Water quality characteristics, sources, and assessment of surface water in an industrial mining city, southwest of China.

This study analyzed the physiochemical factors, spatial-seasonal variations, and correlations of main pollutants, water quality evaluation and possible sources of nitrogen in the surface water of Anning, an industrial mining city, southwest of China. Seventy surface water samples were examined through an analysis of 41 physiochemical indices in the dry and wet seasons in April and July 2019, respectively, while a part of water site samples collected in July 2020 was taken for isotope detections. To identify the water quality, single-factor pollution index (SI), Nemerow pollution index (NPI), and water quality comprehensive pollution index (CPI) were calculated based on 13 pollutants using GB 3838-2002 class III water standard values. Results pointed to typical pollutants of TN, TP, and F with ranges of l.d.-44.8 (2.00 ± 3.69) mg/L, l.d.-250 (2.07 ± 15.35) mg/L, and l.d.-11 (1.48 ± 7.34) mg/L respectively with high spatial variability. The concentrations of heavy metals present in the water samples followed the sequence: Zn > Ni > Cu > As > Pb > Cd > Hg, and most of the samples showed low values relative to the standard permissible limits. In three methods, the water quality evaluation results of SI method were obviously worse than NPI and CPI methods. The NPI and CPI values had ranges of 0.116-887.40 (8.12 ± 74.89) and 0.03-111.54 (1.17 ± 9.40), respectively; consequently, the water quality was considered generally well, with more than 65% of sites classified as "cleanness" or "sub-cleanness." Most of the values of δ15N and δ18O had ranges of 6.62-20.05‰ and - 6.53-4.70‰, which suggested the livestock manure resources were the possible sources of nitrogen that entered the surface water causing more pollution in the wet season. Part of sites with serious water pollution had very high concentrations of P, F, or heavy metals and might be closely correlated with the point source pollution of phosphate chemical industry or iron ore mining and smelting. The results of this study can provide the basic data for efficient water management and human health protection for local government.

Growth rates for freshwater ferromanganese concretions indicate regional climate change in eastern Canada at the Northgrippian-Meghalayan boundary.

The existence of freshwater ferromanganese concretions has been known for decades, but we are not aware of a generally accepted explanation for their formation, and there has been little research into their potential use as records of Holocene climate and paleohydrology. A conceptual model is presented to describe the environmental and geochemical processes which result in the formation and growth of freshwater ferromanganese concretions. In order to evaluate their potential as historical geochemical records, a concretion from Magaguadavic Lake, New Brunswick, Canada is the focus of a detailed geochronological and geochemical investigation. The radiocarbon data provide a coherent growth curve and a maximum age for the concretion of 8448 ± 43 years, consistent with the establishment of Magaguadavic Lake as a stable post-glacial lacustrine system. The data suggest accretion rates of 1.5 and 3.4 mm per 1000 years during the Northgrippian and Meghalayan stages of the Holocene, respectively. The abrupt change in growth rate observed at the stage boundary may be an indicator of Holocene climate change. These features are consistent with inferences from previous research that warmer climate in the Northgrippian led to eutrophication in some lakes in eastern North America. The results confirm that freshwater Fe-Mn concretions may yield important information about past climatic and environmental conditions.

Assessing the uranium DGT-available fraction in model solutions.

The uranium speciation in humic acid (HA) and fulvic acid (FA) model solutions was investigated by diffusive gradients in thin films (DGT). A reference solution was used to normalize the DGT data from different samples. This approach was used to assess uranium DGT-available fraction (FU), which was calculated from experimental data and reflect both the mobility and lability of uranium species. FU decreased with increasing HA or FA concentrations, because more uranium was able to bind the strong binding sites of HA or FA. When copper was spiked, FU increased due to the competition between copper and uranium. In HA model solutions, an increase of ionic strength could increase FU, and when pH was greater than 7, FU increased significantly. The DGT uptake factor (φ), which can be obtained from data fitting, is the ratio of the product of diffusion coefficient and lability degree of the unknown sample to that of the reference solution. In U-HA-NaHCO3 solutions, UO2(CO3)22- had a relatively high φ value and might be the most DGT-available species. This approach allows the comparison of DGT data from different samples, and combining with a data fitting procedure, it can be used to investigate the distribution of metal species.

Determination of Cr(III) solids formed by reduction of Cr(VI) in a contaminated fractured bedrock aquifer: Evidence for natural attenuation of Cr(VI).

