Source identification of heavy metal contamination using metal association and Pb isotopes in Ulsan Bay sediments, East Sea, Korea

Impact of industrial and traffic changes on atmospheric dust and trace element deposition in Didouche Mourad, Algeria

Given the critical environmental and health implications of atmospheric deposition, this study examined the long-term variations in atmospheric dust and trace element deposition in Didouche Mourad, Algeria, from 21/6/2002-20/6/2003 (P1) to 21/12/2017-20/12/2018 (P2), a period marked by significant industrial and infrastructural changes. Using a network of 10 sampling sites, we conducted two-year-long measurement campaigns to quantify the deposition rates of dust and seven trace elements (Pb, Mn, Cr, Ni, Cu, Co, and Cd). We used a combination of techniques, including spatiotemporal analysis and enrichment factor calculations, to understand how local changes affect air quality. The results showed a substantial reduction in the average cross-site deposition rates between the two periods: dust (61 %), Co (98 %), Cd (97 %), Pb (90 %), Mn (76 %), Cu (62 %), Ni (51 %), and Cr (50 %). This improvement was attributed to specific interventions, including new road construction and upgraded industrial filtration systems. Shifts in seasonal deposition patterns were observed, with elevated levels in summer and autumn during 2002-2003, changing to peaks in summer and winter in 2017-2018. Four main pollution sources were identified through PCA for each period: agricultural activity (P1), soil dust (P2), Saharan dust (P1, P2), vehicular emissions (P1), cement plant (P2), and industrial processes (P1, P2). This study provides crucial insights into the long-term effectiveness of air quality management strategies in industrial areas and offers a model for assessing and mitigating atmospheric pollution in similar global settings. The comprehensive approach and extended timeframe of this study significantly contribute to our understanding of the complex dynamics of atmospheric deposition in evolving urban-industrial environments.

Intensification of sediment flux by wind-induced residual currents in a heavily contaminated, micro-tidal bay

Wind-induced currents are the major forces responsible for sediment resuspension and transport in micro-tidal bays. To reveal the impact of wind-induced residual currents on the sediment flux, in-situ measurements using acoustic Doppler current profilers (ADCPs) were conducted at two mooring stations in a heavily contaminated, micro-tidal Onsan Bay. During the mooring period, the suspended sediments at both stations were transported seaward (landward) at the surface (bottom) layer mainly through the residual currents (mean-flow flux Fmean: > 70 % of the total flux). Under northerly winds, the landward bottom residual currents at both stations strengthened, resulting in the "intensification" of landward Fmean. This suggests that the northerly winds might be a primary factor intensifying the landward sediment fluxes, potentially resulting in the increased sediment deposition into the bay. The findings provide insights into managing sedimentation in contaminated coastal bays and highlight the importance of wind effects on sediment transport in micro-tidal bays.

Assessment of particulate Zn and Pb sources in the Orne watershed (Northeast France) using geochemical tools

The Orne River, a tributary of the Moselle River, was highly impacted by industrial activities for more than one century. Land use along the Orne River is highly contrasted, with local specificity from its source to its junction with the Moselle River. The intense industrial activity left behind tons of steelmaking wastes (SMW) on the land surface and within the Orne riverbed. To assess the sources of particulate Zn and Pb transported as suspended sediment in the Orne River, different sets of samples from likely Zn- and Pb-bearing particle sources within the Orne watershed were collected. Three sets of samples were taken from potential sources representing detrital, urban, and inherited industrial particles. Mineralogy, element contents, and Zn and Pb isotope compositions were obtained to characterize and reveal the fingerprint of each set of samples. Soil samples were collected on distinct geomorphological areas characterized by different soil types and land uses. They all display detrital minerals assigned to the geological background. Urban dusts and steelmaking residues display specific mineral phases (sulfates and iron oxides, respectively). Element compositions present strong discrepancies between the distinct sets of samples. SMWs are particularly enriched in Fe, Zn, and Pb. Concerning isotopic composition, SMWs exhibit δ66Zn values ranging from - 0.67 to 1.66‰. Urban samples display δ66Zn values between - 0.11 and 0.13‰, and soils present δ66Zn values between - 0.24 and 0.47‰. The 206Pb/204Pb ratio was estimated to range from 17.550 to 18.807 for soils, from 17.973 to 18.219 for urban samples, and from 18.313 to 18.826 for SMWs. For each of the three sets of samples (soils, urban, industrial), variations of geochemical fingerprint were observed. For soils, the relatively large variations of Zn and Pb isotopic compositions were attributed to distinct land use and the contribution of atmospheric deposition. For industrial samples, the variations were more intense and may be attributed either to distinct industrial processes in the production of pig iron or to distinct furnace-flume treatment modes. The three sets of samples (urban, industrial, and detrital) could be distinguished based on Zn and Pb contents and isotopes. Finally, this study not only highlighted the sources that released particulate Zn and Pb into the Orne River system, it also demonstrated that urban particles are well defined in terms of Zn and Pb isotopic signatures, and those isotopic signatures could be extrapolated to other case studies.

