USGS Fact Sheet FS-086-03

Environmental Biogeochemistry of Trace Metals

Basic knowledge practical application Aquatic terrestrial Hg As & Pb

What do you see What you have learned

Four chats before presentation Micphone use is encouraged Students submit 1 question per lecture

every Monday 3 questions/week Pooled and assigned by Tuesday and discussed on Wednesday We will discuss term paper during our first chat

ChatChat

TP due 3/28/10 (M)

Presentation starts (4-22 last day of class) 4/01/10 (W)

Your presentation is 35-45 minutes long 25-30 minute presentation 10-15 minute questions

Term paper (TP)Term paper (TP)

Homework 60% 4 Dr. Bonzongo 2 Dr. Ma

Term paper 30%

Presentation 10%

Grade policyGrade policy

Complexity of soils

Intensity and capacity concepts

Weathering

Florida soils

Soil reviewSoil review

Complexity of soils Young, I. M. and J. W. Crawford. 2004.

Interactions and self-organization in the soil-microbe complex. Science. 304:1634 Scottish Informatics Mathematics Biology &

Statistics Centre (SIMBIOS)

The most complicated biomaterial

Earth’s most important resource

Fig. 1. A&B: two soil thin sections (30 µm thick & 2 cm long) showing high degree of spatial variability within one undisturbed soil sample.

Pore space imageA/B-L: transmitted light A/B-R: cross polar light, distinguishing pores (white) from quartz grain (black)

Fig. 1C: High-resolution biological thin section (30 µm thick & 600 µm long).

Illumination under ultraviolet light reveals the location of fluorescently labeled microbes, (yellow)

Fig. 3. Distribution of O2 in structured soil vs. microbial respiration rate. Each box represents a 2D soil open to atmosphere with respiration rate decreasing from top to bottom.

Red: low O2

Yellow: atmospheric O2Light blue: soil matrix.

• Pore-scale spatial complexity and diversity of O2 environments

• Spatial proximity of high and low O2 concentration regimes.

• At low microbial respiration, regions of low O2 prevail

Respiration rate

Fig. 4. Self-organization in the soil-microbe complex.Open structure: Optimal configurations for O2 supply in a high activity regimeClosed structure: Protection from desiccation and predation in a low activity regime

Substrate arrives in soil microbial respiration rate ↑ more open aggregated state enhanced O2 supply (R)

Substrate used up microbial activity↓ soil structure collapses to closed state local O2 depletion (L)

Red: low O2, Yellow: atmospheric O2, and Light blue: soil matrix.

Complexity of soils Young, I. M. and J. W. Crawford. 2004.

Interactions and self-organization in the soil-microbe complex. Science. 304:1634 Scottish Informatics Mathematics Biology & Statistics

Centre (SIMBIOS) The most complicated biomaterial Earth’s most important resource Biological Diversity (Fig. 1)

Heterogeneity Diversity in Microenvironments (Fig. 3)

Variability to function: homogenized vs. structured soils Scale dependency: aggregate

System Dynamics (Fig. 4) Dynamic properties Linking physical and biological processes