Seasonal dynamics of trace elements in tidal salt marsh soils as affected by the flow-sediment regulation regime.

Junhong Bai,Junhong Bai,Qiongqiong Lu,Rong Xiao,Qingqing Zhao,K Ramesh Reddy,Junjing Wang,Bo Li

doi:10.1371/journal.pone.0107738

Junhong Bai, Junhong Bai + Show 6 more

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https://doi.org/10.1371/journal.pone.0107738

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Journal: PloS one	Publication Date: Sep 12, 2014
Citations: 82	License type: CC BY 4.0

Affiliation: Beijing Normal University, University of Florida

Abstract

Soil profiles were collected in three salt marshes with different plant species (i.e. Phragmites australis, Tamarix chinensis and Suaeda salsa) in the Yellow River Delta (YRD) of China during three seasons (summer and fall of 2007 and the following spring of 2008) after the flow-sediment regulation regime. Total elemental contents of As, Cd, Cu, Pb and Zn were determined using inductively coupled plasma atomic absorption spectrometry to investigate temporal variations in trace elements in soil profiles of the three salt marshes, assess the enrichment levels and ecological risks of these trace elements in three sampling seasons and identify their influencing factors. Trace elements did not change significantly along soil profiles at each site in each sampling season. The highest value for each sampling site was observed in summer and the lowest one in fall. Soils in both P. australis and S. salsa wetlands tended to have higher trace element levels than those in T. chinensis wetland. Compared to other elements, both Cd and As had higher enrichment factors exceeding moderate enrichment levels. However, the toxic unit (TU) values of these trace elements did not exceed probable effect levels. Correlation analysis showed that these trace elements were closely linked to soil properties such as moisture, sulfur, salinity, soil organic matter, soil texture and pH values. Principal component analysis showed that the sampling season affected by the flow-sediment regulation regime was the dominant factor influencing the distribution patterns of these trace elements in soils, and plant community type was another important factor. The findings of this study could contribute to wetland conservation and management in coastal regions affected by the hydrological engineering.

Highlights

Sediment contamination in rivers, lakes, reservoirs, and wetlands has been widely reported in the developing countries as a result of the intense land use in agricultural and urban environment
The primary objectives of this study were: (1) to determine the dynamic changes of selected trace elements including As, Cd, Cu, Pb, and Zn in wetland soils covered by different dominant plant species (i.e., Phragmites australis, Suaeda salsa and Tamarix chinensis) of the Yellow River Delta; (2) to assess enrichment levels of these trace elements and determine their ecological risks using enrichment and toxic indicators; and (3) to identify the relationships among trace elements and other selected soil properties
Soils in P. australis wetland contained higher moisture contents in spring and summer compared to T. chinensis wetland due to less sand contents in P. australis wetland (p,0.05; Table 2)

Summary

Introduction

Lakes, reservoirs, and wetlands has been widely reported in the developing countries as a result of the intense land use in agricultural and urban environment. Contamination of sediments with trace elements is a major concern [1,2]. These trace elements can be transferred and carried downstream into wetland ecosystems, and accumulate in wetland soils [3,4]. Salt marshes and estuarine sediments can retain these metals as metal sulfides [5,6]. Seasonal hydrological changes and water level fluctuation can affect Eh and pH of wetlands, resulting in mobilizing trace elements [5,7]

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