Coupled anthropogenic anomalies of radionuclides and major elements in estuarine sediments

Elevated rates of organic carbon, nitrogen, and phosphorus accumulation in a highly impacted mangrove wetland

“…The high estuarine water nutrient concentrations in Cubatão (Table ) likely contributes to the fourfold higher OC accumulation than in the undisturbed forest and sixfold higher than the global average of 163 g OC m −2 yr −1 [ Breithaupt et al , ]. The onset of urbanization at the beginning of the twentieth century and major industrial development (iron ore industry in the 1960s and fertilizer plant in the 1970s) may also play a critical role in the high accumulation rates, as noted by the large phosphorus enrichment factors during the previous century [ Luiz‐Silva et al , ; Machado et al , ]. As iron and phosphorus may be limiting to mangrove growth [ Alongi , ; Reef et al , ], the OC accumulation rates in Cubatão are likely upper limit estimates.…”

Problems with the dating of sediment core using excess 210Pb in a freshwater system impacted by large scale watershed changes

“…In order to assess if LOI normalized initial 210 Pb xs activity remains constant, the initial 210 Pb xs activity was calculated for 100% of organic matter (¼initial 210 Pb xs activity * 100/LOI (in %)), the activities varied over an order of magnitude, from 522 mBq/g to 3137 mBq/g, indicating that the amount of organic matter alone does not control the variations of the input of 210 Pb xs activity. Although efforts to improve sediment dating procedures have been carried out by normalizing the radionuclide to Al for grain-size variability (Machado et al, 2008), we do have grain-size data for our sediment core reported in this study. Visual observation did indicate relatively uniform grain sizes and this is supported by the porosity values given in Table 1.…”

Accumulation of trace metals in sediments in a Mediterranean Lagoon: Usefulness of metal sediment fractionation and elutriate toxicity assessment

“…This toxicity (abnormality) may increase with AVS effect under suboxic to anoxic conditions, AVS analysis showing that the eastern and western areas have both attained the highest toxicity possible. Some trace elements associated with the bioavailable fraction may be associated with AVS in the more anoxic area as indicated by Machado et al (2008). For anoxic sediments, sulfide availability controls metal distribution and solubility.…”