Deposition Of Trace Metals Research Articles

Trace metals in coastal marine sediments: Natural and anthropogenic sources, correlation matrices, and proxy potentials

Rapidly spreading industrialization since the 19th century has led to a drastic increase in trace metal deposition in coastal sediments. Provided that these trace metals have remained relatively immobile after deposition, their sedimentary enrichments can serve as records of local–regional pollution histories. Factors controlling this proxy potential include trace metal geochemistry (carrier-, and host phase affinity), and depositional environmental factors (redox variability, particulate shuttling, organic matter loading, bathymetry). Yet, the relative importance and interactions between these controls are still poorly understood, hampering the reliable use of trace metal-based environmental proxies. By summarizing nine site-specific correlation matrices of 16 metal (loid) s (Pb, Cd, Cu, Zn, Sb, Sn, Ni, As, Tl, V, Mo, U, Re, Fe, Mn, Al), total organic C, and S contents in short sediment cores into a single meta-matrix, we test a novel approach for quickly detecting common and contrasting trace metal enrichment patterns across different study locations. Our meta-matrix shows two trace metal groups, within which positive correlations of e.g., Pb, Cd, Zn, Cu, Sb suggest a primary “anthropogenically sourced” (group I) control, whereas known “redox-sensitive” (group II) trace metals (Mo, U, Re) are characterized by fewer positive correlations. However, some group I metals (Cd, Zn, Cu, Sb) also covary with group II metals, inferring that redox variability may obscure primary anthropogenic signals; Sb even shows advantages over Mo and U under oxic conditions. As a more robust pollution indicator we identified Pb; yet for reconstructing historical Pb atmospheric pollution signals (1970s Pb peak), it is crucial to consider the distance from shore. In near-shore environments, local (fluvial) pollution signals may overprint large-scale (atmospheric) signals. Our findings demonstrate that combining site-specific sedimentary correlation and distribution patterns with a meta-matrix considerably aids the understanding of trace metal sequestration in different coastal sedimentary environments, which thereby improves trace metal proxy reliability.

Americium-241 in peat bogs as a global marker of the beginning of the Anthropocene: examples from Europe and North America

Fallout radionuclides are being considered as potential global indicators of the beginning of the Anthropocene, yet questions persist about their preservation in bogs. This study assessed the reliability of 241Am records in peat cores from acidic, ombrotrophic bogs. The source of 241Am (half-life 432.7 years) in these natural archives is radioactive decay of the short-lived plutonium isotope 241Pu (half-life 14.329 years) present in fallout from the atmospheric testing of nuclear weapons. We leveraged previously gathered data to gauge the congruence of 241Am records with 210Pb dates, examining the alignment of the 241Am activity peak with the depth corresponding to the year AD 1963, as determined using the 210Pb constant rate of supply (CRS) model. Our analysis employed 35 peat cores from 30 sites across Europe and North America, collected over the last three decades for trace metal deposition studies. Each core underwent independent 210Pb dating. Among the 35 cores, 10 were excluded because of significant uncertainty in 241Am peak quantification. Among the remaining 25 cores, 22 displayed a single 241Am peak and 3 exhibited two peaks with similar 241Am activities. Of the 22 cores with a single peak, 18 were within 10 years of AD 1963, with 10 of those being within 5 years. For 10 of the 22 cores, 14C dates obtained from the atmospheric bomb pulse curve enabled comparison, with 9 showing ≤10 years of difference and 7 of those showing ≤5 years from the 210Pb CRS model AD 1963. Factors contributing to age discrepancies included (i) analytical limitations of 241Am measurements in peat using gamma spectrometry, (ii) the impact of peat accumulation rates on 241Am activities, i.e., dilution effects, (iii) post-depositional migration of 241Pu and (or) 241Am, (iv) uncertainties introduced during 210Pb age-modelling, and (v) the limited number of samples dated using 14C. The usefulness of 241Am as an Anthropocene marker (assuming AD 1963) hinges on the accepted uncertainty level in defining this epoch. Detection of 241Am through gamma spectrometry was statistically validated as a real peak in 22 out of a total of 35 cores: this fraction (63%) is within the range reported in other studies. Given that the cores were gathered from 16 European and 14 North American sites, these peaks can be taken to denote the hemispheric onset of the Anthropocene. Lastly, common post-depositional migration of 137Cs in ombrotrophic peatlands contrasts with its immobility in minerotrophic peatlands, where the presence of mineral matter and neutral pH inhibit its movement. This observation suggests that fens and swamps, characterized by minerotrophic conditions, may also serve as repositories of nuclear weapons test fallout, including 241Am.

