Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, People's Republic of China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Environ Sci Pollut Res Int. 2019 Apr;26(11):10685-10694. doi: 10.1007/s11356-019-04515-5. Epub 2019 Feb 18.
Copper (Cu) and norfloxacin (Nor) are frequently used as feed additives for animal growth promotion, which results in a great probability of Cu and Nor coexisting in animal excretion and in soils. Sorption of Cu and Nor on soil organic matter (SOM) can markedly affect their environmental fate. Thus, humic acid (HA), a major fraction of SOM, was chosen to investigate the cosorption behaviors of Cu and Nor on HA under different solution chemistry conditions (pHs, ionic strengths, and foreign ions). The addition of Nor decreased the maximum adsorption capacity (Q) of Cu and an increasing effect was observed with increasing Nor concentration. Meanwhile, the addition of Cu also markedly inhibited the sorption of Nor on HA. The Q of Cu increased with increasing pH from 3.0 to 5.0 whether Nor was present or not, but more addition of Nor led to less increment in Q of Cu at the same pH. The Q of Nor was observed at pH 4.0 without Cu, but that was found at pH 5.0 and 3.0 with the addition of 20 and 100 mg L Cu, respectively. The sorption of Cu on HA decreased with increasing ionic strength and followed an order of NaHPO > NaSO ≈ NaNO at pH 5.0 whether Nor was present or not. Additionally, the higher valence cation had a stronger inhibition effect on Cu sorption. The competition between Cu and Nor for sorption on HA under the same conditions indicated that the coexistence of Cu and Nor may enhance the feasibility of their mobility and environmental risk.
铜 (Cu) 和诺氟沙星 (Nor) 常被用作促进动物生长的饲料添加剂，这使得 Cu 和 Nor 在动物排泄物和土壤中共同存在的可能性很大。Cu 和 Nor 在土壤有机质 (SOM) 上的吸附会显著影响它们的环境归宿。因此，选择腐殖酸 (HA) 作为 SOM 的主要成分，研究了在不同溶液化学条件 (pH 值、离子强度和共存离子) 下 Cu 和 Nor 在 HA 上的共吸附行为。Nor 的加入降低了 Cu 的最大吸附容量 (Q)，且随着 Nor 浓度的增加，这种抑制作用逐渐增强。同时，Cu 的加入也显著抑制了 Nor 在 HA 上的吸附。无论是否存在 Nor，Cu 的 Q 都随 pH 值从 3.0 增加到 5.0 而增加，但在相同 pH 值下，加入更多的 Nor 会导致 Cu 的 Q 增加量减少。在没有 Cu 的情况下，Nor 的 Q 在 pH 值为 4.0 时达到最大值，但在加入 20 和 100 mg/L Cu 时，分别在 pH 值为 5.0 和 3.0 时达到最大值。HA 对 Cu 的吸附随离子强度的增加而降低，在 pH 值为 5.0 时，无论是否存在 Nor，其顺序均为 NaHPO > NaSO ≈ NaNO。此外，高价阳离子对 Cu 吸附的抑制作用更强。在相同条件下，Cu 和 Nor 对 HA 吸附的竞争表明，Cu 和 Nor 的共存可能会增强它们的迁移性和环境风险的可行性。