Hexavalent chromium Cr(VI) is toxic and can be highly mobile in many aquifer systems. Redox reactions with naturally occurring minerals and organic compounds can reduce Cr(VI) to Cr(III), forming labile Cr(III) oxyhydroxide precipitates, which is a natural attenuation process. In fractured bedrock aquifers, reduction of Cr(VI) in the rock matrix can enhance attenuation beyond that from matrix diffusion only, and potentially reduce back diffusion if concentrations in fractures decline following source reduction via natural processes or engineered remediation. In this study, we develop an extraction method for labile Cr(III) precipitates from Cr(VI) reduction using 5% hydrogen peroxide (H2O2). Combining Cr(III) extractions with an established sodium hydroxide (NaOH) method for determination of Cr(VI) concentrations in rock porewater, a measure of the labile Cr(III) and Cr(VI) fractions in geologic samples is achieved. The methods were applied to cores from a contaminated groundwater system in fractured porous bedrock in order to assess the effectiveness of natural attenuation and whether Cr(VI) mass that diffused into the bedrock matrix was undergoing reduction. Detailed vertical distributions display two depth intervals with corresponding elevated concentrations of Cr(VI) in the porewater and extractable total Cr. The correspondence of Cr(VI) and labile Cr(III) provides evidence for reduction of Cr(VI) contamination in the bedrock matrix. Mineralogical analysis suggests that Fe(II)-bearing minerals, chlorite and biotite are the most likely candidates for natural reductants. This study provides evidence for the natural attenuation of anthropogenic Cr(VI) contamination in the porewater of a fractured bedrock aquifer, and it outlines a quantitative method for evaluating the effectiveness of natural attenuation in groundwater systems.

An improved method for determination of lanthanoids in environmental samples by inductively coupled plasma mass spectrometry with high matrix introduction system.

The capability of ICP-MS equipped with the high matrix introduction system (HMI) for accurate analysis of lanthanoids in environmental samples was investigated. Compared to the conventional operation, the amounts of oxide and hydroxide molecular species formed in the plasma were reduced by up to 5 times. The relative yields of oxides did not exceed 0.02% for BaO(+) species and were as low as 0.3% for lanthanoids with the highest oxide-formation rates (LaO(+), CeO(+), PrO(+) and NdO(+)). Hydroxide formation was less than 0.02% when HMI system was used. In addition, two digestion procedures were evaluated by the analysis of standard reference materials (SRMs) of different matrices. The digestion efficiency and limits of detection (LOD) were improved when samples were digested with a mixture of HNO(3)/H(2)O(2)/HCl/HF, and HF was removed by evaporation in presence of concentrated HCl. Using this procedure and HMI-ICP-MS analysis, LOD ranged from 0.1 µg kg(-1) to 6 µg kg(-1). Recoveries ranged from 85 to 115% for La to Ho and from 75 to 85% for the other lanthanoids. Relative standard deviations for replicate analysis of SRMs were less than 10%.

Effects of various competing ligands on the kinetics of trace metal complexes of Laurentian Fulvic Acid in model solutions and natural waters.

The objective of this work was to study the effects of the following Ligands: Chelex-100, Dowex MAC-3 and Dowex 50WX-8 using Competing Ligand Exchange Method. This objective was achieved by investigating complex dissociation kinetics of trace metals: Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Mn(II) and Pb(II) of a well-characterized Laurentian Fulvic Acid (LFA) in model solutions and in a natural waters of Lake Heva (Québec, Canada). The effects of variation in the competing ligands (including their quantities) on the complex dissociation kinetics were quantitatively characterized by their first-order dissociation rate coefficients. The kinetic lability of the metal complexes varied with the metal-to-LFA ratio, as expected from the theory of metal complexes of the chemically and physically heterogeneous complexants, LFA. The general trend in the metal-binding by the above competing ligands was: Dowex 50WX-8>Chelex-100>Dowex MAC-3. However, no difference was found between the Dowex 50WX-8 and Chelex-100 for Cd(II), Zn(II), and Co(II). The results revealed the importance of the quantity of Chelex-100 as a competing ligand in the metal(II)-LFA complexation, on the dissociation kinetics of these complexes in model solutions. By developing Competing Ligand Exchange Method as an analytical technique, for studying the relative affinities of the above competing ligands for metals complexation in natural waters this work has made a substantial contribution to analytical chemistry.

