A geochemical perspective on the natural abundance and predominant sources of trace elements in cranberries (Vaccinium oxycoccus) from remote bogs in the Boreal region of northern Alberta, Canada

Determination of Biologically Active Compounds and Antioxidant Capacity In Vitro in Fruit of Small Cranberries (Vaccinium oxycoccos L.) Growing in Natural Habitats in Lithuania

The composition of flavonols, proanthocyanidins, anthocyanins, triterpene compounds, and chlorogenic acid in small cranberry fruit samples collected in natural habitats in Lithuania and variation in the antioxidant capacity of cranberry fruit extracts was determined. This study showed that in the flavonol group, hyperoside and myricetin-3-O-galactoside predominated in cranberry fruit samples; in the anthocyanin group, the predominant compounds were cyanidin-3-O-galactoside, cyanidin-3-O-arabinoside, peonidin-3-O-galactoside, and peonidin-3-O-arabinoside, and in the group of triterpene compounds, ursolic acid was predominant. The highest total amounts of flavonols and anthocyanins were found in the samples collected in Čepkeliai State Strict Nature Reserve (2079.44 ± 102.99 μg/g and 6993.79 ± 350.22 μg/g, respectively). Cluster analysis of the chemical composition of small cranberry fruit samples revealed trends in the accumulation of bioactive compounds in cranberry fruit. Cranberry fruit samples collected in central Lithuania had higher levels of triterpene compounds. Statistical correlation analysis showed the strongest correlation between the quantitative composition of cyanidin-3-O-arabinoside and peonidin-3-O-arabinoside and the reducing capacity of the ethanolic extracts of the cranberry fruit samples assessed in vitro by the FRAP assay (r = 0.882, p < 0.01 and r = 0.805, p < 0.01, respectively). Summarizing the results, the geographical factor affects the variation of the quantitative composition of biologically active compounds in cranberry fruit samples.

Size-resolved distribution of trace elements in lysimeter soil solutions under contrasting long-term agricultural management to assess their bioavailability

The chemical species of trace elements (TEs) in agricultural soils is highly variable under diverse conditions, requiring tools with clear resolution and minimal disturbance for exploration. A novel surgical (316L) stainless steel (SS) lysimeter with a 5 μm pore size was developed to collect field soil solutions. The size-resolved distribution of TEs were characterized into total (nitric acid digestion), particulate (0.45-5 μm), dissolved (<0.45 μm), colloidal (1 kDa to 0.45 μm), and mainly ionic (<1 kDa) fractions in the lysimeter soil solutions. Total concentrations of TEs (dry weight basis) in acid digested Gray Luvisolic soils were analyzed. Most TEs in lysimeter soil solutions were present in particulate phases, relevant to their geochemical affinities and occurrences in soil minerals. Among dissolved fractions, As, Ba, Co, Li, Mn, Tl, and V existed as mainly ionic species in the soil solutions. Copper, Pb, Al, Th, and U showed variable associations with dissolved organic matter (DOM) and/or inorganic colloids among agricultural treatments. Inorganic NPKS or NKS fertilizer applications with lower pH (5.25-5.74) enhanced mobility and potential bioavailability of Ba, Co, Li, Mn, and Pb present in mainly ionic species, compared with other locations (pH 5.82-6.37). Manure application exhibited a dual effect, potentially increasing bioavailability for As, Tl, and V due to probably enhanced cation exchange capacity (CEC), while also facilitating specific adsorption of Cu and U on DOM, potentially reducing their bioavailability depending on DOM molecular weight. Colloidal and ionic Al and Th concentrations were higher in forest soils than agricultural soils, with extremely low potential bioavailability of Th attributed to strong precipitation with inorganic colloids and adsorption on DOM. The lysimeter sampling and size fractionation method provided a clear insight into agricultural effects on TE distributions and enhancing understanding of agricultural soil health in terms of TE bioavailability in situ.

