The effects of the San Francisco Bay plume on trace metal and nutrient distributions in the Gulf of the Farallones

The distributions of particulate elements (Al, P, Mn, Fe, Co, Cu, Zn, Cd, and Pb), dissolved trace metals (Mn, Fe, Co, Cu, Zn, and Cd), and dissolved nutrients (nitrate, phosphate, and silicic acid) were investigated in the Gulf of the Farallones, a region of high productivity that is driven by the dynamic mixing of the San Francisco Bay plume, upwelled waters, and California coastal surface waters. Particulate metals were separated into >10 and 0.4-10 μm size-fractions and further fractionated into leachable (operationally defined with a 25% acetic acid leach) and refractory particulate concentrations. Dissolved metals (< 0.4 μm pore-size filtrate) were separated into colloidal (0.03-0.4 μm) and soluble (<0.03 μm) fractions. The percent leachable particulate fractions ranged from 2% to 99% of the total particulate concentration for these metals with Mn and Cd being predominantly leachable and Fe and Al being predominantly refractory. The leachable particulate Pb concentration was associated primarily with suspended sediments from San Francisco Bay and was a tracer of the plume in coastal waters. The particulate trace metal data suggest that the leachable fraction was an available source of trace metal micronutrients to the primary productivity in coastal waters. The dissolved trace metals in the San Francisco Bay plume and freshly upwelled surface waters were similar in concentration, with the exception of Cu and Co, which exhibited relatively high concentrations in plume waters and served as tracers of this water mass. The dissolved data and estimates of the plume dynamics suggest that the impact of anthropogenic inputs of nutrients and trace metals in the San Francisco Bay plume contributes substantially to the concentrations found in the Gulf of the Farallones (10-50% of estimated upwelled flux values), but does not greatly disrupt the natural stoichiometric balance of trace metal and nutrient elements within coastal waters given the similarity in concentrations to sources in upwelled water. In all, the data from this study demonstrate that the flux of dissolved nutrients and bioactive trace metals from the San Francisco Bay plume contribute to the high and relatively constant phytoplankton biomass observed in the Gulf of the Farallones.     

Tracing Ni, Cu, and Zn kinetics and equilibrium partitioning between dissolved and particulate phases in South San Francisco Bay, California, using stable isotopes and high-resolution inductively coupled plasma mass spectrometry

Additions of the low occurrence stable isotopes ⁶¹Ni, ⁶⁵Cu, and ⁶⁸Zn were used as tracers to determine the exchange kinetics of metals between dissolved and particulate forms in laboratory studies of natural water and suspended sediments from South San Francisco Bay, CA. Dissolved metal isotope additions were made so that the isotope ratios (rather than total metal partitioning) were significantly altered from initial ambient conditions. Dissolved metal concentrations were determined using an organic ligand sequential extraction technique followed by analysis with high-resolution inductively coupled plasma mass spectrometry (HR-ICPMS). Exchangeable particulate concentrations were extracted using a 20% acetic acid leach followed by determination using HR-ICPMS. Equilibrium and kinetic sorption parameters were quantified according to a general model for trace metal partitioning assuming pseudo-first-order kinetics. Partition coefficients (K_D) were tracked as a function of time over the fortnight experiment. For Ni, Cu, and Zn the initial ambient K_D values were found to be 10^3.65, 10^3.88, and 10^4.52 L kg⁻¹, respectively. As a result of the dissolved metal isotope additions, the partition coefficients for all three metals dropped and then increased back to near ambient K_D values after 14 days. Curve-fitting concentration versus time profiles from both dissolved and exchangeable particulate data sets allowed determination of kinetic rate constants. The best estimates of forward and backward kinetic rate constants for Ni, Cu, and Zn respectively are k′_f = 0.03, 0.07, 0.12 d⁻¹ and k_b = 0.13, 0.12, 0.15 d⁻¹. These results predict that sorption equilibria in South Bay should be reached on the order of a month for Ni, on the order of 3 weeks for Cu, and on the order of 2 weeks for Zn. Together, the dissolved and exchangeable particulate data indicate more sluggish sorption kinetics for Ni than for Cu and Zn and suggest that different chemical forms control the speciation of these three metals in South Bay. Order of magnitude metal sorption exchange rates were estimated using these kinetic results. These calculations indicate that sorption exchange between dissolved and suspended particulate phases can cause dynamic internal cycling of these metals in South San Francisco Bay.     

