Trace Elements in Groundwater from Some Crystalline Rocks in the Upper Regions of Ghana

About 20 trace elements were analysed in samples from 60 boreholes located in the Upper East and West Regions of Ghana. Findings from the analysis indicated that most trace element concentrations were higher as compared to their concentrations found in natural water systems. The available chemical data of rocks in the area suggest that local bedrock is the dominant source of the trace elements found in goundwater. Aluminium, Fe, Mn, Zn, Sr, and Ba were excessively high in concentration. In comparison with WHO guidelines, all except Al, Fe, Fe and Mn values were below the recommended limits.     

Trace metal concentrations in the pink shrimp Penaeus notialis from the coast of Ghana

Studies were conducted on the concentrations of Cu, Pb, Zn, Hg, Cd, and Fe in 48 samples of the pink shrimp Penaeus notialis caught off the mouth of the Korle Lagoon, the most polluted coastal lagoon in Ghana. The pattern of occurence in order of decreasing concentration was Zn> Fe> Cu> Pb> Hg> Cd. A positive correlation was found between Hg and body weight suggesting its accumulation by shrimp. Comparatively, the concentrations obtained in the present study were similar to corresponding values for shrimp caught off the coast of West and Central Africa. However, they, except Hg, were higher than values for fin fishes from the Ghanaian coast. Results indicate that the shrimp are safe for human consumption.     

Trace metal concentrations in some Kashmir Himalayan Lakes

The concentrations of trace elements (Pb, Mn, Cu, Zn and Cc) were measured in three Kashmir Himalayan Lakes. Cadmium, Ag, and Hg were not detected. In addition physico-chemical parameters of the lakes were analyzed to asses the water quality. The results indicate that Trigam and Tilwan lakes are more enriched than Khanpur lake. Comparisons of trace metal levels with EPA standards show that Mn and Pb concentrations are well above the permissible levels.     

Trace metal speciation in natural waters: Computational vs. analytical

Improvements in the field sampling, preservation, and determination of trace metals in natural waters have made many analyses more reliable and less affected by contamination. The speciation of trace metals, however, remains controversial. Chemical model speciation calculations do not necessarily agree with voltammetric, ion exchange, potentiometric, or other analytical speciation techniques. When metal-organic complexes are important, model calculations are not usually helpful and on-site analytical separations are essential. Many analytical speciation techniques have serious interferences and only work well for a limited subset of water types and compositions. A combined approach to the evaluation of speciation could greatly reduce these uncertainties. The approach proposed would be to (1) compare and contrast different analytical techniques with each other and with computed speciation, (2) compare computed trace metal speciation with reliable measurements of solubility, potentiometry, and mean activity coefficients, and (3) compare different model calculations with each other for the same set of water analyses, especially where supplementary data on speciation already exist. A comparison and critique of analytical with chemical model speciation for a range of water samples would delineate the useful range and limitations of these different approaches to speciation. Both model calculations and analytical determinations have useful and different constraints on the range of possible speciation such that they can provide much better insight into speciation when used together. Major discrepancies in the thermodynamic databases of speciation models can be evaluated with the aid of analytical speciation, and when the thermodynamic models are highly consistent and reliable, the sources of error in the analytical speciation can be evaluated. Major thermodynamic discrepancies also can be evaluated by simulating solubility and activity coefficient data and testing various chemical models for their range of applicability. Until a comparative approach such as this is taken, trace metal speciation will remain highly uncertain and controversial.     

Trace metal concentrations in marine organisms from St. Vincent Gulf,South Australia

Trace metal concentrations were measured in the tissues of fish, molluscs, crustaceans and macrophytes from St. Vincent Gulf, South Australia. The concentrations of the measured metals (Cd < 0.025 to 2.1 μg g^?1; Cu 0.51 to 9l μg g^?1 5 Pb 0.02 to 3.6 ?g g^?1; Zn l5 to 110 μg g^?1)are similar to those from unpolluted areas and thus give no indication of pollution.     

Assessing Sources of Information for Urban Mushroom Growers in Accra,Ghana

This study assessed information sources for urban mushroom farmers in Accra, Ghana. One hundred farmers were sampled, and a structured questionnaire was administered to solicit information from the respondents. Results showed that the majority of farmers were male (71%) and most (60%) with university education. The majority (44%) had 1–5 years of experience in mushroom cultivation. Co-farmers (89.8%), the Mushroom Growers Association (79.6%), training workshops (73.5%), and the Farmers' Forum (29.6%) readily served as information sources for farmers. The research revealed that, for 52% of farmers, ignorance of information sources was a major hindrance in their quest for information.     

