Recent progress in understanding
PF-03814735 provenance in the Yellow Sea has been driven by improved data acquisition and processing methods, especially with regard to the elemental compositions (Yang et al., 2003a, Lim et al., 2006, Yang and Youn, 2007, Xu et al., 2009, Jung et al., 2012 and Lim et al., 2013). Several elements including iron (Fe), magnesium (Mg), vanadium (V), thorium (Th), and rare earth elements (REEs), and their ratios to aluminum (Al) have been suggested as sediment provenance tracers for the Yellow Sea (Cho et al., 1999, Yang et al., 2003a, Lim et al., 2006, Xu et al., 2009 and Xu et al., 2011). Among these elements, REEs have been preferred as potential tracers for studying provenance because of their low solubility during weathering and diagenetic processes (e.g., McLennan, 1989, Singh and Rajamani, 2001, Prego et al., 2009 and Xu et al., 2009 and references therein). Despite this, some studies have indicated that REEs may behave non-conservatively (Braun et al., 1990 and Sholkovitz et al., 1994). In addition, the sediment grain-size and heavy minerals, together with large portion of labile fractions, can exert some influence on the concentrations and fractionation patterns of REEs, and further may badly interpret the identification of the sediment source (Song and Choi, 2009 and Jung et al., 2012). In this respect, Song and Choi (2009) provided diagnostic and persuasive information on the existing forms of REEs in both KR and CR sediments using two- or five-step leaching experiments. In particular, the authors suggested that the LREE enrichment of KR sediments is most likely related to clay
minerals (especially chlorite) for the leached fraction and heavy minerals (i.e., allanite) for the residual fraction. However, these minerals, suggested as main contributor to LREE enrichment, are accessory with very low contents in bulk sediments, which exert a minor control on the REE compositions (Yang et al., 2002, Yang et al., 2003a and Cai et al., 200
cool . In addition, the difference in contents between KR and CR sediments to explain such different REE enrichment pattern is even not large. The circumstances are demanding more objective explanation for the obvious difference in REE fractionation pattern of two river sediments. Accordingly, their applicability as provenance tracers throughout the Yellow Sea is still questionable (Yang et al., 2003a), even though the potential REE tracers derived from KR and CR sediments have been suggested (Yang et al., 2002, Yang et al., 2003b, Jiang et al., 2009 and Xu et al., 2009).
