生物炭和刺苦草联合修复水体铜污染

REMEDIATION OF COPPER-POLLUTED WATER USING BOTH BIOCHAR AND A SUBMERGED MACROPHYTE, VALLISNERIA SPINULOSA

生物炭和沉水植物对重金属铜(Cu)都有良好的吸附和富集效果,但关于生物炭对沉水植物生长的影响及二者共存对水体Cu污染的修复效果仍不明确。通过设置4个稻壳生物炭添加梯度(CK:0 g/L,T1:3 g/L,T2:6 g/L,T3:12 g/L),研究水体中ρ(Cu)为1 mg/L污染条件下,生物炭对刺苦草(Vallisneria spinulosa)生长和水质的影响。结果表明:1) T1、T2和T3组刺苦草富集的Cu含量相对于CK组分别降低41.01%、41.21%和67.86%,刺苦草叶片叶绿素含量分别提高9.45%、29.94%和53.83%,刺苦草地上部分高度分别增加21.38%、23.38%、5.08%;2)随着生物炭添加量的增加,水体溶解氧和氧化还原电位显著降低,pH和电导率显著增大,T1、T2和T3组水体Cu含量相比CK组分别降低-4.48%、12.58%和31.85%,水体NO^-_3-N分别下降19.53%、25.88%和38.11%,NH^+_4-N分别下降66.78%、72.04%和72.04%,但各处理组磷含量相对于CK组却显著增大。表明:水体施加稻壳生物炭可以降低刺苦草对Cu的富集量,从而缓解Cu对刺苦草的胁迫,生物炭与刺苦草联合对水体Cu的吸附效果优于单独使用刺苦草,但生物炭中磷的释放对水体会产生潜在风险。

Both biochar and submerged macrophytes have good adsorption and enrichment effects on heavy metal, e. g., copper ( Cu). However, effects of biochar on growth of submerged macrophytes and their combined remediation effect on Cu- polluted water are still not clear. In this study, four doses of rice husk biochar (CK: 0 g/L, T1 :3 g/L, T2:6 g/L, T3:12 g/ L) were set to study the effect of biochar on growth of Vallisneria spinulosa and water quality in water with Cu contents of 1 mg*L"1 , where Vallisneria spinulosa grew. The results showed that, 1) compared with CK group, the Cu contents concentrated in V. Spinulosa in Group T1, T2 and T3 decreased by 41.01% ,,41.21% and 67.86% respectively, the chlorophyll contents of V. Spinulosa increased by 9.45% , 29. 94% and 53. 83% respectively, and the height of over-ground part of V. Spinulosa increased by 21. 38% , 23. 38% and 5. 08% respectively; 2) as more biochar were added into the water, the dissolved oxygen and redox potential of the water decreased significantly, while the pH and conductivity increased significantly ; compared with CK group, the Cu contents in the water in Group T1, T2 and T3 decreased by - 4. 48% , 12. 58% and 31. 85% respectively, the nitrate nitrogen contents decreased by 19. 53% , 25. 88% and 38. 11% respectively, the ammonium nitrogen contents decreased by 66.78%, 72.04% and 72. 04% , respectively, but phosphorus contents_____increased significantly. Our study showed that adding rice husk biochar into water could reduce the concentration of Cu in V. spinulosa and ameliorate the Cu stress on V. spinulosa,and the effect of combined utilization of biochar and V. spinulosa was better than single use of V. spinulosa in terms of adsorption of Cu in water. However, the potential risk of phosphorus released into water by biochar should be noticed.