Occurrence Of Trace Metals Research Articles

Possible influence of shipping operations on trace metals gradients along the Commodore Channel, Lagos State, Nigeria

The impact of shipping operations on the level of trace metals along the Commodore Channel of the Lagos lagoon is a topic that requires careful consideration. Shipping activities can have a significant impact on the water quality of the lagoon, which in turn can affect the health of the flora and fauna that depend on it. This study attempts to assess the impact of shipping operations on the level of trace metals along the Commodore Channel of the Lagos lagoon. Concentrations of trace metals in the Lagos Lagoon specifically the Commodore channel were determined in March 2016, and the downstream variation was compared. Trace metals (Pb, Cd, Fe, Zn and Co) were determined using Atomic Absorption Spectroscopy (AAS). The concentration of trace metals were found to be beyond the permissible limits stipulated by World Health Organization (WHO) and European Union (EU). There exists an exception in the mean level of Zn (0.23±0.1107mg/L) in the harbor water which was lower than the WHO standard of 5mg/L as at the time of this study. The trace metals showed the decreasing order of Pb > Fe > Zn > Co > Cd with concentration of 1.0±0.6mg/L, 0.62±0.2mg/L. 0.23±0.1107, 0.14±0.12mg/L and 0.05±0.02mg/L respectively. The result of contamination factor showed the harbor water had very high degree of Pb and Cd contamination. This high CF can be caused by the shipping and vessel transportation route and gateway of the harbor into the country. Continuous monitoring is required to assess environmental quality and adopt suitable management techniques in order to prevent the negative impacts of shipping operations on trace metal occurrence in harbors.

Portunus pelagicus (Linnaeus, 1758) as a Sentinel Species to Assess Trace Metal Occurrence: A Case Study of Kuwait Waters (Northwestern Arabian Gulf).

Heavy metal pollution can adversely impact marine life, such as crabs, which can accumulate it in different organs and potentially transfer and biomagnify along the food chain in aquatic ecosystems. This study aimed to examine the concentrations of heavy metals (Cd, Cu, Pb, and Zn) in sediment, water, and crab tissues (gills, hepatopancreas, and carapace) of the blue swimmer crab Portunus pelagicus in the coastal areas of Kuwait, northwestern Arabian Gulf. Samples were collected from Shuwaikh Port, Shuaiba Port, and Al-Khiran areas. The accumulation of metals in crabs were higher in the carapace > gill > digestive gland, and the highest metal concentration was found in crabs collected from Shuwaikh > Shuaiba > Al-Khiran. The metal concentrations in the sediments were in the order Zn > Cu > Pb > Cd. Zn was the highest metal concentration detected in marine water sampled from the Al-Khiran Area, whereas the lowest metal was Cd sampled in water from the Shuwaikh Area. The results of this study validate the marine crab P. pelagicus as a relevant sentinel and prospective bioindicator for evaluating heavy metal pollution in marine ecosystems.

Physicochemical Quality and Health Risks Associated with Use of Water from Nyamwamba River, Kasese, Western Uganda

Aim: In Kasese district of Western Uganda, farmers cultivating near Nyamwamba River (NR) experience crop wilting whenever the river banks burst. Increased cases of cancer and ulcers in the district is anecdotally blamed on ingestion of contaminated water from water resources polluted by tailings from Kilembe copper mines. Sand miners attested that mining in NR caused body irritations and itching while drinking water from the same river results in abdominal complications in infants. The aim of this study was to assess the seasonal variations in the physicochemical parameters and heavy metals (HMs) content of water from NR, and the associated health risks.
 Place and Duration of Study: The experiments were done at the Department of Chemistry, Faculty of Science, Mbarara University of Science and Technology, Uganda from 2018 to 2019.
 Methodology: This study employed quantitative research design. Water was sampled from down, middle and upstream of NR and Mubuku River, Western Uganda during the dry and wet seasons. The samples were analyzed for physicochemical parameters (pH, conductivity, total dissolved solids, total suspended soils) and HMs: chromium (Cr), cadmium (Cd), zinc (Zn), iron (Fe), lead (Pb), arsenic (As) and copper (Cu) by atomic absorption spectrometry. The estimated daily intake (EDI), target harzard quotient (THQ) and cancer risks were calculated to explore if there are any carcinogenic and non-carcinogenic health risks that could arise from ingestion and dermal contact with water from NR.
 Results: Most physicochemical parameters of the water samples only met WHO guidelines for drinking water in the upstream. The mean concentration of Fe, Cu, Pb, Zn, Cr, Cd and As were 0.90-29.66 mg/L, 0.21-10.74 mg/L, 0.40-8.21 mg/L, 1.10-13.47 mg/L, 0.79-13.47 mg/L, 0.05-1.40 mg/L and 0.22-4.34 mg/L, respectively. Wet season recorded higher HMs concentrations when compared to the dry season, with all its samples exceeding the WHO guidelines for drinking water. There was an extremely high concentration of HMs in the upstream samples than expected. Health risk assessment indicated that the EDI through dermal contact ranged from 0.015 to 4.150 mg/kg/day while through ingestion of contaminated water, the values ranged from 0.008 × 10-6 to 38.266 × 10-6 mg/Lday. Some of the EDI doses were higher than corresponding reference doses for ingestion and contact with the HMs in water. THQ and total THQ exceeded 1 while cancer risk values were beyond the US EPA cancer risk borderline.
 Conclusion: This study revealed that there are serious non-carcinogenic and carcinogenic health risks that could arise from consumption and contact with water from NR. Future studies should examine the relationship between the occurrence of trace metals in food stuffs with cancer, ulcers and other associated diseases in the area.

