Figure 4. Formation of mineral particles in soil water following addition of NaCl.

Soil water was prepared by mixing soil with double distilled water as described in Methods. The solution was centrifuged at 120000 g for 2 hrs at 4 °C and the supernatant was used as such (“Unfiltered”) or filtered through either 0.45-μm or 0.22-μm-pore membranes as indicated. Soil water was incubated at room temperature for the time indicated. Particle size was determined using DLS. In (B) NaCl (0.9%) was added to soil water prior to incubation. Black stars indicate statistically significant results vs. time 0 (p < 0.05). Notice that soil water alone did not lead to statistically significant particle formation (A), unless the solution was filtered and NaCl was added (B).