Uncovering sources, distribution, and seasonal patterns of trace element deposition: the elemental puzzle of the western Himalayas.

The transport and deposition of atmospheric pollutants in the Himalayas have a adverse impact on the climate, cryosphere, ecosystem, and monsoon patterns. Unfortunately, there is a insufficiency of data on trace element concentrations and behaviors in the high-altitude Himalayan region, leading to limited research in this area. This study presents a comprehensive and detailed comprehension of trace element deposition, its spatial distribution, seasonal variations, and anthropogenic signals in the high-altitude Kashmir region of the Western Himalayas. Our investigation involved the analysis of 10 trace elements (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd, and Pb) in glacier ice, snow pits, surface snow, and rainwater collected at various sites including Kolahoi, Thajwas, Pahalgam (Greater Himalayan ranges), and Kongdori and Shopian (Pir Panjal Ranges) during 2021.The study reveals distinct ranges of concentrations for the trace elements at different sampling sites. Our analysis of trace element concentration depth profiles in snow pits reveals seasonal fluctuations during the deposition year. The highest concentrations were found in the autumn(below 20cm) and summer (top layer), compared to the winter concentration (10-20cm). The high enrichment factors (EFs) suggest the severity of human-induced trace metal deposition in the western Himalayan region, relative to surrounding regions. Surprisingly, the concentrations and EFs of trace elements showed seasonal contradictions, with lower concentration values and higher EFs during the non-monsoon season and vice versa. A source apportionment analysis using the positive matrix factorization (PMF) technique identified five sources of trace element deposition in the region, including crustal sources (32.33%), coal combustion (15.62%), biomass burning (17.63%), traffic emission (18.8%), and industrial sources (15.6%). Additionally, the study incorporated backward trajectories coupled with δ18O using the NOAA HYSPLIT model to estimate moisture sources in the region, which suggests atmospheric pollutants predominately deposited from the large-scale atmospheric circulation from westerlies (75%) during non-monsoon season. These findings underscore the urgent need for enhanced monitoring and research efforts in the future.

Emissions and Atmospheric Dry and Wet Deposition of Trace Metals from Natural and Anthropogenic Sources in Mainland China

Trace metals from natural and anthropogenic sources impact the atmospheric environment and enter the soil through dry and wet atmospheric deposition, ultimately affecting human health. In this study, we established an emission inventory of Pb, As, Cr, and Cd in East Asia (80° E–140° E, 15° N–50° N) for the year 2017, including dust and anthropogenic sources from both land and marine. We modified the Community Multiscale Air Quality (CMAQ) model to provide gridded data on concentrations, as well as dry and wet atmospheric deposition fluxes of metals, with a focus on mainland China. The emissions of Pb, As, Cr, and Cd in East Asia were 19,253, 3415, 3332, and 9379 tons, respectively, in 2017, with 55%, 69%, 25%, and 58% distributed in the fine mode. The spatial distribution of atmospheric concentrations and dry deposition of trace metals was similar to that of emissions, while the spatial distribution of precipitation-related wet deposition was further east and greater in the south than in the north. In mainland China, the average bulk-deposition fluxes of Pb, As, Cr, and Cd were 1036.5, 170.3, 465.9, and 185.0 μg·m−2·year−1, respectively. Our study provides gridded data on trace metals in mainland China, which can be used for assessing air quality, human exposure risks, and metal inputs to soils.

Tracing anthropogenic aerosol trace metal sources in the North Atlantic Ocean using Pb, Zn and Ni isotopes

