In regions with high livestock densities, the usage of antibiotics and metals for veterinary purposes or as growth promoters poses a risk in manured soils. We investigated to which degree the concentrations and depth distributions of Cu, Zn, Cr and As could be used as a tracer to discover contaminations with sulfonamides, tetracyclines and fluoroquinolones. Besides, we estimated the potential vertical translocation of antibiotics and compared the results to measured data. In the peri-urban region of Beijing, China, soil was sampled from agricultural fields and a dry riverbed contaminated by organic waste disposal. The antibiotic concentrations reached 110 μg kg?1 sulfamethazine, 111 μg kg?1 chlortetracycline and 62 μg kg?1 enrofloxacin in the topsoil of agricultural fields. Intriguingly, total concentrations of Cu, Zn, Cr and As were smaller than 65, 130, 36 and 10 mg kg?1 in surface soil, respectively, therewith fulfilling Chinese quality standards. Correlations between sulfamethazine concentrations and Cu or Zn suggest that in regions with high manure applications, one might use the frequently existing monitoring data for metals to identify potential pollution hotspots for antibiotics in topsoils. In the subsoils, we found sulfamethazine down to ≥2 m depth on agricultural sites and down to ≥4 m depth in the riverbed. As no translocation of metals was observed, subsoil antibiotic contamination could not be predicted from metal data. Nevertheless, sulfonamide stocks in the subsoil could be estimated with an accuracy of 35–200 % from fertilisation data and potential leaching rates. While this may not be sufficient for precise prediction of antibiotic exposure, it may very well be useful for the pre-identification of risk hotspots for subsequent in-depth assessment studies. 相似文献
The competitive sorption among Cu, Pb and Cr in ternary system on Na-montmorillonite at pH 3.5, 4.5 and 5.5 and at different heavy metal concentrations, and the effect of varying concentrations of Al, Fe, Ca and Mg on the sorption of heavy metals were studied. Competitive sorption of Cu, Pb and Cr in ternary system on montmorillonite followed the sequence of Cr ? Cu > Pb. Moreover, the competition was weakened by the increase of pH while was intensified by the increase of heavy metal concentration. The sorption of heavy metal on montmorillonite was inhibited by the presence of Ca and Mg, while Al and Fe showed different patterns in affecting heavy metal sorption. Aluminum and Fe generally inhibited the sorption of heavy metal when the pH and/or concentration of major elements were relatively low. However, promoting effects on heavy metal sorption by Al and Fe were found at relatively high pH and/or great concentration of major elements. The inhibition of major elements on heavy metal sorption generally followed the order of Al > Fe > Ca ? Mg, while Fe was more efficient than Al in promoting the sorption of heavy metals. These findings are of fundamental significance for evaluating the mobility of heavy metals in polluted environments. 相似文献
Humic acid (HA) derived from rice straw decomposed for 1 (HA-1), 3 (HA-3), 6 (HA-6) and 12 (HA-12) months was characterized by potentiometric titration and solid-state cross-polarization magic-angle spinning 13C nuclear magnetic resonance spectroscopy (CPMAS 13C NMR). The sorption of Cu on examined HA was investigated using a combination of batch sorption, isothermal titration calorimetry (ITC) and sequential desorption. Results showed that the functional group content and the humification degree of HA tended to increase with increasing decomposition time especially in the latter stage of examined decomposition period. Cu sorption on HA was a rapid process that occurred within the first 1 h and the sorption capacity increased from 245.4 mmol kg−1 on HA-1 to 294.6 mmol kg−1 on HA-12. The sorption of Cu was endothermic, spontaneous and the randomness was increased during Cu sorption. Sorbed Cu on examined HA can be hardly released by NH4Ac but nearly fully released by EDTA. Forming inner-sphere complexes was the main mechanism of Cu sorption on examined HA. This study could provide valuable information for a better understanding on the environmental impacts of the decomposition of organic waste.