Soil Morphology and Chemistry

Transcription

1 Soil Morphology and Chemistry

2 NDWRCDP Disclaimer This work was supported by the National Decentralized Water Resources Capacity Development Project (NDWRCDP) with funding provided by the U.S. Environmental Protection Agency through a Cooperative Agreement (EPA No. CR ) 0) with Washington University in St. Louis. These materials have not been reviewed by the U.S. Environmental Protection Agency. These materials have been reviewed by representatives of the NDWRCDP. The contents of these materials do not necessarily reflect the views and policies of the NDWRCDP, Washington University, or the U.S. Environmental Protection Agency, nor does the mention of trade names or commercial cial products constitute their endorsement or recommendation for use. 3/19/2005 Soil and Site. Lindbo et al. DRAFT 2

3 CIDWT/University Disclaimer These materials are the collective effort of individuals from academic, regulatory, and private sectors of the onsite/decentralized wastewater industry. These materials have been peer-reviewed reviewed and represent the current state of knowledge/science in this field. They were developed through a series of writing and review meetings with the goal of formulating a consensus on the materials presented. These materials do not necessarily reflect the views and policies of North Carolina State University, and/or the Consortium of Institutes for Decentralized Wastewater Treatment (CIDWT). The mention of trade names or commercial products does not constitute an endorsement or recommendation for use from these individuals or entities, nor does it constitute criticism for similar ones not mentioned. 3/19/2005 Soil and Site. Lindbo et al. DRAFT 3

4 Citation -Lindbo, D.L., M. H. Stolt, R. Miles, and D. L. Mokma Field Description of Soils: Soil Morphology and Chemistry Power Point Presentation. in (D.L. Lindbo and N. E. Deal eds.) Model Decentralized Wastewater Practitioner Curriculum. National Decentralized Water Resources Capacity Development Project. North Carolina State University, Raleigh, NC. 3/19/2005 Soil and Site. Lindbo et al. DRAFT 4

5 Why does the soil look like this? 3/19/2005 Soil and Site. Lindbo et al. DRAFT 5

6 Are the same processes going on in each of these soils today? 3/19/2005 Soil and Site. Lindbo et al. DRAFT 6

7 What are we trying to determine when investigating soil morphology? 3/19/2005 Soil and Site. Lindbo et al. DRAFT 7

8 Soil Chemistry and Morphology Oxidation-Reduction (redox) reactions and principles Podzolization Cementation 3/19/2005 Soil and Site. Lindbo et al. DRAFT 8

9 Redox Reactions Most common reactions in soils Redox reactions control Soil color Organic matter contents Wastewater treatment Soil water chemistry O 2 NO 3 Fe SO 4 3/19/2005 Soil and Site. Lindbo et al. DRAFT 9

10 Oxidation-Reduction Principles Electrons taken from one substance and given to another Electrons come from OM as it decomposes Oxidation = the production (loss) of electrons Reduction = the consumption (gain) of electrons 3/19/2005 Soil and Site. Lindbo et al. DRAFT 10

11 Redox Principles H + e - e - 3/19/2005 Soil and Site. Lindbo et al. DRAFT 11

12 LEO says GER Loss of Electrons is Oxidation Gain of Electrons is Reduction

13 Order of redox reactions Reactions occur in a specific order based on the amount of energy released. Aerobic respiration (O 2 reduction) Anaerobic Denitrification Fe reduction Sulfate reduction 3/19/2005 Soil and Site. Lindbo et al. DRAFT 13

14 Aerobic soil reactions If air (O 2 ) is in the soil the soil is Aerobic 4e - + O 2 + 4H + 2H 2 O If all O 2 is removed soil becomes anaerobic 3/19/2005 Soil and Site. Lindbo et al. DRAFT 14