Atmospheric deposition of trace metals of natural or anthropogenic origin is an important input of micronutrients to the surface ocean. However, understanding its direct impact on oceanic element cycles is challenging due to scarce data, coupled to diverse aerosol sources and variable solubilities. Here, we present a dataset that combines Ni, Zn and Pb isotopes for samples from the Moroccan and Senegalese coasts and in the high latitude North Atlantic Ocean. We combine the new with published data for other circum-North Atlantic sources to assess the processes that determine the isotope signatures in different types of aerosols. We then use open marine aerosol data to investigate the impact of these signatures in the open ocean. Isotope analyses were conducted on bulk aerosols (TSP), on their ultra-high-purity water leachates, and on rainwaters. Aerosols characterized by crustal elemental abundances have isotope compositions similar to Saharan mineral dust. Mixing with anthropogenic aerosols from Europe/North Africa results in lower 206Pb/207Pb and 208Pb/207Pb values for the Eastern North Atlantic region. Higher 206Pb/207Pb at a given 208Pb/207Pb, observed near the Canadian margin and occasionally at the Senegalese coast, points to anthropogenic inputs from North America. Based on trends in the aerosol data (e.g., δ66ZnJMC-Lyon versus 206Pb/207Pb, δ60NiSRM986 versus Ni/V), we identify several anthropogenic sources of Zn and Ni. The δ66ZnJMC-Lyon of low-temperature pollution (e.g., non-exhaust traffic emission) appears to be around −0.1‰ to 0.2‰, while leachate δ66ZnJMC-Lyon as low as −0.21‰ indicates contributions from high-temperature combustion or smelting processes. Among aerosols with good correlations between Ni and V, δ60NiSRM986 > 0.40‰ traces Ni contributions from oil combustion. Other Ni-enriched sources, possibly originating from laterite or sulfide, show relatively low δ60NiSRM986 (as low as −0.85‰) and low V/Ni. Generally, aerosol sources for Zn are consistent throughout the North Atlantic, while Ni can be highly heterogenous. Combining the new data with literature elemental data, ratios of soluble Zn/Pb in anthropogenic aerosols are 1–100 times surface ocean ratios, suggesting that the low δ66ZnJMC-Lyon observed in anthropogenic aerosol can be key in controlling the upper ocean Zn isotope composition. These aerosols have, however, much less significance for surface ocean Ni.

Impact of Particulate Matter (PM10 and PM2.5) from a Thermoelectric Power Plant on Morpho-Functional Traits of Rhizophora mangle L. Leaves

A conventional thermoelectric plant (TP) in the sandy bar of the Tampamachoco Lagoon (Gulf of Mexico slope) emits particulate matter (PM) transporting trace metals that affect a mangrove forest. Wind transports the emission plume from north to south in the northerly wind season (NWS); the dry season (DS) showed calm periods. We analyzed whether PM2.5 and PM10 emissions from the TP and their trace metals impact Rhizophora mangle leaves. The experimental design included three sampling sites along the main lagoon axis (north to south) during the NWS and DS. Mangrove leaves were collected; PM was obtained with a cascade impactor and trace elements were analyzed by atomic absorption spectrophotometry. Leaves were measured and tested for metal and chlorophyll content, and for metal detection with SEM-EDX. Calm periods in the DS promote high atmospheric PM concentrations. Wet deposition in the NWS caused the highest trace metal deposition on mangrove leaves. A north-to-south gradient was identified on the mangrove forest, being the south site of the lagoon where lower chlorophyll and leaf area, higher stomatal width and density, and higher Cd concentrations were recorded. The morpho-physiological modifications observed on mangrove leaves affect functions such as photosynthesis and gas exchange.

Are Mosses Used in Atmospheric Trace Metal Deposition Surveys Impacted by Their Substrate Soils? A National Study in Albania.

This research used moss biomonitoring to assess the atmospheric deposition of selected trace metals across the whole territory of Albania, a country of diverse lithology, and topography. Here, we assess three elements (Cr, Ni, and Co) that were identified in high concentrations compared to values reported by European moss surveys of 2010 and 2015. The possibility of element uptake by moss from substrate soils was assessed by analyzing moss and topsoil samples from the same areas. For this purpose, moss (Hypnum cupressiforme (Hedw.)) and topsoil samples were collected throughout Albania. Higher concentrations of elements in moss were found in areas of very high element content in soil characterized by no/or thin humus layer and sparse vegetation that stimulates soil dust generation. To compensate for the natural variation of the elements and to show their anthropogenic variation, geochemical normalization was conducted as the ratio of Co, Cr, and Ni concentration data to be concentration. Associations between elements in moss and soil samples, investigated by Spearman-Rho correlation analysis, indicated strong and significant correlations (r > 0.81, p = 0.000) between elements' data in moss or soil, and weak or no correlations (r < 0.4, p > 0.05) between the same data of moss and soil. Factor analysis revealed two main factors that selectively affect the elements in moss and top soil samples. Findings from this research suggested negligible interactions between moss and substrate soils, with the exception of soils with high concentrations of elements.

