The Release of Endogenous Nitrogen and Phosphorus in the Danjiangkou Reservoir: A Double-Membrane Diffusion Model Analysis

Table 1

N and P contents in the overlying water at each sampling site and the original land use type.

Sampling sites	Background concentration in the overlying water (mg·L^-1)		Land use type	Longitude	Latitude
	NH4^+-N	PO4^3--P
DJK1	1.08	0.12	Farmland (corn field)	E 111°2846	N 33°0239
DJK2	0.59	0.08	Farmland	E 111°2711	N 33°0051
DJK3	0.56	0.06	Moving the topsoil to cultivate fertility	E 111°3047	N 32°5445
DJK4	0.35	0.02	Farmland and woodland	E 111°3427	N 32°4923
DJK5	0.53	0.02	Farmland	E 111°3850	N 32°4602