## 5 Conclusions  
This study performed laboratory wind tunnel and penetrometer tests to investigate the wind erosion and penetration resistance of biopolymer-treated soil samples treated with different biopolymer types, concentrations (wt%) and application rates (L/m\({}^{2}\)) on two different mine soils. The following conclusions can be drawn based on the results. 1. In the first laboratory trial, the wind-induced soil losses of medium-grained sand ranged from 1.09 to 423.9 g/m\({}^{2}\) (C = 2645.4 g/m\({}^{2}\)) and from 0.3 to 225.5 g/m\({}^{2}\) (C = 26,177.4 g/m\({}^{2}\)) for fine-grained silica sand, showing that all the treatments significantly enhanced the wind erosion resistance relative to that of the control. Increasing the concentration reduced the soil loss until it reached a plateau concentration, and the protein treatments achieved similar wind erosion resistances as those of the polysaccharides, but they required higher concentrations. 2. In a second laboratory trial, biopolymers were applied at their respective plateau concentration and different application rates. For medium-grained sand, the soil loss ranged from 0.86 to 23.19 g/m\({}^{2}\) (C = 2645.4 g/m\({}^{2}\)), and for fine-grained silica sand, it ranged from 0.62 to 10.67 g/m\({}^{2}\) (C = 26,177.4 g/m\({}^{2}\)), showing that all the treatments achieved a very high dust control effectiveness regardless of the tested application rate. The reason for this is that application at the plateau concentration resulted in a high wind erosion resistance at all tested application rates. 3. The results of the pocket penetrometer tests ranged from 0.98 to 10.95 N (C \(<\) 0.5 N) for medium-grained sand and from 0.5 to 3.76 N (C \(<\) 0.5 N) for fine-grained silica sand. Thereby, the crust strength was significantly affected by the biopolymer type (\(p<\) 0.001) and increased significantly at higher concentrations (\(p<\) 0.001) and application rates (\(p<\) 0.001). In addition, the Spearman rank correlation revealed a moderate-to-strong negative correlation between soil loss (g/m\({}^{2}\)) and penetration resistance (N) for fine-grained silica (\(r(106)=-0.51\), \(p<\) 0.001) and medium-grained sand (\(r(106)=-0.81\), \(p<\) 0.001). This implies that the pocket penetrometer can serve as an indirect indicator for evaluating the performance of potential dust suppressants. This study demonstrated that the tested polysaccharides and proteins have the potential to be applied as dust suppressants and facilitated the selection of application parameters suitable for first field trials. Conceptualization, J.L.S. and J.F. ; methodology, J.L.S. and J.F. ; formal analysis, J.L.S. ; investigation, J.L.S. ; data curation, J.L.S. ; writing--original draft preparation, J.L.S. ; writing--review and editing, J.L.S., B.G.L. and J.F. ; visualization, J.L.S. ; project administration, J.L.S. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Data Availability Statement:Data supporting the findings of this study will be made available from the corresponding author upon reasonable request. We thank the Rheinische Baustoffwerke GmbH and the Quarzwerke Frechen AG for providing the mine soils used in this study. We thank [PERSON] and [PERSON] for assisting in characterising the soil samples and [PERSON] for designing and printing the 3D-printed splash guard. Last, the authors would like to thank the anonymous reviewers for their helpful comments and suggestions, which improved the manuscript. The authors declare no conflict of interest.