Degree Of Metal Pollution Research Articles

Baseline Concentrations of Heavy Metals in Native Soils of the Salamanca and Valladolid Provinces, Spain

Natural soils without apparent human influence were selected to determine the background concentration of Cd, Cu, Pb, Zn, Cr, and Ni. Reference concentrations of soil heavy metals are necessary for assessing the degree of metal pollution affected by anthropogenic activities and inputs. Samples of uncultivated (i.e., native) soils were collected from central-western Spain. For each element studied, the anomaly thresholds, ‘upper whisker,’ and baseline concentrations were calculated. For each main soil group—Luvisols (Alfisols), Cambisols (Inceptisols) and Leptosols/Regosols (Entisols)—the mean contents and baseline concentrations were also reported. Results of these analyses indicated total soil contents were within the normal global range. Geometric mean contents (mg kg−1) were: Cd, 0.21; Cr, 20.4; Cu, 14.4; Ni, 25.7; Pb, 34.7; and Zn, 42.6. A study on the metal cation available contents (extraction with 1 M ammonium acetate) was also conducted, since total contents in affected soils are only indicative of the pollution degree but not of the real risks involved. Risks of pollution of waters and to human health through food chain transfer are determined by the mobility and availability of elements. Relationships between element concentration and some pedological parameters were also determined, as well as element translocation through the soil profile, and the relationship between available to bound (i.e., free Fe oxyhydroxide fractions) forms. A factorial analysis was performed to determine which factors govern soil metal distribution. Soil forming factor that mainly determined the total contents in soils was the nature of the parent rock. Thus, chalcophile elements, Cu, Zn, Cd, and Pb, were more abundant in soils developed from slates of the palaeozoic basement, which contain abundant pyrite, while siderophile elements, Cr and Ni, were more abundant in soils derived from Fe-rich materials, such as clay-rich Tertiary sediments.

Heavy Metal Pollution and Biomonitoring Plants in Lake Manzala, Egypt

In this study, the pollution levels and the toxicity status were estimated regarding four heavy metals (Zn, Pb, Cd and Hg) thought to be among the major contaminants in the environment of Lake Manzala. Our target was to define and utilize certain plant species, from the lakeþs vegetation, as bio-monitors, in comparison with the sediments as abiotic monitor for heavy metal pollution. The native wild plants (passive bio- monitors) were represented by eight species (Atriplex portulacoides, Zygophyllum album, Typha domingensis Juncus rigidus, Cyperus laevigatus, Arthrocnemum macrostachyum, Salsola sp. and Phragmites australis). The introduced plants (active bio-monitors) were represented by two crop- species (Trifolium alexandrinum and Raphanus sativa) grown and irrigated by polluted water at some islands in the southern sector of LM. Based on the concentration and toxicity status, induced in the lake's vegetation and sediments, the four metals are arranged in the following decreasing order: Hg greater than Zn greater than Pb greater than Cd. Compared with the standard normal and critical toxicity ranges in plants and soils, the detected values of Zn, Pb and Cd were within the critical ranges. However, Hg showed the highest values and alarming toxicity levels and it is considered as one of the most hazardous pollutants in Lake Manzala. The overall evaluation of the tested metals showed that their ratios were as much as 2.5 - 5 times higher in active monitors than in passive ones and 2 times than in sediments. They were also 2 times higher in sediments than in passive monitors. The monitoring materials are arranged in a decreasing order, based on their efficiency for accumulating heavy metals as follows: Introduced (active) monitors greater than Sediments greater than Native (passive) monitors. Certain species are also proposed as bio-monitors (and/or bio-filters) for the studied heavy metal pollutants. The results showed that there is a significant difference between the accumulation rate of some metals in different plant organs (e.g. Zn, Hg) since they showed more tendency for accumulation in root more than shoot systems. Also, there is a high positive correlation between combinations of different metal pairs in either plantþs root or shoot system. It is evident that while the degree of metal pollution in the lake increased southwards, the values of water-quality parameters (e.g. dissolved oxygen %, salinity and pH-value) increased northwards.

