Trace Element Fluxes Research Articles

Trace element distribution, sources, toxicity risk characteristics associated with lacustrine groundwater discharge in boreal lakes: Implications for the eco-environmental security in the Yellow River Basin, China

Although the pollution of trace elements has been extensively studied, there is still a lack of comprehensive understanding regarding accumulation of these elements in lake ecosystems within the Yellow River basin, specifically the effects of lacustrine groundwater discharge (LGD) on trace elements. This study investigated the distribution, sources, and toxicity risks associated with 20 target trace elements (i.e., Li, Sc, Ti, V, Mn, Cr, Co, Ni, Cu, Zn, Rb, Y, Mo, Sb, Ba, W, Tl, Pb, U and Sr) in lake water (LW), groundwater (GW), and river water (RW) influenced by the LGD process in lake Ulansuhai and lake Daihai. The natural source is the primary contributor of trace elements in both LW and GW within the two lake basins, while industrial discharge plays a secondary role. The average LGD fluxes in lake Ulansuhai and Daihai basins were 6.39 × 105 m3/d and 1.07 × 105 m3/d, respectively. Additionally, the trace element fluxes from LGD in lake Ulansuhai (mean of 106,659.37 g/d) exceeded those observed in lake Daihai (mean of 3236.57 g/d). The overall toxicity risk was found to be higher in lake Ulansuhai (LW (17.36) > RW (16.81) > GW (12.76)) compared to lake Daihai (GW (10.43) > LW (9.10) > RW (4.63)). As well as the toxicity levels of trace elements in lake Ulansuhai were elevated compared to Daihai, which can be attributed to the influenced of ion compositions and water nutrients. Among them, Ca2+, Mg2+, and SO42+ were identified as key ions impacting the toxicity of trace elements in lake Ulansuhai. These findings provide crucial insights for targeted monitoring and mitigation of trace element pollution in the Yellow River basin’s lake ecosystems.

Variations of dissolved trace elements in precipitation and stream water in Japanese forest area: additional evidence of changing air pollution in the region

Trace elements released into the atmosphere by human activities, such as fossil fuel combustion, flow into forest ecosystems via wet and dry deposition and can flow out via mountainous stream water. The Kajikawa catchment site in Niigata Prefecture, located on the Sea of Japan side in central Japan, suffers from large amounts of acidic substance deposition due to its geographical conditions and meteorological seasonality and is affected by transboundary air pollution originating from the Asian continent due to northwesterly seasonal winds in winter. This study determined the concentrations of trace elements dissolved in precipitation and stream water to comprehensively evaluate the effects of transboundary air pollution on forest ecosystems. The results showed that the concentrations of trace elements and major inorganic ions in precipitation tended to be high in winter and low in summer. The fluxes of many trace elements also increased in winter, reflecting high precipitation amount. Except for Sr, the enrichment factors of the highly enriched trace elements did not show clear seasonality. Therefore, they were continuously influenced by anthropogenic activities. Furthermore, the stable Pb isotope ratio changed significantly during the observation period; however, this was not explained by seasonal changes. This study revealed that trace elements are transported to the Sea of Japan side in central Japan, especially in winter; however, their quantity and content change in response to changes in local and transboundary air pollution.Graphical

Climate Change and the Ob River: A Reassessment of Major and Trace Element Fluxes to the Arctic Ocean

Climate Change and the Ob River: A Reassessment of Major and Trace Element Fluxes to the Arctic Ocean

Long-term biochar application influences phosphorus and associated iron and sulfur transformations in the rhizosphere

The effects of long-term biochar application on soil phosphorus (P) flux across the root-soil interface and its availability in the rhizosphere of rice (Oryza sativa L) remain unclear. We used diffusive gradients in thin films (DGT), laser ablation-inductively coupled plasma mass spectrometry, and planar optode sensor techniques to characterize, in-situ, the 2D heterogeneity and dynamics of rhizosphere soil P, iron (Fe), sulfur (S) and trace element fluxes, dissolved oxygen and pH in paddy soil, after 10 years of biochar application. Compared to the control (no biochar applied), biochar applied at 4.5, 22.5 and 45.0 Mg ha−1 yr−1 decreased rhizospheric P fluxes by 11.6%, 63.4% and 79.0%, respectively. This decrease under biochar treatments was attributed to changed redox status of Fe and S caused by the lower dissolved oxygen in rhizosphere soil and increased soil pH induced precipitating of soluble inorganic P into insoluble P forms, such as calcium-bound and residual P that are unavailable for crop uptake. Higher application rate of biochar resulted in lower As and Pb fluxes in rice rhizosphere and their availabilities for crop uptake. The in-situ observation results in rice rhizosphere at μm-scale after 10 years of biochar addition directly showed the complex effects of long-term biochar and rhizosphere heterogeneity on P transformation process.Graphical

