| What are the two stable isotopes of hydrogen making of the dD? | protium (1H) and deuterium (2H, D). -->deuterium has one proton, one neutron and one electron |
| dD is measured against? | SMOW (Standard Mean Ocean Water) and SLAP (Standard Light Antarctic Precipitation) |
| dD has a much larer range than d13C because? | because of the larger mass difference |
| Clouds are ... in deuterium | depleted (due to the evaporatio-precipitation balance and fractoination) |
| Rain is ... compared to the cloud | enriched (heavier will rain out first, leaving the cloud more depleted) |
| The more inland or the higher the altitude the more ..... your dD becomes | depleted |
| Bulk organic matter contains a lot of exchangeable hydrogen, hence we need to anaylse strongly (covalently) bound hydrogen. Where do we find these? | lipids |
| Largest step in hydrogen isotopic fractionation in organisms is by formation of .... and estimated to be ca. 171 per mill | NADPH - but internally there is more fractionation taking place, but it is hard for us to know which enxymes/pathways are responsible |
| If you make a lipid you will be .... in comparison to total biomass (with some exceptions!) | depleted |
| Hydrogen isotopic fractionation of lipids is depending on carbon/energy metabolism and can help us determine ..? | if it is a chemautotroph or photo(auto/hetero)troph |
| hydrogen isotopic fractionation in plants: Lipid classes have different hydrogen isotopic compositions (but differently from 13C), name the pattern | n-alkanoic acids least depleted, then sterol, then lastly phytols (compared to water!) -> compared to bulk: phytols least depleted and then n-alkanoic&sterols |
| Straight chain compounds are more ... than isoprenoid compounds | enriched (n-alkanoic acids vs phytols) |
| Differences in hydrogen isotopic composition between isoprenoid lipids due to different ... | biosynthethic pathways |
| Where it is synthesised in the cell determines .... | the starting pool of hydrogen isotopes |
| hydrogenation of doublebonds during biosynhtesis leads to ... in dD | increasing depletion |
| dD of n-alkanes (from plants) mostly reflects ... | precipitation/evaporation balance because this affects the dD of the source water |
| influences on dD of terrestrial n-alkanes | source water dD(precip/evap), fractionation due to biosynthesis of lipids and minorly by C3/C4 metabolism |
| hydrogen isotopes reflect the input of freshwater through rivers and throught that also correlates with ...? | salinity |
| there is no large impact of ... on hydrogen isotopic fractonation | temperatures -> but there is of salinity |
| lower dD = ? | more rain out(wet climate)/fresh water |
| hydrogen fractionation is impacted by light | more fractionation at light optimum |
| The hydrogen isotopic composition of lipids from aquatic organisms is influenced by the following major factors: | - Metabolism of organisms
- Biosynthesis lipids
- dD of the source water
- Salinity – in marine environment
- Light – we like to ignore this
- Only minor effect of growth rate/nutrients |