Trace Element Geochemistry from the Birrimian Metasediments of the Northern Region of Ghana

Trace element distributions in rock, soil and groundwater from the Birrimian metasediments and granites located in the Northern Region of Ghana are described. High positive correlations are observed between selected major elements and trace metals (e.g. K₂O and Rb, Al₂O₃ and V, Fe₂O₃ and V, and K₂O and Y) in rocks and soils, and attributed to the presence of major source minerals. Ca and Sr were strongly correlated in groundwater, suggesting greater water-rock interaction. Low association of V with Fe is explained by (i) relatively higher mobility of V as against Fe; (ii) low Fe content in the parent rocks and (iii) variable sources of Fe and V.     

Composition of lysimetric waters from soils of the Upper Volga landscapes

The results of six-year-long observations of the chemical composition of lysimetric waters from soils of three biogeocenoses (forest, meadow, and agrocenosis) in the vicinity of the Ivan’kovo water reservoir were analyzed. It was found that the lysimetric waters of in the three biogeocenoses belonged to the class of fresh calcium-bicarbonate waters. Some differences in chemical compositions of these waters were identified; these differences were due to the impact of biogenic, lithogenic, and anthropogenic factors on the soils in which these waters were formed.     

Observations on metal concentrations in three species of shark (Deania calcea, Centroscymnus crepidater, and Centroscymnus owstoni) from southeastern Australian waters

Deep sea dog sharks (Deania calcea, Centroscymnus crepidater, and Centroscymnus owstonii) were captured from the waters off western Victoria, Australia, in April and May 1998. The elements As, Ca, Cd, Cu, Fe, Hg, K, Mg, Mn, Na, Sr, and Zn were detected in the muscle tissue. The concentrations of Al, Ba, Be, Cr, Mo, Ni, Pb, and V were below the detection limits of the instrumental techniques employed (ICP-ES and GF-AAS). However, significant concentration differences between species were detected for As, Cd, Hg, and Zn. C. owstoni contained the highest concentrations of each of these elements. The concentrations of Cu, Pb, and Zn in each species were below the maximum levels permitted in food by the Australian Food Standards Code. The maximum permitted concentrations of As and Hg were exceeded in all species, and weekly consumption of 400 g of any of these sharks would result in intake of more than the FAO's provisional tolerable weekly intake. Although C. crepidator and D. calcea have strong relationships between length and mercury concentration, C. owstoni does not. Placing C. crepidator and C. owstoni in the same genus, therefore, is worth re-examination as the mechanisms for controlling mercury in C. owstoni appear to differ from that used by both C. crepidator and D. calcea.     

Trace metal concentrations in selected biological,sediment, and water column samples in a Northern New England river

A baseline ecosystem study was undertaken in a relatively non-industrialized New England river to determine trace metal levels of Cr, Cu, Pb and Zn concentrations in water column, sediment, fish, mollusks and aquatic macrophytes. Additional analyses were completed on fish and mollusks for Hg. Results showed metal concentrations in the study area were in general agreement with literature values. Both mollusks and aquatic macrophytes exhibited the highest levels of accumulated metals.     

Trace metals concentrations in marine organisms from the coastal areas of Bahrain,Arabian Gulf

A total of 162 fish and shellfish samples representing important species have been collected from different coastal areas of Bahrain in the Arabian Gulf, and analyzed for lead, cadmium, mercury, and arsenic using electrothermal atomic absorption spectrophotometric method. The dverall mean levels for Pb, Cd, Hg and As in fish samples were 0.132, 0.032, 0.084 and 1.7 µg g^?1 wet weight, respectively, whereas for shellfish they were 0.149, 0.045, 0.042 and 3.61 µg g^?1 wet weight. These values indicate higher levels of metals in shellfish when compared with fish, except for mercury, and reveal that generally the levels of metals in these organisms are lower than existing guidelines, except for arsenic. The provisional tolerable weekly intake of Pb, Cd, Hg and As through fish was estimated to be 0.7, 0.17, 0.45 and 9 µg kg^?1 bodyweight per week, respectively. Our results did not reveal a clear pattern regarding variations of metals concentration between areas and species.     

