Spatial contaminant heterogeneity: quantification with scale of measurement at contrasting sites

Material within the terrestrial environment is rarely homogeneously distributed, either spatially or temporally. One consequence of heterogeneity is that uncertainty is usually generated in measurements that are taken with the aim of characterising the environment. For example, a measurement of analyte concentration within soil taken from one sampling location on contaminated land can vary substantially when compared against another sample taken at effectively the same nominal location. The measurement uncertainty arising from the heterogeneity can substantially limit the reliability of the interpretations made upon environmental investigations. The sampling uncertainty usually outweighs the analytical uncertainty from the laboratory, often by a factor of 20 or more. One approach to reducing the uncertainty is to design a more suitable sampling strategy. This might be achieved by predicting the degree of heterogeneity prior to the investigation, but this is often difficult to achieve accurately. Another approach, which was investigated here, is to actually characterise the heterogeneity prior to the main investigation using rapid and inexpensive technology, such as in situ measurement techniques. In situ portable X-ray fluorescence (PXRF) and X-ray microprobe (XMP) techniques were employed to test the feasibility of this approach. Two contrasting contaminated land sites were chosen to characterise the two-dimensional spatial heterogeneity of heavy metal contamination in topsoil at a range of scales (50 m to 0.001 m). The spatial heterogeneity of contaminants, expressed as relative standard deviations, was found to differ between the two sites by a factor of two, largely due to the mode of deposition of pollution. The study also indicated that the heterogeneity did not change systematically with the scale of measurement between sampling locations at either site.     

Geochemistry and mobilization of arsenic in Shuklaganj area of Kanpur–Unnao district, Uttar Pradesh, India

The level of arsenic (As) contamination and the geochemical composition of groundwater in Shuklaganj area located on the banks of the Ganges Delta of Kanpur-Unnao district were elucidated. Samples (n?=?59) were collected from both India Mark II hand pumps (depth, 30-33 m) and domestic hand pump tube wells (10-12 m) located within 5 km from the banks of Ganges. Samples were analyzed for various parameters, including total inorganic As, sulfate, nitrate, alkalinity, ammonia, and iron. Hydrochemistry of the groundwater aquifer was studied through the trilinear plots between monovalent and divalent cations and anions. In Indian mark II hand pumps, arsenic concentration ranged from below detection limit to 448 μg/L. Most of the samples contained both As(III) and As(V). The pH of the samples ranged from 7.1 to 8.2. Except for a few, most of the samples were reducing in nature as evident by their negative oxidation reduction potentials. A positive correlation for arsenic with iron, ammonia, and dissolved organic carbon shows the probability of biodegradation of organic matter and reductive dissolution of Fe oxyhydroxide processes to leach As in aquifers. For confirmation of the suggested arsenic mobilization mechanism, the presence and absence of sulfate-reducing bacteria and iron-reducing bacteria were also tested.     

Desorption of arsenic from drinking water distribution system solids

Previous work has shown that arsenic can accumulate in drinking water distribution system (DWDS) solids (Lytle et~al., 2004) when arsenic is present in the water. The release of arsenic back into the water through particulate transport and/or chemical release (e.g. desorption, dissolution) could result in elevated arsenic levels at the consumers' tap. The primary objective of this work was to examine the impact of pH and orthophosphate on the chemical release (i.e. desorption) of arsenic from nine DWDS solids collected from utilities located in the Midwest. Arsenic release comparisons were based on the examination of arsenic and other water quality parameters in leach water after contact with the solids over the course of 168~hours. Results showed that arsenic was released from solids and suggested that arsenic release was a result of desorption rather than dissolution. Arsenic release generally increased with increasing initial arsenic concentration in the solid and increasing pH levels (in the test range of 7 to 9). Finally, orthophosphate (3 and 5 mg PO₄/L) increased arsenic release at all pH values examined. Based on the study results, utilities with measurable levels of arsenic present in their water should be aware that some water quality changes can cause arsenic release in the DWDS potentially resulting in elevated levels at the consumer's tap.     

