Vertical distribution and release characteristics of nitrogen fractions in sediments in the estuaries of Dianchi Lake, China

Figures & data

Figure 1. The geographic location of the sampling sites.

Table 1. Sampling location and the overlying water parameters in Dianchi Lake.

Sample site	Position	Water depth (m)	pH	DO (mg·L^−1)	TP (mg-P·L^−1)	TN (mg-N·L^−1)	TDN (mg-N·L^−1)
A	24°57′10.99″N 102°40′53.76″E	3.0	7.54	6.23	0.18	1.81	1.62
B	24°49′40.72″N 102°45′31.68″E	2.5	7.99	6.11	0.12	1.78	1.48
C	24°46′51.97″N 102°43′51.96″E	3.0	8.10	5.85	0.15	1.70	1.52
D	24°44′13.07″N 102°36′43.56″E	3.0	7.52	5.27	0.21	1.49	1.32
E	24°48′40.22″N 102°39′45.00″E	3.0	7.88	4.88	0.26	1.70	1.52

Figure 2. Vertical variations of IEF-N, CF-N, IMOF-N, OSF-N, TN and C/N in core sediments.

Figure 3. The relative contribution of different N fractions to TN in core sediments.

Table 2. Pearson inter-correlation coefficients between the N fractions and the Pearson correlation coefficients between the N fractions and sediment properties in superficial core sediments (n = 15)

	IEF-N	CF-N	IMOF-N	OSF-N	TT-N	NT-N	TOC	Clay	Silt	Sand	C/N	SiO2 %	TFe2O3 + MnO	Fe2O3 + MnO + Al2O3	CaO + MgO
IEF-N	1.00						0.83**	0.77**	0.72**	−0.79**	0.31	−0.91**	0.17	0.17	0.41
CF-N	0.30	1.00					0.28	0.22	0.58*	−0.33	0.53*	−0.19	−0.26	−0.10	0.18
IMOF-N	0.91**	0.43	1.00				0.92**	0.89**	0.91**	−0.93**	0.58*	−0.92**	0.39	0.43	0.45
OSF-N	0.81**	0.45	0.83**	1.00			0.63*	0.62*	0.83**	−0.70**	0.24	−0.87**	0.12	0.19	0.41
TT-N	0.88**	0.56*	0.92**	0.97**	1.00		0.76**	0.73**	0.90**	−0.80**	0.41	−0.89**	0.17	0.25	0.44
NT-N	0.34	−0.62*	0.24	−0.12	−0.06	1.00	0.47	0.47	−0.03	−0.35	0.07	−0.36	0.57*	0.41	0.20
TN	0.92**	0.04	0.89**	0.69**	0.76**	0.61*	0.91**	0.88**	0.69**	−0.87**	0.38	−0.94	0.51	0.47	0.47

^* p < 0.05

^** p < 0.01.

Table 3. Pearson inter-correlation coefficients between the N fractions and the Pearson correlation coefficients between the N fractions and sediment properties in deeper core sediments (n = 25)

	IEF-N	CF-N	IMOF-N	OSF-N	TT-N	NT-N	TOC	Clay	Silt	Sand	C/N	SiO2 %	TFe2O3 + MnO	TFe2O3 + MnO + Al2O3	CaO + MgO
IEF-N	1.00						0.81**	0.68**	0.67**	−0.71**	−0.04	−0.83**	0.22	0.41*	0.08
CF-N	0.33	1.00					0.07	0.14	0.03	−0.12	−0.26	−0.23	−0.38	−0.14	0.23
IMOF-N	0.89**	0.29	1.00				0.87**	0.80**	0.75**	−0.83**	0.08	−0.74**	0.50*	0.67**	0.41*
OSF-N	0.76**	0.33	0.69**	1.00			0.46*	0.38	0.64**	−0.46*	−0.51	−0.89**	−0.07	0.11	0.12
TT-N	0.86**	0.47*	0.83**	0.96**	1.00		0.60**	0.53**	0.68**	−0.59**	−0.37	−0.89**	0.04	0.25	0.23
NT-N	0.71**	0.09	0.74**	0.44*	0.55**	1.00	0.81**	0.75**	0.64**	−0.76**	0.00	−0.71**	0.43*	0.55**	0.23
TN	0.89**	0.33	0.89**	0.81**	0.89**	0.87**	0.79**	0.72**	0.75**	−0.77**	−0.22	−0.91**	0.26	0.45*	0.26

^* p < 0.05

^** p < 0.01.

Figure 4. The contribution of the N released from different N fractions to total released N in core sediments.

Figure 5. The relationship between the N released of different N fractions and TN concentrations in core sediments.