A 120-year record of burial fluxes and source apportionment of sedimentary organic carbon in Alian Bay, China: Implication for the influence of mariculture activities, and regional environment changes

Abstract

Sediment cores collected from the mariculture area in Ailian Bay, China, and adjacent area were analyzed using a variety of bulk organic chemical and chronological techniques, including grain size composition, elemental composition (C and N), C/N ratio, stable isotopic composition (δ13C and δ15N), and 210Pb activities. We aimed to investigate the response of burial and sources of sedimentary organic carbon (SOC) to the mariculture activities and regional environmental changes on a centennial scale. Sediment chronology results showed that the sediment cores in the abalone culture area and control area covered a period of 45 years (1971–2016), and 120 years (1896–2016). The sediment accumulation rate in the abalone culture area and control area were 0.95 cm·a−1 and 0.30 cm·a−1, respectively. And the TOC and TN burial fluxes in the abalone culture area (35.41 ± 0.25 g·m−2·a−1 and 4.58 ± 1.70 g·m−2·a−1, respectively) were about 5 and 7 times higher than those in the control area (7.03 ± 1.39 g·m−2·a−1 and 0.72 ± 0.17 g·m−2·a−1, respectively), respectively. The source contributions and increasing trend of marine-sourced OC were significantly higher in the abalone culture area (range: 47–126%; average: 89 ± 20%) than in the control area (range: 35–73%; average: 59 ± 10%). In conclusion, our results indicated the burial process and sources of SOC in the mariculture areas and its adjacent areas were significantly enhanced by the mariculture activities and were influenced by the environmental changes.