«Dissertation zur Erlangung des Grades “Doktor der Naturwissenschaften” Im Promotionsfach Geowissenschaften Am Fachbereich Chemie, Pharmazie und ...»
Acute gastrointestinal effects with various symptoms such as vomiting, diarrhea, nausea, abdominal pain and metallic taste in the mouth were observed when human exposuring Cu 2+ in a range of 0.07-1421 mg/kg. (Chuttani et al. 1965; Dash 1989; Holleran 1981; Jantsch et al. 1984Karlson and Noren 1965; Klein et al. 1971; Manzler and Schreiner 1970; Nicholas and Brist 1968; Semple et al. 1960; Walsh et al.1977). World Health Organization estimated the fatal oral human dose of various inorganic copper salts is approximately 200 mg/kg bw with a considerable variability in individual sensitivity.
It has been identified that four groups of people may be at a greater risk of copper overexposure/loading: people with Wilson’s disease, young children, occupationally exposed workers and individuals with glucose-6-phosphate dehydrogenase (G-6-DP) deficiency. Table (5) shows the general Canadian population being divided into five age classes: infants (birth to 6 months), preschoolers (7 months to 4 years), school-age children (5 to 11 years), adolescents (12 to 19 years), and adults (20 years and older), daily intakes of copper for each age class of the general population were estimated. Copper does not show any significant to be teratogenic or carcinogenic. Chronic exposure in humans resulting in toxic levels is rare. A sufficient intake of copper is desired to maintain good health.
* Reference values for average body weights and air and water intakes were obtained from Human Health Risk Assessment for Priority Substances (HC 1994). The average soil intake estimates were taken from Angus Environmental Limited (1991).
†Water intakes are presented separately as tapwater/tapwater+tapwater-based beverages such as coffee, tea, and reconstituted beverages. Breast-fed infants were assumed not to require additional liquids during the first 6 months. Formula-fed infants are assumed to consume 750 mL of formula made from powdered formula and 750mL tapwater. For the present exposure assessment, the lesser water intake values were chosen because drinking water was already included in water-based food items. Infants exclusively formula-fed with ready-to-serve formula were assumed to consume no tap water. Infants fed a mixed diet were assumed to consume 0.2 L water per day on top of the water already included in foods.
‡Assuming that soil ingestion occurs outdoors for 4 h per day, and that dust ingestion occurs indoors for 20 h per day.
(1.2.5) Existing guidelines of copper in soils and criteria in various media European Union (EU) recommends warning legislative limit of copper concentration in soil is 50 mg/kg and the critical legislative limit at 140 mg/kg (values above which the application of sewage sludge is not suitable; Council Directive 86/278/EC, 1986). According to the Ministry of the Environment of the Czech Republic (regulation number 13/1994), the limit values of copper concentration in coarse textured agricultural soils (∼20% clay) is 60 mg/kg and for agricultural soils with high clay contents (∼20% clay) is 100 mg/kg. In Australian and New Zealand a site is considered to be contaminated if the total copper concentrations in soil exceeding 60 mg/kg with environmental investigation needed (Pietrzaka and McPhail, 2004). In India the proposed safety limit of copper in agricultural soils should be in a range between 135mg/kg (Awashthi 2000).
The Canadian Council of Ministers of the Environment (CCME) interim soil assessment criterion for copper was set at 30 mg/kg for dry soil, adopted from the British Columbia Ministry of the Environment A-level criterion (BC MOE 1989) for soils with 10% clay. The province of Quebec recommends an assessment value of 50 mg/kg dry matter (MENVIQ 1988). The determined CCME interim criteria for the remediation of copper in agricultural, residential/parkland, and commercial/industrial land sites were 150, 100, and 500 mg/kg respectively (CCME 1991). The CCME interim criteria of 150 mg/kg for agricultural land remediation were adopted from the Ontario Ministry of the Environment agriculture/residential/parkland value for coarse soils (CCME 1991). Soil concentrations above this value indicate the need for remedial action. The CCME interim criteria for the remediation of residential/parkland and commercial/industrial land sites were adopted from British Columbia’s B-level and C-level criteria (BC MOE 1989).In British Columbia the A, B and Clevel soil quality criteria of 30, 100 and 500 mg/kg dry soil based on the Netherlands ABC approach (BC MOE 1989). The recommended levels are in similar with Quebec’s A, B and Clevel values in which set at 50, 100 and 500 mg/kg dry matter. Exceeding the above values require further investigation and remediation procedure. Under the Ontario Ministry of the Environment and Energy the background copper concentration on rural land is 41 mg/kg compared to 65 mg/kg on old urban land (OMEE 1994a). The authority proposed subsurface soil cleanup with copper concentration exceeding 225 mg/kg.
IntroductionVarious authorities such as United Kingdom’s Interdepartmental Committee on the Redevelopment of Contaminated Land (ICRCL) suggested the safety threshold level of copper should not be above 130 mg/kg. In New Jersey a remediation criterion of 170 mg/kg copper in soil for residential sites is required. (NJDEP 1990). Across Netherlands (HSPE 1994) a soil target value of 36 mg/kg of copper was deemed negligible risks to the environment whereas an intervention value of 190 mg/kg would require urgent cleanup process of the pollution.
According to Canadian Council of Ministers of the Environment (1997) a soil quality guidelines were developed to protect four different types of lands: agricultural, residential/parkland, commercial and industrial (table (6). The threshold effects concentration (TEC), the effects concentration low (ECL), the nutrient and energy cycling check, and the soil quality guidelines for soil contact and soil and food ingestion can be calculated. Further details of calculation can be referred to CCME 1997.
