Trace metal

About: Trace metal is a research topic. Over the lifetime, 5125 publications have been published within this topic receiving 181046 citations.

Macro and micro plastics sorb and desorb metals and act as a point source of trace metals to coastal ecosystems.

Abstract: Nine urban intertidal regions in Burrard Inlet, Vancouver, British Columbia, Canada, were sampled for plastic debris. Debris included macro and micro plastics and originated from a wide diversity of uses ranging from personal hygiene to solar cells. Debris was characterized for its polymer through standard physiochemical characteristics, then subject to a weak acid extraction to remove the metals, zinc, copper, cadmium and lead from the polymer. Recently manufactured low density polyethylene (LDPE), nylon, polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS) and polyvinyl chloride (PVC) were subject to the same extraction. Data was statistically analyzed by appropriate parametric and non-parametric tests when needed with significance set at P < 0.05. Polymers identified in field samples in order of abundance were; PVC (39), LDPE (28), PS (18), polyethylene (PE, 9), PP (8), nylon (8), high density polyethylene (HDPE, 7), polycarbonate (PC, 6), PET (6), polyurethane (PUR, 3) and polyoxymethylene (POM, 2). PVC and LDPE accounted for 46% of all samples. Field samples of PVC, HDPE and LDPE had significantly greater amounts of acid extracted copper and HDPE, LDPE and PUR significantly greater amounts of acid extracted zinc. PVC and LDPE had significantly greater amounts of acid extracted cadmium and PVC tended to have greater levels of acid extracted lead, significantly so for HDPE. Five of the collected items demonstrated extreme levels of acid extracted metal; greatest concentrations were 188, 6667, 698,000 and 930 μgg-1 of copper, zinc, lead and cadmium respectively recovered from an unidentified object comprised of PVC. Comparison of recently manufactured versus field samples indicated that recently manufactured samples had significantly greater amounts of acid extracted cadmium and zinc and field samples significantly greater amounts of acid extracted copper and lead which was primarily attributed to metal extracted from field samples of PVC. Plastic debris will affect metals within coastal ecosystems by; 1) providing a sorption site (copper and lead), notably for PVC 2) desorption from the plastic i.e., the “inherent” load (cadmium and zinc) and 3) serving as a point source of acute trace metal exposure to coastal ecosystems. All three mechanisms will put coastal ecosystems at risk to the toxic effects of these metals.

Model of trace-metal partitioning in marine sediments.

Abstract: An equilibrium adsorption model is developed to predict the partitioning of trace metals between different geochemical phases in aquatic sediments. The model uses conditional equilibrium constants determined from linear portions of adsorption isotherms. As an example of how the model can be used, the adsorption and the partitioning of Cu and Cd on several select artificial geochemical phases were studied. Conditional equilibrium constants for adsorption of Cu and Cd on bentonite clay, Fe(OH)S, MnOz, and humic acid in seawater show the model’s applicability for trace-metal concentrations existing in natural environments. The adsorption constants for Cu were much higher than for Cd for all solid phases. The affinity of the metals for humic acid relative to other phases was high for Cu and low for Cd. The model predicts that the clay fraction is a major sink for Cu and Cd for the artificial geochemical phases used.

Sedimentation and trace metal distribution in selected locations of Sundarbans mangroves and Hooghly estuary, Northeast coast of India

Abstract: Four sediment cores were collected from selected locations of Sundarbans mangroves and Hooghly estuary, northeast coast of India to establish 210Pb geochronology and trace metal distribution in sediments. Core sites were chosen to reflect a matrix of variable anthropogenic input and hydrological conditions. The vertical distribution of 210Pbxs (210Pbtotal–226Ra) provided reliable geochronological age to calculate the mass accumulation rates and historic trace element inputs and their variations. The mass accumulation rates ranged from 0.41 g cm−2 year−1 (estuarine region) to 0.66 g cm−2 year−1 (mangrove region). Both in mangroves and estuarine systems, Fe–Mn oxy-hydroxides are observed to be a major controlling factor for trace metal accumulation when compared to organic carbon. Core collected from Hooghly estuary shows less contamination when compared to the mangrove region due to high energy and mostly coarse grained. Fe-normalized enrichment factors (EFs) of trace metals were calculated based on crustal trace element abundances. The EFs are typically >1 for Cd, Pb, Co, and Cu indicating that these metals are highly enriched while other metals such as Zn, Ni, Cr, and Mn show no enrichment or depletion. Both Sundarbans mangroves and Hooghly estuary have been receiving considerable pollution loads from anthropogenic sources such as industrial, domestic, and shipping activities in recent times, indicating high concentration of metals in the top few layers. This study suggests that the variation in trace metals content with depth or between mangrove and estuarine system results largely from metal input due to anthropogenic activities rather than diagenetic processes.