The ashing method (Briggs, 1977) was used to measure sediment organic content. The mass
of each crucible was recorded as W1. W2 was represented by weighing approximately 10 g of the
sediment sample into each crucible. The crucibles were then placed in the ashing oven for 8 h at
600°C (Briggs, 1977). After removing the crucibles from the ashing oven, the samples were cooled to
room temperature and weighed (W3). Percentage sediment organic matter was calculated
using the following equation: