Evaluation of the in situ, time-integrated DGT technique by monitoring changes in heavy metal concentrations in estuarine waters

Abstract

Various natural and anthropogenic processes influence heavy metal concentrations within estuaries. In situ, time-integrated DGT measurements made over concurrent tidal phases found significantly higher concentrations of Cu (probability p=0.017), Zn (p=0.003) and Ni (p=0.003) during the flood phase, because the incoming tide passes several point sources. DGT-reactive Cu concentrations significantly decreased with increased tidal-flushing and vice versa within a marina (correlation r=-0.788, p=0.02). DGT measurements also recorded significant increases in Cu (4 out of 4 sites, p<0.001) and Zn (3 out of 4 sites, p< or =0.015) after a 24 mm rainfall event. Finally, DGT-reactive Cu increased significantly (p<0.001) during peak boating times, due to increased numbers of Cu-antifouled boats. This study demonstrates that, with judicious selection of deployment times, DGT measurements enable changes in heavy metal concentrations to be related to various cycles and events within estuaries.

A novel gel‐based technique for the high resolution, two‐dimensional determination of iron (II) and sulfide in sediment

“…A key difficulty in interpreting results for this purpose will be the temporal factor, as the DET and DGT technique measure over a relatively long period (hours) in potentially very dynamic systems. It is not possible to extract temporal information about discrete events from a single probe, so combining the data with measurements made using temporally discrete techniques, such as microelectrodes, or using systematic repeated probe deployments, as in Dunn et al (2003), may be necessary. There are some limitations on the application of this technique in the field.…”

Assessing contaminated sediments in the context of multiple stressors

“…Some excellent papers on methods for determining free metal ion concentration, labile species fraction, metal complexation capacity in waters, and sediment flux have been published [218,[249][250][251][252][253][254][255][256][257][258][259][260][261][262]. A wide range of biomimetic approaches exists [263].…”

Labile copper and zinc fractions under different salinity conditions in a shipyard area in the patos lagoon estuary, south of Brazil

“…12 Because of recent increases in the amount of Cu used in antifouling paints, the concentration of this element is high in the waters around marinas and port areas. 47 In addition, Warnken et al 6 and Dunn et al 19 demonstrated a direct relationship between the DGT-Cu and DGT-Zn concentrations and the number of recreational boats in marinas. Both Cu and Zn found in paints produce a synergic effect on organisms.…”

“…In total, 6 deployments were carried out, two in each seasonal period. Following a conceptual model of the distribution and behavior of dissolved metals vs. salinity in the Patos Lagoon estuary, the range of salinity was classified as low (0-6), intermediate (6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) or high (above 25). 22 In each deployment period, four devices were attached to a rope fixed on a pier at 0.5 m depth about 10 m from the margin area of the estuary.…”

“…6,18 The DGT device accumulates trace metals in situ to obtain time-averaged concentrations of the metals, 19,20 thereby reducing the uncertainties that occur in conventional analytical methods for predicting bioavailability. 11 Studies undertaken in the Patos Lagoon estuary in southern Brazil have measured the total trace metal concentrations in water and SPM in the estuary channel.…”