Copper and nickel speciation in mine effluents by combination of two independent techniques.

To control potentially toxic metals in water resources it is necessary to know metal speciation and changes in the metal speciation that occur after aqueous effluents containing metals are discharged into freshwaters. This work explores the speciation of nickel and copper in metal-mining aqueous effluents. Diffusive gradients in thin films (DGT) technique and competing ligand exchange (CLE) method have been applied to determine the speciation of nickel and copper. The results of this investigation demonstrate that combination of two analytical techniques having complementary analytical capabilities can provide a better physicochemical picture of metal speciation than either one of the analytical technique can do alone. The combined use of these techniques revealed that copper formed labile complexes having slow diffusion coefficient along with the presence of small labile copper complexes. Nickel-dissolved organic complexes (DOC) complexes in the aqueous effluent have been found to have fast diffusion coefficient. The results are likely to have environmental significance for providing a link between the metal species in mine aqueous effluent and their bioavailability by determining the characteristics of copper and nickel complexes in metal-mine aqueous effluents. This knowledge is expected to promote a better understanding of the lability of DOC complexes of copper and nickel in mining effluents.

Kinetic study of uranium speciation in model solutions and in natural waters using Competitive Ligand Exchange Method.

Kinetic speciation of uranium in model solutions containing uranium and humic acid (HA) and in natural waters has been investigated by Competitive Ligand Exchange Method (CLEM). In alkaline freshwaters, most of uranium species were uranium-carbonate species, which were labile in the CLEM experiment. The uranium speciation of every sample was characterized either as "labile" or "non-labile" uranium complexes depending on the dissociation rate coefficients of the complexes. The results showed that as the U(VI)/HA ratio was decreased, the dissociation rate coefficients decreased and the labile fraction decreased as well. When the U(VI)/HA ratio was 0.1, the labile fraction of the U(VI)-HA increased with increasing pH; however, there was no pH effect on the dissociation of U(VI)-HA complexes at lower U(VI)/HA ratios. Chelex-100 had some limitations in its use for the study of dissociation of U(VI)-HA complex at very low U(VI)/HA ratios. By developing an analytical method and procedure for quantitative determination of kinetic parameters for the dissociation of uranium-HA complexes in model solutions and natural waters, this work has made a substantial contribution to analytical chemistry.

Diffusive gradients in thin films technique for uranium measurements in river water.

The diffusive gradients in thin films technique (DGT) was used for uranium measurements in water. DGT devices with Dowex resin binding phase (Dow DGT) were tested in synthetic river water, which gave 84% response to total uranium concentration. The devices were also deployed in natural river water and compared to devices with other types of binding phases, Chelex 100 resin beads imbedded in polyacrylamide hydrogel (Chelex DGT) and DE 81 anion exchange membrane (DE DGT), deployed in the same location at the same time. The measurement by Dow DGT was the lowest among the different types of the DGT devices, 45% of total uranium, while measurement by DE DGT was the highest, 98% of total uranium. The results achieved by the three types of DGT devices were explained by three DGT working mechanisms, equilibrium between complexes of resin/uranyl carbonates and complexes of resin/competitive ligands in water, effective reduction of uranyl carbonate concentration by the binding phase and dissociation of UO2(CO3)2(2-) and UO2(CO3)3(4-) within the diffusive layer in a DGT device. It is hoped that by deploying the DGT devices with different binding phases in natural waters, additional information on uranium speciation could be obtained.

Accumulation of mercury, selenium and their binding proteins in porcine kidney and liver from mercury-exposed areas with the investigation of their redox responses.

