Extraction and quantification of phosphorus derived from DNA and lipids in environmental samples

Understanding the flux and turnover of phosphorus (P) in the environment is important due to the key role P plays in eutrophication and in the ambition to find cost-effective measures to mitigate it. Orthophosphate diesters, including DNA and phospholipids (PLs), represent a potentially degradable P pool that could support future primary production and eutrophication. In this study, extraction techniques were optimized and combined with colorimetric determination of extracted P to provide a selective quantification method for DNA-P and PL-P in agricultural soil, sediment and composted manure. The proposed method is rapid and reproducible with an RSD of <10%. Recovery, evaluated by spiking the sample matrices with DNA and PL standards, was over 95% for both DNA and PLs. The method can be used for the determination of the pool size of the two organic P fractions. Results show that DNA-P comprises 3.0% by weight of the total P (TP) content in the studied soil, 10.4% in the sediment and 8.4% in the compost samples. The values for PL-P are 0.5%, 6.0% and 1.7% for soil, sediment and compost, respectively.