Spatial variation and chemical reactivity of dusts from open-pit bitumen mining using trace elements in snow

The chemical reactivity of trace elements (TEs) in dusts from bitumen mining, upgrading and related industrial activities in the Athabasca Bituminous Sands region (ABS), Alberta, Canada, was evaluated using the acid-soluble fraction of snow. Samples were collected at 14 sites along the Athabasca River (AR) and its tributaries, and at 3 remote locations. Following metal-free, ultra-clean procedures for processing and analysis, samples were leached with nitric acid (pH < 1), filtered (<0.45 μm), and analyzed using ICP-MS. Insoluble particles (>0.45 μm) were examined using SEM-EDS. Along the river, acid-soluble concentrations of TEs varied by 6 orders of magnitude, from 1 mg/L (Al) to less than 1 ng/L (Tl). Conservative (Al, Y, La, Th) and mobile (Li, Be, Cs, Sr) lithophile elements, those enriched in bitumen (V, Ni, Mo), and potentially toxic chalcophile elements (As, Cd, Pb, Sb, Tl) showed considerable spatial variation. Normalizing the concentrations of TEs in samples collected near industry to the corresponding concentrations in snow from the reference site (UTK), resulted in enrichments of V and most of the lithophile elements. Dust reactivity, quantified as the ratio of acid-soluble to total concentrations, was less than 50% suggesting limited bioaccessibility. The large differences in behaviour between Cd and Pb versus Ni and V could be due to the occurrence of the former pair in carbonate or sulfide minerals, versus acid-insoluble petcoke particles for the latter couple. Spatial variations in the reactivity of TEs most likely reflect the range in diversity and chemical stability of dust particles, and variations in their abundance in primary source areas. The leaching conditions employed here are extreme (pH < 1) and intended to identify an upper limit of chemical reactivity, with far less dust dissolution expected when these dusts encounter natural waters of the area which range in pH from 4 to 8.

Comparison of trace elements in tissue of beaver (Castor canadensis) and local vegetation from a rural region of southern Ontario, Canada

Beavers have been analyzed in several studies examining trace elements (TEs) in wildlife; however, most of these studies were undertaken in areas with known environmental pollutants. To understand and quantify natural enrichments of TEs in beaver tissue, samples of kidney, liver, muscle from 28 animals were compared with bark from 40 species of trees and shrubs, from the same, uncontaminated watershed. Pearson correlation and factor analysis show that conservative, lithophile elements such as Al, Ga, Th, and Y, all surrogates for mineral dust particles, explain 61% of the variation in the bark data. In contrast, Cd, Co, Cu, Mn, Mo, Ni, Rb, Se, Sr, and Tl in bark are independent of Al, and therefore most likely occur in non-mineral forms. Comparing tissue concentrations of beaver and bark, the organs are enriched in micronutrients such as Cu, Fe, Mo, Se, and Zn, but also non-essential, benign elements such as Cs and Rb, and potentially toxic elements such as Cd and Tl. Thus, the elements most enriched in beaver organs are those that apparently occur in biological form in the plant tissue. The elements enriched in these animals, relative to bark, appear to offer the most promise for monitoring environmental contamination by TEs using beavers. The majority of TEs of environmental relevance are most abundant in beaver kidney. However, monitoring studies must consider the variation in TE concentrations in beaver tissue, including those due to sex and age. Also, due consideration must be given to background concentrations of TEs in the vegetation composing the diet of the animals. The natural enrichment in the case of elements such as Cd, in beaver tissue relative to bark, is profound. These data establish critical baseline values for TEs in beavers in an unpolluted environment, thereby allowing for their use as model organisms in tracking how heavy metal pollutants may affect wildlife.

