Environmental contamination of Zn,Cd, Ni,Cu, and Pb from industrial areas in Hamadan Province,western Iran

Eleven surface soil samples from calcareous soils of industrial areas in Hamadan Province, western Iran were analyzed for total concentrations of Zn, Cd, Ni, Cu and Pb and were sequentially extracted into six fractions to determine the bioavailability of various heavy metal forms. Total Zn, Cd, Ni, Cu and Pb concentrations of the contaminated soils were 658 (57–5,803), 125.8 (1.18–1,361), 45.6 (30.7–64.4), 29.7 (11.7–83.5) and 2,419 (66–24,850) mg kg⁻¹, respectively. The soils were polluted with Zn, Pb, and Cu to some extent and heavily polluted with Cd. Nickel values were not above regulatory limits. Copper existed in soil mainly in residual (RES) and organic (OM) fractions (about 42 and 33%, respectively), whereas Zn occurred essentially as RES fraction (about 69%). The considerable presence of Cd (30.8%) and Pb (39%) in the CARB fraction suggests these elements have high potential biavailability and leachability in soils from contaminated soils. The mobile and bioavailable (EXCH and CARB) fractions of Zn, Cd, Ni, Cu, and Pb in contaminated soils averaged (7.3, 40.4, 16, 12.9 and 40.8%), respectively, which suggests that the mobility and bioavailability of the five metals probably decline in the following order: Cd = Pb > Ni > Cu > Zn.     

Chemical characteristics of groundwater in parts of mountainous region, Alvand, Hamadan, Iran

Eighty-seven groundwater samples have been collected from a mountainous region (Alvand, Iran) for hydrochemical investigations to understand the sources of dissolved ions and assess the chemical quality of the groundwater. Most water quality parameters are within World Health Organization acceptable limits set for drinking water. The least mineralized water is found closest to the main recharge zones and the salinity of water increased towards the north of the basin. The most prevalent water type is Ca–HCO₃ followed by water types Ca–NO₃, Ca–Cl, Ca–SO₄ and Mg–HCO₃. The Ca–NO₃ water type is associated with high nitrate pollution. Agricultural and industrial activities were associated with elevated level of NO₃⁻. Mineral dissolution/weathering of evaporites dominates the major element hydrochemistry of the area. Chemical properties of groundwater in Alvand region are controlled both by natural geochemical processes and anthropogenic activities.     

The interaction of two asymmetric quasi-geostrophic vortex patches

ABSTRACT

Herein we study the general interaction of two vortex patches in a single-layer quasi-geostrophic shallow-water flow. Steadily-rotating equilibrium states are found over a wide parameter space spanning the Rossby deformation length, vortex area ratio, potential vorticity ratio, and gap between their innermost edges. A linear stability analysis is then used to identify the critical gap separating stable and unstable solutions, over the entire range of area and potential vorticity ratios, and for selected values of the Rossby deformation length. A representative set of marginally unstable equilibrium states are then slightly perturbed and evolved by an accurate contour dynamics numerical algorithm to understand the long-term fate of the instabilities. Not all instabilities lead to vortex merger; many in fact are characterised by weak filamentation and a small adjustment of the vortex shapes, without merger. Stronger instabilities lead to material being torn from one vortex and either wrapped around the other or reduced to ever thinning filamentary debris. A portion of the vortex may survive, or it may be completely strained out by the other.     

Hydrogeochemistry of Groundwater and Its Suitability for Drinking and Agricultural Use in Nahavand,Western Iran