Short-term biogeochemical influence of a diatom bloom on the nutrient and trace metal concentrations in South San Francisco Bay microcosm experiments

Two laboratory microcosm experiments were conducted to mimic an annual spring diatom bloom in South San Francisco Bay by isolating the phytoplankton community from the benthic grazing pressure to induce a phytoplankton bloom. The purpose of these experiments was to isolate the impact of a spring diatom bloom on the nutrient and trace metal geochemical cycling. Microcosms were created in 2.5 L incubation bottles and subjected to one of 4 treatments (control, copper [Cu] addition, manganese [Mn] addition, and both Cu and Mn addition) to investigate the toxicity of Cu on the resident plankton and the potential antagonistic effects of Mn on reducing Cu toxicity. Dissolved macronutrient (nitrate + nitrite, phosphate, and silicate), and dissolved and particulate trace metal (Cu, Ni, Mn) concentrations were monitored in the grow-out incubations on a daily basis. Chlorophylla concentrations were also monitored over the course of the experiment and used to calculate diatom-specific growth rates. In the experiments containing ambient South San Francisco Bay surface waters, average specific growth rates were on the order of 1.1 d^?1. The induced diatom blooms resulted in significant removal of macronutrients from the microcosms over the course of the experiments. Our research supports previous suggestions that dissolved Ni and Cu concentrations in South San Francisco Bay have a very low biological availability as a result of organic chelation. Ni(EDTA)^2? has been found to be the dominant dissolved Ni species by other researchers and Cu speciation analyses from this study and others indicate that > 99% of the dissolved Cu in South San Francisco Bay is strongly chelated as CuL₁. The free cupric ion concentration was on the order of 10^?12 M. Marked removal of dissolved Mn was observed in the control treatments, well exceeding expected dissolved Mn removal by diatom uptake. Additions of 375 nM Cu resulted in the complete titration of the chelating ligand (L₁) concentrations. The elevated [Cu²⁺] (≈10^?8MM) appeared to have a toxic effect on the diatom community observed in the significant decreases in their specific growth rates (μ=0.4 d^?1). The suppression of dissolved Mn removal from solution was also observed in treatments spiked with high levels of dissolved Cu, providing support that Mn precipitation was due to biologically mediated oxidation not phytoplankton assimilation. The observed geochemical behavior in the concurrent Cu and Mn addition treatments provide evidence in support of Mn alleviation of Cu toxicity. The biological role in the ambient short-term biogeochemical cycling of Cu and Ni in South San Francisco Bay appears to be minimal due to the inert character of the organic ligand-metal complexes. A significant portion of the annual macronutrient and Mn cycling occurs as a result of spring diatom blooms in South San Francisco Bay.     

Uptake of hazardous elements by spring onion (<Emphasis Type="Italic">Allium fistulosum</Emphasis> L.) from soil irrigated with different types of water and possible health risk

Bio-concentration of elements such as Mo, As, Se, Fe, Cu, Zn, Ni and Pb was analyzed in spring onion (Allium fistulosum L.) in three different locations of central Punjab, Pakistan. At location GW, relatively low level of hazardous elements was found in spring onion, suggesting that groundwater is a safe source of water for irrigating food crops. The pH of soil at wastewater irrigation was found less acidic (pH 7.4) than the other sites. The range of concentration in the different samples of spring onion was as follows: 6.15–8.16 mg kg^?1 for Mo, 2.77–4.28 mg kg^?1 for As, 0.395–0.705 mg kg^?1 for Se, 36.73–48.17 mg kg^?1 for Fe, 10.58–16.26 mg kg^?1 for Cu, 28.87–39.79 mg kg^?1 for Zn, 6.66–8.75 mg kg^?1 for Ni and 4.33–6.09 mg kg^?1 for Pb, respectively. High bio-concentration of Zn (15.37) from soil to spring onion was found at canal water irrigated location. The estimated daily intake of metal for spring onion was less, but the health risk index was higher than 1 for Mo, As, Cu, Pb and Ni, respectively. This was due to higher proportion of spring onion in diet, which consequently increased the health risk index for metals. Therefore, it is recommended to avoid growing vegetables in untreated urban and rural wastewater containing elevated amounts of metals.     