Environmental significance of trace elements in the Athabasca Bituminous Sands: facts and misconceptions

The bituminous sands of Alberta, Canada, represent the second largest reserves of hydrocarbons on earth. Open pit bitumen mining and upgrading of the Athabasca Bituminous Sands (ABS), the largest of the deposits, began in 1967. Concerns about fugitive release of trace elements (TEs) to the environment began with studies of V, as this is the most abundant trace metal in bitumen. Recent studies, however, have extended to Ag, As, Be, Cd, Cr, Cu, Pb, Sb, and Tl, and this has led to considerable confusion about which TEs are relevant to ecosystem health. While V along with Ni, Mo, Se and Re are enriched in bitumen, Ag, As, Be, Cd, Cr, Cu, Pb, Sb and Tl are found almost exclusively in the mineral (i.e. sand) fraction of the ABS, with limited opportunity to become bioaccessible, much less bioavailable. Here, a summary is given of ten misunderstandings that have arisen regarding TEs in the environment of the ABS region. To help illustrate the significance of the misconceptions that have arisen regarding (a) air and (b) water resources, published and unpublished TE data obtained from the metal-free, ultraclean SWAMP lab is presented for: (a) snow, moss, and peat cores from bogs, and (b) the dissolved, particulate, and colloidal fractions of water from the Athabasca River (AR), as well as pristine groundwater. Natural enrichments of Ni in plants such as Rat Root (Acorus calamus) and pine (Pinus banksiana), Tl in fish (Percopsis omiscomaycus) and Cd in cranberries (Vaccinium oxycoccus), Labrador Tea (Rhododendron groenlandicum) and beaver (Castor canadensis), are also presented.

Metals in Plant Functional Types of Ombrotrophic Peatlands in the Sudetes (SW Poland)

The Sudetes are remarkable for the variety and number of peat bogs which receive nutrients via precipitation from atmospheric deposition as the only source of minerals. As this type of peat bogs with a very low buffering capacity is affected in the Sudetes by long-range exhausts from the former Black Triangle, strong response to atmospheric contamination may be expected. Therefore these peat bogs are highly suitable for bioindication purposes. As a result, metal levels in peat and plants should be controlled to evaluate potential ecological damage and to devise treatment strategies. The aim of this study was to evaluate the concentration of Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn in species from different plant functional types (PFTs): shrubs, evergreen dwarf shrubs, deciduous dwarf shrubs, tussock sedges, non-tussock sedges, forbs, Sphagnum mosses, brown mosses, liverworts, and algae collected from peat bogs of the Izera, Karkonosze, and Bystrzyckie Mountains. PFTs of the Karkonosze peat bogs situated above the upper forest line contained higher metal concentrations than those of the Izera and Bystrzyckie peat bogs from lower altitudes and surrounded by forests. Of all PFTs, the algae Zygogonium ericetorum accumulated the highest levels of Fe, Pb, and Zn. The PFTs of Sphagnum mosses were also very effective bioindicators of Cd, Cr, Fe, Hg, and Pb deposition to peat bog ecosystems. Pb, Fe, and Cr found in the examined vascular PFTs originated from atmospheric deposition. The results showed that airborne contaminants, including the ones connected with long-range transport, can make a significant contribution to a load of trace metals in peat bogs located above the upper forest line. These airborne depositions facilitate better recognition of the transport of contaminants carried over great distances and should be taken into account in monitoring and environmental protection programs. In particular, the results, first of all, show the differences in the bioaccumulation of metals in PFTs and their response to trace metal levels in such habitats. Of all PFTs, algae and Sphagnum mosses were the best choices for bioindication of trace metal pollution in ombrotrophic mountain mires. PFTs have not been used so far for investigating ombrotrophic mountain mires in Europe. Thus results of this investigation could be extended to this type of peat bogs in the mountains of Central Europe for better selection of PFTs for bioindication purposes.

Impacts of smelter atmospheric emissions on forest nutrient cycles: Evidence from soils and tree rings