Spatio-temporal accumulation and sources of anthropogenic Pb in Ulleung Basin sediments, East/Japan Sea, based on stable Pb isotope ratios

The accumulation, pathways, and sources of anthropogenic lead (Pb) in Ulleung Basin sediments were investigated based on the temporal and spatial variations in the Pb concentration and stable Pb isotopes for 21 dated box core sediments collected from the shelf, slope, and basin in the southern East/Japan Sea. Leached (1 M HCl) Pb concentrations and isotope ratios (207Pb/206Pb and 208Pb/206Pb) were nearly constant before 1930, but have increased rapidly until the present. The primary source of anthropogenic Pb is considered to be atmospheric deposition, showing the signature of a mixture of leaded gasoline and coals, which was the major anthropogenic source in the basin. However, after the 1990s, anthropogenic Pb from dumping materials added as much as 10-25% to the slope sediment and has been spreading out from the water column accompanied by the movement of the East Sea Intermediate Water. In shelf areas, inputs from nonferrous refineries in the coastal industrial complexes play an important role in pollution from anthropogenic Pb.

Influence of land cover, point source pollution, and granularity on the distribution of metals, metalloids, and organic matter in the river and stream sediments in the Republic of Korea

With increasing anthropogenic activities, rivers and streams have become vulnerable to pollution; therefore, monitoring potential contaminants and the pollution status of surface sediments is essential. This study analyzed the concentrations of organic matter, metals, and metalloids; indices for organic, metal, and metalloid pollution; and ecological risk in river and stream sediments at 82 stations across Korea in 2017, 2018, and 2020. We performed bootstrapped analysis of variance, principal component analysis, and cluster analysis and used a structural equation model (SEM) to investigate spatiotemporal changes in the pollution status, main pollutant chemicals, and the exogenous factors affecting pollution status. The results suggest no significant differences in any of the twelve single chemical parameters and three pollution indices across the surveyed years. Metals, metalloids (Cu, Zn, Pb, and Hg), and organic matter with nutrients were identified as the main pollutants. The SEM demonstrated the significant influence of pollution sources-water used for industrial purposes, landfill wastewater discharge, and industrial wastewater discharge-on organic pollution, metal and metalloid pollution load, and environmental toxicity. This study identified consistently polluted areas, proposed additional management policies and stricter regulations on major point pollution sources rather than on broader land-use types, and suggested the combined consideration of metal toxicity risk with nutrient accumulation for future risk assessments.

Characterization of microalgal toxicants in the sediments from an industrial area: Application of advanced effect-directed analysis with multiple endpoint bioassays

Microalgal toxicants in sediments from an industrialized area (Ulsan Bay) in South Korea were identified using effect-directed analysis (EDA) with full-scan screening analysis (FSA) and microalgal bioassays with multiple endpoints. The growth rate and cell viability of three microalgae (Isochrysis galbana, Dunaliella tertiolecta, and Phaeodactylum tricornutum) were strongly inhibited following exposure to raw organic extracts of sediments from Site D5 (Woehang River). The polar fraction separated using a silica gel column significantly inhibited growth rate, esterase activity, cell membrane intensity, and chlorophyll a autofluorescence. In comparison, non- and mid-polar fractions induced non-toxic or esterase inhibition. Target toxicants, such as polycyclic aromatic hydrocarbons, styrene oligomers, and alkylphenols, were detected at low concentrations (450, 79, and 98 ng g^-1 dw, respectively) in the sediment of D5, indicating the presence of unmonitored toxicants. FSA was performed for the polar fraction using LC-QTOFMS, and 31 candidates of toxicants were selected. Toxicological confirmation was conducted for 7 candidates for which standards are available. Out of these, 2-nitrophenol, 3-nitrophenol, and 4-nitrophenol showed significant microalgal toxicity; however, these compounds did not fully explain the induced toxicity. Overall, combining EDA and FSA with multiple endpoint bioassays demonstrated the benefits of characterizing the microalgal toxicants in the environments.