Groundwater is the major source of drinking water in Nahavand city. However, the groundwater quality at the agricultural areas has been deteriorating in recent years. Ground water quality monitoring is a tool which provides important information for water management and sustainable development of the water resources in Nahavand. Hydrochemical investigations were carried out in an agricultural area in Nahavand, western Iran, to assess chemical composition of groundwater. In this study, 64 representative groundwater samples were collected from different irrigation wells and analyzed for pH, electrical conductivity, major ions, and nitrate. The results of the chemical analysis of the groundwater showed that concentrations of ions vary widely and the most prevalent water type is Ca–Mg–HCO₃, followed by other water types: Ca–HCO₃, Ca–Na–HCO₃, and Na–Cl, which is in relation with their interactions with the geological formations of the basin, dissolution of feldspars and chloride and bicarbonate minerals, and anthropogenic activities. Thirty-seven percent of the water samples showed nitrate (NO₃ ⁻) concentrations above the human affected value (13 mg L⁻¹). The phosphorous (P) concentration in groundwater was between 0.11 and 0.90 mg L⁻¹, with an average value of 0.30 mg L⁻¹, with all of the samples over 0.05 mg L⁻¹. The most dominant class C2-S1 (76.5%) was found in the studied area, indicating that sodicity is very low and salinity is medium, and that these waters are suitable for irrigation in almost all soils. Agronomic practices, such as cultivation, cropping, and irrigation water management may decrease the average NO₃ ⁻ concentration in water draining from the soil zone.     

Nitrate pollution of groundwater in Toyserkan,western Iran

A total of 95 groundwater samples were collected from Toyserkan, western Iran to assess the chemical composition and nitrate (NO₃ ⁻) status of groundwater. The most prevalent water type is Ca–HCO₃ followed by water types Ca–Mg–HCO₃. In comparison with the World Health Organization (WHO) drinking water guideline of 50 mg l⁻¹ for NO₃ ⁻, a total of nine wells (9.5%) showed higher concentrations. In 36% of samples (34) NO₃ ⁻ concentration was low (<20 mg l⁻¹), and in 53.7% of samples (51), in the range of 20–50 mg l⁻¹. The samples were classified into four groups based on NO₃ ⁻ and chloride (Cl⁻) concentrations. Of the samples, 40% were classified as group 4 and were relatively high in Cl⁻ and NO₃ ⁻ (Cl⁻ > 47 mg l⁻¹, NO₃ ⁻ > 27 mg l⁻¹). The high correlation between NO₃ ⁻ and Cl⁻ (r = 0.86, p < 0.01) is consistent with a manure source, resulting from the practice of adding salt to animal feed. Pollution of groundwaters appeared to be affected by the application of inorganic fertilizer at greater than agronomic rates, Cl-salt inputs, and irrigation practice.     

Effect of water quality on the leaching of potassium from sandy soil

When potassium (K⁺) fertilizers are applied to soil, K⁺ is subject to displacement through the soil profile. More generally, the application of K⁺ fertilizers to sandy soils with low clay content and small buffer capacity, in which K⁺ does not interact strongly with the soil matrix, results in localized increases in K⁺ concentration in the soil solution. Losses of K⁺ depend on the concentration of calcium (Ca²⁺) as a competing ion in the leaching water and the amount of water that passes through the soil. In this study, we examined the adsorption and movement of applied K⁺ in columns of sandy soil. Glass tubes, 4.8 cm in diameter and 40 cm in length, were packed with either native soil or Ca²⁺-saturated soil. The resulting 10-cm-long column of soil had a bulk density of 1.65 g cm⁻³. Native soil was leached with distilled water and CaCl₂ solutions of various concentrations. In the Ca²⁺-saturated soil, a pulse of K⁺ was leached with CaCl₂ solutions of various concentrations or distilled water. Increasing the CaCl₂ concentration from 3 to 15 mm resulted in earlier breakthrough, a higher peak concentration of K⁺, and greater amounts of leached K⁺. The breakthrough curve for K⁺, when leached with distilled water, showed very low concentrations and was more delayed than the other treatments. In Ca²⁺-saturated soil, the amount of K⁺ leached increased as Ca²⁺ concentration increased, with up to 54% of the added pulse K⁺ being removed from 10 pore volumes (Pv) (387 mm) of 15 mm CaCl₂. The presence of Ca²⁺ in irrigation water and soil minerals able to release Ca²⁺ is important in determining the amount of K⁺ leached from soils. Large amounts of K⁺ are leached from soils in areas where crops are irrigated with water that contains significant concentrations of Ca²⁺ and other cations.     

