Cu and Zn concentrations in CaCl2-extracts of spiked and contaminated soils

The data set contain chemical analyses of element concentrations in CaCl2-extracts of spiked soils and contaminated soils. The data is a part of the published study: Combining a Stand-ardized Batch Test with the Biotic Ligand Model to Predict Copper and Zinc Ecotoxicity in Soils. One set of 22 uncontaminated soils (soil 1-22 see Table Data SND BLMprojekt.xls) were spiked with Cu2+ or Zn2+ salts. Another set of soils from four different sites, the validation soils (soil 23–26 see Table Data SND BLMprojekt.xls), were field-contaminated. All soils were extracted with 0.001 M CaCl2 in batch tests. Soil samples (soil 1-22) were preincubated for 1 week at 20 °C at a mois-ture content equivalent to 70% of field capacity (pF 2.0) before spiking. Uncontaminated soils (soil 23-26) were then spiked to 10, 30, 100, 300, 1000, and 3000 mg Cu  or Zn kg−1 dry soil, with CuCl2 or ZnCl2. Two soils were spiked with only five different concentrations because of limited amounts of available soil material, and two soils were spiked with an addi-tional dose of 6000 mg kg−1 dry weight. In total, 21 soils were spiked with Cu and 17 soils with Zn. Finally, deionized water was added to the spike solution to adjust the soil moisture content to pF 2.0. Spiked soils were subsequently equilibrated for 1 week at 20 °C before the batch test. Spike solutions were analyzed to confirm the added doses. Soil samples were equilibrated with 0.001 M CaCl2 at a liquid-to-solid ratio of 10 according to ISO 21268-2. Samples (5 g dry wt with 50 ml solution) were equilibrated for 24 ± 0.5 h in acid-washed polycarbonate vials at 10 rpm in an end-over-end shaker and then centrifuged at 4000 g for 15 min. The pH was measured on a portion of the eluate, and the rest was filtered through a 0.45-µm filter before analysis of Cu, Zn, Ca, Na, K, Mg, Fe, Al, and dissolved organic carbon (DOC). Samples for elemental anal-ysis were acidified with 5 µL ml−1 suprapure HNO3 before analysis with inductively coupled plasma (ICP) sector field mass spectrometry (Ele-ment1; Thermo Fisher) or ICP atomic emission spectroscopy (ICP optical emission spectrometer 725; Agilent). The DOC was determined by com-bustion and infrared detection (Nicolet Fourier transform infrared; Thermo Fisher) after acidification and removal of inorganic carbon. Chemical analyses were performed at laboratories accredited in accordance with the international standard ISO/IEC 17025 (ISO, 2005).