GEOTRACES: Fifteen Years of Progress in Marine Aerosol Research

The international GEOTRACES program has allowed unprecedented access to aerosols in the remote marine environment, moved the community toward standardized methodologies, and contributed to expanding research capabilities around the globe. A key aspect of GEOTRACES aerosol research is the quantification of deposition fluxes of trace elements and isotopes to the surface ocean as a source for biolimiting nutrients and anthropogenic contaminants. New methods for quantifying flux have been developed that leverage radioisotope tracers in the surface ocean to estimate bulk deposition rates on longer and more relevant timescales. The question as to what fraction of aerosols is soluble remains and is a source of continuing uncertainty. To that end, the community has engaged in coordinated study to address questions regarding the fractional solubility of aerosol trace elements and isotopes through the evaluation of widely used dissolution and extraction techniques. Intercalibration efforts, method standardization, and normalization of open-access data archiving will be the legacy of GEOTRACES-era aerosol research.

Dynamics of trace element enrichment in blue carbon ecosystems in relation to anthropogenic activities

Blue carbon ecosystems (BCEs), located at the land-sea interface, provide critical ecological services including the buffering of anthropogenic pollutants. Understanding the interactions between trace element (TE) loads in BCEs and socioeconomic development is imperative to informing management plans to address pollution issues. However, the identification of anthropogenic TE pollution in BCEs remains uncertain due to the complex geochemical and depositional processes and asynchronous socioeconomic development along continental coastlines. Here, priority-controlled TE (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) concentrations in the mangrove, saltmarsh and seagrass soils and plant tissues along the coastline of China were investigated while taking bare flat and upland soils as corresponding references. We demonstrate that blue carbon (BC) soils accumulated markedly higher concentrations of anthropogenic TEs than the reference soils, mainly due to the effective trapping of fine-grained particles and higher binding capacities. We identify the time course of TE changes over the last 100 years which shows increasing anthropogenic TE accumulation resulting from military activities (1930–1950) and the growth of industrial and agricultural activities (1950–1980), then reaching a maximum after national economic reform (1980–2000). Since the 2000s, decreases in TE discharges driven by socioeconomic reform and strengthened environmental regulations have led to a widespread reversal of anthropogenic TE concentrations in BC soils. Based on the current TE flux we estimate that BCEs can filter over 27.3–100 % of the TEs emitted in industrial wastewaters from Chinese coastal provinces annually. However, the uptake of these TEs by plants can be substantially reduced through various mechanisms offered by edaphic properties such as organic carbon, clay, and sulfur contents. Therefore, enhancing TE filtering while preventing TEs from entering food webs through the conservation and restoration of BCEs will greatly aid in achieving the sustainable development goal of the coastal zone under intensified anthropogenic activities.

Extreme hydrological regimes of a small urban river: impact on trace element partitioning, enrichment and fluxes.

The input of trace elements from a small urban river (Las River, Toulon, France) located on the northern Mediterranean coast was studied during both base flow and flood events. A 2-year monitoring period of water flow and suspended particulate matter (SPM) showed a typical Mediterranean hydrological regime: a strong increase in water flow and SPM during short flood periods. During the flood event, an up to 2-fold increase in dissolved trace element (DTM) concentrations and particulate trace element content in SPM (PTM) was observed compared to the baseline discharge. The enrichment factor of elements in the SPM ranges from low or moderate for Co, Ni and Cr (1.0-4.7) to extremely high for Cd (157). However, the enrichment factors decrease from base flow to flood, indicating a dilution effect with a large yield of weathering particles with higher particle size. The most significant total trace element loading occurred during flood, ranging from 78% for As and Ni to 91% for Pb, while PTM loading during flood ranged from 35% for As to 77% for Pb. The specific dissolved fluxes during the flood are significantly higher for Pb, Cu and Zn than in the surrounding rivers, indicating specificity in the catchment (lithology). This study shows the importance of monitoring the transport of pollutants through small urban rivers and their potential impact on the coastal region, especially when they enter small and closed bays, as a receiving pool.

