Table 1.

Physical and chemical properties of the water column in the Dongjiang River.

Environmental factorsa	Sampling sites
	HYb	GZb	HZb	QTb	HYWc	GZWc	HZWc	QTWc
Time	Mar.	Mar.	Mar.	Mar.	Sep.	Sep.	Sep.	Sep.
Longitude (°E)	114.701	114.689	114.408	114.104	114.701	114.689	114.408	114.104
Latitude (°N)	23.730	23.518	23.098	23.051	23.730	23.518	23.098	23.051
Distance (kilometer)d	-	28.24	93.98	42.29	-	28.24	93.98	42.29
PHYSICAL
pH	6.50	6.67	6.58	7.20	7.31	7.39	6.88	7.02
DO (mg/L)	9.78	8.90	7.20	7.80	7.45	8.26	4.88	3.96
Turbidity (NTU)	3.20	8.60	18.50	25.80	4.13	14.93	16.33	27.63
Tem (°C)	16.1	15.9	17.3	17.5	23.5	21.6	25.7	26.4
TSS (mg/L)	15.0	25.0	28.3	75.0	14.5	20.0	24.4	26.7
NITROGEN
${\text{NH}}_4^{+}$-N (mg/L)	0.18	0.27	2.19	1.13	0.25	0.19	1.04	0.31
${\text{NO}}_2^{-}$-N (mg/L)	0.011	0.029	0.065	0.080	0.008	0.033	0.188	0.053
${\text{NO}}_3^{-}$-N (mg/L)	0.92	1.32	1.42	1.38	0.76	1.12	1.72	2.64
DIN (mg/L)	1.117	1.622	3.675	2.588	1.020	1.338	2.960	3.001
TN (mg/L)	5.15	6.47	9.78	9.19	1.49	1.69	3.14	3.15
CARBON
TIC (mg/L)	7.30	7.38	8.78	8.67	4.81	4.96	6.22	5.93
TOC (mg/L)	4.70	4.86	5.80	5.39	2.08	1.95	2.83	2.56
TC (mg/L)	12.00	12.24	14.58	14.06	6.89	6.91	9.05	8.49
PI (mg/L)	3.86	3.29	3.63	3.13	2.17	1.59	3.34	1.99

^aDO, dissolved oxygen; TSS, total suspended solids; TIC, total inorganic carbon; TOC, total organic carbon; TC, total carbon; TN, total nitrogen; PI, permanganate index.

^bWater samples in March; XF, Xinfeng; HY, Heyuan; GZ, Guzhu; HZ, Huizhou; QT, Qiaotou.

^cWater samples in September; XFW, Xinfeng; HYW, Heyuan; GZW, Guzhu; HZW, Huizhou; QTW, Qiaotou.

^dDistance, the distance between adjacent sampling sites.