures: (1) micritic calcite, which seems to be the original material; (2) light-colored sparite in moldic voids; and (3) asymmetrical radiaxial laminated fibrous cement. Some micritic aggregates and hemi-spherulites (vaterite) were found in the sap on the trunk as well as in soils on silica grains and the wood itself. The mineralogy of all these carbonate forms is mainly a stoichiometric calcite or a moderately enriched Mg calcite. However, some samples contain monohydrocalcite, as well as two polymorphs of calcium oxalate (weddellite and whewellite). Calcite precipitation is facilitated by the oxidation of oxalate by soil bacteria that contributes to the increase in pH in Biga soils. This is in contrast to conventional orthox soils. Therefore, three conditions are necessary for biologically induced precipitation of calcium carbonate in orthox soils associated with iroko trees: the presence of a large amount of oxalate (originating from the tree and fungi), the existence of an oxalotrophic flora for oxalate oxidation into carbonate, and a dry season.     

中国太原市农业土壤的重金属污染状况

To evaluate the current state of the environmental quality of agricultural soils in Taiyuan City, a hotspot for China’s industrial development, the concentrations of 8 heavy metals in soils were investigated by means of extensive sampling in farmlands, forestlands, and grasslands in the city. Statistical analyses and spatial distribution maps were used to identify the most significant heavy metal pollutants. The mean concentrations of As, Cd, Cu, Hg, Pb, Zn, Ni, and Cr were slightly higher than their background values in Taiyuan’s topsoil, but were lower than the maximum permissible concentrations in the Chinese Environmental Quality Standard for agricultural soils. Farmland soils in Taiyuan had the highest average Cd, Cu, Hg, Pb, Zn, and Cr concentrations, but the As and Ni concentrations did not differ significantly among the farmland, forestland, and grasslands. Soil contamination by Cd, Cu, Hg, Pb, Zn, and Cr was mainly derived from farming practices, especially the use of sewage water for irrigation. In contrast, As and Ni might derive mainly from the soil parent material. The identification of heavy metal sources in agricultural soils may provide a basis for taking appropriate action to protect soil quality.     

土壤重金属污染的植物修复与金属超富集植物及其遗传工程研究

本文综述了土壤重金属污染的植物修复、金属超富集植物及其遗传工程的最新研究进展及存在问题,并提出加紧筛选和发现野生高生物量的金属超富集植物,在现有高生物量作物种质资源中筛选金属超富集作物,应用遗传工程技术把野生植物的超富集基因转移到现有高生物量植物(作物)中,寻找综合、可持续的植物修复手段等对策。     

Effect of coffee residues on growth and reproduction of Hyperiodrilus africanus (Oligochaeta, Eudrilidae) in Ivory Coast

Hyperiodrilus africanus (Beddard) is a 12-cm to 16-cm-long earthworm, which is widely distributed in West and Central Africa. It lives in the upper 10–20 cm of the soil, and feeds on a mixture of soil and above-ground litter. Cocoons obtained in the laboratory hatched on average 17 days after deposition and produced two juveniles on average. Paired individuals fed soil amended with 2% coffee residues grew significantly (P<0.05) faster than those in the control soil. Daily individual weight increments were respectively 6.1 mg worm^–1 day^–1 and 1.0 mg worm^–1 day^–1 in supplemented and control soil. The generation time was short, and cocoon production reached 9.6 month^–1 (i.e. 115 cocoons adult^–1 year^–1). When H. africanus collected from the field were raised in the laboratory, they grew slowly, laid fewer cocoons and mortality was high. Demographic parameters indicated an improvement when H. africanus were raised in batches rather than individually. Mating enhanced cocoon production although parthenogenesis was possible. Received: 4 April 1997     