Monitoring and risk assessment of arsenic species and metals in the Taehwa River in Ulsan, the largest industrial city in South Korea

Toxic metals, As, and As species were monitored at 18 stations along the Taehwa River in Ulsan. The concentrations of Ni (98.4 μg/L) at stations near industrial areas were relatively high and exceeded the WHO's drinking water guidelines (70 μg/L) and the US EPA's national recommended water quality criteria (52 μg/L). Principal component analysis and cluster analysis revealed that Ni and Cu were more strongly influenced by industrial activity than other elements in the Taehwa River estuary. Analysis of the hazard quotient (HQ) and cancer risk (CR) indicated that As was of the greatest non-carcinogenic and carcinogenic concern. Notably, the HQ and CR of As^III at suburban stations exceeded 1 and 10^-4, respectively, representing a significant health risk. These results indicate that As speciation testing is crucial for the development of effective management plans based on health risks because the toxicity and mobility of As depend on its chemical form.

Differences in macroelements, trace elements and toxic metals between wild and captive-reared greater amberjack (Seriola dumerili) from the Mediterranean Sea

Despite its legislative regulation and control, the quality and safety of aquatic products is somewhat questioned due to the potential bioaccumulation of pollutants. The elements (Al, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, Pb, Sr, V and Zn) were determined in the liver and muscle of wild and captive-reared Seriola dumerili with the aim of studying possible differences between origins, and sex-related variations. Additionally, the dietary intake of these elements derived from its consumption was also evaluated. Most of the elements and metals analyzed were accumulated to a higher extent in the liver of wild specimens whereas lower differences were observed in the muscle. Overall, the elements and metal composition of wild females strongly differed from that of captive-reared specimens probably related to the mobilization of nutrients for the spawning season in wild mature females, which were greater than their captive-reared counterparts.

Source Identification of Cd and Pb in Typical Farmland Topsoil in the Southwest of China: A Case Study

Cd and Pb in farmland topsoil are controlled by many factors. To identify the source of potential toxic metals in the farmland topsoil around Mianyuan River, the chemical analysis and multivariate statistical analysis are performed in this study. The results indicate the following: (1) The concentration of Cd and Pb in soil exceed the background value of Chinese soil elements. (2) Cd is significantly enriched in the whole region and Pb is locally enriched, both of them are more or less influenced by human activities. (3) The contents of Cd and Pb increase significantly following the flow direction of river. (4) Pb isotope analysis indicates that the main source of Pb in the soil include the air dust, coal and phosphate plant, and the contribution of them decreases successively. (5) Linear correlation analysis and principal component analysis show that the main sources of Cd in the soil are mining phosphate rock, air dust, phosphate plant and coal mining.

Recent history of metal contamination in the Fangcheng Bay (Beibu Gulf, South China) utilizing spatially-distributed sediment cores: Responding to local urbanization and industrialization

In this study, the recent history of heavy metal pollution in the Fangcheng Bay (South China) was reconstructed utilizing three ²¹⁰Pb-dated sediment cores. The metal concentration profiles display three trends since the 1970s and clearly reflect local urbanization and industrialization. The metals in the Fangcheng Bay started to accumulate in the 1970s but remained relatively low until the 1990s which corresponds to the slow urbanization and industrialization. The metal accumulation in the eastern Fangcheng Bay peaked in the early 2000s following the steep increases in accordance with the rapid industrialization of the eastern Fangcheng Bay where the core HSL was collected. Conversely, the heavy metal profiles in the western Fangcheng Bay present slight step increases in the early 2000s followed by a dramatic metal enrichment in the late 2000s; the expansion of these two cores, which begins in the early 2000s, concurs well with the rapid local urbanization and industrialization.

