Trace element patterns in Dutch coastal dunes after 50 years of artificial recharge with Rhine River water

“Trace elements (TEs) are important in water
quality monitoring of managed aquifer recharge (MAR)
systems, because they need to be tested against maximum
permissible concentrations (MPCs), and some can be used
as a tracer of either infiltration water, pollution or geochemical
processes. The behavior of 55 dissolved trace
elements and 20 major constituents is shown for an 800 m
long, 35 m deep transect with slow groundwater flow
(*0.01–0.1 m/day) and a nearby 100 m long 20 m deep
transect with fast groundwater flow (0.3–2 m/day), both
between a recharge and recovery canal, in the coastal dune
aquifer system of the Netherlands. This study demonstrates
how TEs behaved in a pH 7–8 artificial recharge system in
coastal sediments, where pretreated Rhine River water has
been infiltrated in the period 1957–2007. The spatial and
age distribution of the infiltrated Rhine water was mapped
using a combination of environmental tracers (Cl/Br, 18O,
3H, Cl and SO4), allowing the comparison between young
and old Rhine water, and between Rhine and dune
groundwater. It is revealed which TEs can be used in
specific cases as additional tracers (B, F, Mo), which TEs
showed clear redox dependent behavior (As, Mo, U) or
clear sorptive behavior (B, Ba, Co, Cs, Cu, F, Li, Mo, Ni,
Rb, Sb, Sr, U, W), which TEs received significant geogenic
inputs (As, Sr, U, W), which ‘classical’ TEs need much
less monitoring compared to the 1970s and 1980s (B, Ba,
Be, Cd, Co, Ni, Hg, Pb, Zn), and which TEs can normally
be neglected (rare earth elements, precious metals).”
(Citaat: Stuyfzand, P.J. Trace element patterns in Dutch coastal dunes after 50 years of artificial recharge with Rhine River water – Environmental Earth Sciences 73(2015)12, 7833-7849)