Nitrogen dynamics in tropical soils of Mali,West Africa

Soil samples were collected from a loamy sand and a clayey soil near Cinzana, Mali, for the purpose of documenting the seasonal dynamics of soil inorganic N after 9 years under five crop-management systems. The cropping systems were: continuous grain sorghum (Sorghum bicolor) or millet (Pennisetum glaucum) without residue return, continuous grain with stalk residue returned to the field every second year, grain in rotation with cowpea (Vigna unguiculata), and grain in rotation with the green manure crops, sesbania (Sesbania rostrata) and dolichos (Dolichos lablab). A sharp increase in soil N was observed early in the rainy season in both soils. Extractable N concentration in loamy sand and clayey soils, respectively, peaked between 15–22 kg and 33–51 kg N ha^–1 in the upper 10 cm of soil. In the clayey soil, the higher soil N concentrations associated with the early season flush lasted 8 weeks after the onset of rain. Nitrogen addition through rotational crops and crop residue was low. Significant improvement of cereal grain yield may not be possible solely by rotation with sesbania and dolichos green manure or cowpea without additional nutrient input. Earlier cereal planting, where feasible, is recommended to improve synchrony of soil N mineralization and crop demand.     

Dust deposition and particle size in Mali, West Africa

Dust deposition samples were collected during April and May (1990) at four sites on the inland delta region of Mali in West Africa. High dust deposition rates were measured and characterised by considerable variations between sites. A major dust plume passed over the area, following a dust storm near Gao, 500 km to the east, however the contribution of this plume to overall deposition was surprisingly small.Dust particle-size characteristics indicate mixing of dusts from three sources. Long-distance dust deposition producing fine deposits (mainly < 5 μm); dust from regional sources producing deposits mainly in the size range 20–40 μm; and local dust arising from human activities, particularly vehicle and livestock movements, producing relatively coarse material in the size range 50–70 μm, plus some fines. Local dusts appear to have made the greatest contribution to deposition, with a moderate (though less than expected) contribution from the plume and a minor contribution from long-distance dusts.These results have implications for dust deposition studies aimed at quantifying dust contributions to soils. Although these Mali dust deposition rates are high (2.5–28.6 t⁻¹ km⁻² day⁻¹), the significant proportion of locally derived dust means that new dust inputs to the soils of the Inland Delta region of Mali are small.     

Synergistic trace metal effects in plants

Abstract

An experiment was conducted in Yolo loam soil with bush beans (Phaseolus vulgaris L. C.V. Improved Tendergreen) with single and combination treatments of moderately high levels of Cd, Li, Cu, and Ni to test whether or not effects could be additive or synergistic. Copper and Ni together were more toxic than either alone. Copper, Ni, and Cd were more toxic together than any one alone. These effects were probably additive and may be related to a 0.2 pH change caused by Cu which increased uptake of Ni and Mn. Synergistic effects were observed in the Cd and Ni concentrations, especially in the stems of the plants. Because of these interactions, the effects were then tested in solution culture. In solution culture with bush beans Cu and Ni when applied together had synergistic effects on plant concentrations of P, Zn, and Fe (all were decreased) and on the Ni concentration in roots. Also, in solution culture with (2.5 × 10^‐5 M) Zn, Cu, and Cd added singly, in pairs, and together, Zn and Cu additively decreased Cd concentrations in roots. Synergistic effects on yield depressions were observed in solution culture for 5 × 10^‐5 M Zn + 3 × 10^‐5 M Cu+ 2 x10^‐5 M Ni. An additive effect on yield depression was observed for 2 × 10^‐4 MCd + 2 × 10^‐5 M Ni. There were many complex interactions among the trace metal concentrations in these plants.     

A study of heavy metal contamination in the Rhondda Fawr,South Wales

Analysis of vegetation and soils of the Rhondda Fawr, South Wales, shows that there is contamination by the heavy metals Pb, Cd, Cu and Ni throughout the valley, in particular within the urban development area. It is suggested that this contamination occurs mainly by aerial deposition, and that in the case of Pb, Cd and Ni the motor vehicle is the primary source. A correlation between the average heavy metal load of the soil of the urban strip, the urban strip width, and traffic frequency is established. Levels of heavy metals in soils and grasses within rural areas of the valley could be high enough to affect N mineralization in the soil, and could also have adverse effects upon grazing animals.     