Trace metal and radionuclide pollution in marine sediments of the Aegean Sea (Izmir Bay and Didim)

To determine radioactivity and trace metal levels, surface sediments were collected from two important areas (?zmir Bay and Didim) in the Aegean Sea region of Turkey, and were analyzed for concentrations of ²¹⁰Po, ²¹⁰Pb and trace metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn). The average ²¹⁰Po and ²¹⁰Pb massic activities in sediments varied in the range of 24 ± 5 to 126 ± 6 Bq kg^?1 dry wt. and 18 ± 3 to 59 ± 4 Bq kg^?1 dry wt., respectively. Izmir Bay exhibited the highest polonium activities in sediments, likely due to specific sedimentation processes and other sediment characteristics. The trace metal results showed that the Izmir Bay is facing trace metal pollution. The metal concentrations in sediment samples are low compared to those from the other neighboring marine environments.     

Late Holocene δC and pollen records of paleosalinity from tidal marshes in the San Francisco Bay estuary, California

Records of stable carbon isotopes (δ¹³C) are presented from cores collected from four San Francisco Bay marshes and used as a proxy for changes in estuary salinity. The δ¹³C value of organic marsh sediments are a reflection of the relative proportion of C₃ vs. C₄ plants occupying the surface, and can thus be used as a proxy for vegetation change on the marsh surface. The four marshes included in this study are located along a natural salinity gradient that exists in the San Francisco Bay, and records of vegetation change at all four sites can be used to infer changes in overall estuary paleosalinity. The δ¹³C values complement pollen data from the same marsh sites producing a paleoclimate record for the late Holocene period in the San Francisco Bay estuary. The data indicate that there have been periods of higher-than-average salinity in the Bay estuary (reduced fresh water inflow), including 1600-1300 cal yr B.P., 1000-800 cal yr B.P., 300-200 cal yr B.P., and ca. A.D. 1950 to the present. Periods of lower-than-average salinity (increased fresh water inflow) occurred before 2000 cal yr B.P., from 1300 to 1200 cal yr B.P. and ca. 150 cal yr B.P. to A.D. 1950. A comparison of the timing of these events with records from the California coast, watershed, and beyond the larger drainage of the Bay reveals that the paleosalinity variations reflected regional precipitation.     

Heavy metals in sediments from San Antonio Bay and the northwest Gulf of Mexico

Sediments from San Antonio Bay, the northwest Gulf of Mexico, and the Mississippi River Delta were acid leached and analyzed for Fe, Mn, Pb, Zn, Cd, Cu and Ni by atomic absorption spectrophotometry. In order to account for differences in sediment clay, carbonate, and organic matter content, metal concentrations were normalized to Fe. Significant linear correlations of metals to Fe were obtained for unpolluted sediments and deviations from these “natural” statistical populations were found for areas thought to have metal input caused by man. San Antonio Bay sediments show little evidence of metal pollution despite 70 years of shell dredging in the bay. However, the San Antonio-Guadalupe River system, the bay's prime sediment source, has 10% to 50% higher than natural levels of Pb, Cd and Cu. Sediments from a 1500 km² area of the Mississippi River Delta have Pb and Cd concentrations 10% to 100% higher than expected levels. The vertical distribution of Pb and Cd in these sediments suggests that inputs have occurred during the past 30 to 40 years. We find no indication of metal pollution in other areas of the Delta or along the continental shelf of the northwest Gulf of Mexico.     