Background concentrations and loadings of nitrogen in Danish surface waters

Quantitative knowledge of background nitrogen (N) concentrations and loadings is essential for as it determines the minimally disturbed conditions for N in surface waters as a near reference condition. To determine background N concentrations, a total of 39 smaller Danish streams draining relatively undisturbed catchments in different regions were selected and screened for N concentrations and discharge during a 1-year period (2004–2005). Only 19 of the streams fulfilled the threshold set for least disturbed conditions (LDC) in their catchments (proportion of agricultural land <10%). Within the five sampled dominant landscape types in Denmark, the concentrations of ammonium N and total organic N in the LDC streams were found to be nearly constant: 0.05 ± 0.01 mg N L^?1 and 0.53 ± 0.07 mg N L^?1, respectively. In contrast, the concentration of nitrate N differed significantly (P < 0.05) between the five landscape types, with variations between 0.06 and 0.83 mg N L^?1. An analysis of all the 39 streams sampled demonstrated significantly different relationships between the proportion of land use and the flow-weighted annual concentration of nitrate N for two dominant soil types with a Y-axis intercept equal to 0.12 mg N L^?1 for streams draining coarse textural soils and 0.76 mg N L^?1 for streams draining finer textural soils. A significant (P < 0.05) downward trend (18–41%) emerged for flow-weighted annual total N concentrations in four of the five streams that were sampled during the period 1990–2011. A 5 × 5 km grid map of Denmark showing nitrate N and total N background concentrations was produced and used for estimating background N losses to Danish surface waters. Based on the grid map, the average annual background loss of total N was calculated to be 13,000 tonnes N or 19% of the total N loading to Danish coastal waters during the period 2004–2005.     

Trace element concentrations in fish from three Adirondack lakes with different pH values

Concentrations of 29 elements were detected in the axial muscle, and 44 elements were detected in the gut contents of white suckers (Catostomus commersoni) and yellow perch (Perca favescens) from three lakes located in the New York State Adirondack Preserve. The study lakes were acidic Darts Lake, variable pH Lake Rondaxe, and circumneutral Moss Lake. For the majority of the elements, there were no clear differences in the muscle concentrations among fish inhabiting the three types of lakes. Two notable exceptions were Hg and Pb. With some exceptions, the highest muscle tissue Pb concentrations were found in fish from the acidic lake. For both species, the Hg was higher in the muscle than in the gut regardless of lake acidity. Other elements potentially toxic to humans (As, Cd, Ga, Pb, Se, and TI) were not accumulated in the muscle relative to the gut.     

Trace element concentrations in the dorsal muscle of white suckers and brown bullheads from two acidic Adirondack lakes

Concentrations of 14 elements (Ag, As, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, Sn, Tl, V, and Zn) were measured in the dorsal muscle of omnivorous white suckers and brown bullheads, fish likely to ingest sediment while feeding. The fish were collected in two acidic Adirondack lakes known to have elevated concentrations of several of these elements in their surface sediment. Trace element concentrations in the muscle of the white suckers and brown bullheads were compared with government guidelines for edible fish and survey data for concentrations present in commercial species. Only the largest white sucker exceeded the U.S. Food and Drug Administration's guidelines for Hg in food of 1 ppm (wet wt). Concentrations of all the other elements measured were at low or innocuous levels in the edible muscle. A significant positive correlation was found between body weight and Hg concentrations in both species. Zinc was negatively correlated for the same parameters in white suckers. With the possible exception of Hg, our results indicate that elevated levels of potentially toxic elements in the surface sediment of the two acidic Adirondack lakes are not reflected in the edible muscle of the omnivorous bottom feeding fish present in these systems.     

Trace metal analysis of sewage sludge and soils in Bahrain

Trace metals such as Pb, Zn, Cu, Ni, Cd and Fe were determined in sewage sludge produced at a sewage treatment plant in Bahrain (Tubli) and soils. The soils, both untreated and treated with the sludge, are used for agricultural purposes in Bahrain. The Trace-metals level showed the following range (μg g^?1 dry weight); Pb, 242 to 609; Zn, 704 to 836, Cu, 329 to 512; Ni, 23 to 41; Cd, 1.8 to 3.9 and Fe, 1867 to 4284. The data show the degree to which untreated soils have already been contaminated with trace elements. The level of trace-elements found in sludge showed the following range (μg g^?1 dry weight); Pb, 140 to 186; Zn, 597 to 836; Cu, 348 to 449; Ni, 47 to 53; Cd 5.7 to 9.2 and Fe, 5950 to 8520. Mean levels were generally close or lower than mean concentration reported in the United Kingdom and the United States for sludge. They were also lower than the suggested concentration limits for application of sludge on agricultural land, which is one of the most cost effective and attractive techniques for sludge disposal. Soils treated with this sludge (after 1 yr) were also analyzed and showed substantial enhancement of the available level of trace elements in the soil. This eventually will lead to an increase in the trace-element level in plants grown for human or animal consumption. This could have phytotoxic effects, and the possibility of toxic effects on live-stocks and human beings.     