Heavy metal contamination of soils in a mining area in South Africa and its impact on some biotic systems

In soils, animals and plants from selected sites in the Rustenburg mining area, a part of the South African ore belt, the heavy metal burden was examined. These sites belong to different soil types and are characterized by different land-use (agriculture, grassland). The heavy metal contamination of the soil samples is relatively high and is dominated by chromium and nickel, metals, which are extracted in the mine near the sampling sites. These high heavy metal concentrations had no clear inhibitory influence on micro-organisms or the enzyme activity of soils. It appears that the high clay content of the soils may counteract the influence of heavy metals. On the other hand, tolerant microbial populations may have been established. In addition, the investigated culture plants there was no correlation between the heavy metal content of the soils and the concentrations in roots and shoots. The dangerous, potential contamination of organs in humans seems to be modest, with the exception of tobacco leaves. The heavy metal content of tissues in the examined animals reflect the environmental habitat in situ with no obvious influence on the health of the animals.     

Impact of trace metal contamination and in situ remediation on microbial diversity and respiratory activity of heavily polluted Kastanozems

Biology and Fertility of Soils - Agriculturally used soils (Kastanozems) of experimental fields in the Mashavera Valley in southeast Georgia show various degrees of trace metal contamination (Cd,...     

西非加纳地区”哈麦丹”干燥热风尘埃中养分沉积状况

In order to measure dust's nutrient input on farmland in different agro-ecological zones, Harmattan dust was sampled by mats with plastic straw in Ghana between 2002–2006. The inputs of total nutrients by Harmattan dust in Ghana per Harmattan period were about 1–2 kg Ca ha-1, 0.5–2 kg K ha-1, 0.5–1.5 kg Mg ha-1and less than 0.5 kg P ha-1. Compared with the annual input of nutrients by precipitation, the dust accounted for 10% or less of Ca, Mg and K but approximately 20%–40% of P. The input of nutrients by dust was only valid for areas with vegetation, because in areas with none or sparse vegetation, loss of soil due to wind erosion and hereby loss of nutrients might be significant. In farmland areas with bare and vegetated fields there seemed to be an internal redistribution of the nutrients and not a net gain of nutrients from outside the area(long-range transported dust). The input of P by dust might be of some importance in the traditional shifting cultivation systems, while the inputs of other three nutrients of Ca, Mg and K were so low that they must be considered insignificant. In the intensive agriculture systems with huge inputs of manures and fertilizers the nutrient input by dust is insignificant and could be neglected.     

Dust transportation and deposition in a superhumid environment,West Coast,South Island,New Zealand

Contemporary rates of dust deposition monitored along a 300-km section of the superhumid West Coast of New Zealand's South Island are presented. In this setting, dust is entrained primarily from the dry channels of braided glaciofluvial rivers that drain the western slopes of the Southern Alps. Measured dust deposition ranged between 0.21 and 118.9 kg⁻¹ ha⁻¹ month⁻¹, which is similar to dust deposition rates monitored in arid and semiarid environments. However, these are not considered to be sufficient for present day loess genesis. Dust deposition was highest in summer because of the greater frequency of favourable dust transporting winds, and the effect of rainfall was secondary. Dust transportation occurred mainly during the passage of nonprecipitating cold fronts or postfrontal southwesterlies. Transportation also occurred during prefrontal conditions, and in winter föhn southeasterlies were the predominant dust transporting winds to affect the West Coast.     

