For the first two days of last week, I finished my last batch of hot-water extraction. My data turned out well for the majority of the samples, but there were some samples that had TOC concentrations over the measuring range and one sample that had a negative number. I planned to dilute the over-range samples but had no idea what to do with the negative one. I might rerun the negative sample just to see if it's an analysis error. It is unsatisfying to see such a result, but as Dr. Dmochowski said during our lunch meeting: no progress is progress, so I hope to learn something from this negative number. Since both Kyle and I were using mid-range kits for our TOC analysis, we ran out of kits and needed to wait for more to come, and I used this time to do some data calculation. I used the total carbon amount/percentage data from Liz and calculated the percentages of TOC that were extracted by hot-water extraction. The results turned out interesting: even though there is more carbon in the 0-20cm soils compared to 50-80cm soils, deeper-depth soils have more TOC extracted. I plan to read more papers to come up with an explanation.
Besides hot-water extraction, I started another extraction: alkali extraction. It extracts the fulvic and humic acid in the soil samples. Even though scientists do not use the term humic acid anymore, this extraction focuses on extracting carbon, so the terms do not affect the extractions. I read some papers about alkali extractions and am going to start my extractions this week. I hope to see some different results between the alkali extractions and hot-water extractions.
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