Metabolomic and phenotypic implications of the application of fertilization products containing microcontaminants in lettuce (Lactuca sativa)

Cultivation practice using organic amendments is plausible to ensure global food security. However, plant abiotic stress due to the presence of metals and organic microcontaminants (OMCs) in fertilization products cannot be overlooked. In this study, we monitored lettuce metabolism and phenotypic response following the application of either sewage sludge (SS), the organic fraction of municipal solid waste, swine manure (SM), chemical fertilizers (CF), or no amendment (C) in a greenhouse facility. The experimental set-up consisted of five treatments with five replicates (25 experimental units randomly distributed). All fertilizers were supplied at the equivalent agronomic total nitrogen dose, but the occurrence of trace metals and/or OMCs was greater in the SS and SM than the rest. Non-target metabolomic analysis (high-resolution mass spectrometry coupled with partial least squares regression) identified more than 300 plant metabolites (amino acids, organic acids, sugar alcohols, and sugars), 55 of which showed significant changes in their relative abundances depending on the type of amendment. Functional analysis indicated that the use of CF or SS increased the levels of metabolites involved in carbohydrate and nitrogen metabolism. Therefore, although SS and SM fertilizers had a greater presence of heavy metals and/or OMCs, our results indicate that they did not induce measurable adverse effects in the lettuce phenotype or metabolism. Metabolic changes between fertilizers (CF and SS vs. C and SM) were mainly due to nitrogen availability.

Occurrence of trace metals in fish from South Italy: Assessment risk to consumer’s health

The concentrations of nine trace elements (Hg, Cd, Pb, V, Ni, Co, Cr, Cu and Zn) were determined in sixteen fish species collected in commercial centers of South Italy. Additionally, the assessment of risk indices (Hazard Quotient, Hazard Index, Incremental Lifetime Cancer Risk) through the consumption of various fish species were estimated in different age groups. The concentrations fell under the maximum permissible levels (MPLs) for human consumption recommended by European Union, with an only exception regarding Cd, which exceeded the tolerable value in Atlantic bluefin tuna samples. The estimated weekly intakes of metals, all below Provisional Tolerable Weekly Intakes (PTWIs), were in the following decreasing order: children > teenagers > adults > elders. The estimated hazard quotient (HQ) of Hg being above or close to 1 indicated a high probability of experiencing non-carcinogenic health risks, while the noncarcinogenic threats associated with exposure to other metals were insignificant (< 1) for all age groups. The cumulative cancer risk (ΣILCR) in children (1.86 × 10−3) and teenagers (1.10 × 10−3) exceed the cancer benchmark by a greater margin than adults (7.53 × 10-4) and elders (6.43 × 10-4). These results impose a systematic monitoring of fish, especially of large predatory fish, so to ensure the continuing safety of this food safeguarding human health.

Occurrence of Trace Metals in Food Crops Grown on the Mbale Dumpsite, Uganda, and Human Health Risks.