Vertical distribution and trace element contamination in sediment cores affected by gold mining in Colombia

The vertical distribution, level of contamination, potential ecological risks, and historical fluxes of trace elements (Pb, As, and Hg) were evaluated from 210Pb-dated sediment cores in three different areas with gold mining impacts in northern Colombia: the Atrato River (AR), the Delicias Marsh (DM) and the Encaramada Marsh (EM). All cores spanned ∼100 years; the mass accumulation rates followed the order AR > DM > EM. The average trace elements concentrations in the sediment cores were: Pb 2.41 ± 0.72, As 0.65 ± 0.32, Hg 0.07 ± 0.02 μg g−1 in the Atrato River; Pb 23.49 ± 2.59, As 2.46 ± 0.88, Hg 0.10 ± 0.02 μg g−1 in the Delicias Marsh; and Pb 9.76 ± 4.18, As 2.44 ± 1.26, Hg 0.17 ± 0.06 μg g−1 in the Encaramada Marsh. Sediments are classified according to the contamination factor (CF) and geoaccumulation index (Igeo) as low to very highly contaminated. The Pollution load index (PLI) indicates environmental deterioration (PLI> 1), and the Sediment quality guidelines (SQGs) indicate that only Hg may produce adverse biological effects in the EM core. This study is an example of the reconstruction of temporal changes in pollution levels and impacts of potentially toxic elements caused by gold mining in remote ecosystems, which can be reproduced in other areas where environmental monitoring is scarce or non-existent.

Production, Concentration and Flux of Major and Trace Elements in Juniperus przewalskii Litter of the Qilian Mountains, China

Forest litter is an important guarantee for maintaining forest soil fertility and circulating material in forest ecosystems. The input of litter plays an important role in soil organic matter formation and biogeochemical cycles in forest ecosystems. However, the production and elements concentrations of Juniperus przewalskii (JP) litter in the Qilian Mountains are still unknown. In this study, we investigated the production of needle, branch and bark, cone, and impurity litters. We determined the concentrations and fluxes of major (K, Mg, Al, and Fe) and trace (Na, Mn, Zn, Cr, Ni, Cu, Pb, Co, Cd, and Ag) elements in needle litter of JP from September 2020 to August 2021. The results showed that the annual litter production was 4040.74 ± 495.96 kg ha−1 a−1. Needle and cone litters were the main components of the total litter production. The major elements (MEs) and trace elements (TEs) fluxes of litter were consistent with the litter production trend. The concentrations and fluxes of MEs and TEs in needle litter decreased in the order: K > Mg > Al > Fe > Na > Mn > Zn > Cr > Ni > Cu > Pb > Co > Cd > Ag. These results have important implications for understanding the migration processes of MEs and TEs in forest ecosystems of the Qilian Mountains.

Seasonal variation, contribution and dynamics of trace elements in the drainage basin and estuary of the Serinhaém river, BA

In the present study a mass balance calculation was used to quantify trace elements (Al, Ba, Cd, Cr, Cu, Fe, Mn, Pb, Ti, V and Zn) fluxes exported from the Serinhaém River estuary to the Atlantic Ocean. The studied elements exportation in the particulate fraction showed higher fluxes in the first sampling campaign and a high export rate to the Atlantic Ocean during this period. The physical-chemical parameters showed the highest values in sampling campaign 1. These variations are probably the cause of the different trace elements behavior in fluvial and estuarine areas, where removal and addition processes between particulate and dissolved phases took place, affecting distribution coefficient and fluxes to the Atlantic Ocean. EPA ecosystems present values in accordance with Brazilian legislation for pristine areas, however, monitoring programs must be carried out in the region, to avoid future environmental problems.

Nutrient and Trace Element Contributions from Drained Islands in the Sacramento–San Joaquin Delta, California

