期刊名称：International Journal of Environmental Problems
印刷版ISSN：2410-9339
出版年度：2015
卷号：2 (2)
期号：6469
页码：136-153
语种：
出版社：Academic Publishing House Researcher
摘要：The thermodynamic model is proposed of heavy metals state in nosaline chernozem common carbonate of steppe zone of South Russia. The climate is continental semiarid, annual precipitation of 500–550 mm. The parent rocks are Carbonate and Carbonate-sulfate loess-like loam and clay. The chernozem common is thick, not solonized, humus 4.2%, physical clay 49.3%, clay 31.3%, CaCO3 0.14% (up to 3–6% at the depth of 1,3–1,6 m), pH = 7.8, exchangeable cations: Ca2+ – 342 mmol kg-1, Mg2+ – 27 mmol kg-1, Na+ – 6 mmol kg-1. The soil section in autoromorphic landscape. The soil solution water extract analyzed by standard methods. The state of ions in soil solution is influenced by ion association. The method of ion pairs in water solution is used. At high ionic force in soil solution are formed electrically neutral ion pairs СаСО3°; CaSO4°, MgCO3°, MgSO4°, charged ion pairs CaHCO3+, MgHCO3+, NaCO3-, NaSO4-, CaOH+, MgOH+. On the basis of of ion pair’s method the algorithms and computer programs were developed to calculate the real equilibrium forms of ions in the soil solution. The concentration of free and associated macro-ion’s forms were calculated by iteration procedure according to analytical ion concentration considering ion material balance, linear interpolation of equilibrium constants, Method of ionic pairs, laws of: initial concentration preservation, operating masses of equilibrium system. Concentration constants of ion pair dissociation were calculated following the law of operating masses. Were determined the quantity of macro-ion free form and coefficient of ion association γe as a ratio of ions free form to its analytical content . To interpret a behavior of heavy metal in soil solution two appraches are proposed: an additional equation for microelement to the mathematical model of macro-ions; an individual equation for microelement based on calculated quantities of macro-ions and their forms after the solution of mathematical model equations for macro-ions. The latter approach is reasonable because the quantity of microelement is for 100–1000 times less of quantity of macro-ions, and on this reason the contribution of microelement into the value of soil solution ionic strength is negligible. Besides, the latter approach help to reduce the number of equations in the system of equation, thus the calculation procedure is simpler, reliability of calculation is higher. To characterize Cd2+ Pb2+ ion’s binding was proposed the ratio of heavy metal ion’s association degree – the coefficient of association kas Me. To To characterize Sr2+ ion association an additional equation for Sr2+ was encluded to material balance equation system. The models were tested on the data of laboratory and field experiment in Krasndar krii, chernozem common, phosphogypsum utilization at dose of 10–40 t ha- in the soil layer of 20–50, 30–60 cm. According to the model, the molar fractions of associated calcium and magnesium are 2.0–6.1% (Ca2+) and 1.4–6.6% (Mg2+), carbonate and sulfate – 27.7–57.7%, 6.3–12.9%. The Cd2+ association coefficient is of 0.919–1.243. The association coefficient of Pb2+ is 25.193–31.207. At the phosphogipsum dose of 40 t/ha the molar fraction of the active concentration of free ions is: Cd2+ – 28.0–38.1%; Pb2+ – 3.66–5.06. The level of the Sr2+ ion binding into associates in original soil is 1.5%, after apply of phosphogypsum increases respectively to dose for 12.5; 15.0; 19.3%. The activity of the Sr2+ ion in the control variant is 83.3%, after apply of phosphogypsum it is of 60.4%; 55.6%; 48.4% respectively. The recycling of phosphogypsum in soil is ecology safe, concentration of heavy metals supplied to the soil with phosphogypsum are lower than Clark. Utilization of pollutant increases the soil fertility, ensures the environmental stability of soil and landscape, gives high biological production of soil and recreational result.
