Arsenic and heavy metal pollution in wetland soils from tidal freshwater and salt marshes before and after the flow-sediment regulation regime in the Yellow River Delta, China Junhong Bai a,⇑ , Rong Xiao a , Kejiang Zhang b , Haifeng Gao a a State Key Laboratory of Water Environment Simulation, School of Environment, Beijing Normal University, Beijing 100875, PR China b Department of Civil Engineering, University of Calgary, 2500 University Drive NW, Calgary, Alberta, Canada T2N 1N4 article info Article history: Received 1 February 2011 Received in revised form 30 April 2012 Accepted 3 May 2012 Available online 16 May 2012 This manuscript was handled by Laurent Charlet, Editor-in-Chief, with the assistance of Prosun Bhattacharya, Associate Editor Keywords: Marsh soils Flow-sediment regulation Geoaccumulation index Primary component analysis Factor analysis summary Soil samples were collected in tidal freshwater and salt marshes in the Yellow River Delta (YRD), northern China, before and after the flow-sediment regulation. Total concentrations of arsenic (As), cadmium (Cd), copper (Cu), lead (Pb) and zinc (Zn) were determined using inductively coupled plasma atomic absorp- tion spectrometry to investigate the characteristics of heavy metal pollution in tidal wetlands before and after the regulation regime. The results demonstrated that marsh soils in both marshes had higher silt and total P contents, higher bulk density and lower sand contents after the flow-sediment regulation; moreover, soil salinity was significantly decreased in the tidal salt marsh. As and Cd concentrations were significantly higher in both marsh soils after the regulation than before, and there were no significant dif- ferences in the concentrations of Cu, Pb and Zn measured before and after the regulation. No significant differences in heavy metal concentrations were observed between freshwater and salt marsh soils, either before or after the regulation. Before the regulation regime, soil organic matter, pH and sulfer (S) were the main factors influencing heavy metal distribution in tidal freshwater marshes, whereas for tidal salt marshes, the main factors are soil salinity and moisture, pH and S. However, bulk density and total P became the main influencing factors after the regulation. The sediment quality guidelines and geoaccu- mulation indices showed moderately or strongly polluted levels of As and Cd and unpolluted or moder- ately polluted levels of Cu, Pb and Zn; As and Cd pollution became more serious after the regulation. Factor analysis indicated thatthese heavy metals including As were closely correlated and orginated from common pollution sources before the flow-sediment regulation; however, the sources of As and Cd sep- arated from the sources of Cu, Pb and Zn after the regulation regime, implying that the flow-sediment regulation regime contributed to As and Cd accumulation in the YRD. Ó 2012 Elsevier B.V. All rights reserved. 1. Introduction Estuarine and coastal wetlands are complex and important eco- systems in which many critical environmental processes including sediment deposition, fresh water–salt water interaction, delta accretion, pollutant retention, and material-energy exchanges oc- cur. They also provide habitats for a diverse array of flora and fauna (Mitsch and Gosselink, 2007). However, more than 90% of formerly important species and 65% of seagrass and wetland habitats have been depleted and destroyed due to anthropogenic activities, lead- ing to degraded water quality and an increasing number of species invasions in these areas (Lotze et al., 2006). As one of the most important effects caused by anthropogenic activities in large river/estuary systems, the global regulation of rivers and streams by building reservoirs and dams has altered downstream ecosystems and significantly changed many environ- ment components during the twentieth century (Brandt, 2000). A variety of effects caused by flow regulation, e.g., the alteration and other effects of landscape elements and channel development (Wiens, 2002), river chemistry and sediment movement (Lake et al., 2000), nutrient cycling and decomposition rates (Harris, 2001), the survival of aquatic and terrestrial flora and fauna (Nilsson and Berggren, 2000) and the recruitment and survival of herbaceous community members associated with abuscular mycorrhizal fungi (Osmundson et al., 2002; Valett et al., 2005; Beauchamp et al., 2007; Smedberg et al., 2009; Navarro-Llacer et al., 2010), have been reported. Other studies have focused on 0022-1694/$ - see front matter Ó 2012 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.jhydrol.2012.05.006 Abbreviations: SOM, soil organic matter; I geo , geoaccumulation indices; YRD, Yellow River Delta; BD, bulk density; PCA, primary component analysis; SQGs, sediment quality guidelines; ISQVs, interim sediment quality values. ⇑ Corresponding author. Tel.: +86 010 58802029; fax: +86 010 58800397. E-mail address: junhongbai@163.com (J. Bai). Journal of Hydrology 450–451 (2012) 244–253 Contents lists available at SciVerse ScienceDirect Journal of Hydrology journal homepage: www.elsevier.com/locate/jhydrol