Biomonitoring with epiphytic lichens as a complementary method for the study of mercury contamination near a cement plant

The study was focused on understanding the mercury contamination caused by a cement plant. Active and passive biomonitoring with epiphytic lichens was combined with other instrumental measurements of mercury emissions, mercury concentrations in raw materials, elemental mercury concentrations in air, quantities of dust deposits, temperatures, precipitation and other measurements from the cement plant's regular monitoring programme. Active biomonitoring with transplanted lichens Pseudevernia furfuracea (L.) Zopf was performed at seven of the most representative sites around the cement plant and one distant reference site for periods of 3, 6 and 12 months. In situ lichens of different species were collected at the beginning of the monitoring period at the same sites. Mercury speciation of the plant exhaust gas showed that the main form of emitted mercury is reactive gaseous mercury Hg2?, which is specific for cement plants. Elemental mercury in air was measured in different meteorological conditions using a portable mercury detector. Concentrations in air were relatively low (on average below 10 ng m?3). In situ lichens showed Hg concentrations comparable to lichens taken from the background area for transplantation, indicating that the local pollution is not severe. Transplanted lichens showed an increase of mercury, especially at one site near the cement plant. A correlation between precipitation and Hg uptake was not found probably due to a rather uniform rainfall in individual periods. Dust deposits did not influence Hg uptake significantly. Lichens vitality was affected over longer biomonitoring periods, probably due to some elements in dust particles, their alkalinity and the influence of other emissions. Mercury uptake measured in vital transplanted lichens was in a good correlation with the working hours (i.e. emitted Hg quantity) of the kiln. The study showed that selected lichens could be used to detect low to moderate Hg emissions from a cement plant and that the biomonitoring procedure could be further standardized and used as part of an environmental monitoring programme.     

Methylated arsenic, antimony and tin species in soils

Methylated species of antimony, arsenic and tin were examined in urban soils of the Ruhr basin, near the cities of Duisburg and Essen, Germany. The main aim of this study was to investigate the occurrence of mono-, di- and trimethylated species of these elements in urban soils. The influence of historical and present land use upon the species content was examined. The distribution of inorganic As, Sb and Sn and their methylated species along the profile depth was investigated. As, Sb and Sn speciation was performed by pH-gradient hydride generation purge and trap gas chromatography, followed by inductively-coupled plasma mass spectrometry (HG-PT-GC/ICP-MS). Species' structures were confirmed by GC-EI/MS-ICP-MS. Monomethylated Sb and As were the dominant species detected: the concentration of these metal(loid) species varied between <0.07-56 microg kg(-1) per dry mass. All dimethylated species and monomethyltin concentrations were between <0.01-7.6 microg kg(-1) per dry mass, and for the trimethylated species of all examined elements, concentrations between <0.001-0.63 microg kg(-1) per dry mass were detected. The highest organometal(loid) concentrations were observed in agricultural soils and garden soils; lower concentrations were found in the soils of abandoned industrial sites (wasteland, primary forest and grassland) and a flood plain soil of the Rhine. This result can be ascribed to both the cultivation and the increased biological activity of the agricultural soils, and the generally higher contamination, the disturbed structure and the artificial substrates (deposits from industrial sources) of the abandoned industrial soils. Due to periodical sedimentation, the flood plain profile was the only one where no depth dependence of organometal(loid) species concentration was detected. The other soil profiles showed a decrease of species content with increasing depth; this was particularly noticeable in soils with a clear change from a horizon with an organic character towards a mineral horizon, i.e. decreasing vitality from profile top to bottom. It is not as yet clear whether the organometal(loid) species are formed in the mineral horizons of the profiles or whether they are displaced from the organic, biologically-active horizons towards the mineral horizons. Field studies revealed that soil parameters like pH, water content or temperature did not correlate significantly with the degree of biomethylation observed. In contrast to the lower in vitro biomethylation efficiency of Sb vs. As in microbial incubations, we consistently detected higher proportions of transformed Sb compounds in situ in soil samples. These data may indicate a need to re-examine the currently accepted model of Sb biogeochemical cycling in the real environment.     