Spatial distribution and source analysis of airborne trace metal deposition using moss biomonitoring in Huai'an, China.

Terrestrial mosses are tracers for studying atmospheric trace metal deposition and pollution. Here, Al, Fe, Zn, Mn, Ba, Cu, V, Cr, Pb, Ni, Co, and Cd concentrations in mosses from Huai'an, China, were measured to investigate their contamination level, spatial distribution, and sources. The average concentration of all the metals (except Ni) was much higher than those in Albania, a "hotspot" of toxic metal contamination in Europe. The pollution degree of the metals varied significantly: moderate contamination by Al, Fe, Mn, Zn, Cr, V, and Cd; slight contamination by Ba, Cu, Ni, and Pb; and suspected contamination by Co. Based on the Nemerow index (PN), only 8% of the moss samples were graded as moderate pollution, while the remaining 92% were rated as heavy pollution, with Cd and Zn contributing the most. The potential ecological risk index (RI) indicated a moderate potential ecological risk from the metals in Huai'an, with the atmosphere most heavily polluted by Cd. Further, the positive matrix factorization (PMF) model was applied to confirm the metal contamination sources and allocate their source contributions in Huai'an mosses. The results showed that the source contributions of industrial activities related to metal smelting, textile dyestuff and agricultural activities, mining development, natural source, and coal burning and traffic emission accounted for 28.86%, 20.29%, 19.83%, 17.98%, and 13.04%, respectively.

Atmospheric Wet Iron, Molybdenum, and Vanadium Deposition in Chinese Terrestrial Ecosystems

Iron (Fe), molybdenum (Mo), and vanadium (V) are the main components of the three known biological nitrogenases, which constrain nitrogen fixation and affect ecosystem productivity. Atmospheric deposition is an important pathway of these trace metals into ecosystems. Here, we explored the deposition flux, spatiotemporal pattern, and influencing factors of atmospheric wet Fe, Mo, and V deposition based on China Wet Deposition Observation Network (ChinaWD) data from 2016 to 2020. Our results showed that atmospheric wet Fe, Mo, and V deposition was 7.77 ± 7.24, 0.16 ± 0.11, and 0.13 ± 0.12 mg m-2 a-1 in Chinese terrestrial ecosystems, respectively, and revealed obvious spatial patterns but no significant annual trends. Wet Fe deposition was significantly correlated with the soil Fe content. Mo and V deposition was more affected by anthropogenic activities than Fe deposition. Wet Mo deposition was significantly affected by Mo ore reserves and waste incineration. V deposition was significantly correlated with domestic biomass burning. This study quantified wet Fe, Mo, and V deposition in China for the first time, and the implications of atmospheric trace metal deposition on biological nitrogen fixation were discussed.

In utero deposition of trace elements and metals in tissues

IntroductionAll animals, including humans, are exposed to heavy metals which are known to accumulate in different tissues, especially in bone. During pregnancy, the maternal bone turnover is increased and the metals in the mother’s body can be mobilized into the bloodstream. Heavy metals in maternal blood are known to pass through the placenta to the fetal blood and finally, deposited to bone tissue. However, there are no studies on the concentration of metals in the fetal solid tissues and until now, the rate of metal transfer from mother to fetus is not exactly known. Materials and methodsSamples of the blood, liver, placenta, and three different bones were collected from 17 pregnant ewes and their 27 fetuses. The animals had no known exposure to heavy metals. The concentrations of Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, Sb, Sn, Sr, Te, Ti, Tl, V, and Zn were analyzed using ICP-MS. Results and discussionThe concentration of Sb, Sn, Te, and Tl were under the detection limit in all the samples. The other metals were found in all maternal and fetal tissues, suggesting that all detectable metals cross the placenta. Blood concentrations were low compared to solid tissue concentrations. The concentrations of essential elements varied between maternal and fetal tissues, which could be explained by biological differences. The differences in concentrations of non-essential elements between the ewe and fetuses were smaller. The most significant differences were between maternal and fetal concentrations of Ba and Sr, which is at least partly explained by the mineralization degree of the bone. ConclusionHeavy metals accumulate in fetal solid tissues in sheep that are not directly exposed to heavy metals. Because of the differences in anatomy between human and sheep placenta, the accumulation in the tissue of human fetuses should be extrapolated cautiously. However, there might be some clinical relevance for fertile aged women who are exposed to heavy metals, such as women who work in the metal industry or who have undergone joint replacement surgery.