Newly Identified AhR-Active Compounds in the Sediments of an Industrial Area Using Effect-Directed Analysis

Effect-directed analysis was used to identify previously unidentified aryl hydrocarbon receptor (AhR) agonists in sediments collected from a highly industrialized area of Ulsan Bay, Korea. The specific objectives were to (i) investigate potent fractions of sediment extracts using the H4IIE-luc bioassay, (ii) determine the concentrations of known AhR agonists (polycyclic aromatic hydrocarbons (PAHs) and styrene oligomers (SOs)), (iii) identify previously unreported AhR agonists in fractions by use of GC-QTOFMS, and (iv) evaluate contributions of individual compounds to overall AhR-mediated potencies, found primarily in fractions containing aromatics with log K_ow 5-8. Greater concentrations of PAHs and SOs were also found in those fractions. On the basis of GC-QTOFMS and GC-MSD analyses, 16 candidates for AhR agonists were identified in extracts of sediments. Of these, seven compounds, including 1-methylchrysene, benzo[j]fluoranthene, 3-methylchrysene, 5-methylbenz[a]anthracene, 11H-benzo[b]fluorene, benzo[b]naphtho[2,3-d]furan, and benzo[b]naphtho[2,1-d]thiophene, exhibited significant AhR activity. Relative potency values of newly identified AhR agonists were found to be greater than or comparable to that of benzo[a]pyrene (BaP). The potency balance analysis showed that newly identified AhR agonists explained 0.07-16% of bioassay-derived BaP-EQs. These chemicals were widely distributed in industrial sediments; thus, it is of immediate importance to conduct studies on sources and potential effects of those chemicals.

Heavy metals and PAHs in an open fishing area of the East China Sea: Multimedia distribution, source diagnosis, and dietary risk assessment

This study involved a comprehensive investigation of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in seawater, sediments, and seafoods in an important open fishing area connecting China and Japan. Cu, Pb, Cd, Cr, As, and PAHs were detected in all the studied environmental media. Specifically, Pb and low molecular weight PAHs (LMW-PAHs) were observed at high levels, due to intensive ship activities and accidental crude oil spills. Additionally, source diagnosis of PAHs suggested a potential impact from combustion. Bioaccumulation factors (BAFs) and biota-sediment accumulation factors (BSAF) suggested moderate or low bioaccumulation potentials of the analytes from water and sediments, respectively. Noncarcinogenic risk assessment, based on target hazard quotients (THQs), indicated a potential low risk by consuming the studied seafoods, while the incremental lifetime carcinogenic risk assessment (ILCRs) suggested "acceptable risk" or "potential risk." However, it should be noted that there have been possibilities that the carcinogenic risk could be elevated due to bioaccumulation of the PAHs in the seafoods after long-term exposure. In summary, it is necessary to evaluate the seafood security carefully in this open fishing area due to the potential health risks.

Major ion and dissolved heavy metal geochemistry, distribution, and relationship in the overlying water of Dongting Lake, China

Deteriorating lake water quality has become a serious environmental issue around the globe. Heavy metals dissolved in the overlying water of lakes are notably more toxic than those found in lake sediment. Given this, we sought to better understand the characteristics of particular major ion and dissolved heavy metal in Dongting Lake-the second largest freshwater lake in China. Overlying water samples were collected from Dongting Lake to investigate the major ion geochemistry and to examine the relationship between the major ions and dissolved heavy metals. Chemical analysis of the overlying water showed that the average cation concentration was the highest for Ca²⁺, followed by Mg²⁺, Na⁺, and K⁺. Similarly, the highest anion concentration was SO₄^2-, followed by Cl^-, NO₃^-, and HCO₃^-. Total dissolved solids in the overlying water of Dongting Lake ranged from 66.19 to 159.20 mg/L, with an average value of 93.13 mg/L. The predominant hydrochemical type was Ca-SO₄. The mean concentrations of dissolved heavy metal in both surface and deep waters decreased in the following order: Zn > Cr > Ni > Cu > Pb > Cd. Importantly, all of the selected heavy metals tested in the overlying water were lower than the corresponding toxicity reference values. Co-occurrence network analyses were performed and compared the correlations between all measured major ions and heavy metals. Results of the subsequent principal component analyses revealed that heavy metal levels in the aquatic environment primarily originated from natural processes and were enhanced by anthropogenic activities.