Inventorying nutrient and trace element sources in the Sacramento-San Joaquin Delta (the Delta) is critical to understanding how changes—including alterations to point source inputs such as upgrades to the Sacramento Regional Wastewater Treatment Plant (SRWTP) and landscape-scale changes related to wetland restoration—may alter the Delta’s water quality. While island drains are a ubiquitous feature of the Delta, limited data exist to evaluate island drainage mass fluxes in this system. To better constrain inputs from island drains, we measured monthly discharge along with nutrient and trace element concentrations in island drainage on three Delta islands and surrounding rivers from June 2017 to September 2018. These data were used to calculate island-level fluxes and then upscaled to estimate Delta-wide contributions from island drains. Based on these results, we present (1) new estimates of gross and net nutrient and trace element fluxes from Delta island drains, and (2) concomitant N stable isotope data to improve our understanding of island N cycling. Over 60% of nearly all island drainage gross nutrient and trace element loads occurred in winter and spring. Upscaled island drainage net annual total nitrogen (TN), total dissolved nitrogen (TDN), and NH4+ loads comprised an estimated 9%, 7%, and 4%, respectively, of annual inputs to this system in 2018, before the SRWTP upgrade. Under a post-upgrade scenario, we estimated net annual island drainage TDN contributions to increase to 11% and NH4+ contributions to 45% of total Delta inputs as the SRWTP NH4+ load diminished to near zero. Our results suggest that island drainage is a measurable N source that has likely become increasingly important now that the SRWTP upgrade is complete. With over 200 potential active outfalls, these inputs may affect aquatic biogeochemical cycling in many regions of the Delta, especially in areas with long residence times.

Dissolved trace element concentrations and fluxes in the Irrawaddy, Salween, Sittaung and Kaladan Rivers

The Irrawaddy (Ayeyarwaddy) and Salween (Thanlwin) globally rank among the largest rivers for supplying dissolved and particulate material to the ocean. Along with the Sittaung and Kaladan rivers they have societal importance to Myanmar in terms water sources and food production. Despite their importance for global biogeochemical cycles and the ~50 million people who live in their catchments, the chemistry of these rivers is poorly known. This study presents a comprehensive survey of dissolved (<0.22 μm) trace element concentrations (Sr, Fe, Al, Ba, Mn, V, Rb, Cu, Zn, As, Li, Ni, Mo, Cr, U, Pb, Sb, Co, Cs, Tl and Cd) at 38 locations within these river catchments, spanning a period of 2 years. The results highlight the global importance of the Irrawaddy and Salween rivers for trace element global biogeochemical cycles; contributing between 1 and 17 % of global dissolved riverine fluxes to the land-ocean interface for the studied elements. Area normalized dissolved fluxes in these catchments are ~2 to 10 times higher than global average values for most elements, consistent with high rates of chemical weathering. In general, anthropogenic activities have yet to significantly perturb dissolved trace element fluxes in these river systems. The presented dataset should therefore serve as a useful ‘natural’ baseline, against which future perturbations driven by climate change and/or the development of Myanmar's mining industry could be assessed. Exceptions to this include As in the Sittaung River and Sb, Zn, Pb and As in the Salween River, which may already be significantly impacted by anthropogenic inputs. The former represents a water quality issue of concern for public health, and so constraining the exact sources of As in the Sittaung River should be considered a priority for future research.

Vertical Flux of Trace Elements Associated With Lithogenic and Biogenic Carrier Phases in the Southern Ocean

AbstractTrace elements (TE) are tracers of multiple biotic and abiotic processes in the ocean and some of them are essential for marine life. Vertical export by particles is a major removal process of a large fraction of TE from the surface ocean. However, the seasonal export dynamics and its controlling factors, critical for the understanding of the internal TE cycling, remain poorly constrained. Here, we report and discuss the seasonal export of 15 TE in sinking particles collected by a sediment trap deployed in a highly productive region of the Southern Ocean. Basalt material was the main carrier phase for the export flux of 9 TE, and its dynamic was characterized by a strong decrease over time. TE export driven by biological carriers such as diatom spores and vegetative cells added pulsed seasonal dynamics to the lithogenic signal, while the contribution of fecal pellets was less variable over the season. For each TE, we were able to decipher the biological carrier phases that represent the most dominant export pathway. We discuss this partitioning with regards to the known metabolic functions of the different trace metals or TE of biological interest.

A Novel Tracer Technique to Quantify the Lithogenic Input Flux of Trace Elements to Qinghai Lake