Deposition of trace metals associated with atmospheric particulate matter: Environmental fate and health risk assessment

Anthropogenic and natural sources influence trace metals (TMs) bound to different sized particulate matter (PM) in dry and wet atmospheric deposition, which can create ecosystem and human health issues in the long run. Limited reviews are available summarizing worldwide concentrations in TMs in atmospheric PMs, their sources and pathways. Simultaneously, quantitative assessment of the potential human and ecosystem health risks imposed by the atmospheric particulate matter has not been adequately reviewed. Addressing this gap, here we review, the concentration of TMs in dry deposition mainly varies with the responsible sources, whereas, in wet deposition, it depends on the solubility of TMs. Other than deposition on impervious surfaces, the TMs incorporated PM can be deposited on biological agents. Health risk assessments show that ingestion and dermal contact pathways are more likely to cause health issues, however, the probability of occurring ingestion and dermal contact pathways is limited. Attention must be paid to the contribution from non-exhaust and exhaust vehicular emissions for TMs in atmospheric deposition, understanding their impact on stormwater management and urban agriculture. Behaviors of TMs in the atmosphere depends on many complex factors including origin, wind patterns, and weather conditions. Therefore, future research needs to be carried to model and predict the fate and transfer of TMs once they are generated through natural and anthropogenic sources. We believe that such research would allow establishing pollution control policies and measures in urban environments which will be critical to reduce the levels of TMs associated with atmospheric deposition in the environment.

The large-scale period of atmospheric trace metal deposition to urban landscape trees as a biomonitor

The large-scale period of atmospheric trace metal deposition to urban landscape trees as a biomonitor

A historical record of trace metal deposition in northeastern Qinghai-Tibetan Plateau for the last two centuries.

Owing to rapid socio-economic development in China, trace metal emissions have increased and lakes even in remote areas have experienced marked changes in the last century. However, there are limited studies revealing long-term trends, anthropogenic fluxes, and spatial characteristics of trace metals in lakes. In this study, we present a geochemical record from Lake Qinghai in the northeastern Qinghai-Tibetan Plateau and reconstruct trace metal pollution history during the last two centuries. The lacustrine sediment core was dated by 137Cs and 210Pb, and sediments deposited prior to the 1850s were selected as the pre-industrial background. Factor analysis and enrichment factor indicated Cr, Cu, and Ni generally originated from natural sources, while Cd, Pb, and Zn have been influenced by human contamination since the mid-1980s. The anthropogenic Cd mainly derived from non-ferrous metal smelting in Gansu Province, and fluxes to Lake Qinghai sharply increased after the mid-1980s. The metal reconstruction is similar to other lake sediment records from China and corresponds well with rapid economic development in China. The spatial pattern of anthropogenic Cd fluxes to lakes is primarily attributed to regional industrial emission, phosphate fertilizers, and manure applied in agriculture.

Trend analysis of anthropogenic activities affecting trace metals deposition in core sediments from the coastal and four rivers estuary of Sarawak, Malaysia.

This study reports the concentrations of trace metals in core sediments profile from the coastal and four rivers estuary in the Kuching Division of Sarawak, Malaysia, and the controlling mechanisms influencing their availability in sediments of the studied area. The bonding of trace metals with non-mobile fractions was confirmed with the sequential extraction. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) was used to measure the concentrations of the trace metals. Granulometric analyses were performed using normalized sieve apertures to determine the textural characteristics of the sediments. Enrichment factor was used to evaluate the level of metal enrichment. Heavy metals concentrations in sediment samples varied in the range: Pb (8.9-188.9mg/kg d.w.), Zn (19.4-431.8mg/kg d.w.), Cd (0.014-0.061mg/kg d.w.), Ni (6.6-33.4mg/kg d.w.), Mn (2.4-16.8mg/kg d.w.), Cu (9.4-133.3mg/kg d.w.), Ba (1.3-9.9mg/kg d.w.), As (0.4-7.9mg/kg d.w.), Co (0.9-5.1mg/kg d.w.), Cr (1.4-7.8mg/kg d.w.), Mg (68.8-499.3mg/kg d.w.), Ca (11.3-64.9mg/kg d.w.), Al (24.7-141.7mg/kg d.w.), Na (8.8-29.4mg/kg d.w.), and Fe (12,011-35,124.6mg/kg d.w.). The estimated results of the enrichment factor suggested enrichments of Pb, Zn, and Cu in all the core sediment samples and depths at all sites. The other trace metals showed no enrichments in almost all the sampled stations. Continuous accumulation of Pb, Zn, and Cu metals over a period can be detrimental to living organisms and the ecology. The results obtained from the statistical analyses suggested that the deposition of trace metals in the studied sites is due to anthropogenic inputs from the adjacent land-based sources.

