Table 1.
Environmental parameters (mean and SE) for high-NO3−-lakes (n = 6) and low-NO3−-lakes (n = 6), and results of a t-test or Mann-Whitney U-test* comparing the oxygen, nitrate, ammonium and phosphate concentrations, temperature, catchment field area (ha), averaged N2Oexcess concentrations, and maximum observed N2excess concentrations between the two lake groups.
Fig 1.
Abundance of nirS, nirK, nosZI, and nosZII genes relative to the amount of 16S rRNA genes (A), and ratios of nir and nos genes in sediments of lakes with high and low nitrate concentrations (high-NO3−-lakes and low-NO3−-lakes) (B).
* = significantly different between the two lake groups (Mann-Whitney U-test, p = 0.006).
Table 2.
Copy numbers (mean ±SE) of nirS, nirK, nosZI, and nosZII gene amplicons as percentages of 16S rRNA gene copy numbers (nd, no data).
Table 3.
Correlations of functional gene ratios and accumulated N2O and N2 gas concentrations with environmental parameters in the inter-lake dataset.
Correlation coefficients with 0.01 < p < 0.05 and p < 0.01 are written in normal text and bold, respectively.
Fig 2.
Relationship between hypolimnetic nitrate concentration and the sedimentary (0–2cm) (nirS+nirK)/nosZI+II gene ratio (r = 0.98 and p = 0.001), and depth-integrated N2Oexcess (r = 0.89 and p = 0.02) in Lake Vanajavesi.