Impact of Ship Traffic on the Characteristics of Shelf Sediments: An Anthropocene Prospective

Abstract

Humans have been sailing across seas and oceans for thousands of years. However, the story of large ships capable of affecting coastal ecology and shelf sedimentary processes is only about 100 years old. Modern large seagoing vessels with a draft of 10–20 m can cause resuspension of seabed sediment, erosion of the channel slope and shoal, enhancement of seafloor sediment activity and thickening of the active layer, thereby having a significant impact on seabed topography and sedimentation processes. However, little is known about the effects of this anthropogenic agent on shelf sedimentation due to limited observational data. Here, two sediment cores were collected from a shipping lane used by vessels of 5,000- to 50,000-ton off the coast of China to analyze their sedimentary properties, with focus on both the grain size and elements. It was found that ship disturbance selectively modified the sedimentary record, with the fine-grained sediment becoming increasingly unstable. In addition, there was a reduction in grain size of sediment finer than 6.25 Φ, which decreased by 11% after the disturbance by ship. Biogenic elements that were closely related to the ecological environment were significantly altered, with Br/Cl, Si/Ti, and Ca/Ti ratios all becoming significantly smaller. This indicated that frequent disturbance caused by ships had reduced the productivity in the waters near the shipping lane. In terms of sensitivity to the effects of ship navigation, the sedimentation response was relatively rapid and began to emerge from the commencement of ship navigation, whereas the ecological response became evident later than the sedimentation response and only appeared after a significant growth in the maritime transportation of China. Following the comparison of the two sediment cores, we propose that the constant rate of supply (CRS- with ship disturbance)–constant initial concentration (CIC- without ship disturbance) dual dating model be used to establish a dating framework in waters frequently disturbed by ship. This type of anthropogenic sedimentary dynamic process and its sedimentary–ecological effects deserve attention on this era where there is a surge in shipping globally. Shipping lanes present an excellent area for quantitative studies on the impacts of human activity and defining the Anthropocene in the context of shipping.

Evolution Modeling and Protection Scheme for Tidal Flats Under Natural Change and Human Pressure, Central Jiangsu Coast

“…However, the Yellow River migrated northwards from Shandong into the Bohai Sea in 1855, which meant that the entire Jiangsu coast lost its most important source of material, and some tidal flats gradually changed from accretion to erosion. Due to the “lag effect” of the depositional effects (Xue et al., 2021), the response of the Jiangsu coast to this event is manifested as the gradual erosion of tidal flats from north to south. Studies have shown that tidal flats in the northern part of the research area are currently experiencing erosion, while those in the southern part are still accreting.…”

Typhoon and flooding occurrences on Chongming Island, Changjiang Estuary, as revealed by a newly acquired sedimentary record

“…This instrument offers advantages over more traditional methods, such as non-destructive analyses, rapid measurement, and high resolution, and it has been applied in fields like sedimentology and paleoclimatology (Swindles et al, 2018;Croudace et al, 2019;Seki et al, 2019). Its applications include paleoclimate reconstruction; identification of event deposits such as river floods and typhoons; tracing of marine and terrestrial sediments; as well as delineation of sedimentary strata (Huang et al, 2019;Wang et al, 2019;Xue et al, 2021).…”

The operational concept of Mini LNG Carrier: Preventing sedimentation on the seabed

“…Sedimentation caused by shipping activities causes ecological changes where the ratio of the composition of the chemical elements of the basic structure of the water changes. The ecological response becomes slower than the sedimentation process so it affects the sedimentation date records on a hundred-year scale [26].…”