Quantitative compensation of grain-size effects in elemental concentration: A Korean coastal sediments case study

- Grain-size effect in elemental concentrations of sediments exists even after Al-normalization.
- Grain-size effects are divided into physical and chemical components, especially in metals.
- We quantitatively normalized these grain-size effects in elemental concentrations.
- The concentrations can be expressed as a quadratic equation [Celement=a0·CAl+a1·(CAl)2].

Element concentrations (Celement) of the sediments in the diverse Korean coastal environments were constrained strongly by the grain-size effect (GSE), especially after compensation for metal-free carbonate and organic material contents. However, the GSE in some elements (especially metallic elements) was not completely offset by conventional Al-normalization (Celement/CAl ratio), and further the best-fit regression lines between the concentrations of Al and elements may not be linear, but instead curved, and also cannot pass through the origin point (0, 0). The results suggest the presence of conventional GSE (primary GSE) as well as another GSE (i.e., secondary GSE), which was well supported by the factor analysis for the variable of Celement/CAl ratios. Such primary and secondary GSEs are likely caused by physical and chemical processes, respectively, such as the quartz-dilution effect by metal-free, coarse-grained sediments and diagenetic reactions in organic-rich, fine-grained sediments. Furthermore, these GSEs in Korean coastal sediments can be quantitatively normalized by a quadratic equation: Celement=a0·CAl+a1·(CAl)2, where a0 and a1 are constants for the primary and the secondary GSEs, respectively.