andy baker university of birmingham [email protected]
DESCRIPTION
All DOC is not the same : DOC classified by functional properties and their environmental significance. Andy Baker University of Birmingham [email protected]. Battin et al. doi:10.1038/ngeo618. The microbial loop. Fenchel, doi:10.1016/j.jembe.2008.07.013 . - PowerPoint PPT PresentationTRANSCRIPT
All DOC is not the same: DOC classified by functional properties and their environmental significance
Andy BakerUniversity of [email protected]
The microbial loop. Fenchel, doi:10.1016/j.jembe.2008.07.013
Battin et al. doi:10.1038/ngeo618
(In predominantly natural systems)
Evidence of DOC processing within rivers. DOC becomes increasingly ‘young’ in 14C age and hydrophilic with distance from source. Rivers evade CO2. Photodegradation and biodegradation occurs, arguably of all DOM fractions.
Seasonal variations in riverine DOM character, typically a hydrophobic / aromatic ‘flush’. Differences in DOM character between catchments, depending on soil type, land cover and human impact.
Evidence of greater variability in DOC characteristics in headwaters and low order streams with ‘fresh’ DOM. Downstream DOC might be 14C ‘young’, but it is more homogenous and biogeochemically ‘aged’.
Anthropogenic inputs typically introduce hydrophilic, relatively colourless, DOC.
Clear links between DOC character and function. Aromatic DOC has greater chemical and ecological function (metal binding, contaminant binding, UV screening), and is easy to treat. Hydrophilic DOC difficult to remove during drinking water treatment.
Variable and high fluorescence / g C in bog waters
Less variable and less fluorescent / g C river waters
IHSS standards have atypically low fluorescence
Time /Processing
Peak
C fl
uore
scen
ce
250
500
750
1000
1250
1500
FE
FC
MC
ME
PGweir
Pweir
CBweir
Pea
k C
int/a
340
Mean and standard deviation colour/DOC
CBweir 10.7 (1.4)
Pweir 10.0 (1.2)
PGweir 8.4 (2.5)
ME 10.8 (3.7)
MC 9.5 (0.8)
FE 12.4 (3.7)
FC 11.5 (2.0)
‘fresh’ DOC is more coloured
Different DOC character between sub-catchments
‘fresh’ DOC is more fluorescentper unit absorbance
Photodegradation of lignin over two months
Sampling Period
8 (µ
g L-1
)
40
60
80
100
120
140
Sampling Period
8
(mg
(100
mg
OC
)-1)
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
Sampling Period
V (
mg
(100
mg
OC
)-1)
0.4
0.5
0.6
0.7
0.8
0.9Lignin phenol concentration and relationship with optical characteristics through the ‘wet’
Sampling Period
SR
0.7
0.8
0.9
1.0
1.1
Sampling Period
SU
VA
254
(L m
g C
-1 m
-1)
3.0
3.1
3.2
3.3
3.4
3.5
3.6
Sampling Period
Flu
ores
cenc
e In
dex
1.1
1.2
1.3
1.4
1.5
Summary
River microbial ecosystem processes DOC. Aromatic bonds in DOC relatively easier to break. DOC therefore less aromatic with residence /travel time. Easily measured ‘in-situ’ using UV absorbance or fluorescence.
River experience seasonal variations in riverine DOC character. Typically with ‘flush’ of relatively fresh (therefore aromatic) DOC. Groundwater rivers will have a groundwater hydrophilic DOC source.
Catchment mean DOC character depending on soil type, land cover and human impact.
Evidence of greater variability in DOC characteristics in headwaters and low order streams with ‘fresh’ DOM; variability decreases downstream as this is processed.
Anthropogenic inputs typically introduce relatively hydrophilic, colourless, DOC.
Aromatic DOC has greater chemical and ecological function (metal binding, contaminant binding, UV screening), and is easy to treat. Hydrophilic DOC difficult to remove during drinking water treatment.
0.01 0.1
1
10
1
1
1
1
22
2
2
23
3
3
3
3
4
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4
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10
1011
1111
11
1112
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13 1414
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2121
21
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2323
23
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2526
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40 40
4040
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4141
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43 43
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4444
444444
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46 46
4646
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484848
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DO
C (m
g/l)
UV Absorbance (410 nm) /cm