Effects of polluted seawater on oxidative stress, mortality, and reproductive parameters in the marine rotifer Brachionus koreanus and the marine copepod Tigriopus japonicus

Although many efforts have been made to understand the toxic effects of metals in aquatic invertebrates, there are limited data regarding metal toxicity in natural ecosystems, as most previous studies were conducted under controlled laboratory conditions. To address this data gap, we analyzed toxic effects and molecular responses in the marine rotifer Brachionus koreanus and the marine copepod Tigriopus japonicus following in vivo exposure to a seawater sample collected from a polluted region in South Korea. Inductively coupled plasma-mass spectrometry (ICP-MS) analysis of the field seawater sample found a variety of metals. Exposure to several dilutions of the field seawater sample impacted several endpoints in both species, including mortality and reproduction. Interestingly, the rotifer and copepod test species exhibited different patterns of effects on reactive oxygen species (ROS) and antioxidant enzymatic activities, suggesting that different regulatory mechanisms may be activated in the two species in response to exposure to toxic chemicals. Our study helps to better understand the defense mechanisms activated in aquatic invertebrates in response to metal-induced oxidative stress induced by contaminated seawater.

Major threats of pollution and climate change to global coastal ecosystems and enhanced management for sustainability

Coastal zone is of great importance in the provision of various valuable ecosystem services. However, it is also sensitive and vulnerable to environmental changes due to high human populations and interactions between the land and ocean. Major threats of pollution from over enrichment of nutrients, increasing metals and persistent organic pollutants (POPs), and climate change have led to severe ecological degradation in the coastal zone, while few studies have focused on the combined impacts of pollution and climate change on the coastal ecosystems at the global level. A global overview of nutrients, metals, POPs, and major environmental changes due to climate change and their impacts on coastal ecosystems was carried out in this study. Coasts of the Eastern Atlantic and Western Pacific were hotspots of concentrations of several pollutants, and mostly affected by warming climate. These hotspots shared the same features of large populations, heavy industry and (semi-) closed sea. Estimation of coastal ocean capital, integrated management of land-ocean interaction in the coastal zone, enhancement of integrated global observation system, and coastal ecosystem-based management can play effective roles in promoting sustainable management of coastal marine ecosystems. Enhanced management from the perspective of mitigating pollution and climate change was proposed.

An optimized method for the analysis of cyclic and linear siloxanes and their distribution in surface and core sediments from industrialized bays in Korea

Environmental contamination by siloxanes is a matter of concern due to their widespread consumption in personal care as well as industrial products and potential toxicity. Nevertheless, methods for simultaneous determination of cyclic and linear siloxanes in sediment are lacking. In this study, we developed an optimized analytical method to determine cyclic and linear siloxanes based on gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). This method was applied to determine concentrations of 19 siloxane compounds in surface and core sediments from industrialized bays in Korea to assess contamination status, spatial distribution, and historical trends. Total concentrations of siloxanes ranged from 15.0 to 11730 (mean: 712) ng/g dry weight, which were similar to or higher than those reported in other countries. The highest concentrations of siloxanes were found in rivers/streams that discharge into coastal waters and bays close to industrial complexes, indicating that industrial activities are major sources of siloxane contamination. Cyclic siloxanes such as D5 and D6 were predominant in surface and core sediments. A significant correlation existed between the concentrations of cyclic and linear siloxanes, suggesting similar sources in the marine coastal environment. The historical record of cyclic siloxanes in core sediments revealed a clear increasing trend since the 1970s. This finding is consistent with the history of local industrialization and global production of siloxanes. This is the first study of historical trends in siloxanes in the coastal environment.

Isotope Tracing of Long-Term Cadmium Fluxes in an Agricultural Soil

Globally widespread phosphate fertilizer applications have resulted in long-term increases in the concentration of cadmium (Cd) in soils. The accumulation of this biotoxic, and bioaccumulative metal presents problems for the management of soil-plant-animal systems, because the magnitude and direction of removal fluxes (e.g., crop uptake, leaching) have been difficult to estimate. Here, Cd isotopic compositions (δ^114/110Cd) of archived fertilizer and soil samples from a 66 year-long agricultural field trial in Winchmore, New Zealand, were used to constrain the Cd soil mass balance between 1959 and 2015 AD, informing future soil Cd accumulation trajectories. The isotopic partitioning of soil Cd sources in this system was aided by a change in phosphate source rocks in 1998 AD, and a corresponding shift in fertilizer isotope composition. The dominant influence of mixing between isotopically distinct Cd end-members was confirmed by a Bayesian modeling approach. Furthermore, isotope mass balance modeling revealed that Cd removal processes most likely increased in magnitude substantially between 2000 and 2015 AD, implying an increase in Cd bioaccumulation and/or leaching over that interval. Natural-abundance stable isotopes are introduced here as a powerful tool for tracing the fate of Cd in agricultural soils, and potentially the wider environment.