Food crops can be used as biomonitors to assess potential public health food safety hazards from contaminated agricultural environments. Globally, more than 800 million people grow fruits, vegetables, and grains on urban garden soils with unknown health risks. This worldwide practice has exposed consumers to pathogenic and carcinogenic risks from locally grown and imported contaminated foodstuffs such as Amaranthus cruentus and Zea mays, traditional and widely consumed crops across the globe. This study used Z. mays and A. cruentus crops to investigate the occurrence and spatial variations of aluminum (Al), chromium (Cr), iron (Fe), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), arsenic (As), selenium (Se), cadmium (Cd), mercury (Hg), and lead (Pb) concentrations across the Mbale dumpsite, Uganda. Mean concentrations for Fe, Al, Zn, Mn, and Cu were high in both crops, whereas Pb, Cr, Co, Cd, As, Hg, Se, and Ni occurred in trace amounts. Using the 2 crops as biomonitors, significant variations for Al, Zn, Fe, Cr, and Co concentrations in individual crops were identified across the dump center, hill slope, and riverbank. The variations in Al, Zn, Fe, Cr, and Co concentrations were specific for crop types, crop parts, and location. The highest overall accumulation of metals was at the dump center and in crop leaves. Except Pb concentrations in Z. mays seeds, Cr, Pb, Zn, and Al concentrations in other crop parts were above World Health Organization/Food and Agricultural Organization consumer food safety limits. Therefore, Z. mays and A. cruentus consumption could pose health risks to consumers. Further health assessments and potential regulations are recommended to reduce potential health risks from metals in crops for human consumption. Integr Environ Assess Manag 2020;16:362-377. © 2019 SETAC.

Trace metal occurrence in Mediterranean seaweeds.

Seaweeds have been used as animal feed since a long time and are consumed as food in several cultures. In fact, macroalgae are a source of protein, fiber, polyunsaturated fat, and minerals. The concentration of trace elements was determined in dominant macroalga species from three sites of the northwestern Mediterranean Sea. A high interspecies variability was observed, with higher metal levels in brown and green than those in red seaweeds. The maximum values set by European regulations for arsenic, mercury, and cadmium in food and feed were never exceeded, but a few samples were very close to limits set for mercury. Conversely, the maximum limit for lead in feed was exceeded in all species from one of the considered sites. Analogously, lead in seaweeds could constitute a potential risk for human health, due to the exceeding of the maximum value set for food supplements.

Occurrence of trace metals of toxicological potential in common grass African foxtail (Cenchrus ciliaris)

Occurrence of trace metals of toxicological potential in common grass African foxtail (Cenchrus ciliaris)

Pesticide and trace metal occurrence and aquatic benchmark exceedances in surface waters and sediments of urban wetlands and retention ponds in Melbourne, Australia.

Samples of water and sediments were collected from 24 urban wetlands in Melbourne, Australia, in April 2010, and tested for more than 90 pesticides using a range of gas chromatographic (GC) and liquid chromatographic (LC) techniques, sample 'hormonal' activity using yeast-based recombinant receptor-reporter gene bioassays, and trace metals using spectroscopic techniques. At the time of sampling, there was almost no estrogenic activity in the water column. Twenty-three different pesticide residues were observed in one or more water samples from the 24 wetlands; chemicals observed at more than 40% of sites were simazine (100%), atrazine (79%), and metalaxyl and terbutryn (46%). Using the toxicity unit (TU) concept, less than 15% of the detected pesticides were considered to pose an individual, short-term risk to fish or zooplankton in the ponds and wetlands. However, one pesticide (fenvalerate) may have posed a possible short-term risk to fish (log10TUf > -3), and three pesticides (azoxystrobin, fenamiphos and fenvalerate) may have posed a risk to zooplankton (logTUzp between -2 and -3); all the photosystem II (PSII) inhibiting herbicides may have posed a risk to primary producers in the ponds and wetlands (log10TUap and/or log10TUalg > -3). The wetland sediments were contaminated with 16 different pesticides; no chemicals were observed at more than one third of sites, but based on frequency of detection and concentrations, bifenthrin (33%, maximum 59 μg/kg) is the priority insecticide of concern for the sediments studied. Five sites returned a TU greater than the possible effect threshold (i.e. log10TU > 1) as a result of bifenthrin contamination of their sediments. Most sediments did not exceed Australian sediment quality guideline levels for trace metals. However, more than half of the sites had threshold effect concentration quotients (TECQ) values >1 for Cu (58%), Pb (50%), Ni (67%) and Zn (63%), and 75% of sites had mean probable effect concentration quotients (PECQ) >0.2, suggesting that the collected sediments may have been having some impact on sediment-dwelling organisms.

