Evaluation of the Single Dilute (0.43 M) Nitric Acid Extraction to Determine Geochemically Reactive Elements in Soil.
Recently a dilute nitric acid extraction (0.43 M) was adopted by ISO (ISO-17586:2016) as standard for extraction of geochemically reactive elements in soil and soil like materials. Here we evaluate the performance of this extraction for a wide range of elements by mechanistic geochemical modeling. Model predictions indicate that the extraction recovers the reactive concentration quantitatively (>90%). However, at low ratios of element to reactive surfaces the extraction underestimates reactive Cu, Cr, As, and Mo, that is, elements with a particularly high affinity for organic matter or oxides. The 0.43 M HNO3together with more dilute and concentrated acid extractions were evaluated by comparing model-predicted and measured dissolved concentrations in CaCl2soil extracts, using the different extractions as alternative model-input. Mean errors of the predictions based on 0.43 M HNO3are generally within a factor three, while Mo is underestimated and Co, Ni and Zn in soils with pH > 6 are overestimated, for which possible causes are discussed. Model predictions using 0.43 M HNO3are superior to those using 0.1 M HNO3or Aqua Regia that under- and overestimate the reactive element contents, respectively. Low concentrations of oxyanions in our data set and structural underestimation of their reactive concentrations warrant further investigation.
Department Soil Quality, Wageningen University and Research , Wageningen, The Netherlands.|CNRS, LIEC, UMR7360, 15 Avenue du Charmois, Vandoeuvre-lès-Nancy F-54501, France.|Université de Lorraine , LIEC, UMR7360, 15 Avenue du Charmois, Vandoeuvre-lès-Nancy, F-54501, France.
Jan E
0000-0002-3227-4052
JE
Groenenberg
Environmental Research (Alterra), Wageningen University and Research , Wageningen, The Netherlands.
Paul F A M
PF
Römkens
Energy Research Centre of The Netherlands, Petten, The Netherlands.
André Van
AV
Zomeren
Centre for Environmental and Marine Studies (CESAM)/Departamento de Química, Universidade de Aveiro , Aveiro, Portugal.
Sonia M
SM
Rodrigues
Department Soil Quality, Wageningen University and Research , Wageningen, The Netherlands.
Rob N J
RN
Comans
D019216:Metals, Heavy; D017942:Nitric Acid; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants
D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants; D017942:Nitric Acid