华南大宝山矿周边土壤和大豆的重金属污染

Concentrations of Pb, Cd, Cu, Zn, Cr and Ni in soybean (Glycine max L.) grown near the Dabaoshan Mine were investigated, and their potential risk to the health of inhabitants was estimated. In the Fandong (FD) and Zhongxin (ZX) villages, which are near the Dabaoshan mineral deposit, concentrations of Pb (0.34 mg kg^-1 for FD), Cd (0.23 mg kg^-1 for ZX) and Cr (1.14 and 1.75 mg kg^-1 for FD and ZX, respectively) in the seeds of soybean exceeded the tolerance limit set by Chinese standards. The estimated daily intakes (EDIs) from consumption of soybean seeds for FD inhabitants were 0.570, 0.170, 38.550, 142.400, 1.910 and 14.530 μg d^-1 kg^-1 boby weight for Pb, Cd, Cu, Zn, Cr and Ni, respectively. Our results indicate that soybeans grown in the vicinity of the Dabaoshan Mine accumulate some metals, and the seeds pose a potential health risk to the local inhabitants.     

Survey on the metal contamination of agricultural soils in Georgia

There is only sparse information on the metal contamination of agricultural soils in the former Soviet Union and the development of impacts during the process of transformation to a private structure of production. In this study a first overview on the metal load (Pb, Zn, Cu, Cr, Mn) of agricultural soils in central and eastern regions of Georgia is given using 251 subsamples from 106 profiles on 37 plots. While the data sets for lead (Pb) and chromium (Cr) are rather homogeneous and range only within narrow limits, the contents of zinc (Zn) and copper (Cu) vary much more. Additionally, manganese (Mn) was tested. Here the data vary largely, which is probably due to the natural soil loads. Very low loads for all investigated metals are typical for communally used pastures (Allmende) and especially for a biologically managed farm. On the contrary, Cu loads frequently exceed the median by more than five to ten times (the maximum value is 1023 mg kg⁻¹) in vineyards. The comparison of complete soil profiles proves that this is due to the application of copper sulphate for pest control. In the Bolnisi region south of Tbilisi extremely high loads in the upper soil horizons are found not only for Cu, but for Zn as well, ranging up to 794 mg kg⁻¹. Compared to all other data, the loads for Pb and Cr are also high in several samples. Cu, Zn and Pb are significantly correlated to one another in the Bolnisi region. This striking situation most probably results from the frequent irrigation of the plots by industrially contaminated water from the Mashawera River. Due to economic deficiencies the application of chemicals in Georgian agriculture has dropped heavily since 1990. Consequently, the metal contamination of agricultural soils in general is rather low, being far below western European tolerance limits. Intensive pasturing might even cause values close to the natural loads due to erosion and/or the export by the way of plants and livestock. On the other hand, some specific types of land use cause serious environmental problems. This is especially true for vineyards and plots that are irrigated with contaminated water. Overgrazed plots tend to soil erosion. Copyright © 1999 John Wiley & Sons, Ltd.     

Platinum-group and other traffic-related heavy metal contamination in road sediment, Guangzhou, China

Purpose

Human exposure to particulate matter emitted from on-road motor vehicles includes complex mixtures of heavy metals from tyres, brakes, part wear, and resuspended road sediment. The purpose of this study was to determine the concentrations of 14 platinum-group and other traffic-related heavy metals in road sediment within the metropolitan area of Guangzhou, China, with a view to identifying their sources and assessing the extent of anthropogenic influence on heavy metal contamination of road sediment.

Materials and methods

Thirty-five samples of road sediment were collected. The concentrations of Cr, Mn, Ni, Cu, Zn, La, Ce, Mo, Cd, Pb, Ba, and Rh were measured by inductively coupled plasma?Cmass spectrometry. Pt and Pd were analyzed by isotopic dilution?Cinductively coupled plasma?Cmass spectrometry. Multivariate statistical analysis and enrichment factor methods were employed to identify the sources of these heavy metals and to assess anthropogenic influences on their occurrence.

Results and discussion

The mean concentrations of Pt, Pd, Rh, Cr, Mn, Ni, Cu, Zn, La, Ce, Mo, Cd, Pb, and Ba in the road sediment samples were 68.24, 93.15, 23.85, 147.5, 712.3, 47.24, 177.5, 1254, 47.50, 96.62, 4.91, 3.00, 198.1, and 641.3?ng?g^?1, respectively. Very weak to significant linear positive correlations were found among the various heavy metals. The elemental composition of road sediment was dominated by five principal components. Three clusters were identified through cluster analysis, and enrichment factors were calculated relative to soils in China. The sources and degree of contamination of the heavy metals are discussed based on the results.

