## 3 Results and Discussion
### Biogenic Components  
#### 3.3.1 Effect of Temperature at Low Initial Concentrations  
Change of the equilibrium sorption capacity of reactive materials with regard to ammonium ions and phosphates in the temperature range from 3 \({}^{\circ}\)C to 30 \({}^{\circ}\)C with empirical fits are presented in Figure 7. Results of tests conducted at 40 \({}^{\circ}\)C were not presented for biogenic components because the differences in the measured equilibrium concentrations for the three replicates exceeded 10%. At initial concentrations of contaminants at 10 mg/L NH\({}_{4}\)-N and PO\({}_{4}\)-P, no significant influence of temperature on the intensity of biogenic components removal was observed. The sorption capacity of the analyzed materials in relation to ammonium ions increased with temperature change from 3 \({}^{\circ}\)C to 22 \({}^{\circ}\)C. However, the difference between total amounts of ammonium ions removed by the materials at 3 \({}^{\circ}\)C and 22 \({}^{\circ}\)C was not large, and varied from 0.038 mg/g for halloysite to 0.174 mg/g for diatomic in the studied temperature range. Further temperature increase caused higher intensity of contaminant removal on limestone sand, whereas a decrease of NH\({}_{4}\)-N removal was observed in the case of the remaining materials. However, taking into account practical significance, such variability will not have substantial impact on the degree of stormwater treatment. All terms of the polynomial functions turned out to be statistically significant for all materials with the exception of functions describing removal of ammonium ions on limestone sand. For this material, a description of the observations by a polynomial equation did not cause an increase of the determination coefficient value; therefore, Figure 7 shows a linear relationship. Additionally, the efficiencies of diatomic, halloysite, limestone sand and activated carbon to remove NH\({}_{4}\)-N ions were similar; only zeolite was characterized by a higher sorption capacity in comparison to the remaining materials. In the case of phosphate ion removal on all analyzed materials, there was a statistically significant (at \(p\) < 0.05) positive correlation between temperature and the dependent variable, i.e., sorption capacity (Table 3). However, similar to the case of ammonium ions, the changes of the equilibrium sorption capacity were insignificant, in the range from 0.019 mg/g for limestone sand to 0.299 mg/gfor halloysite. It should be emphasized that for these materials temperature increase above room levels was linked with a decrease of \(Q_{e}\). These relationships were described with a polynomial function and the analysis of polynomial regression showed statistical significance of all three terms of the equation for all materials. The material that best removed phosphates from water solutions was activated carbon, followed by halloysite and diatomite, whereas phosphates were least removed by limestone sand and zeolite. However, negative correlations between the sorption capacity of the applied materials and temperature increase have been documented in the literature, e.g., for some natural zeolites [61; 62] and halloysite [63]. A relationship similar to that presented herein was observed by [PERSON] et al. [64] for halloysite from a Chinese reservoir; in those studies, the sorption capacity increased with rising temperature. In turn, [PERSON] et al. [34] observed that the removal efficiency of the ammonium ion increased with rising temperature at temperatures below 25 \({}^{\circ}\)C, and further temperature increase caused decrease in the efficiency of contamination removal. These authors have explained this phenomenon by the low rate of chemical adsorption, which increased with temperature rise to room temperature. However, in the case of exothermic processes, further temperature increase causes larger desorption of contaminants.