Assessment and source identification of trace metals in the soils of greenhouse vegetable production in eastern China

Worldwide concern about the occurrence of trace metals in greenhouse vegetable production soils (GVPS) is growing. In this study, a total of 385 surface GVPS samples were collected in Shouguang and four vegetable production bases in Nanjing, Eastern China, for the determination of As and Hg using atomic fluorescence spectrometry and Pb, Cu, Cd, and Zn using inductively coupled plasma-mass spectrometry. Geo-accumulation indices and factor analysis were used to investigate the accumulation and sources of the trace metals in soils in Eastern China. The results revealed that greenhouse production practices increased accumulation of the trace metals, particularly Cd, Zn, and Cu in soils and their accumulation became significant with increasing years of cultivation. Accumulation of Cd and Zn was also found in soils from organic greenhouses. The GVPS was generally less polluted or moderately polluted by As, Cu, Zn, and Pb but heavily polluted by Cd and Hg in some locations. Overall, accumulation of Cd, Zn, and Cu in GVPS was primarily associated with anthropogenic activities, particularly, application of manure. The high level of Hg found in some sites was related to historical heavy application of Hg containing pesticides. However, further identification of Hg sources is needed. To reduce accumulation of the trace metals in GVPS, organic fertilizer application should be suggested through development and implementation of reasonable and sustainable strategies.

Trace Metal Occurrence and Mobility Assessment in Stream Sediments near the Sungun Porphyry Copper Deposit in Northwest Iran

The Sungun porphyry copper deposit is located 100 km northeast of Tabriz in the Azarbaijan province of Iran. The total concentration and chemical fractionation of metals and metalloids (As, Se, Cd, Cr, Ni, Co, and Zn) in sediment downstream of the Sungun mine was investigated. The degree of contamination was evaluated using the sediment pollution index (SPI) and enrichment factor. The concentrations of As, Cd, Se, and Zn in the contaminated sediments were elevated due to anthropogenic activities. According to the SPI, surface sediments in the ephemeral rivers flowing in the vicinity of the Sungun porphyry copper deposit are classified as natural sediment with no ecological risk, while sediments that received contaminated effluents are classified as slightly polluted. Sequential extraction indicated that Co was principally associated with the iron and manganese oxide fraction, while other elements (As, Zn, Cr, Se, and Ni) were mainly distributed in residual phases. Cadmium is the only element that has a high potential for mobility and bioavailability in the sediments and, of the investigated elements, it poses the greatest potential risk to the local aquatic ecosystems. The chemical fractionation pattern of elements appears to be influenced by industrial effluents. Although the bioavailable fraction of most contaminant metals is low due to the freshness of the sediments, over time, the oxidation of sulfide minerals in these sediments could contribute contaminant elements in soluble form.

Trace elements in streambed sediments of floodplains: consequences for water management measures

The occurrence of trace metals was studied at the interface between groundwater and the drainage system of a large floodplain in NE Germany, the Oderbruch region. Depending on the predominant hydraulic connectivity between groundwater and the drainage channels, the geochemical environment creates a high variability in the accumulation of Fe, Mn, Cd, Zn, Cu, and As. The mobility of the trace metals depends on spatial variable redox transition zones which act as geochemical barriers between the anaerobe aquifer and the oxic surface waters. In drainage ditches with high exchange flow between groundwater and surface water the transition zone is small and unstable with a low retention potential for trace metals. Decreasing hydraulic gradients and respectively decreasing base flow cause the change for an extensive transition zone with increasing trace metal accumulation in the channel sediments. The accumulation is mainly controlled by oxidation and degassing of CO2. In the streambed sediments of channels which periodically run dry an effective chemical barrier can be observed. This Fe dominated oxic horizon controls the accumulation of Mn > Cu > As > Zn > Cd, which are mainly associated with fresh, amorphous Fe oxyhydroxides. The chemical barriers can be instable and reversible. Therefore, water management decisions are discussed which stabilize the barriers by controlling aquifer-channel exchange rates, channel oxygen content and surface water levels.