The subcellular localization of Se and Hg and their cytosolic binding proteins, including cellular oxidative status, in porcine liver and kidney have been studied by using samples from a chronic Hg-contaminated area and a non-Hg-contaminated area. Coaccumulation and redistribution of Se and Hg in subcellular fractions due to mercury exposure were found. The Hg and Se concentrations in tissues from Hg-exposed porcine were 80 fold and 5-20 fold higher than controls, respectively. Interestingly, the retention of both Se and Hg increased 10% in mitochondria, while decreased 10% in cytosol of Hg-exposed pig liver. Mercury was mainly in the form of MTs in the cytosol of the non-Hg-exposed porcine kidney. MT binds Hg in the cytosol with limited capacity, and the rest Hg was redistributed to the high molecular weight (MW) proteins (80-100 kDa) in the Hg-exposed group. The coaccumulation of Hg and Se was also found in high MW proteins, where their molar ratio tended to be 1:1. Moreover, the Se-containing polypeptides (3-6 kDa) increased significantly both in hepatic and renal cytosol of the Hg-exposed pigs. Se-dependent GSH-Px and SOD activity were increased to cope with Hg-induced oxidative stress. In previous studies, the roles of Se and MTs were generally taken into account separately; we discussed their combining roles in the case of high Hg exposure. The present results were beneficial to understand the existing states of Hg in vivo and evaluate the interaction of toxic and essential elements.

The roles of serum selenium and selenoproteins on mercury toxicity in environmental and occupational exposure.

Many studies have found that mercury (Hg) exposure is associated with selenium (Se) accumulation in vivo. However, human studies are limited. To study the interaction between Se and Hg, we investigated the total Se and Hg concentrations in body fluids and serum Se-containing proteins in individuals exposed to high concentrations of Hg. Our objective was to elucidate the possible roles of serum Se and selenoproteins in transporting and binding Hg in human populations. We collected data from 72 subjects: 35 had very low Hg exposure as evidenced by mean Hg concentrations of 0.91 and 1.25 ng/mL measured in serum and urine, respectively; 37 had high exposure (mean Hg concentrations of 38.5 and 86.8 ng/mL measured in serum and urine, respectively). An association between Se and Hg was found in urine (r = 0.625; p < 0.001) but not in serum. Hg exposure may affect Se concentrations and selenoprotein distribution in human serum. Expression of both selenoprotein P and glutathione peroxidase (GSH-Px) was greatly increased in Hg miners. These increases were accompanied by elevated Se concentrations in serum. In addition, selenoprotein P bound more Hg at higher Hg exposure concentrations. Biochemical observations revealed that both GSH-Px activity and malondialdehyde concentrations increased in serum of the Hg-exposed group. This study aids in the understanding of the interaction between Se and Hg. Selenoproteins play two important roles in protecting against Hg toxicity. First, they may bind more Hg through their highly reactive selenol group, and second, their antioxidative properties help eliminate the reactive oxygen species induced by Hg in vivo.

Speciation measurements of uranium in alkaline waters using diffusive gradients in thin films technique.

This work investigated the application of diffusive gradients in thin films technique (DGT) to uranium speciation measurements in natural water. Two binding phases were examined, a commercially available affinity membrane, Whatman DE 81 (DE 81), with amino binding functional groups and the conventionally used Chelex 100 beads imbedded polyacrylamide hydrogel (Chelex) with iminodiacetate functional groups. The DGT devices assembled with the binding phases of DE 81 (DE 81 DGT) and Chelex gel (Chelex DGT) were tested both in synthetic river water solutions and in local river water. DE 81 DGT and Chelex DGT measured 80% and 75% of the total uranium in synthetic river water solution, respectively, and measured 73% and 60% of the total uranium in St. Lawrence River, Canada, respectively. The binding properties of the DE 81 membrane and Chelex gel for uranium, and the diffusion of uranyl complexes in the polyacrylamide gel (PAM) were also studied.

[Preliminary study on cellular status of selenium and oxidative stress in human hepatocellular carcinoma and normal liver].

To investigate the roles of essential trace element selenium and cellular antioxidative systems in human hepatocellular carcinoma, we analyzed cellular distribution of selenium and assayed cytosolic and mitochondrial superoxide dismutase, glutathione peroxidase, thioredoxin reductase, glutathione and total protein thiols in 10 control healthy subjects, 6 cases of hepatocellular carcinoma and 2 cases of normal liver adjacent to the hepatocellular carcinoma. In hepatoma tissues, the Se contents in lysosome (P < 0.05), microsome (P < 0.05) and cytosol were higher than in the control liver. In 2 cases, normal liver adjacent to hepatocellular carcinoma had decreased Se content. In hepatoma tissues, GSH and protein thiols content and activities of SOD, GSH-Px and TrxR were all much higher than in normal liver tissue. These findings suggested the antioxidative defense-related enzymes and antioxidant were largely regulated in hepatoma cells, whereas the cause is not clear and requires further studies.

[Correlation of mercury, selenium and other elements in the tissues of fishes from the regions at different mercury exposure level].

