Distributions, fluxes, and toxicities of heavy metals in sediment pore water from tributaries of the Ziya River system, northern China

Abstract

The distributions and mobilities of metals in pore water strongly influence the biogeochemical processes and bioavailabilities of metals at sediment-water interfaces. Heavy metal concentrations were measured in pore water samples from the Shaocun River (SR), the Wangyang River (WR), and the Xiao River (XR), tributaries of the Ziya River system, northern China. The aim was to assess heavy metal contamination in the system and the associated environmental risks. The mean Cd, Cr, Cu, Ni, Pb, and Zn concentrations in all three tributaries were 0.373, 57.1, 37.7, 20.4, 14.0, and 90.6 μg/L, respectively. The calculated Cd, Cr, Cu, Ni, Pb, and Zn diffusion fluxes in the rivers were −0.427 to 0.469, −71.8 to 42.5, 3.16 to 86.6, 5.29 to 14.0, 7.24 to 19.0, and −204 to 21.9 μg/(m 2 day), respectively, showing that the pore water was a source of most of the metals to the water column. Only Cu and Pb in the XR and Cu in the WR exceeded the final chronic value recommended by the US Environmental Protection Agency, but the metals in the WR sediment could have caused toxic effects.These results are likely to be useful to the authorities responsible for sustainable river management.

Effects of Hyporheic Water Fluxes and Sediment Grain Size on the Concentration and Diffusive Flux of Heavy Metals in the Streambed

“…However, at the majority of test points, Cu and Zn were being released to the surface water from the sediment pore water. The release of these heavy metals may have negative effects on the surface water quality and river ecosystem health and may pose health risks and potential ecological risk [ 46 ]. Furthermore, higher positive diffusive fluxes of Zn (ranging from −53.014 to 118.187 µg·m −2 ·d −1 ) and Cu (ranging from 2.737 to 10.743 µg·m −2 ·d −1 ) were observed at the downstream Site 2 compared to the upstream Site 1, indicating significant regional differences ( p = 0.033 for Zn and p = 0.025 for Cu) at the 95% confidence level based on the Two Independent Samples Test.…”

“…Based on the concentration gradients in the pore water, the diffusive flux of the heavy metals was estimated from the pore water profile on the basis of the Fick’s first law [ 45 ]: where F is the diffusive flux of heavy metal (µg·m −2 ·d −1 ), is the porosity of the surface sediment, x is the vertical depth beneath the sediment-water interface (cm), and is the molecular diffusion coefficient (cm 2 ·s − 1 ). is the concentration gradient of heavy metal across the sediment-water interface (µg·L −1 ·cm −2 ) and can be estimated from the porewater profiles, with the assumption that the gradient is one-dimensional [ 46 ] and can be approximated as [ 47 ]: where is the Cu or Zn concentration in pore water of the uppermost sediment layer (µg·L −1 ). is the Cu or Zn concentration in pore water (µg·L −1 ).…”

Two Approaches to Measure Trace Metals Fluxes at the Sediment–Water Interface: Sediment Porewater Profile and Benthic Incubation

“…A portion of the metals released into the aquatic environment will be transferred to sediment through being adsorbed onto suspended matter and subsequently undergoing a sedimentation process (Zhu et al 2016). Marine sediments are the main sink for trace metals that are caused by most metals having a high affinity with metal oxide, organic matter, or clay minerals that can lead to the occurrence of a metal accumulation process in the benthic sediment over time (Kang et al 2009).…”

Will heavy metals in the soils of newly submerged areas threaten the water quality of Danjiangkou Reservoir, China?

“…Sampling sites were distributed evenly across the newly submerged area of Xichuan County, covering the different land-use types and elevations. In July 2014, the soil samples were collected, the methods was detailed description in the previous paper (Zhu et al, 2015;Tang et al, 2015).…”

“…Soil pH, soil organic matter (SOM) in sediment, the grain-size distribution, and analysis of Fe, Al, Ca, Mn, Ni, Cu, Zn, Cd, Pb, As and Cr contents was detailed description in the previous paper (Zhu et al, 2015;Tang et al, 2015).…”