Effects of 12 years’ operation of a sewage treatment plant on trace metal occurrence within a Mediterranean commercial sponge ( Spongia officinalis, Demospongiae)

The present field study uses Spongia officinalis for assessing trace metals occurrence in time and space within Mediterranean rocky communities. Nine sites were selected in the Marseille area for studying spatial trends in 12 metal concentrations. Long term changes in 8 metal concentrations were assessed at sites that had been sampled before and 12 years after the opening of a treatment plant. Spongia officinalis highly concentrated all the trace metal surveyed excepted Hg and Cd. The overall contamination level registered provided a classification of the study sites which is congruent with that given by other studies on pollutant accumulation in neighbouring sandy-bottoms or benthic assemblages. Among the metals studied, Fe, Pb, Cr are those that best highlighted a pollution gradient. In the present study, only Cd concentration did not vary in space. Except for Ni, all pollutant concentrations clearly decreased between 1984 and 1999. This very impressive decrease in heavy metal concentrations within the Marseille area represents an indisputable evidence of the improvement of the seawater quality resulting from 12 years’ operation of the Marseille sewage plant. Moreover, the significant decrease also recorded in the reference population at Port-Cros might reflect an overall improvement in the seawater quality of the NW Mediterranean.

Selected toxic metal levels in seasonal fruits of Pakistan

Levels of selected essential and non‐essential metals (Cd, Cr, Pb, Cu, Fe and Zn) and those of macro‐nutrients (Ca, K, Mg and Na) are estimated in 15 different seasonal fruits available in local Pakistan markets. The wet digestion oxidation method was used for the analysis of samples by the flame atomic absorption technique. The results indicated almost 100 percent incidence of occurrence of trace metals and macro‐nutrients in all fruits. The highest concentration was observed for zinc, ranging between 0.13 and 79.9mg/kg, wet weight, respectively for banana and mango. The iron levels ranged from 0.55 to 44.8mg/kg, wet weight, for pomegranate and mango. The concentrations of Cd, Cr, Pb and Cu remained at marginal levels, except for certain fruits where the concentrations were very high. The data are compared with allowed safe limits laid down by WHO.

Trace metal occurrence and distribution in sediments and mangroves, Pumicestone region, southeast Queensland, Australia

The Pumicestone region is a unique catchment in northern Moreton Bay, southeast Queensland. The region supports a wide range of land-use activities as well as attractions such as nature conservation areas. One environmental aspect that has not previously been addressed in this area is the occurrence of minor and trace metals in estuarine sediments associated with the main estuaries of the region. The trace metals included in this investigation are: vanadium, chromium, molybdenum, cobalt, nickel, copper, zinc, cadmium, lead and arsenic. To determine and evaluate the occurrence and distribution of metals in the area, several components have been analysed: bedrock material, pre-industrial settings, recent estuarine sediments, soils of estuarine origin and mangrove pneumatophores. The 40 sites chosen for sediment and soil samples cover a variety of estuarine settings and represent a range of natural conditions in terms of channel and bank morphology, tidal energy, vegetation cover, relationship to bedrock, water salinity and land disturbance. The chemical, mineralogical and statistical analyses employed in this study enabled (a) establishment of background values for the area, (b) determination of relationships between metals and (c) identification of sites with anomalous metal concentrations. All the metals found in the sediments of the area are sourced from the geological bedrock. The dominant trace elements identified in sediments are Zn, V and Cr. The remaining metals are highly variable spatially. All trace metals are controlled by the presence of Fe and Mn oxides, and by the grainsize of the sediment. Typically, fine-grained Fe-rich materials tend to adsorb more trace metals than sandy sediments. In soils that have developed from estuarine muds, some metals such as Cr, Mo, Pb and As tend to be in larger quantities than in the estuarine counterparts. Some of the elements, which occur in significant amounts in the sediment, have been detected in mangrove tissue ( Avicennia marina) such as V, Cr, Zn, Fe and Mn. Of particular note is Cu, which is present in mangrove tissue in quantities many times exceeding the sediment concentration. The comparative analysis of pre-industrial settings and recent sediments and soils highlighted some areas of metal enrichment such as acid-affected sites where oxidation of pyrite has mobilised metals from sediments; these metals are then redistributed in Fe-rich surficial layers. Disturbed banks within the estuaries are also likely to have low levels of metal enrichment due to boating activities.

