Characteristics of the environmental sample

For nutrient determination, sediment sample was centrifuged at 2,000 × g for 10 min to extract interstitial and pore water. The pore water was filtered with 0.45 μm mixed cellulose hydrophilic filter paper (Millipore, MA) and ammonia (NH₃), nitrite (NO₂), nitrate (NO3-), total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) were quantified using HACH methods HACH 8155, TNT839, TNT835, TNT826, TNT843, and HACH 10128, respectively, according to the manufacturer's instructions. In order to ensure that the high salinity of the samples did not interfere with the measurement procedure and reading the spectrophotometer, control samples with known concentration of ammonia, nitrite, nitrate, and phosphorus were also used alongside each sample. Total solids (TS) and volatile solids (VS) were also measured by drying the sediment sample at 103°C for 24 h followed by igniting at 550°C for 2 h according to EPA Method 1684 (USEPA, 2001). In addition, to study the biogeochemistry of the sediment sample, trace metal concentrations (Mn, Fe, Co, Ni, Cu, Zn, Se, Mo, and Pb) were measured by using 15 g of sediment, centrifuging at 5,000 × g for 10 min and filtering the supernatant with 0.22 μm hydrophilic filter and then analyzed using inductively coupled plasma mass spectrometry (ICP-MS, Agilent 7500ce, CA).