Distribution, contamination status and bioavailability of trace metals in surface sediments along the southwest coast of India

This study investigates the influence of upwelling induced seasonal hypoxia in the sediment-water interface on the distribution, bioavailability and geochemical partitioning of selected trace metals in surficial sediments along the southwest coast of India based on two successive cruises. The first cruise was during the southwest monsoon (SWM) season when coastal waters exhibited intermittent bottom hypoxia due to upwelling. The second cruise during the northeast monsoon (NEM) season was characterised by a uniformly warm and well-oxygenated water column in the study region. The results showed that grain size, organic carbon and Fe are the major factors influencing the distribution of trace metals in the surface sediments. Based on the geochemical indices (contamination factor, enrichment factor and geo-accumulation factor), the study region appears to be moderately contaminated by Ni, Cr, and Pb. Based on the ecological risk assessment criteria, the enrichment of Pb, Cr and Ni may cause adverse effects on the benthic organisms. The fractionation studies demonstrated that the major pathway of metal deposition in the sediment is lithogenic. The data also showed that labile and organic fractions are the second dominant forms, while other fractions (exchangeable and carbonate) are insignificant. The consistency in the reactive Fe concentrations during SWM and NEM could be due to the absence of Fe dissolution in sediments under mild reducing condition (intermittent hypoxia). In addition to the above, an enrichment of organic matter also leads to increased deposition of trace metals in sediments. Conversely, the secondary phase enrichment factor and risk assessment code calculated based on the metal fractionation data indicated low risk and contamination along the southwest coast of India except for Zn that showed moderate contamination in some transects. The study provides the need for regular geochemical assessment to control metal pollution in the coastal environment, which is a major resource of the fishery.

Atmospheric trace metal deposition to remote Northwest Ontario, Canada: Anthropogenic fluxes and inventories from 1860 to 2010

National and global inventories of anthropogenic trace element emissions to air is a comparatively recent phenomenon (post-1993 in Canada) as is the monitoring of atmospheric metal deposition, the latter being also very spatially limited. Paleo-reconstructive methods offer a contiguous record of environmental contamination providing a needed framework to establish locally relevant “pre-industrial” (~natural) conditions which can be compare with relative and quantitative deviations away from reference conditions. In this study, we reconstruct the history of the long-range, anthropogenic sourced atmospheric trace element deposition to the remote region of Northwestern Ontario Canada (Experimental Lakes Area (ELA)) using dated sediment records from five lakes. Several elements are shown to be highly enriched in lake sediments relative to pre-1860 sediments (Antimony, Lead, Tellurium, Tin, Arsenic, Bismuth, Cadmium and Mercury) and moderately (Zinc, Tungsten, Thallium, Copper, Silver, Selenium, Nickel and Vanadium). Mean decadal anthropogenic atmospheric fluxes (mg m-2 yr-1) are reconstructed for 1860–2010 and compare well with available local (ELA), regional (NW Ontario Canada, N Michigan USA) monitoring data, as well as global assessments of anthropogenic contribution to atmospheric trace metal burdens. Quantitative paleo reconstructions of atmospheric contamination history using the collective signal from multiple lakes provide a rigorous methodology to assess trends, uncertainties, evaluation with monitoring data and, provide an opportunity to explore landscape processes of contaminant transport and storage. Further study of the latter is recommended to understand the latency of legacy anthropogenic contamination of the environment.