Table (6) Table shows environmental and human health guidelines of copper (CCME 1997)
*As per the CCME (1996) protocol, the SQGsc for agricultural and residential/parkland land uses corresponds to the 25th percentile for the effects and no effects data distribution when using the weight of evidence method, while the SQGsc for commercial and industrial land uses corresponds to the 25th percentile of the effects data distribution only. The other percentiles are presented for comparison purposes only.
†This guideline applies only to the part of the agricultural land that is used as a residential property.
(1.2.6) Copper speciation in soils (188.8.131.52) Properties of Copper in soils Copper in soil is retained as exchangeable and insoluble complexes. Fixation and availability of copper are influenced by pH, amount of organic matter, clay, micro-organism and calcium carbonate (Peech 1941; and Piper 1942). Soil properties such as the acidity level and organic matter content can affect the amount of copper being taken up. Copper tends to complex strongly with organic matter and is not efficiently extracted by EDTA and DPTA. The most available copper in soils is held in a Cu2+ form on surfaces of clay minerals or in association with organic matter. The copper and organic matter association can be due to formation of strong innersphere complexes. Copper existing as an impurity in silicate mineral is largely unavailable.
Organic matter and soil pH are the predominant factors influencing copper availability with organic matter can bind copper more tightly than any other micronutrient. Under this condition the organic soils are more likely to be deficient in copper than mineral soils. Adjusting the soil pH by liming can increase the amount of copper held by clay, organic matter, Fe and Mn oxy(hydro) oxides and decrease the copper availability.
Copper is usually strongly adsorbed to soil particles and is comparatively less mobile.
Copper in soils tend to be accumulated and being remained in six different conditions listed as follow: (1) Copper in soil solution. (2) Exchangeable copper (Cu being bound electrostatically to charge surfaces). (3) Copper being sorbed and complexed. (4) Copper bound to the soil minerals.
(5) Copper associates with humus like organic materials. (6) Copper exists in residual form from the soil parental mineral.
Copper presents in first condition is very mobile while at conditions between two to four the copper can be mobilized under changing soil conditions, pH, cation exchange capacity (CEC) of the soil, organic matter, the amount and type of clay, the existence of oxides of iron, manganese and aluminum and the reduction-oxidation (redox) potential of the soil are all detrimental to the distribution of copper in the above conditions.
Copper is less soluble when pH increases. Adriano (1986) demonstrated positive correlation between adsorbed copper capacity of soil and pH with optimum pH in a range of 6.7Copper favors precipitation in alkaline with increasing pH led to hydrolyse or precipitation of Al3+ ions. Al is precipitated at above pH 5 however Cu absorption still increases due to sorption on OM. The available exchange sites can therefore be used for copper adsorption.
The cation exchange capacity (CEC) of soil is considered as the maximum number of moles of adsorbed ion charge that can be desorbed from a unit mass of soil under certain environmental conditions such as temperature, pressure and pH. The CEC is further influenced by four key factors listed at following table (7).
Table (7) Table shows key factors affecting cation exchange capacity (CEC)
Factor 1 the kind of clay mineral present (different clays have different CEC values) 2 the quantity of clay minerals (soils with a finer texture have greater CEC values) 3 the amount of organic matter present (organic matter has a relatively high CEC value) 4 the pH of the soil (CEC increases with increasing soil pH)
Copper has a high affinity to organic matter and can be strongly bounded compared with other trace elements. With this observation, Cu/C ratio (grams per kilogram) is often used in extractions to determine copper availability. For many soils 20 to 50% of copper occurs in organically bound forms (Adriano 1986; Hunter et al. 1987; Loneragan et al. 1981; Slooff et al.
1989). The high adsorption ability of copper with organic matter can be due to high CEC and chelating ability (Adriano 1986; Hunter et al. 1987). Copper ions in this case are mostly bound to carboxyl and phenolic type functional groups of the organic matter. The formation of copper complexes can regulate copper mobility and availability. The amount of clay in soil can also affect the CEC and hence influencing copper adsorption. Copper can be adsorbed by Fe, Al and Mn oxides (Alloway and Jackson 1991). Copper is the most strongly adsorbed divalent transition and trace metals on Fe and Al oxides and oxyhydroxides (Adriano 1986). Studies suggested the binding affinity between soil constituents and copper can be ranked as follow: Mn oxide organic matter Fe oxide clay minerals (Adriano 1986).
Copper minerals in solution is soluble with the order of decreasing solubility: CuCO3 Cu3(OH)2(CO3)2 (azurite) Cu(OH)2 Cu2(OH)2CO3 (malachite) CuO (tenorite) CuFe2O4 (cupric ferrite) soil Cu (Alloway 1990). Divalent Cu2+ ion in soil solution can exist in different inorganic and organic complexes. Soil types have finite holding capacities for copper ions, and leaching can occur when the copper levels applied exceed this capacity (Adriano 1986). Mineral soils in the vicinity of the nickel and copper smelters in Coniston, Ontario were acidified to a pH of 2.4 as a result of aerial emission of sulphur-containing compounds over time increasing the mobility of soil copper in the area (Adriano 1986). Acidic rainfall would only result of significant leaching of copper once the pH decreases below 3.0 (HSDB). The transport pathway of copper from soils is lateral movement (Adriano 1986; Williams et al. 1987) such as run-off and erosion result from mechanical cultivation and/or erosion, including aeolian and fluvial transport (McGrath and Lane 1989).