Spatial distribution of total halogenated organic compounds (TX), adsorbable organic halogens (AOX), and heavy metals in wetland soil irrigated with pulp and paper wastewater

Figures & data

Figure 1. Schematic diagram of the reed wetland.

Notes: Red arrow and line: irrigation ditches; black arrow and line: water stored gutters; and Pck: reed field that was not irrigated with pulping wastewater.

Figure 2. The concentration of Cu (a), Cd (b), Pb (c), and Zn (d) in the soil profile in 2014.

Figure 3. The concentration of Cu (a), Cd (b), Pb (c), and Zn (d) in the soil profile in 2015.

Figure 4. The concentration of TX (a) and AOX (b) in 2014 and TX (c) and AOX (d) in 2015 in the soil profile.

Notes: TX, total halogenated organic compounds; AOX, halogenated organic compounds adsorbable on activated carbon.

Table 1. Quality of the water samples from the wetland system (mg L⁻¹, except pH).

Site	pH	CODCr	SS	NH3-N	TP	Ca	Mg	Na	Cu	Pb	Cd	AOX
P0	8.01	1426	25.0	14.0	32.12	6.1	3.4	1043	0.10	0.05	0.03	8.6
P2	7.82	1184	20.3	10.5	27.23	4.5	2.5	861	0.08	0.03	0.02	6.3
P4	7.99	1056	15.7	7.6	23.45	3.6	1.3	721	0.07	0.02	0.01	5.4

Notes: AOX, halogenated organic compounds adsorbable on activated carbon; COD, chemical oxygen demand; SS, Suspended Solids; TP, Total Phosphorus content.

Figure 5. The pH (a, c) and EC (b, d) of soil samples at different depth in 2014 (a, b) and 2015 (c, d).

Figure 6. Total N (a), total P (b), CEC (c), and SOM (d) of the soil samples obtained in 2014.

Figure 7. Total N (a), total P (b), CEC (c), and SOM (d) of the soil samples obtained in 2015.

Figure 8. Principal component analysis (PCA) for the evaluation of distribution and concentrations of heavy metals, TX and AOX in 2014 (a) and 2015 (b).

Table 2. Correlation matrix of the factors in 2014 and 2015.

	Depth	pH	EC	N	P	CEC	SOM	Cu	Cd	Pb	Zn	AOX	TX
Depth	1.00
pH	0.42	1.00
EC	0.09	0.61	1.00
N	−0.67	−0.55	−0.35	1.00									2014
P	−0.43	−0.70	−0.68	0.71	1.00
CEC	−0.46	−0.30	−0.13	0.45	0.36	1.00
SOM	−0.69	−0.50	−0.13	0.81	0.64	0.58	1.00
Cu	−0.23	−0.58	−0.47	0.46	0.59	0.57	0.56	1.00
Cd	−0.28	−0.38	−0.25	0.44	0.49	0.36	0.39	0.36	1.00
Pb	−0.32	−0.58	−0.41	0.55	0.65	0.54	0.56	0.71	0.68	1.00
Zn	0.08	−0.48	−0.49	0.04	0.39	0.05	0.13	0.62	−0.13	0.35	1.00
AOX	−0.60	−0.72	−0.33	0.73	0.70	0.50	0.85	0.58	0.50	0.57	0.31	1.00
TX	−0.46	−0.76	−0.56	0.68	0.47	0.51	0.88	0.61	0.52	0.65	0.41	0.65	1.00
Depth	1.00
pH	0.54	1.00
EC	−0.07	−0.73	1.00
N	−0.77	−0.65	0.43	1.00
P	−0.72	−0.48	0.27	0.78	1.00								2015
CEC	−0.41	−0.39	0.28	0.33	0.26	1.00
SOM	−0.68	−0.48	0.26	0.59	0.63	0.65	1.00
Cu	−0.70	−0.34	0.19	0.68	0.62	0.46	0.81	1.00	0.60
Cd	−0.80	−0.50	0.13	0.70	0.57	0.68	0.59	0.60	1.00
Pb	−0.61	−0.48	0.21	0.49	0.32	0.67	0.52	0.85	0.51	1.00
Zn	−0.77	−0.42	0.13	0.66	0.56	0.48	0.57	0.79	0.63	0.61	1.00
AOX	−0.56	−0.29	0.16	0.58	0.62	0.56	0.81	0.58	0.78	0.48	0.46	1.00
TX	−0.31	−0.60	0.61	0.44	0.23	0.83	0.67	0.52	0.53	0.60	0.38	0.62	1.00