Unique Organic Matter and Microbial Properties in the Rhizosphere of a Wetland Soil.
Wetlands attenuate the migration of many contaminants through a wide range of biogeochemical reactions. Recent research has shown that the rhizosphere, the zone near plant roots, in wetlands is especially effective at promoting contaminant attenuation. The objective of this study was to compare the soil organic matter (OM) composition and microbial communities of a rhizosphere soil (primarily an oxidized environment) to that of the bulk wetland soil (primarily a reduced environment). The rhizosphere had elevated C, N, Mn, and Fe concentrations and total bacteria, including Anaeromyxobacter, counts (as identified by qPCR). Furthermore, the rhizosphere contained several organic molecules that were not identified in the nonrhizosphere soil (54% of the >2200 ESI-FTICR-MS identified compounds). The rhizosphere OM molecules generally had (1) greater overall molecular weights, (2) less aromaticity, (3) more carboxylate and N-containing COO functional groups, and (4) a greater hydrophilic character. These latter two OM properties typically promote metal binding. This study showed for the first time that not only the amount but also the molecular characteristics of OM in the rhizosphere may in part be responsible for the enhanced immobilization of contaminants in wetlands. These finding have implications on the stewardship and long-term management of contaminated wetlands.
Savannah River National Laboratory , Aiken, South Carolina 29808, United States.
Daniel I
DI
Kaplan
Texas A&M University , Galveston, Texas 77553, United States.
Chen
C
Xu
Princeton University , Princeton, New Jersey 08540, United States.
Shan
S
Huang
Texas A&M University , Galveston, Texas 77553, United States.
Youmin
Y
Lin
Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory , Richland, Washington 99352, United States.
Nikola
N
Tolić
Idaho National Laboratory , Idaho Falls, Idaho 83415, United States.
Kristyn M
KM
Roscioli-Johnson
Texas A&M University , Galveston, Texas 77553, United States.
Peter H
PH
Santschi
Princeton University , Princeton, New Jersey 08540, United States.
Peter R
PR
Jaffé
D001419:Bacteria / Q000235:genetics; D008670:Metals / Q000032:analysis; D010084:Oxidation-Reduction; D058441:Rhizosphere; D012987:Soil / Q000737:chemistry; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis; D013022:South Carolina; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D014501:Uranium; D053833:Wetlands
D008670:Metals; D012987:Soil; D012989:Soil Pollutants; D014501:Uranium