Assessment of heavy metal contamination levels of street dust in the city of Lublin,E Poland

Heavy metals are constantly emitted into the environment and pose a major threat to human health, particularly in urban areas. The threat is linked to the presence of Cd, Cr, Cu, Ni, Pb, and Zn in street dust, which consists of mineral and organic particles originating from the soil, industrial emitters, motor vehicles, and fuel consumption. The study objective was to determine the level of street dust contamination with trace metals in Lublin and to indicate their potential sources of origin. The analyses were carried out with an energy-dispersive X-ray fluorescence spectrometer. The sampling sites (49) were located within the city streets characterised by varying intensity of motor traffic. The following mean content values and their variation (SD) were determined: Cd: 5.1?±?1.7 mg kg^?1, Cr: 86.4?±?23.3 mg kg^?1, Cu: 81.6?±?69.2 mg kg^?1, Ni: 16.5?±?3.9 mg kg^?1, Pb: 44.1?±?16.4 mg kg^?1, and Zn: 241.1?±?94.6 mg kg^?1. The level of pollution was assessed with several widely used geochemical indices (geoaccumulation index, enrichment factor, pollution index, index of ecological risk, and potential ecological risk index). For most of the indices, the mean (median) values are arranged in the following manner: Zn?>?Cu(or Cd)?>?Pb?>?Ni?>?Cr. In general, street dust in Lublin does not show pollution with Cr, Ni, and Pb. I_geo and EF indices show moderate levels for Cu, Cd, and Zn; their presence in street dust is linked with anthropogenic factors (motor traffic). A significant threat is posed by Cd, and more than half of the samples show considerable pollution with cadmium (median for the index of ecological risk: 151). The spatial pattern of indices and the results of statistical analyses (CA, PCA) indicate three groups of elements: (1) Cr and Ni: natural origin; (2) Pb: mixed origin; and (3) Cd, Cu, and Zn: anthropogenic origin (mainly motor vehicle traffic). Higher content values for metals of anthropogenic origin in street dust indicate that it is a source of pollution of soil and air in the city.     

Silver in San Francisco Bay estuarine waters

Spatial gradients of silver concentrations in the surface waters of San Francisco Bay reveal substantial anthropogenic perturbations of the biogeochemical cycle of the element throughout the estuarine system. The most pronounced perturbations are in the south bay, where dissolved (<0.45 μm) silver concentrations are as high as 250 pM. This is more than one order-of-magnitude above baseline concentrations in the northern reach of the estuary (6 pM) and approximately two orders-of-magnitude above natural concentrations in adjacent coastal waters (3 pM). The excess silver is primarily attributed to wastewater discharges of industrial silver to the estuary on the order of 20 kg d^?1. The contamination is most evident in the south bay, where wastewater discharges of silver are on the order of 10 kg d^?1 and natural freshwater discharges are relatively insignificant. The limited amount of freshwater flushing in the south bay was exacerbated by persistent drought conditions during the study period. This extended the hydraulic residence time in the south bay (≥160 d), and revealed the apparent seasonal benthic fluxes of silver from anthropogenically contaminated sediments. These were conservatively estimated to average ≈16 nmol m^?2 d^?1 in the south bay, which is sufficient to replace all of the dissolved silver in the south bay within 22 d. Benthic fluxes of silver throughout the estuary were estimated to average ≈11 nmol m^?2 d^?1, with an annual input of approximately 540 kg yr^?1 of silver to the system. This dwarfs the annual fluvial input of silver during the study period (12 kg yr^?1) and is equivalent to approximately 10% of the annual anthropogenic input of silver to the estuary (3,700–7,200 kg yr^?1). It is further speculated that benthic fluxes of silver may be greater than or equal to waste water fluxes of silver during periods of intense diagenic remobilization. However, all inputs of dissolved silver to the estuary are efficiently sorbed by suspended particulates, as evidenced by the relatively constant conditional distribution coefficient for silver throughout the estuary (K_d≈10⁵).     