Assessment of heavy metal contamination in sediments along the coast of South Korea using Cs-normalized background concentrations

To assess metal contamination in sediments along the entire coastline of South Korea, we estimated the regional background concentrations of metals and assessed the degree of contamination. Major and heavy metal concentrations, grain sizes, and sedimentation rates were analyzed. Regional background concentrations were established by identifying uncontaminated sediments in the cores, using first-order linear regression of background concentration against Cs concentration. The metal contamination of surface sediments was assessed using Korean sediment quality guidelines and a modified geo-accumulation index (I_geo^⁎). In total, 14 sediments exceeded the threshold and probable effects level for Cu, 39 for Zn, and 19 for Pb. Based on I_geo^⁎, most sediments were not contaminated with Cr, Co, or Ni, whereas 31% (Zn), 34% (Cu), and 43% (Pb) in total surface sediments were contaminated with other metals; 14% of total sediments were contaminated with Cu, and those above class 2 were concentrated near industrial and shipyard facilities.

Heavy metal contamination status and source apportionment in sediments of Songhua River Harbin region, Northeast China

The Songhua River represents one of the seven major river systems in China. It flows through Harbin city with 66 km long, locating in the northern China with a longer winter time. This paper aimed to study concentration distributions, stability, risk assessment, and source apportionment of heavy metals including chromium (Cr), cadmium (Cd), lead (Pb), mercury (Hg), arsenic (As), copper (Cu), zinc (Zn), and nickel (Ni) in 11 selected sections of the Songhua River Harbin region. Results showed that Cr, Cd, Pb, Hg, and As exceeded their respective geochemical background values in sediments of most monitoring sections. Compared with other important rivers and lakes in China, Cr, Hg, Cd, and As pollutions in surface sediments were above medium level. Further analysis of chemical speciation indicated that Cr and As in surface sediments were relatively stable while Pb and Cd were easily bioavailable. Correlation analysis revealed sources of these metals except As might be identical. Pollution levels and ecological risks of heavy metals in surface sediments presented higher in the mainstream region (45° 47.0' N ~ 45° 53.3' N, 126° 37.0' E ~ 126° 42.1' E). Source apportionment found Hejiagou and Ashi River were the main contributors to metal pollution of this region. Thus, anthropogenic activities along the Hejiagou and Ashi River should be restricted in order to protect the Songhua River Harbin region from metal contamination.

Tracing metal sources in core sediments of the artificial lake An-Dong, Korea: Concentration and metal association

The concentration and source of trace metals in the artificial lake An-Dong, which has widespread abandoned mines and a Zn smelter upstream of the drainage basin, were investigated. Soils (18ea), stream waters (15ea) and sediments (15ea) in the main channel and five tributaries downstream of the Zn smelter towards the lake (~ 50 km downstream) were collected. And two core sediments were also taken from the middle of the lake. All samples were analyzed for trace metals in bulk and in a 1N HCl-leached fraction. Although the soil and stream sediments consisted mostly of sand-sized grains, concentrations of metals (Cu, Zn, Cd and Pb) were very high in all samples, including soils, stream waters and sediments at sites near the Zn smelter. However the metal concentrations decreased rapidly downstream, suggesting that the area of impact of the smelter lies within 5 km. Highly enriched metal concentrations were also found in dated core sediments from the lake; while the highest concentrations of Co, Ni, As, Cu, Zn, Cd and Pb were detected in the bottom of the sediment core (dated 1980) they decreased towards 2000, and only Cu, Zn and Cd concentrations increased again in present-day samples. Since the temporal variation in metal concentrations appeared consistent with historical variation in ore mining and Zn smelter production rates, a model combining the production rates of each was developed, which estimated 3%, 12% and 7% contributions from Zn smelter compared to ore mining production rate to levels of Cu, Cd and Zn, respectively, suggesting the different pathways by different sources. In addition, analysis of Cd/Zn and Cu/Zn ratios showed that contamination from ore mining decreased from 1980 to 2000, and smelting processes were most likely responsible for metal enrichment (Cu, Cd and Zn) from 2000 to the present.