Assessment of sediment toxicity by metal speciation in different particle-size fractions of river sediment

Mobility and toxicity of metals associated with sediments are generally affected by metal speciation and granular compositions. Due to the various speciation patterns of heavy metals in sediments, it is not reliable to assess the potential toxicity of heavy metals on the aquatic environment with the total concentrations of heavy metals in sediments. The purposes of this study were to investigate the distribution of metal speciation in different particle-size fractions of sediments collected from two rivers (the Ke-Ya River and Ell-Ren River) in Taiwan, and to assess their potential toxicity to the aquatic ecosystem. Metals in the exchangeable, carbonate-bound and Fe/Mn oxide-bound forms obtained by sequential extraction were considered to be mobile and related with anthropogenic pollution. The degree of metal pollution and potential toxicity of sediments were higher in the lower reaches of both rivers. The metal speciation in sediments had a bimodal distribution over particle-size fractions. Heavy metals were subject to accumulation in the silt/clay fraction (< 25 microm) and coarse sand (420-2,000 microm). By normalizing the sum of the exchangeable, carbonate-bound, and Fe/Mn oxide-bound metals, it suggested that the potential toxicity to the aquatic ecosystem was caused by the fine sediments as well as coarse sediments.

Effects of Copper Pollution on the Benthic Community in the Le An River, China

ABSTRACT Pollution by heavy metals and acid mine wastewater completely eradicated the benthic community from a section of the Le An River, China. Downstream changes in the benthic community directly reflected the degree of metal pollution in the sediments.

Trace element distributions in aquatic sediments of Danang - Hoian area, Vietnam

Distribution of the trace elements Cr, Cu, Ni, Pb and Zn in surficial sediments of the river/sea environment in Danang – Hoian area (Vietnam) was investigated to examine the degree of metal pollution caused by anthropogenic activities. Point sources from domestic and industrial wastes are identified as dominant contributors of trace element accumulation. Surficial sediments of Hoian River show extremely high total concentrations of Cu (Average Concentration 295 μg/g), Ni (AC 112 μg/g), Pb (AC 396 μg/g) and Zn (AC 429 μg/g) that exceed assigned safety levels ER-M. Similarly, the sediments of Han River show high Pb (AC 188 μg/g) and Zn (AC 282 μg/g) contents. In marine sediments of Thanhbinh beach Pb is also enriched (138 μg/g) above guideline levels. In contrast the sediments of the Cude River are dominated by trace element concentrations close to background values.

Influence of heavy metal exposure during different phases of the ontogeny on the development of pied flycatchers, Ficedula hypoleuca, in natural populations.

A 2-year experiment was performed with pied flycatchers in natural populations to study influences of heavy metal contamination of the eggs (ultimately via the breeding females) and of the nestlings, respectively. This was made possible by an interchange of eggs between two populations: one at a highly contaminated site with elevated concentrations of heavy metals and arsenic, and the other at a clean reference site. Comparisons between these exchanged clutches and control clutches, kept at their original site, were made with regard to breeding results, health-related variables (body weights, hemoglobin concentrations, hematocrit, brain weights), and blood and liver concentrations of cadmium and lead in fully grown nestlings. The results were interpreted in terms of their relation to the time during ontogeny of the metal exposure. Lead concentration, but not cadmium were increased in the eggs laid at the polluted site. The hatchability of the eggs was not significantly influenced by the actual concentrations of these elements. In nestlings the blood and liver concentrations of lead and cadmium were higher at the polluted site. The actual concentrations of toxic metals in the eggs laid at the different sites did not influence lead concentrations in blood or liver of the fully grown nestlings. Instead, lead concentrations were associated with the degree of metal pollution of the nestlings' environment. The results were less clear for the cadmium concentrations in the nestling tissues, as there were situations when the blood cadmium levels in nestlings of the exchanged clutches were significantly different from those of the original clutches of the receiving site. Nestling mortality rate was significantly increased in the control clutches at the polluted site compared to the reference site. The mortality rates of nestlings from exchanged clutches and control clutches were similar at each site, but mortality rates tended to be different between sites for nestlings whose eggs originated from the same site. This was in accordance with the nestling mortality increase at the polluted site being related to metal exposure during the nestling period of life only. Similarly, it was indicated that the pattern of variation of body weight, hemoglobin concentration, hematocrit, and median cell hemoglobin concentration of the blood in nestlings of the differently exposed clutch categories was assigned to the exposure during the nestling phase of ontogeny. Brain development, however, was affected by the toxic metal exposure during early ontogeny in the eggs laid at the polluted site.