Total concentration,speciation and mobility of potentially toxic elements in soils around a mining area in central Iran

The current study was designed to investigate the extent and severity of contamination as well as the fractionation of potentially toxic elements (As, Cd, Cr, Cu, Pb, Zn, Ni) in minesoils and agricultural soils around a Pb–Zn mine in central Iran. For this purpose, 20 agricultural soils and eight minesoils were geochemically characterized. Results showed that minesoils contained elevated concentrations of As (12.9–254 mg kg⁻¹), Cd (1.2–55.1 mg kg⁻¹), Pb (137–6239 mg kg⁻¹) and Zn (516–48,889 mg kg⁻¹). The agricultural soils were also polluted by As (5.5–57.1 mg kg⁻¹), Cd (0.2–8.5 mg kg⁻¹), Pb (22–3451 mg kg⁻¹) and Zn (94–9907 mg kg⁻¹). The highest recorded concentrations for these elements were in soils influenced directly by tailing ponds. Chromium, Cu and Ni content in agricultural soils (with average value of 74.1, 34.6 and 50.7 mg kg⁻¹, respectively) were slightly higher than the minesoils (with average value of 54.5, 33.1 and 43.4 mg kg⁻¹, respectively). Sequential extraction data indicated that there were some differences between the speciation of PTEs in soil samples. In the agricultural soils, Zn and Cd were mainly associated with carbonate bound fraction, As and Pb with reducible fraction, Cu with oxidisable fraction and Cr and Ni with residual phase. With respect to mobility factor values, Zn and Cd in the agricultural soils have been found to be the most mobile while As mobility is negligible. Also, the mobility factor of As, Cd and Pb in agricultural soils adjoining tailing ponds was high. In minesoil sample Cd was most abundant in the carbonate form, whereas other studied elements were mainly present in the reducible and residual fractions; therefore, despite the high total concentrations of As, Pb and Zn in the minesoils, the environmental risk of these elements was low. Based on the obtained data, a portion of Cu, Cr and Ni input was from agricultural activities.     

Multivariate statistical analysis of heavy metals in foliage dust near pedestrian bridges in Guangzhou, South China in 2009

The heavy metal content of particulate matter was investigated in the city of Guangzhou in southern China. Samples of urban foliage near 36 pedestrian bridges were analyzed to determine their Zn, Pb, Cu, Cr, V, Ni, and Co contents after digestion in a mixture of strong acids composed of HNO₃, HCl, HF, and HClO₄. The results revealed a severe heavy metal pollution compared with the background levels in Chinese soils, except for Co and V. The mean concentrations of Zn (1,024 mg kg^?1), Pb (233 mg kg^?1), Cu (203 mg kg^?1), Cr (118 mg kg^?1), V (41.9 mg kg^?1), Ni (41.4 mg kg^?1), and Co (11.3 mg kg^?1) in urban dust were higher than the reference levels, and were highest in samples located near high-traffic areas. Multivariate statistical methods (correlation analysis, principal-components analysis, and clustering analysis) were used to identify the possible sources of the metals. Three main pollutant sources are assigned: Zn, Cu and Ni levels were strongly correlated and were possibly related to combustion processes and vehicles; Pb, Cr and Co were mainly derived from traffic sources, combined with soil sources; and V mainly originated from natural sources.     

Leachable trace elements in San Francisco bay sediments: Indicators of sources and estuarine processes

Geographic variations of leachable Fe, Mn, Cu, Zn, Co, and Ni in San Francisco Bay sediments indicate that Fe, Mn, Co, and Ni are all predominantly supplied to bay sediments from the San Joaquin-Sacramento River system, with little evidence for direct contributions from municipal and industrial sources. In contrast, both Cu and Zn have significant sources within the Bay system, probably municipal and industrial discharges. Precipitation and coagulation of Fe oxides in the low-salinity region of the estuary results in significantly greater concentrations of that element in the most landward portion of the estuary. Co and Ni appear to be actively coprecipitating with Fe but their distributions are also influenced by other factors. Mn is not a major geochemical agent in this system. Its pattern is different from the other elements and it does not account for any of the other elemental variance. The behavior of Cu and Zn is affected not only by the presence of nonriverine sources but also through surface-active processes and organic complexing, coupled with the transportation of fine-grained sediment.     