汀江上游流域生态水文分区研究

为反映生态水文系统的相似性和差异性规律,理解人类活动对生态水文系统的干扰规律,为流域资源开发、灾害预防和生态调控提供科学依据。以汀江上游流域为例,以地形、土壤、植被、水文、水资源与人口统计资料为基础,从生态现状、水文条件、生态背景和人类活动4个方面共14个指标统计各个子流域指标的特征值。采用主成分分析和聚类分析的方法将汀江上游流域内35个子流域划分为五类生态水文分区,并对每个分区的特征指标进行分析并命名,同时基于分区结果提出了相应的生态调控措施。分区结果能够揭示汀江上游流域生态水文特征空间上的差异性和相似性以及人类活动的影响,能够指导具有不同生态水文特征的区域进行因地制宜的发展。     

Increased predicted losses of phosphorus to surface waters from soils with high Olsen-P concentrations

Abstract. Diffuse soluble reactive P (SRP) & total P (TP) loads from over 50 major river catchments in Northern Ireland were predicted using an export coefficient modelling approach. Phosphorus export coefficients for each CORINE land cover class, derived from satellite imagery, allowed the prediction of P loads from a breakdown of the CORINE land cover classes by catchment using a GIS. This approach was validated using observed P loads calculated from flow and concentration data. Mean measured Olsen-P concentrations in the soil A-horizon were also determined on a catchment basis. Plots of P loads to the watercourse versus Olsen-P concentrations in the soil showed a breakpoint around 22 mg Olsen- P l⁻¹ for both SRP & TP data. Below Olsen-P concentrations of 22 mg l⁻¹, SRP & TP losses were essentially independent of Olsen-P at 0.28 and 0.63 kg P ha⁻¹ yr⁻¹, respectively. Above Olsen-P concentrations of 22 mg l⁻¹, there was considerable spread in the P loss data. Nevertheless, significant upward trends in SRP and TP losses to watercourses were detected with increasing Olsen-P at a rate of approximately 0.5 and 1.0 kg P ha⁻¹ yr⁻¹, for SRP and TP respectively, for each 10 mg l⁻¹ increase in Olsen-P.     

Estimation of background sulphate concentrations in natural surface waters in Sweden

In order to measure the extent of acidification the background, ‘preindustrial’ conditions must be known. An equation for the estimation of background concentrations of sulphate in surface water in Norway was proposed by Henriksen. When applied on data from the Swedish lake survey in 1990 it was found that the calculated background concentrations exceeded those measured for about one-third of the lakes. The proposed revision is based on a background concentration in precipitation and an estimated contribution from weathering, the latter associated with base cations. Three different approaches were tested to establish the contribution from weathering; geochemical ratios or groundwater chemistry data as a basis, and historical data on denudification. The weathering calculated from groundwater chemistry data seems to give the best estimate of the background sulphate concentration in surface water. Organic matter as source or sink of sulphur is discussed and considered negligible.     

Effects of acidification on the concentrations of heavy metals in running waters in Sweden

Heavy metals in running water are analysed within the Swedish Surface Water Monitoring Programme at about 80 stations. Data for selected rivers and brooks has been used to assess the effect of soil acidification on the concentrations of metals in waters. In southern Sweden, acidification shows a significant effect on Zn and Cd. In the upper parts of the drainage areas, there is an marked increased leakage of these metals from soils to waters indicated by elevated concentrations of Zn and Cd in brooks and also by high maxima during periods of low pH values. The increased leaching from forest soils also influences the concentrations in rivers in southern Sweden. During periods of high water flow, the pH values of the rivers decreases and the concentrations of Zn and Cd increases. At pH levels of 6.2–6.5 the concentrations of these metals are mostly 2–5 times higher as compared to pH levels of about 7.0. Since high concentrations of Zn and Cd coincides with high water flow, the transport of these metals has most certainly increased several times compared to the pre-industrial period. Hence, the by far most important human impact on the loading of Zn and Cd on the marine areas, surrounding southern Sweden is the increased leakage of these metals due to acidification. In northern Sweden the effects of acidification on Zn and Cd are less evident. In general, the concentrations of these metals are lower and the connection between pH and these metals are much less significant in the rivers. The links between acidification and the concentrations of Pb and Cu in the watercourses are comparatively much weaker. These two metals are more related to the content of organic matter in the waters and a possible effect of acidification is overshadowed by natural transport processes in soils and waters.