Trace metal occurrence in a mineralised and a non-mineralised spodosol in northern Sweden

In order to determine the metal-bearing phases with special emphasis on Cu, a sequential extraction has been carried out on seven soil samples from a sulphide-bearing spodosol profile in Liikavaara Östra, close to the Aitik Copper Mine in northern Sweden. A reference spodosol profile with very low abundances of sulphides located far from anthropogenic emissions was also studied. Five fractions were selected for the extraction: (I) CH 3COONa-extractable (exchangeable/adsorbed/carbonate); (II) Na 4P 2O 7-extractable (labile organics); (III) 0.25 M NH 2OH·HCl-extractable (amorphous Fe oxyhydroxides/Mn oxides); (IV) 1 M NH 2OH·HCl-extractable (crystalline Fe oxides); and (V) KClO 3/HCl-extractable (organics and sulphides). The distribution of trace elements (Co, Cr, Cu, Ni, Pb and Zn) in the profile in Liikavaara Östra is different from that in the reference profile. Possible explanations for these differences are (i) the presence of sulphides in the soil, (ii) atmospheric deposition of dust derived from mining activities at the Aitik Copper Mine, and (iii) mineralogical heterogeneities inherited from the deposition of the till. There is no straightforward correlation between the amount of the extracted phases and the metal extractability in the soils. This fact indicates that other factors are important for the retention of trace metals as well. The data presented in this study suggest that Co, Cr and Ni, to a fairly large extent, are associated with the organic matter in the B-horizon in both profiles, while in the C-horizon in Liikavaara Östra, sulphides are probably the more important carriers of these elements. For Co and Ni, Fe oxyhydroxides seem to be important. Most of the Cr occurred in the residual remaining after the leaching procedure. Copper and Zn seem to be associated with the organic matter to some extent in the B-horizon. The concentration of Cu in the C-horizon in Liikavaara Östra is high (2310 ppm), but only a very small fraction is likely to be hosted by sulphides. It is concluded that the major part of Cu in the C-horizon and a prominent fraction in the B-horizon in Liikavaara Östra are associated with some secondary phase that is extractable during extractions III and IV. Possible candidates for this phase are goethite and inclusions of native Cu in weathered biotite.

HAEMOCYTES OF THE FRESHWATER MUSSEL, DREISSENA POLYMORPHA PALLAS: CYTOLOGY, CYTOCHEMISTRY AND X-RAY MICROANALYSIS

The haemocytes of Dreissena polymorpha were examined by light and electron microscopy. On the basis of cytology and cytochemistry, three main haemocyte types were identified' agranular haemocytes or hyalinocytes, granular haemocytes represented by the neutrophihc granulocytes and the large basophilic haemocytes (LBH). These cell types correspond to the haemocyte classification scheme commonly established for bivalve molluscs: the granular haemocytes (granulocytes) and the nongranular haemocytes (hyalinocytes) Hydrolytic enzyme activities, such as acid phosphatase and non-specific esterases, were demonstrated within the cytoplasmic inclusions of the neutrophilic granulocytes and the LBH- f} glucuronidase activity was also detected in the cytoplasnuc granules and vacuoles of the LBH. Ultrastructural and phosphatase reactivity was revealed within the matrix of the cytoplasmic granules. The presence of a range of hydrolytic enzymes, including hydrolases and glycosidases in the granules, suggests that these organelles belong to the lysosomal system X-ray microanalysis showed the presence of P, S, Si, Mg, Ca and heavy metals such as Cu, Zn, Pb and Fe in the matrix of the granules of the haemocytes in a natural population of zebra mussels. The occurrence of trace metals sequestrated in the lysosomes suggests the involvement of the granular haemocytes in metal accumulation, transport and detoxication mechanisms.

Adoption of Common Schemes for Single and Sequential Extractions of Trace Metal in Soils and Sediments

Abstract The various methods for determining the mode of occurrence of trace metals in sediments and soils have a long history which dates back to the determinations of the availability of metals for plant nutrition performed earlier. Various methods have been developed in the 70′s and 80′s dealing with both single and sequential extraction schemes. Although some schemes received wide acceptance, none of them developed into a commonly accepted procedure. As a result, the information obtained was site-specific and the interpretation of the results scientist-specific. The workshop on single and sequential extraction in sediments and soils held at Sitges

Occurrence of trace metals Fe, Mn, Zn, Cu in the wedge shellDonax trunculusL. (Bivalvia)

Abstract The first results of a study on the occurrence of trace metals in Donax are given here briefly.

Removal of Trace Metals During Conventional Water Treatment

Widespread occurrence of trace metals and their potential impact have only recently been extensively recognized. It took the mercury crisis of 1970 to demonstrate the inadequate state‐of‐knowledge concerning trace‐metal pollution. Presented here are the results of a study made of trace‐metal removal.