Conclusions

The mean concentrations of heavy metals are higher than background values, especially for Pt, Pd, Rh, Cd, and Zn. Four main sources are identified: (1) Pt, Pd, and Rh were derived from traffic sources; (2) La, Ce, Mn, and Ba were derived mainly from natural sources; (3) Cr, Ni, Cu, Mo, Cd, and Pb showed mixed traffic-industry sources; and (4) Zn originated mainly from industrial sources. Enrichment factor analysis supported this source identification and further indicated that contamination of road sediment in Guangzhou is extremely high for Pt, Pd, and Rh; moderate to very high for Cd, Zn, Pb, Cu, and Mo; and minimal for Cr, Ni, La, Ce, and Ba.     

Fallow cultivation system and farmers' resource management in Niger,West Africa

A survey was carried out in 136 farm‐households from seven villages in 1995 and 1996 to analyse the traditional fallow cultivation system in Niger. Farmers were asked to give information about land use on their fields, focusing on cropping and fallow periods as well as on cultivation changes compared to the past. In addition, they were interviewed about their management strategies to maintain or improve soil fertility. Millet‐based systems clearly dominate at all sites, either in pure form or intercropped with cowpea, groundnut, sorghum or roselle. At present, almost half of all farmers cultivate their fields on average up to 5 years until it is left fallow. About one‐third use their fields permanently. Most farmers use short fallow periods of 1 to 5 years. Moreover, there was a decrease in the cropping area left fallow, and the fallow period also decreased steadily in the past years. In the mid‐1970s the average fallow period was about 8 years, decreasing to 2.5 years in 1996. The actual fallow periods are too short to allow sufficient positive effects on soil fertility and farmers are aware of this problem. Consequently, farmers employ different fertilization techniques which aim at maintaining or restoring the soil nutrient pool of the fields while providing physical protection against wind and water erosion. Most farmers use animal manure to improve soil fertility and apply mulch from different sources, millet stalks and branches, for soil regeneration. Few farmers employ other strategies such as mineral fertilizer or planting pits. The farmers try to optimize the use of internal and external resources resulting in a mixture of different fertilization and soil protection methods. Internal resources play by far the most important role. Due to the generally limited resource availability farmers concentrate their management efforts on certain areas within each field or on selected fields only. This means a decreased crop production for the individual household and a higher risk of soil degradation because of soil mining or increased erosion risk on the field area where soil fertility management cannot be practised. Copyright © 2002 John Wiley & Sons, Ltd.     

Heavy metal contamination of soils in Northern Slovakia

Environmental damages like forest decline in Northern Slovakia could be a result of long-distance transport of pollutants with the dominating north-west winds. On 10 sites, primarily in the northbound upper slopes of west-east oriented mountain ranges in Northern Slovakia, the extent of the heavy metal contamination in soils along a north-south transect was examined. Oi, Oe, Oa, A, and B horizons were sampled and the total concentrations of Al, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were determined. The ranges of heavy metal concentrations in the forest floor were higher than reported for comparable samples from Bavarian soils except for Zn (Cd: 0.65–1.77; Cr: 12–40; Cu: 19–41; Ni: 8–24; Pb: 70–187; Zn: 31–92 mg kg^?1), in the mineral soil the concentrations were lower. The depth distribution of the metal concentrations indicated a contamination with Cd, Cr, Cu, Ni, Pb, and Zn. The concentration differences between forest floor and mineral soil tended to be higher at the northern than at the southern sites for Cu, Ni, Pb, and Zn, indicating a long-distance transport from the north. Correlation and principal component analyses of the total metal concentrations revealed three groups: Cu, Pb, and Zn inputs mainly seemed to result from long-distance transport from the north, Cr and Ni inputs additionally from local sources. Cd probably had its origin mainly in local sources. This result was further confirmed by the grouping of the sites when clustered.