The contents of selenium and other elements in fish liver and muscle tissues collected from mercury polluted area of Wanshan, Guizhou province of China and non-known mercury polluted one of Beijing were determined with instrumental neutron activation analysis, and that of mercury was determined with atomic fluorescence spectrometry. The correlation among the determined elements, especially between mercury and selenium, in the fish tissues were studied. For most of the elements significant difference of elemental content was found between tissues of liver and muscle, and mostly the content in liver was higher than that in muscle. It was interesting to note that the average content of mercury in Guizhou fish liver was 25-fold higher than that in Beijing one, and 5-fold higher in Guizhou fish muscle than that in Beijing one. For most of the elements no significant difference on the average content was found between the same tissues of the two areas. The molar ratio of Hg/Se increased with the increasing of Hg content at the low Hg level, but the alteration trend became gently and reached to a higher constant value (about 0.2) at the higher Hg level. Only the element of bromine and rubidium was found to have strong linear correlation between the two different tissues of liver and muscle. Though certain correlation existed among the different elements of fish tissues from the two areas, the most significant and the closest one existed between the mercury and selenium of muscle tissue of Guizhou fishes. A closer correlation was also found between them of liver tissue of Guizhou fishes. As for Beijing fish tissues, the correlation of mercury and selenium only existed in liver but no correlation of them was found in muscle. Our results confirm the fact that a certain interaction exists between mercury and selenium in organisms including fish, and it is more evident as the mercury-exposed level is higher. Some significant correlation was also observed between other elements, such as potassium and sodium, cesium and rubidium, iron and zinc, in fish tissues and it could be well explained by their similar chemical and physical properties or their different biological functions.

Element content and element correlations in Chinese human liver.

The amounts of the 19 elements As, Br, Ca, Cd, Ce, Co, Cr, Cs, Fe, K, La, Mo, Na, Rb, Sb, Sc, Se, Sm, and Zn in 92 lyophilized autopsy human liver samples from normal subjects have been analyzed by instrumental neutron-activation analysis (INAA). For intercomparison and quality control ten samples were independently analyzed in two institutes, the Institute of High Energy Physics in China and the "Jozef Stefan" Institute in Slovenia. Most of the element contents determined by the two institutes were in quite good agreement, even though different experimental conditions were applied, indicating the reliability of the analytical results. Analysis of the chemical species of mercury present in the ten liver samples was also performed in Slovenia. Possible differences between the element content of male and female liver samples were studied by means of Student's t-test, but significant differences were found only for Ce, Co, Fe, La, Mo, and Zn. The results obtained were also compared with those reported from other areas of the world; no appreciable differences were observed. Correlation among the various elements in the human liver samples was studied using multivariate statistics. It was found that there was relatively close correlation between some elements, for example As-Fe, Ca-Fe, Cd-Co, Cd-Zn, Mo-Zn, Co-Se, Cs-Rb, Br-Rb, Sc-Sm, La-Sm, La-Ce, etc.; these correlations could be rationally explained by the similarity of the electronic structures of the elements and/or their physiological functions in the human body.

Mercury and trace element distribution in organic tissues and regional brain of fetal rat after in utero and weaning exposure to low dose of inorganic mercury.

Since it is still absent data about the toxic risk of low dose, especially an environmentally relevant dose of mercury to fetus after their prenatal exposure, this present work was designed to investigate the metabolism of Hg and its effect on the levels of essential trace elements in the organic tissues and the brain regions of infant rats after their exposure to environmentally relevant low dose of Hg(II) during the whole pregnant and weaning period. The pregnant female rats were exposed to a very low dose of 0.2 microg Hg2+/ml (as HgCl2, 12 rats/group) in drinking water from prenatal day 0 continued to postnatal day 20. The contents of Hg and other elements (Cu, K, Mg, Mn, Na, Ca, Co, Fe, Se and Zn) in the liver, kidney, heart, spleen, pancreas and the brain regions (cerebrum, cerebellum, brain stem, hippocampus, thalamus and the remains) of the maternal and their infant rats were determined. The highest Hg contents were found in kidney of both maternal and infant rats. Considering the percentage of Hg accumulation, approximately 52.7%, 38.7%, and 1.66% were found in kidney, liver and brain for maternal rats, respectively, while 23.7%, 48.9% and 15.6% for infant rats. The important findings in this work were that the low dose of inorganic mercury appeared to accumulate in the brain of offspring and more Hg was present in infant brain than in their mother. As in the brain regions, the highest Hg content was present in infant hippocampus and cerebellum, whereas the Hg contents in maternal brains varied not so much. The imbalances of Fe/Cu, Cu/Zn, Zn/Se mass ratios and the molar ratios of Hg over other elements in the Hg-exposed rats were observed.