Effects of heavy metals on benthic macroinvertebrate communities in New Zealand streams

AbstractWe performed chemical analyses of heavy metals in water and periphyton, toxicity tests with Daphnia magna and an indigenous mayfly (Deleatidium sp.), and field surveys of benthic macroinvertebrates to estimate the degree of metal pollution in three catchments in the Coromandel Peninsula of New Zealand. Good agreement was found between toxicity tests and measures of benthic community structure, particularly at stations with the highest metal levels. Responses of benthic communities at stations with low or moderate levels of metal contamination were variable and were probably confounded by factors other than heavy metals. Effects of heavy metals on benthic communities in New Zealand streams were similar to those reported for metal‐polluted streams in North America and Europe, suggesting that responses to metal contamination are predictable. Abundance and species richness of mayflies, number of taxa in the orders Ephemeroptera, Plecoptera, and Trichoptera, and total taxonomic richness were the best indicators of heavy metals in New Zealand streams. In contrast, the quantitative macroinvertebrate community index (QMCI), a biotic index proposed for assessing effects of organic enrichment in New Zealand streams, could not distinguish between reference and metal‐polluted streams. The poor performance of the QMCI was primarily due to incorrect tolerance scores for some taxa to heavy metals. Because of concerns regarding the subjective assignment of tolerance values to species, we recommend that tolerance values for dominant species in New Zealand streams should be verified experimentally in stream microcosms.

Classification of Japanese rivers by heavy metals in bottom mud

Bottom mud was collected from the upper and lower reaches of 92 rivers in Japan to determine the distribution of 0.5N-HCI-soluble heavy metals. The average concentrations of Cu, Zn, Pb, and Cd in the mud from the lower reaches were from two to three times higher than those in the upper reaches. Japanese rivers were classified according to the degree of heavy metal pollution by using the values of 0.5N-HCI-soluble metals in the lower reaches of rivers. The content of 0.5N-HCI-soluble heavy metals in the mud of the upper reaches was used as the standard value. The classification of rivers was made by a cluster analysis according to Euclidian distance. As a result, rivers in Japan could be classified into three groups based on the degree of metal pollution, and the classification was in agreement with the pollution index.

Species associations and metal contents of algae from rivers polluted by heavy metals

SUMMARY. The algal flora of the Rivers Hayle and Gannel. whieh drain copper and lead mining regions of Cornwall, are described and compared. Although fluctuations in the rarer members of the algal communities were observed, the dominant filamentous algae at most sites did not change over the year of study. Both the total algal abundance and the number of species were depressed at high metal sites. Associations of species that were evident in field samples were confirmed and correlated with water metal levels by principal component analysis. The close similarity between the flora of similar sites on the copper‐polluted River Hayle and the lead‐polluted River Gannei implies that the degree of metal pollution, rather than the polluting metal per se, determines the species present. All mine sites were characterized by a Microspora ‐community whereas a Zygnemales community of Spirogyra and Mougeotia species was typical of low metal pollution. Moderately polluted sites downsteam of the mines had an intermediate flora of Zygnemaies, Microsporales. Ulotrichales and gelatinous Volvocales and Tetrasporales species. No species could be said to invariably indicate metal pollution; the most abundant species at highly contaminated sites were also those with the widest distributions.Field samples of filamentous algae (mainly Spirogyra, Zygogonium, Mougeotia and Microspora species) contained metal concentrations several orders of magnitude greater than ambient levels. For copper and iron, both algal metal contents and concentration ratios (μg g‐1 algae/μg ml‐1 water) were positive functions of water metal levels, although algal iron appeared to plateau at water concentrations of about 1 mg ml‐1. Algal lead concentrations, but not the concentration ratios, also were positively correlated with water lead levels. Thus, for these three metals, the algal metal contents were indicative of ambient conditions. In contrast, algal zinc concentrations were nearly constant and consequently the concentration ratios for this metal were inversely related to water levels. This result suggests that unlike the uptake of other metals, uptake of zinc by these aigae may be strictly regulated.