Mineral components in a peat deposit: looking for signs of early mining and smelting activities in Silesia–Cracow region (Southern Poland)

The results of investigations (SEM/EDS and AAS) of a peat deposit, spanning 13,000 years of peat accumulation, are shown. The peat deposit is located in a region of shallow occurrence of Zn–Pb ores, near Tarnowskie Góry town, within the Cracow–Silesia district (southern Poland). Exploitation of lead, silver and iron during the medieval times (Twelfth and thirteenth century) was confirmed by historical documents whereas there are no unambiguous data showing that there was metal mining during the Romanian or earlier times in the region. The peat deposit is located within the influence of atmospheric Pb and Zn emission from a nearby Zn–Pb smelter. Two vertical peat profiles were investigated (120 and 140 cm depth of profile) showing variable concentrations of Zn up to 713 mg kg^?1, Pb up to 317 mg kg^?1, Cd up to 13 mg kg^?1 and Tl up to 31 mg kg^?1. The highest concentrations were recorded for the uppermost peat layers. SEM and EDS investigations revealed the occurrence of metalbearing, submicroscopic mineral components: Fe, Mn, Ti and Zn oxides and Zn and Pb carbonates. The top layer of the deposit contained Zn, Pb and Cd sulphides. The occurrence of aggregates of Au–Ag, Cu–Zn and Au–Ag–Cu alloys can be possibly related to pre-historical mining and smelting or be explained by geochemical transformations. The preservation of carbonates and oxides in the peat is discussed, indicating a generally neutral to alkaline peat water chemistry and maintenance of an oxidized environment in the fen.     

An evaluation of trace metal distribution and environmental risk in sediments from the Lake Kalimanci (FYR Macedonia)

Pollution from mining activities is a significant problem in several parts of the Republic of Macedonia. A geochemical study of the surficial sediments of Lake Kalimanci in the eastern part of the Republic of Macedonia was carried out to determine their elemental compositions and to evaluate the pollution status of lake sediments by employing an enrichment factor (EF). The major and trace element contamination in surficial lake sediments was studied to assess the effects of metalliferous mining activities. The mean concentrations of major elements (wt%) Si 23.5, Al 7.9, Fe 6.6, Mg 1.3, Ca 3.8, Na 1.1, K 2.3, Ti 0.4, P 0.2, Mn 0.6 and trace elements ranged within Mo 1.0–4.6 mg kg^?1, Cu 144.4–1,162 mg kg^?1, Pb 1,874–16,300 mg kg^?1, Zn 2,944–20,900 mg kg^?1, Ni 21.7–79.3 mg kg^?1, Cd 16.5–136 mg kg^?1, Sb 0.6–3.6 mg kg^?1, Bi 3.0–24,3 mg kg^?1 and Ag 1.4–17.3 mg kg^?1. The EF ranged within 0.12–590.3. Among which, Cd, Pb, Zn and As have extremely severe enrichment. The data indicate that trace elements had extremely high concentrations in Lake Kalimanci surficial sediments owing to the anthropogenic addition of contaminants.     

Contamination of the biological compartment in the Seine estuary by Cd, Cu, Pb, and Zn

A study of contamination of the biological compartment of the Seine estuary was carried out by measuring the concentrations of cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) in 29 estuarine and marine species belonging to 6 phyla. Species came from three main biological zones of the estuary: the Seine channel (copepods, mysids, shrimps, and fish), the intertidal mudflats (Macoma balthica community), and the subtidal mudflats (Abra alba community). Two fish species, the bass (Dicentrarchus labrax) and the flounder (Platichthys flesus), were also selected for analyses. A comparison of metal concentrations in estuarine species of the Seine with those found in the same species collected on contaminated and non-contaminated sites showed a contamination of the estuary by Cu, Zn, and Pb. For Cd, the contamination is mainly observed in bivalves, although the concentrations observed were low and less than 2 μg g^?1 d.w. High concentrations of Cu were found in copepods, shrimps, and fish. Pb contamination was mainly found in species living in the Seine channel where the copepodEurytemora affinis shows an average concentration of 22 μg g^?1 d.w. High concentrations of Pb (>10 μg g^?1 d.w.) were found in deposit-feeders benthic invertebrates. Elevated levels of Zn were seen in all species collected in the Seine estuary, including fish and in particular small flounder. The concentrations of Cd, Cu, Pb, and Zn found in edible estuarine species (shrimp and fish) were in the same order of magnitude than those found in fish and shrimps fished along the French coast.     