15 Respiration CO 2 O 2 H 2 O 3/19/2005 Soil and Site. Lindbo et al. DRAFT 15

16 Anaerobic soil reactions Denitrification 10e H + + 2NO 3 N 2 + 6H 2 O Iron (Manganese) Reduction 4e - + 6H + + 2Fe 3 O 2 2Fe(II) + 3H 2 O Sulfate Reduction 8e H + + SO 4 H 2 S + 4H 2 O 3/19/2005 Soil and Site. Lindbo et al. DRAFT 16

17 Denitrification N 2 gas NO 3 3/19/2005 Soil and Site. Lindbo et al. DRAFT 17

18 Iron Reduction Fe 2+ Fe 3+ 3/19/2005 Soil and Site. Lindbo et al. DRAFT 18

19 Redox Transformations Coating of Fe 2 O 3 Remove Fe Brown Soil Fe 3+ Fe 2+ Gray Soil 2e - + 6H + + Fe 2 O 3 2Fe(II) + 3H 2 O 3/19/2005 Soil and Site. Lindbo et al. DRAFT 19

20 Sulfate Reduction CO 2 SO 4 H 2 S 3/19/2005 Soil and Site. Lindbo et al. DRAFT 20

21 What does it mean to have a soil that is Saturated? Anaerobic? Reduced? Are these the same thing? What was the intent of onsite wastewater regulation? 3/19/2005 Soil and Site. Lindbo et al. DRAFT 21

22 Redoximorphic Features Formed by changes in redox conditions in seasonally saturated soil Reduction and oxidation of C, Fe, Mn, and S compounds Translocation of C, Fe, Mn, and S compounds 3/19/2005 Soil and Site. Lindbo et al. DRAFT 22

23 In order to form features: must have anaerobic conditions (reduced and saturated) must have Fe and/or Mn (electron acceptor) must have microbes (bugs( bugs) must have carbon (food for the bugs) 3/19/2005 Soil and Site. Lindbo et al. DRAFT 23

24 Features form near organic matter O 2 O 2 O 2 O 2 O 2 3/19/2005 Soil and Site. Lindbo et al. DRAFT 24

25 Aerobic or Anaerobic? 3/19/2005 Soil and Site. Lindbo et al. DRAFT 25

26 Aerobic or Anaerobic? 3/19/2005 Soil and Site. Lindbo et al. DRAFT 26

27 Aerobic or Anaerobic? 3/19/2005 Soil and Site. Lindbo et al. DRAFT 27

28 What does it mean to have a soil Saturated? Anaerobic? Reduced? that is Are these the same thing? Do the rules/regulations see them the same? 3/19/2005 Soil and Site. Lindbo et al. DRAFT 28

29 So why do we care about redoximorphic features?

30 Use these to assess the saturation and aeration status of the soil These features indicate reduction has occurred Influence land use decisions 3/19/2005 Soil and Site. Lindbo et al. DRAFT 30

31 Effects of Reduction on Color Gray colors usually mean no iron on particle surface Sometimes gray colors mean there was never any iron present High (rust) and low (gray) colors are evidence of soil wetness (redox reactions) Soils with gray colors produced by reduction often have some Fe concentrations within the profile 3/19/2005 Soil and Site. Lindbo et al. DRAFT 31

32 Interpretations of Color Gray depletions are where reduction has occurred Low chroma colors No Fe on surfaces Soil may have been reduced for significant periods 3/19/2005 Soil and Site. Lindbo et al. DRAFT 32

33 Interpretations of Color (cont.) Mottles (redoximorphic features) lower in chroma than the matrix suggest: Soils may have been reduced for short periods Soils may be saturated for significant periods, particularly if soil organic matter contents are <1%, and are on slopes 3/19/2005 Soil and Site. Lindbo et al. DRAFT 33

34 Features formed by reducing reactions Element Indicator O2 Organic Matter Accumulation Fe(III) S Redoximorphic Features Rotten egg odor 3/19/2005 Soil and Site. Lindbo et al. DRAFT 34

35 Carbon-Based Features OM builds up when soils are waterlogged and reduced Decomposition is slower than Accumulation Low O 2 content 3/19/2005 Soil and Site. Lindbo et al. DRAFT 35

