title: Role of divalent cations on deposition of Cryptosporidium parvum oocysts on natural organic matter surfaces.
abstract: A Radial Stagnation Point Flow (RSPF) system coupled with a microscope was used to study deposition of Cryptosporidium parvum oocysts on quartz and Suwannee River Natural Organic Matter (SRNOM)-coated surfaces in solutions with different Ca(2+) or Mg(2+) concentrations. Both untreated and proteinase K-treated oocysts were used. Deposition of oocysts on a SRNOM surface in Ca(2+) solution was higher than in Mg(2+) solution, even though the energy barriers calculated from Derjaguin-Landau-Verwey-Overbeek (DLVO) theory for Ca(2+) solution were higher than for Mg(2+) solution. On the other hand, the attachment of oocysts on a quartz surface was the same in both Ca(2+) and Mg(2+) solution and in qualitative agreement with the DLVO energy profiles. Inductive coupled plasma (ICP) was employed to measure the free divalent cation concentration in solutions containing oocysts. ICP data showed more Ca(2+) bound to oocyst surface than Mg(2+). Moreover, proteinase K treatment of oocysts led to a significant decrease in deposition rate due to less binding of Ca(2+) to the surface of the treated oocysts as shown by the ICP data. The deposition and ICP results suggested that inner-sphere complexation of Ca(2+) with carboxylate groups on both SRNOM and oocyst surfaces enhanced deposition of oocysts on a SRNOM surface.
authors.affiliation: Department of Civil and Environmental Engineering, The Center of Advanced Materials for the Purification of Water with Systems, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Dao
authors.initials: D
authors.lastname: Janjaroen
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Liu
authors.forename: Mark S
authors.initials: MS
authors.lastname: Kuhlenschmidt
authors.forename: Theresa B
authors.initials: TB
authors.lastname: Kuhlenschmidt
authors.forename: Thanh H
authors.initials: TH
authors.lastname: Nguyen
mesh_terms: D000268:Adhesiveness / Q000187:drug effects; D000818:Animals; D002413:Cations, Divalent / Q000494:pharmacology*; D016785:Cryptosporidium parvum / Q000166:cytology* / Q000187:drug effects*; D004586:Electrophoresis; D007087:Illinois; D007700:Kinetics; D033661:Oocysts / Q000187:drug effects*; D009930:Organic Chemicals / Q000494:pharmacology*; D011791:Quartz / Q000494:pharmacology; D045483:Rivers / Q000737:chemistry; D013499:Surface Properties / Q000187:drug effects; D013816:Thermodynamics
chemical_list: D002413:Cations, Divalent; D009930:Organic Chemicals; D011791:Quartz