Investigation of periodic orbits in elliptical galaxies using the method of implicit functions

Existence of periodic orbits inside elliptical galaxies has been investigated. Necessary conditions for regular, small amplitude periodic motion around the center of galaxy have been derived using implicit functions and solved by approximating through Taylor's series. The solution procedure requires to obtain functions of partial derivatives of dependent variables with respect to initial conditions. Derivation of these functions can be accomplished through solving a set of ordinary differential equations by proper choices of associated initial conditions. The results obtained show complete agreement with those obtained through the application of Poincaré-Lindstedt's method.     

Major ion chemistry of groundwaters in the Bahar area, Hamadan, western Iran

Hydrochemical investigations were carried out in Bahar area, Hamadan, western Iran, to assess the chemical composition of groundwater. The area falls in a semi-arid type of climate. In this area, groundwater has been exploited over the past century mainly for irrigation and water supply. A total of 135 representative groundwater samples were collected from different wells to monitor the water chemistry of various ions. Chemical analysis of the groundwater shows that the mean concentration of the cations is of the order Ca²⁺>Mg ²⁺>Na⁺>K⁺, while that for anions is SO₄^2–>HCO₃^–>Cl^–>NO₃^–. Statistical analyses indicate positive correlation between the following pairs of parameters Cl^– and Mg ²⁺ (r=0.71), Cl^– and Na⁺ (r=0.76), HCO₃^– and Na⁺ (r=0.56), SO₄^2– and Mg²⁺ (r=0.76), SO₄^2– and Na⁺ (r=0.69). Water presents a large spatial variability of the chemical facies (Ca-HCO₃, Ca-SO₄, Mg-HCO₃, Mg-SO₄, Na-HCO₃) which is in relation to their interaction with the geological formations of the basin (carbonates, dolomite and various silicates) and evaporation. The hydrochemical types Ca-HCO₃ and Ca-SO₄ dominate the largest part of the studied area. The dissolution of halite, calcite, dolomite, and gypsum explains part of the contained Na ⁺, Ca²⁺, Mg²⁺, Cl^–, SO₄^2– and HCO₃^–, but other processes, such as cation exchange and weathering of aluminosilicates also contribute to the water composition.     

Salinization of groundwater in arid and semi-arid zones: an example from Tajarak,western Iran

Study of the groundwater samples from Tajarak area, western Iran, was carried out in order to assess their chemical compositions and suitability for agricultural purposes. All of the groundwaters are grouped into two categories: relatively low mineralized of Ca–HCO₃ and Na–HCO₃ types and high mineralized waters of Na–SO₄ and Na–Cl types. The chemical evolution of groundwater is primarily controlled by water–rock interactions mainly weathering of aluminosilicates, dissolution of carbonate minerals and cation exchange reactions. Calculated values of pCO₂ for the groundwater samples range from 2.34 × 10⁻⁴ to 1.07 × 10⁻¹ with a mean value of 1.41 × 10⁻² (atm), which is above the pCO₂ of the earth’s atmosphere (10^−3.5). The groundwater is oversaturated with respect to calcite, aragonite and dolomite and undersaturated with respect to gypsum, anhydrite and halite. According to the EC and SAR the most dominant classes (C3-S1, C4-S1 and C4-S2) were found. With respect to adjusted SAR (adj SAR), the sodium (Na⁺) content in 90% of water samples in group A is regarded as low and can be used for irrigation in almost all soils with little danger of the development of harmful levels of exchangeable Na⁺, while in 40 and 37% of water samples in group B the intensity of problem is moderate and high, respectively. Such water, when used for irrigation will lead to cation exchange and Na⁺ is adsorbed on clay minerals while calcium (Ca²⁺) and magnesium (Mg²⁺) are released to the liquid phase. The salinity hazard is regarded as medium to high and special management for salinity control is required. Thus, the water quality for irrigation is low, providing the necessary drainage to avoid the build-up of toxic salt concentrations.