Study of chromium-containing proteins in subcellular fractions of rat liver by enriched stable isotopic tracer technique and gel filtration chromatography.

Ten male Wistar rats were intravenously injected with a single approximately physiological dose of enriched stable isotopic Cr-50 tracer solution (200 ng (50)Cr(3+)/100 g body wt). The fundamental distribution patterns of the chromium-containing proteins in the nucleic, mitochondrial, lysosomal, microsomal, and cytosolic subcellular fractions of the rat liver were investigated by means of Sephadex G-100 gel chromatography combined with neutron activation analysis via (50)Cr (n, gamma) (51)Cr reaction. In total, nine kinds of Cr-containing proteins were found in the five subcellular fractions, whose relative molecular masses were 96.6+/-6.2, 68.2+/-1.4, 57.9+/-4.7, 36.6+/-1.2, 24.2+/-1.8, 14.0+/-1.5, 8.8+/-0.6, 6.9+/-0.4, and 4.2+/-0.4 kDa. Approximately 64.5% of Cr proteins accumulated in the cytosolic fraction. The second enriched part was the nucleic fraction; about 12.2% Cr proteins were stored in this section. The 4.2-kDa molecular mass might contain the so-called low molecular weight chromium-containing substance; however, in this research, it was only observed in the mitochondria, lysosome, and microsome. In the mitochondrial fraction, most of the Cr proteins were present as relatively low molecular weight substances: about 56% of chromium-containing proteins had molecular masses < or =6.9 kDa. Nevertheless, more than 69% of Cr-containing proteins were observed with molecular masses > or =57.9 kDa in the liver cytosolic fraction.

Speciation and subcellular location of se-containing proteins in human liver studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and hydride generation-atomic fluorescence spectrometric detection.

Speciation of Se-containing proteins in the subcellular fractions of human liver was studied by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) followed by hydride generation-atomic fluorescence spectrometric (HG-AFS) detection. It was found that about 24 kinds of Se-containing proteins existed in subcellular fractions of normal human liver. The molecular weights (MW) of the subunits were mostly in the range 20-30 kDa and 50-80 kDa. Major Se-containing protein fractions at 61 kDa and 21 kDa are probably selenoprotein P and glutathione peroxidase, respectively. The 54 kDa protein is probably a thioredoxin reductase, which is presented in nuclei, mitochondria, lysosome, microsome and cytosol. We noticed that the Se-containing protein with the lowest MW of 9.3 kDa only existed in lysosome. Most of the proteins have not been identified and would require further investigation to characterize them. The specific subcellular distributions of different Se-containing proteins suggest that they could play important biological roles in each organelle.

Detection of metalloproteins in human liver cytosol by synchrotron radiation X-ray fluorescence combined with gel filtration chromatography and isoelectric focusing separation.

Synchrotron radiation X-ray fluorescence (SRXRF) spectroscopy is an advanced method of quantitative multielemental analysis with space resolution of several microm and sensitivities in the microg g(-1) range. It can be used for keeping track of trace elements after an electrophoretic separation of biological samples. In this paper, proteins in human liver cytosol were separated with gel filtration chromatography and thin layer isoelectric focusing (IEF). The contents of metal ions in protein bands were determined by SRXRF. The results showed that in the molecular weight (MW) range of 10 approximately 25 kDa, there were at least 2 Zn-containing bands with isoelectric point (pI) of 5 approximately 6 and 6.2 approximately 7, respectively and about 11 Fe-containing proteins with pI of 4.4, 4.6, 4.8, 5.0, 5.2, 5.3, 5.5, 5.6, 6.6, 6.8, and 7.2, respectively, present in human liver cytosol. The Zn-containing band with pI of 5-6 is the dominant species of zinc in this MW range. In addition, the Cu-containing bands with pI of 5.0 and below 4.8 were also detected. It is demonstrated that the procedure could be widely used in further investigations of the chemical species of trace elements in biological samples.