Vertical profile,contamination assessment of mercury and arsenic in sediment cores from typical intertidal zones of China

The vertical profiles, contamination levels, and potential ecological risks of mercury and arsenic were studied from the sediment cores of seven typical intertidal zones, including the Liaohe River Estuary, the Jianhe River Estuary, the Dagu River Estuary, Yancheng Shoal, the Dongtan Yangtze River Estuary, Hangzhou Bay, and the Pearl River Estuary. Marine sediment quality standards, the threshold effect level (TEL), and the probable effect level (PEL) were used as guidelines to evaluate sediment quality. In addition, the geo-accumulation index (I_geo) and potential ecological risk index (\( {E}_r^i \)) were used to assess contamination and potential ecological risks from mercury and arsenic. The results showed that the Pearl River Estuary was moderately polluted by mercury and represented a high potential ecological risk, while other areas were uncontaminated or mildly contaminated with low or moderate potential ecological risks. The Pearl River Estuary was mildly polluted by arsenic and represented a mild potential ecological risk, while other areas were unpolluted and also posed a mild potential ecological risk.     

Uptake of arsenic by alkaline soils near alkaline coal fly ash disposal facilities

The attenuation of arsenic in groundwater near alkaline coal fly ash disposal facilities was evaluated by determining the uptake of arsenic from ash leachates by surrounding alkaline soils. Ten different alkaline soils near a retired coal fly ash impoundment were used in this study with pH ranging from 7.6 to 9.0, while representative coal fly ash samples from two different locations in the coal fly ash impoundment were used to produce two alkaline ash leachates with pH 7.4 and 8.2. The arsenic found in the ash leachates was present as arsenate [As(V)]. Adsorption isotherm experiments were carried out to determine the adsorption parameters required for predicting the uptake of arsenic from the ash leachates. For all soils and leachates, the adsorption of arsenic followed the Langmuir and Freundlich equations, indicative of the favorable adsorption of arsenic from leachates onto all soils. The uptake of arsenic was evaluated as a function of ash leachate characteristics and the soil components. The uptake of arsenic from alkaline ash leachates, which occurred mainly as calcium hydrogen arsenate, increased with increasing clay fraction of soil and with increasing soil organic matter of the alkaline soils. Appreciable uptake of arsenic from alkaline ash leachates with different pH and arsenic concentration was observed for the alkaline soils, thus attenuating the contamination of groundwater downstream of the retired coal fly ash impoundment.     

Use of portable X-ray fluorescence spectrometry for environmental quality assessment of peri-urban agriculture

Urban expansion into traditional agricultural lands has augmented the potential for heavy metal contamination of soils. This study examined the utility of field portable X-ray fluorescence (PXRF) spectrometry for evaluating the environmental quality of sugarcane fields near two industrial complexes in Louisiana, USA. Results indicated that PXRF provided quality results of heavy metal levels comparable to traditional laboratory analysis. When coupled with global positioning system technology, the use of PXRF allows for on-site interpolation of heavy metal levels in a matter of minutes. Field portable XRF was shown to be an effective tool for rapid assessment of heavy metals in soils of peri-urban agricultural areas.     

Seasonal perspective of dietary arsenic consumption and urine arsenic in an endemic population

Exposure to arsenic in arsenic endemic areas is most remarkable environmental health challenges. Although effects of arsenic contamination are well established, reports are unavailable on probable seasonal variation due to changes of food habit depending on winter and summer seasons, especially for endemic regions of Nadia district, West Bengal. Complete 24-h diets, drinking–cooking water, first morning voided urine samples, and diet history were analyzed on 25 volunteers in arsenic endemic Chakdah block of Nadia district, once in summer followed by once in winter from the same participants. Results depicted no seasonal variation of body weight and body mass index. Arsenic concentration of source drinking and cooking water decreased (p?=?0.04) from 26 μg L^?1 in summer to 6 μg L^?1 in winter season. We recorded a seasonal decrease of water intake in male (3.8 and 2.5 L day ^?1) and female (2.6 and 1.2 L day^?1) participants from summer to winter. Arsenic intake through drinking water decreased (p?=?0.04) in winter (29 μg day^?1) than in summer (100 μg day^?1), and urinary arsenic concentration decreased (p?=?0.018) in winter (41 μg L^?1) than in summer (69 μg L^?1). Dietary arsenic intake remained unchanged (p?=?0.24) over the seasons. Hence, we can infer that human health risk assessment from arsenic needs an insight over temporal scale.     