The legacy of trace metal deposition from historical anthropogenic river management: A regional driver of offshore sedimentary microbial diversity

River management, both modern and historical, have dramatically modified offshore environments. While numerous studies have described the modern impacts, very few have evaluated the legacies remaining from hundreds of years ago. Herein, we show trace metal enrichment in the surface sediment of the abandoned Yellow River Delta, hypothesized to be associated with ancient river management. Essentially, anthropogenic modification caused the river to shift, creating a 12.4×103 km2 area with elevated trace metals; characterized by clear metal deposition gradients. Geographical factors related to the ancient river mouth had the most significant influences on Zn (explained by distance to the river mouth, DTM) and Cd (DTM and sediment salinity), while the sediment absorptive capacity was associated with the reallocation of Cu (clay, silt, and iron), Ni (clay and iron), and Pb (silt and iron). Trace metal legacies showed stronger influences on prokaryotic diversity than on micro-eukaryotic diversity, with the former best described by changes in rare, rather than dominant families and classes, and explainable by an “overlapping micro-niche” model. The ancient river’s legacies provide evidence of longer-term human disturbance over hundreds of years; as its impacts on associated benthic microbiomes have led to lessons for modern-day waterway management of benthic ecosystems.

Trace metal pollution in the environment: a review

Trace metal (TM) pollution is a worldwide problem of late. The rapid pace of urban transition, globalization and industrialization has resulted in the deposition and conversion of trace metals in the environment. The effects of TM pollution have not only harmed the plants and crops, but also have posed severe health hazards in animals during recent years. The dynamics of inter- and intra-compartmental metal exchange and the involved kinetics have some role to play in mobility and availability of TM in a particular compartment and have impacted every sphere of environment. Technological advancements coupled with the bioremediation process are gaining popularity in addressing the growing issue nowadays. The current review therefore attempts not only to highlight the dynamics of TM stay in the environment but also to trace the fluctuation in the TM biogeochemical cycle with an analysis of compartmental source-sink of TM. It also attempts to expose the knowledge gap in addressing the effects of TM on pollution tolerance ability of green vegetation and the role of urban biotopes and green belts in mitigating TM pollution.

Atmospheric Trace Metal Deposition from Natural and Anthropogenic Sources in Western Australia

Aerosols from Western Australia supply micronutrient trace elements including Fe into the western shelf of Australia and further afield into the Southern and Indian Oceans. However, regional observations of atmospheric trace metal deposition are limited. Here, we applied a series of leaching experiments followed by total analysis of bulk aerosol samples to a unique time-series of aerosol samples collected in Western Australia to determine atmospheric concentrations and solubilities of Fe and V, Mn, Co, Zn, and Pb. Positive matrix factorisation analysis indicated that mineral dust, biomass burning particulates, sea salt, and industrial emissions were the major types of aerosols. Overall, natural sources dominated Fe deposition. Higher atmospheric concentrations of mineral dust (sixfold) and biomass burning emissions were observed in warmer compared to cooler months. The fraction of labile Fe (0.6–6.0%) was lower than that reported for other regions of Australia. Bushfire emissions are a temporary source of labile Fe and may cause a peak in the delivery of its more easily available forms to the ocean. Increased labile Fe deposition may result in higher ocean productivity in regions where Fe is limiting, and the effect of aerosol deposition on ocean productivity in this region requires further study.

Atmospheric Trace Metal Deposition near the Great Barrier Reef, Australia

Aerosols deposited into the Great Barrier Reef (GBR) contain iron (Fe) and other trace metals, which may act as micronutrients or as toxins to this sensitive marine ecosystem. In this paper, we quantified the atmospheric deposition of Fe and investigated aerosol sources in Mission Beach (Queensland) next to the GBR. Leaching experiments were applied to distinguish pools of Fe with regard to its solubility. The labile Fe concentration in aerosols was 2.3–10.6 ng m−3, which is equivalent to 4.9%–11.4% of total Fe and was linked to combustion and biomass burning processes, while total Fe was dominated by crustal sources. A one-day precipitation event provided more soluble iron than the average dry deposition flux, 0.165 and 0.143 μmol m−2 day−1, respectively. Scanning Electron Microscopy indicated that alumina-silicates were the main carriers of total Fe and samples affected by combustion emissions were accompanied by regular round-shaped carbonaceous particulates. Collected aerosols contained significant amounts of Cd, Co, Cu, Mo, Mn, Pb, V, and Zn, which were mostly (47.5%–96.7%) in the labile form. In this study, we provide the first field data on the atmospheric delivery of Fe and other trace metals to the GBR and propose that this is an important delivery mechanism to this region.