36 Carbon-Based Features Types of features Layer of organic material Layers of mineral soil material Colors 3/2 or darker Black coated grains Mucky mineral layers 3/19/2005 Soil and Site. Lindbo et al. DRAFT 36

37 Carbon-Based Features Permanent over short term Common features as C is widespread Must be used to identify reduction if Fe is absent 3/19/2005 Soil and Site. Lindbo et al. DRAFT 37

38 Organic Soil 3/19/2005 Soil and Site. Lindbo et al. DRAFT 38

39 Coated Grains 3/19/2005 Soil and Site. Lindbo et al. DRAFT 39

40 Fe-Based Features Features formed by the reduction, translocation, and oxidation of Fe/Mn oxides Types Redox concentrations (Fe masses, Fe pore linings) Redox depletions (Fe depletions) Reduced matrix 3/19/2005 Soil and Site. Lindbo et al. DRAFT 40

41 Redox concentrations (Fe masses, Fe pore linings)

42 Fe masses and Fe pore linings Pore lining on root channel Fe mass in matrix Pore lining on Ped surface Concretion Nodule 3/19/2005 Soil and Site. Lindbo et al. DRAFT 42

43 Fe masses 3/19/2005 Soil and Site. Lindbo et al. DRAFT 43

44 Fe pore linings 3/19/2005 Soil and Site. Lindbo et al. DRAFT 44

45 Redox depletions (Fe depletions)

46 Fe depletion on ped face Fe depletions Fe depletion in ped interior Fe depletion on pore 3/19/2005 Soil and Site. Lindbo et al. DRAFT 46

47 Fe depletion 3/19/2005 Soil and Site. Lindbo et al. DRAFT 47

48 Fe depletions 3/19/2005 Soil and Site. Lindbo et al. DRAFT 48

49 Reduced matrix

50 Reduced matrix 3/19/2005 Soil and Site. Lindbo et al. DRAFT 50

51 Reduced matrix 3/19/2005 Soil and Site. Lindbo et al. DRAFT 51

52 Using a dye to determine reduced matrix 3/19/2005 Soil and Site. Lindbo et al. DRAFT 52

53 Fe-Based Features Widespread features Generally permanent Destroyed by reduction or mixing All need Fe to form 3/19/2005 Soil and Site. Lindbo et al. DRAFT 53

54 S-Based Features H 2 S gas production Conclusive indicator of reduction, but rarely identified in the field usually misidentified 3/19/2005 Soil and Site. Lindbo et al. DRAFT 54

55 Rotten egg smell 3/19/2005 Soil and Site. Lindbo et al. DRAFT 55

56 Rotting vegetation 3/19/2005 Soil and Site. Lindbo et al. DRAFT 56

57 Podzolization Generally in sandy soils Eluviation of OM, Fe, and Al by organic acids Illuviation as organic-oxide oxide compounds May or may not be related to groundwater 3/19/2005 Soil and Site. Lindbo et al. DRAFT 57

58 Incipient formation 3/19/2005 Soil and Site. Lindbo et al. DRAFT 58

59 Well-drained 3/19/2005 Soil and Site. Lindbo et al. DRAFT 59

60 Poorly-drained 3/19/2005 Soil and Site. Lindbo et al. DRAFT 60

61 Tree throw effects 3/19/2005 Soil and Site. Lindbo et al. DRAFT 61

62 Poorly-drained with ortstien 3/19/2005 Soil and Site. Lindbo et al. DRAFT 62

63 Cementation Illuviation and precipitation of cementing agents Common cementing agents: Fe-oxides Mn-oxides CaCO 3 Al-oxides Organic material 3/19/2005 Soil and Site. Lindbo et al. DRAFT 63

64 Fe and Mn cementation 3/19/2005 Soil and Site. Lindbo et al. DRAFT 64

65 Organic/Fe/Al cementation 3/19/2005 Soil and Site. Lindbo et al. DRAFT 65

66 Multiple layers 3/19/2005 Soil and Site. Lindbo et al. DRAFT 66