Toxic metal contamination and distribution in soils and plants of a typical metallurgical industrial area in southwest of China

In this work, the total and each fraction concentration of toxic metals (Pb, Zn, Cu and Cd) in soils as well as in plants from a typical metallurgical industrial area in southwest of China were determined. The obtained experimental results demonstrated that the total toxic metal content in contaminated soils was in the order of Zn > Pb > Cu > Cd. Modified microwave-assisted extraction showed that the distributions of each fraction of toxic metals in soils were different and some soil properties may play a role in the fraction distributions. The content of Cu, Zn, Cd and Pb in different vegetables ranged from 9.82 ± 1.02 to 39.3 ± 1.13 mg kg^?1, 1,321 ± 10.50 to 3,153 ± 11.30 mg kg^?1, 4.47 ± 0.21 to 18.9 ± 0.37 mg kg^?1 and 28 ± 1.2 to 102 ± 1.5 mg kg^?1, respectively. And the accumulation of toxic metals in plants was in the order of Cd > Zn > Cu > Pb. The bioconcentration factor (BCF) values of Cd, Zn, Cu and Pb in the different tissues of plants were in the range of 0.03–0.43, 0.027–0.35, 0.014–0.12 and 0.004–0.051, respectively. The distribution of each toxic metal in plants indicated that the ability for plants to accumulate toxic metals in different tissues followed the sequence of leaf > stem.     

Temporal Trends of Dissolved Trace Metals in Jamaica Bay,NY: Importance of Wastewater Input and Submarine Groundwater Discharge in an Urban Estuary

Jamaica Bay, NY, is a highly urbanized estuary within the boroughs of New York City conspicuously lacking published information on dissolved trace metal concentrations. The current study examines the distribution and cycling of trace metals in that embayment with data gathered during cruises in November 2004, April 2005, and June 2006. Most of the metal distributions (Fe, Zn, Co, Ag, Cu, Pb, Ni) in the water column are explained by the input of substantial volumes of treated wastewater effluent. However, several lines of evidence suggest that submarine groundwater discharge (SGD) is also an important source of dissolved Fe, Zn, Co, Ni, and isotopically distinct stable Pb ratios (²⁰⁶Pb, ²⁰⁷Pb, ²⁰⁸Pb) in the Bay. Conversely, the recirculated seawater component of SGD is an apparent sink for dissolved Mo. This study provides the first measurements of dissolved trace metals in the Jamaica Bay water column and subterranean estuary and provides evidence for trace metal input due to SGD.     

Trace metals (Cd,Pb, Cu,Zn and Ni) in sediment of the submarine pit Dragon ear (Soline Bay,Rogoznica, Croatia)

Vertical profiles of trace metal (Cd, Pb, Zn, Cu, Ni) concentrations, organic matter content, carbonate content and granulometric composition were determined in two sediment cores from the submarine pit Dragon Ear (Middle Adriatic). Concentrations of the analyzed metals (Cd: 0.06–0.12 mg kg⁻¹, Pb: 28.5–67.3 mg kg⁻¹, Zn: 17.0-65.4 mg kg⁻¹, Cu: 21.1–51.9 mg kg⁻¹, Ni: 27.8–40.2 mg kg⁻¹) were in usual range for Adriatic carbonate marine sediments. Nevertheless, concentrations of Cu, Zn, and especially Pb in the upper layer of sediments (top 12 cm) were higher than in bottom layer, while Cd and Ni concentration profiles were uniform. Regression analysis and principal component analysis were used to interpret distribution of trace metals, organic matter and carbonate content in sediment cores. Results of both analysis showed that concentrations of all trace metals in the core below the entrance to the pit were significantly positively correlated with organic matter and negatively correlated with carbonate, while in the core more distant from the entrance only Pb showed significant positive correlation with organic matter. Obtained results indicated that, except for lead which was enriched in surface sediment, in the time of sampling (before the building of the nautical marina) investigated area belonged to unpolluted areas.     