Thorium (Th) isotopes were applied to quantify the contributions of lithogenic inputs to the Qinghai Lake (QHH). Concentrations of dissolved 232Th and 230Th were measured in 59 water samples collected from Qinghai Lake and its exogenous recharge rivers. There are significant differences in the concentration of 232Th of the sampled water in QHH that confirm the input of variable lithogenic material sources. The 230Th concentrations were used to calculate a scavenging residence time for Th, which was then applied to calculate the flux of dissolved 232Th by matching the measured concentrations of dissolved 232Th. Then the 232Th content of lithogenic material was used with the solubility of Th from the preliminary particle data from the Qinghai–Qaidam district. When using a Th solubility from particles of 1%, the fluxes of lithogenic material range from 0.03 to 25.25 g/m2/yr in the surface water, consistent with the flux results of settled particles from the previous study. When a large number of exogenous recharge rivers are mixed into the northwest basin of Qinghai Lake, the 232Th content and lithogenic flux of the lake water are mainly influenced by the type and content of the particles in the Buha and Shaliu rivers. Conversely, in south basin with limited recharging rivers, the 232Th content of the lake water away from the estuary is mainly influenced by atmospheric dust. Furthermore, based on the 230Th normalization method (combining with 232Th and τTh), the Buha and Shaliu rivers located in the northwest basin contribute about 90% of the detrital flux to the lake. The lithogenic flux in the southeast lake is dominated by dust flux with a value of ∼0.109 g/m2/yr, while the higher lithogenic flux at the bottom of the lake was likely generated by accumulated sinking particulate matter and resuspension of bottom sediments in September. This study confirms the utility of long-lived Th isotopes to quantify lithogenic inputs based on the Th content of the dissolved lake water and also supply deposition resolution information for QHH sediment records with some certainty.

Background concentrations and accumulation rates in sediments of pristine tropical environments

Trace elements are pollutants that can be released into the environment and cause adverse effects to ecosystems and human health. Once released into the environment, they can be dispersed by the wind and deposited in soils and sediments of both marine and inland aquatic systems. After entering the food web, trace elements can accumulate at harmful concentrations in higher trophic levels, including humans. Background concentrations of trace elements such as As, Co, Cr, Cu, Ni, Pb, V and Zn were measured in sediment cores from pristine marine environments near Panama. Temporal records of trace element concentrations and fluxes were determined for the period 1906 to 2017, using the 210Pb dating technique. Higher accumulation rates of trace elements since the 1950s were attributed to an increase in human activities and climate shifts. The enrichment factor in cores was < 2, indicating there has been no substantial human-mediated contamination, and that trace elements were derived mainly from lithogenic sources. Nevertheless, the Threshold Effect Level and Probable Effect Level (TEL and PEL) indicated that Cr, Cu, As, and Ni can pose a risk to biota and therefore to humans, even at natural concentrations. Periodic monitoring of marine environments is recommended to minimize human health risks, reduce detrimental effects to biota, and promote monitoring of human activities that have the potential to cause trace metal contamination.

Permafrost, geomorphic, and hydroclimatic controls on mercury, methylmercury, and lead concentrations and exports in Old Crow River, arctic western Canada

Permafrost degradation has been implicated as a dominant control on riverine mercury fluxes in arctic watersheds. However, the importance of permafrost thaw on fluxes of mercury, methylmercury, and trace metals such as lead—relative to other geomorphic and hydroclimatic controls—remains unclear. To investigate these controls, we conducted ~weekly water chemistry sampling at the mouth of the Old Crow River, a pristine, 13,900 km2 watershed in arctic Canada underlain entirely by continuous permafrost. Mercury, methylmercury, and lead concentrations were low on average (~ 2 ng/L, 0.04 ng/L, 0.8 μg/L, respectively), and peaked during the freshet (< 7 ng/L, 0.11 ng/L, 11 μg/L, respectively). The trace elements had strong positive association with suspended sediment, and were mobilized during periods of high discharge (freshet and rainfall). Summer time sampling of major tributaries and at thaw slumps revealed that trace element concentrations were not elevated downstream of thaw slumps or thermokarst lakes across the watershed. Ubiquitous thermokarst in the Old Crow basin did not result in anomalously high catchment-scale concentrations, fluxes, and yields of mercury, methylmercury, nor lead. Rather, warming-driven increases in precipitation and elevated discharge during freshet and rainfall promoted permafrost and talik river bank erosion. This erosion, which was controlled by landscape and geomorphic factors, supplied short-lived increases in particle-bound trace element flux.

Dissolved Trace Element Concentrations and Fluxes in the Irrawaddy, Salween, Sittaung and Kaladan Rivers

Dissolved Trace Element Concentrations and Fluxes in the Irrawaddy, Salween, Sittaung and Kaladan Rivers

Hydrobiogechemical interactions in the hyporheic zone of a sulfate-impacted, freshwater stream and riparian wetland ecosystem.

