2.2. Sample collection and pre-treatment
Composite samples from the surface sediments (0e5 cm) were
collected from the six stations using an Ekman Grab Sampler. The
pH of fresh sediments was measured immediately with a handheld
pH meter (WTW 330i) on site. The sediment samples were placed
in air-sealed plastic bags, set in a portable cooler maintained at 4 C,
transported to the laboratory and stored in the freezer at 20 C
until further analysis.