Although the environmental impacts of metal atmospheric emissions from point sources such as smelter have been extensively studied, very few studies have attempted to understand the influence of those emissions on nutrient cycles in the surrounding forests. This study investigates nutrient variations in space and time along with trace metals by statistical analysis of tree-ring series combined with the characterization of element concentrations in soil horizons. The research focuses on the Horne smelter (Rouyn Noranda, Québec, Canada), because it released high atmospheric emissions of metals and gases between 1928 and 1990s. Tree-ring Sr/Mn ratios, and Mn and Sr z-score series reveal that surface soil pH recovered progressively within the 45 km footprint of the smelter since the end of acidic deposition in the late 1970s. The influence of acidic deposition on the current soil pH has become negligible. In other words, element bioavailability and root assimilation have changed through time due to soil acidification at proximal sites. The detrended tree-ring elemental series during the last century also suggest that summer temperatures partly control the elemental bioavailability to trees in soils. Moreover, tree-ring Zn and Mg series appear as key environmental indicators of metal deposition from the smelter. This research confirms previous findings indicating that elemental concentrations in black and white spruce trees may be used to evaluate the potential influence of smelter emissions on nutrient cycles. For a future informed and adaptive management of forests, understanding the potential modifications of nutrient regimes caused by anthropogenic contaminations is critical, especially in the context of global warming.

Trace elements in Labrador Tea (Rhododendron groenlandicum): How predominant sources to the plants impact the chemical composition of hot water extracts

Labrador Tea (Rhododendron groenlandicum) has been an important food and medicinal plant to First Nations communities in North America for millenia, but little is known of its geochemical properties. Using plants from 10 sites in 4 provinces, including pristine and industrial regions, and employing the metal-free, ultraclean SWAMP laboratory facilities and procedures, we provide an estimate of the natural abundance of trace elements in the leaves, and the extent of their release during hot water extraction. Elements decrease in abundance in the order Mn > Al > Fe > Zn > Cu > Ni > V > Pb > La > Mo > Y > La > Tl > Cd > Th > Ag. The greatest concentrations of conservative, lithophile elements such as Al, La, Th and Y, are found in samples collected on lands reclaimed from open pit bitumen mines in northern Alberta, reflecting elevated inputs of atmospheric dusts. In contrast, micronutrients such as Cu and Zn are remarkably uniform which suggests that these are supplied almost exclusively by plant uptake via roots. Deionized, reverse osmosis water is more effective in removing some elements (e.g. Al, La, Y, Fe, Zn, Cd) whereas others are more readily extracted using groundwater (e.g. Cu, Ni, Pb); V behaves independently of water composition. In both types of water, the elements most readily extracted are plant micronutrients (Mn, Ni, Cu, and Zn) whereas those supplied primarily by dust exhibit much lower yields; Al shows behaviour intermediate between these two extremes. While element concentrations in the infusions increase with increasing concentrations in the leaves, the abundance of potentially toxic chalcophile elements such as Cd, Pb, Sb and Tl in the infusions are extremely low (ng/l). Plants from British Columbia, Ontario and Quebec provide evidence of atmospheric Pb contamination, yielding greater ratios of Pb/La compared to the samples from Alberta where crustal values are found. Given that this plant is common and found across the northern half of the continent, it shows great promise as a tool for biomonitoring of air quality. For consumers, Labrador Tea may represent an important dietary source of Mn.

Contemporary and Historical Atmospheric Deposition of Arsenic and Selenium in the Athabasca Bituminous Sands Region

Selenium (Se) is one of the trace elements that is enriched in bitumen. To assess the importance of atmospheric Se deposition from mining and upgrading of bituminous sands in northern Alberta, Canada, Sphagnum moss was obtained from 25 bogs near industrial operations. The average Se concentration in moss near industries (58 ± 13 μg/kg; n = 75) was greater than in remote sites in Alberta (29-50 μg/kg), but comparable to bogs in central regions of the province and lower than bogs in southern Ontario (121-244 μg/kg) or the west and east coasts (230-285 μg/kg). In bog vegetation and peat, arsenic (As) concentrations and accumulation rates are 10 times greater at the industrial site (MIL) compared to the control site (UTK), but this is proportional to the differences in scandium (a surrogate for mineral matter concentrations), which points to dust as the predominant As source. An age-dated peat core collected near industries revealed that both Se and As deposition have declined in recent years. A peat core from UTK provided a record of atmospheric deposition dating back over 2700 years, indicating that As and Se deposition in northern Alberta increased considerably in the early 19th century and then went into decline during ∼1950-1970.