Coupled abiotic and biotic processes in the hyporheic zone, where surface water and groundwater mix, play a critical role in the biogeochemical cycling of carbon, nutrients, and trace elements in streams and wetlands. Dynamic hydrologic conditions and anthropogenic pollution can impact redox gradients and biogeochemical response, although few studies examine the resulting hydrobiogeochemical interactions generated within the hyporheic zone. This study examines the effect of hyporheic flux dynamics and anthropogenic sulfate loading on the biogeochemistry of a riparian wetland and stream system. The hydrologic gradient as well as sediment, surface water, and porewater geochemistry chemistry was characterized at multiple points throughout the 2017 spring-summer-fall season at a sulfate-impacted stream flanked by wetlands in northern Minnesota. Results show that organic-rich sediments largely buffer the geochemical responses to brief or low magnitude changes in hydrologic gradient, but sustained or higher magnitude fluxes may variably alter the redox regime and, ultimately, the environmental geochemistry. This has implications for a changing climate that is expected to dramatically alter the hydrological cycle. Further, increased sulfate loading and dissolved or adsorbed ferric iron complexes in the hyporheic zone may induce a cryptic sulfur cycle linked to iron and carbon cycling, as indicated by the abundance of intermediate valence sulfur compounds (e.g., polysulfide, elemental sulfur, thiosulfate) throughout the anoxic wetland and stream-channel sediment column. The observed deviation from a classical redox tower coupled with potential changes in hydraulic gradient in these organic-rich wetland and stream hyporheic zones has implications for nutrient, trace element, and greenhouse gas fluxes into surface water and groundwater, ultimately influencing water quality and global climate.

Trace element fluxes during the "Anthropocene" in a large South American industrial and port area (Santos and São Vicente estuarine system, SE, Brazil).

The worldwide evidence of human activities on the environment led the scientific community to recognize a new geologic time unit known as the "Anthropocene." Since the twentieth century, urbanization and industrialization needs driven by population and economic growth have impacted several ecosystems including the estuaries. To assess the contamination, provenance, and fluxes of trace elements (As, Cr, Cu, Ni, Pb, Sc, V, and Zn) over the last century, a geochemical and chemometric technique was employed in sediment cores of an industrial and port region of international importance, the Santos and São Vicente Estuarine System (SSVES). The results indicated low contamination, with the highest enrichment factors (EFs) for Cu (EF = 3.1), Pb (EF = 2.7), Zn (EF = 2.4), and As (EF = 2.3) found next to the harbor area. The Pre-industrial records confirm the relatively high concentrations of As and its naturally enriched occurrence on the Brazilian shelf. Sediment accumulation rates and trace element fluxes showed a general increase over the years, since the early 1960s, associated with the "Great Acceleration" of the mid-twentieth century. These alterations are human-induced and include urbanization and industrialization. Nonetheless, as the contents and enrichment of trace elements indicate that the region is not severely polluted, we hypothesize that the contamination in the SSVES is likely related to the drainage and erosion of the urbanized adjacent area, rather than direct disposal of inorganic contaminants from the industrial activity.

Settling particles in the Golden Horn estuary, Sea of Marmara: Concentrations and fluxes of trace elements and radionuclides

The Golden Horn estuary, which is located along the Sea of Marmara adjacent to the center of Istanbul, has been heavily polluted for centuries due to concentrated shipping activities, and a legacy of industrial and municipal discharges. The municipalities and associated governments have implemented environmental rehabilitation projects for over 25 years. However, the Golden Horn estuary is still exposed to various pollutants such as vehicle emissions including from fossil-fuel combustion. In this study, two sediment traps were deployed in the Golden Horn estuary to obtain information on settling particle (SP) composition and fluxes, trace element and radionuclide concentrations, and fluxes thereof. Conventional sediment traps (Trap-1 and Trap-2) were installed side-by-side, at a depth of 15-m and moored for 18 months during which time the sediment traps were periodically sampled. Over this time period, settling particle fluxes (SPFs) were calculated. The concentrations and fluxes of radionuclides (137Cs, 226Ra, 228Ra, 210Po, and 210Pb) and trace elements (Ag, Al, As, Cd, Cu, Fe, K, Mn, Mo, Ni, Pb, Sb Sn, Tl, V, and Zn) were determined in SPs for each sampling period. Normalized enrichment factors (EF) and a Geoaccumulation Index (Igeo) showed that Ag, Cd, and Pb were statistically enriched in SPs. Together, the results of this study show that the Golden Horn estuary is still enriched in some environmental pollutants which could be a source term for the water column and associated marine animals.