@misc{DimitrovaRepmannFreese, author = {Dimitrova, Tsvetelina and Repmann, Frank and Freese, Dirk}, title = {Degradation of ferrocyanide by natural isolated bacteria}, series = {International Journal of Phytoremediation}, volume = {22}, journal = {International Journal of Phytoremediation}, number = {1}, issn = {1549-7879}, doi = {10.1080/15226514.2019.1633996}, pages = {20 -- 28}, abstract = {This study aims at investigating the iron cyanide (CN) degradation potential of two natural bacterial isolates with the purpose of their application in iron CN phytoremediation. The strains were isolated from contaminated soil and incubated over 4 months with 50mg L⁻¹CN (as ferrocyanide) as the sole iron and nitrogen source. Unlike previous reports, the study provides control for bacterial growth, biotic and abiotic CN losses. Bacterial growth, CN, ammonium, and nitrate concentrations were monitored regularly. Both strains grew less rapid with iron CN compared with the positive control. However, the growth was diauxic. The CN concentration in the media decreased with 20\% and 25\% respectively, while that in the sterile controls remained stable. Ammonium was detected in the media of both strains implying that a fraction of the initially applied ferrocyanide has been converted. The nitrogen lost from the system evened out with that in the cells at the end of the experiments. These results showed that the investigated strains were undoubtedly able to grow on iron CN as an alternative nitrogen source, but contrary to some previous findings, the iron CN utilization is much slower and takes place only after complete exhaustion of the cellular nitrogen reserves.}, language = {en} } @misc{GypserHirschSchleicheretal., author = {Gypser, Stella and Hirsch, Florian and Schleicher, Anja M. and Freese, Dirk}, title = {Impact of crystalline and amorphous iron- and aluminum hydroxides on mechanisms of phosphate adsorption and desorption}, series = {Journal of Environmental Sciences}, volume = {70}, journal = {Journal of Environmental Sciences}, doi = {10.1016/j.jes.2017.12.001}, pages = {175 -- 189}, language = {en} } @misc{DimitrovaRepmannRaabetal., author = {Dimitrova, Tsvetelina and Repmann, Frank and Raab, Thomas and Freese, Dirk}, title = {Uptake of ferrocyanide in willow and poplar trees in a long term greenhouse experiment}, series = {Ecotoxicology}, volume = {24}, journal = {Ecotoxicology}, number = {3}, issn = {1573-3017}, doi = {10.1007/s10646-014-1398-0}, pages = {510}, abstract = {Phytoremediation of sites contaminated with iron cyanides can be performed using poplar and willow trees. Poplar and willow trees were grown in potting substrate spiked with ferrocyanide concentrations of up to 2,000 mg kg-1 for 4 and 8 weeks respectively. Soil solution and leaf tissue of different age were sampled for total cyanide analysis every week. Chlorophyll content in the leaves was determined to quantify cyanide toxicity. Results showed that cyanide in the soil solution of spiked soils differed between treatments and on weekly basis and ranged from 0.5 to 1,200 mg l-1. The maximum cyanide content in willow and poplar leaves was 518 mg kg-1 fresh weight (FW) and 148 mg kg-1 FW respectively. Cyanide accumulated in the leaves increased linearly with increasing cyanide concentration in the soil solution. On the long term, significantly more cyanide was accumulated in old leaf tissue than in young tissue. Chlorophyll content in poplar decreased linearly with increasing cyanide in the soil solution and in leaf tissue, and over time. The inhibitory concentration (IC50) value for poplars after 4 weeks of exposure was 173 mg l-1 and for willow after 8 weeks of exposure—768 mg l-1. Results show that willows tolerate much more cyanide and over a longer period than poplars, making them very appropriate for remediating sites highly contaminated with iron cyanides.}, language = {en} }