Table 1.

Basic statistical characteristics of water quality testing data for the Xizhijiang River Basin.

Index	Parameters	Unit	Mean±sda	Min	Max	Standard	Exceeding standard rate (%)c
pHc		–	7.40 ± 0.40	6.84	8.62	6∼9	0
DOc	Dissolved oxygen	mg/L	8.35 ± 1.58	1.27	10.92	5	2.63
TN	Total nitrogen	mg/L	3.40 ± 3.05	0.25	10.60	1.00	94.74
NH3-N	Ammonia nitrogen	mg/L	0.63 ± 1.49	0.01	9.00	1.00	7.89
NO3−	Nitrate	mg/L	1.75 ± 1.88	0.10	6.60	10	0
NO2−	Nitrite	mg/L	0.06 ± 0.08	0.002	0.24	–	–
TC	Total carbon	mg/L	13.15 ± 5.31	6.31	30.15	–	–
DOC	Dissolved organic carbon	mg/L	9.67 ± 3.36	4.80	22.33	–	–
TPc	Total phosphorus	mg/L	1.38 ± 2.06	0.25	9.45	0.2	100
TDP	Total dissolved phosphorus	mg/L	0.53 ± 0.34	0.03	1.94	0.2	–
PO43-	Orthophosphate	mg/L	0.26 ± 0.29	0.02	1.45	–	–

b The "Environmental Quality Standards for Surface Water" Class III water standard limits.

^asd: standard deviation.

^cExceeding standards rate is the number of exceeded samples to the total number of samples.

^cFiltered indicators.