Soil contamination by metals with high ecological risk in urban and rural areas

Industrial development, intensive agriculture and fast urbanization have caused the metal contents of soils to increase to many times the allowable limits. To assess this impact on urban and rural soils, we quantified the Cd, Cr, Cu, Pb, Ni and Zn contents of 258 soil samples from the Recife metropolitan region (RMR). The objectives of the study were to estimate the probability of ecological risk, to determine the spatial pattern of the metals’ accumulation in the soil and to identify potential sources for the metals using a multivariate geostatistical approach. Mean concentrations of Zn, Cr, Pb, Cu, Ni and Cd in soils were 65.2, 17.9, 16.5, 12.8, 6.3 and 1.5 mg kg^?1, respectively. The results demonstrated that the Cd was anthropogenic in origin, the Cr and Ni were lithogenic (natural) in origin and the Cu, Pb and Zn were mixed in origin. Cd contaminated 91% of the samples; the median content of Cd (1.4 mg kg^?1) was three times the quality reference value for soil. The Cd contents of sugarcane fields exceeded the allowable limit (3.0 mg kg^?1) for agricultural areas. The spatial variability of the metals in the RMR showed that metallurgy, cement production, vehicle exhaust and vehicular traffic were the main sources of metals in urban areas, while phosphate-based fertilizers were the main sources in rural areas. More than 80% of the metropolitan region surveyed in the study was at moderate to high ecological risk.     

Anthropogenic components of heavy metal (Cd,Zn, Cu,Pb) budgets in the Lot-Garonne fluvial system (France)

Heavy metal (Zn, Cd, Cu and Pb) mass balances in the Lot-Garonne fluvial system have been established for 1999 and 2000. The mean annual discharges of these years are close to the mean discharge of the previous decade. The estimated annual dissolved and particulate fluxes in this model watershed integrate daily input from diffuse and point sources, diffusive fluxes at the water/sediment interface, changes in the dissolved-particulate partition and changes in sediment stock. Cadmium, Zn, Cu and Pb entering the Gironde estuary via the Garonne River (11–14 t a⁻¹ of Cd; 1330–1450 t a⁻¹ of Zn; 126–214 t a⁻¹ of Cu and 127–155 t a⁻¹ of Pb) are mainly transported in the particulate phase and the major part (i.e. ∼74 to 96% for Cd, ∼60% for Zn, ∼50 to 60% for Cu and ∼80% for Pb) is transported by the Lot River. The main anthropogenic heavy metal point source is located in a small upstream watershed (Riou-Mort River) accounting for at least 47% (Cd), ∼20% (Zn), ∼4% (Cu) and ∼7 to 9% (Pb) of the total heavy metal inputs into the Garonne River, although it contributes only 1% of the discharge. Mass balances for 1999 suggest that under mean annual hydrologic conditions on the basin scale, the heavy metal budget of the Lot-Garonne fluvial system is balanced and that the stocks of Cd [200 t; Environ. Tech. 16 (1995) 1145] and Zn in the Lot River sediment are constant under mean discharge conditions. Heavy metal input by molecular diffusion at the sediment surface represents an important component of dissolved metal inputs into the system (e.g. 30% for Cu). Except for Cu, these dissolved inputs are totally removed from solution by SPM. Based on the generally constant Zn/Cd (∼50) concentration ratio in sediment cores from the polluted Lot River reaches and the sediment stock of Cd [200 t; Environ. Tech. 16 (1995) 1145], the present day Zn stock in the Lot River sediments has been estimated at about 10,000 t. In addition to the mobilization of river-bed sediment and associated heavy metals by intense floods, local human activities, including river-bed dredging, may strongly modify the heavy metal budget of the river system. In 2000, the dredging-related remobilization of polluted Lot River sediment released 2–6 t Cd. This additional Cd point source was estimated to account for 15–43% of the gross inputs into the Gironde Estuary.