ANALYTICAL STUDY OF THE DISSOLUTION AND DIFFUSION OF ROCK PHOSPHORUS IN CHAOHU LAKE CATCHMENT, CHINA

The rock phosphorus is the phosphorus (P) released from phosphate rock (PR) to the environment, which may result in the eutrophication of water body. However, it has been ignored for a long time for the rare existence of P within the structure of primary rick minerals ^[1], and difficulties on the measurement of releasing rate under field condition. However, the increase content of P derived from rock in vegetation ^[2-3] indicated that the rock P should draw more attention from the public.

Method

In this study, accumulative contents of P were tested from the 12 PR samples in north shore of Chaohu Lake, and its variation with time was fitted by the one-dimensional advection-dispersion equation (1-D ADE). Fitted value of distance from the source (L), diffusion coefficient (D_L), and distribution coefficient (K_d) were obtained. Then these values were substituted to the release rate of the rock P and compared with the experimental data.

Discussion and Results

Good accordance (>98%) was obtained through the fitting between accumulative content of P and 1-D ADE, when the fitted value of L, D_L, and K_d ranges between 0.16-0.27 cm, 5.42-7.67*10^-8 cm²/s, and 3.79-9.11 L/kg, respectively. Then the correctness of them was verified by high correlation between experimental data and equation results of P releasing rate for most of the samples, with exception of No. 9 and No. 12. The low correlation coefficient of No. 9 and No. 12 was most probably due to the small scale of dispersivity of the experiment(Grants: No. 2009HGCX0233; No. 2008ZX07103-003-01)

[1] Walker et al. (1976) J. Geoderma. 15(1):1-19.[2] Bern et al. (2005) J. Ecology. 86(3):626-632.[3] Porder et al. (2005) J. Oecologia. 142(3):440-449.