Fluvial transport and surface enrichment of arsenic in semi-arid mining regions: examples from the Mojave Desert, California

As a result of extensive gold and silver mining in the Mojave Desert, southern California, mine wastes and tailings containing highly elevated arsenic (As) concentrations remain exposed at a number of former mining sites. Decades of weathering and erosion have contributed to the mobilization of As-enriched tailings, which now contaminate surrounding communities. Fluvial transport plays an intermittent yet important and relatively undocumented role in the migration and dispersal of As-contaminated mine wastes in semi-arid climates. Assessing the contribution of fluvial systems to tailings mobilization is critical in order to assess the distribution and long-term exposure potential of tailings in a mining-impacted environment. Extensive sampling, chemical analysis, and geospatial mapping of dry streambed (wash) sediments, tailings piles, alluvial fans, and rainwater runoff at multiple mine sites have aided the development of a conceptual model to explain the fluvial migration of mine wastes in semi-arid climates. Intense and episodic precipitation events mobilize mine wastes downstream and downslope as a series of discrete pulses, causing dispersion both down and lateral to washes with exponential decay behavior as distance from the source increases. Accordingly a quantitative model of arsenic concentrations in wash sediments, represented as a series of overlapping exponential power-law decay curves, results in the acceptable reproducibility of observed arsenic concentration patterns. Such a model can be transferable to other abandoned mine lands as a predictive tool for monitoring the fate and transport of arsenic and related contaminants in similar settings. Effective remediation of contaminated mine wastes in a semi-arid environment requires addressing concurrent changes in the amounts of potential tailings released through fluvial processes and the transport capacity of a wash.     

Speciation of arsenic using solid phase extraction cartridges

Various solid phase extraction (SPE) cartridges were investigated for speciation of arsenite [As(III)], arsenate [As(v)], monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). Cartridges containing different types of sorbent materials were tested for arsenic retention and elution characteristics. Alumina cartridges were found to completely retain all the four target arsenic species, and are suitable for removal and preconcentration purposes. For speciation analysis, different arsenic species were separated on the basis of their selective retention on and elution from specific cartridges. DMA was retained on a resin-based strong cation exchange cartridge and eluted with 1.0 M HCl. MMA and As(v) were both retained on a silica-based strong anion exchange cartridge and sequentially eluted with 60 mM acetic acid (for MMA) and 1.0 M HCl [for As(v)]. As(III) was not retained on either cartridge and remained in solution. Arsenic species in solution and those eluted from the cartridges were subsequently quantified by using flow injection with hydride generation atomic fluorescence spectrometry (FI-HGAFS) and hydride generation atomic absorption spectrometry (FI-HGAAS). A detection limit of 0.05 microg L(-1) arsenic in water sample was achieved using HGAFS. An application of the method was demonstrated at a drinking water treatment facility. As(III) and As(v) species were determined in water at various stages of treatment. The method is suitable for routine determination of trace levels of arsenic in drinking water to comply with more stringent environmental regulations.     

Monitoring of copper,arsenic and antimony levels in agricultural soils impacted and non-impacted by mining activities,from three regions in Chile

This paper reports a comparative study of the concentration of three important environmental elements that are often found together in mineral deposits and then associated with mining activities; copper, arsenic and antimony. These elements were determined in 26 different agricultural soils from regions I, II and V in Chile, zones where the most important and biggest copper industries of this country are located. As background levels of these elements in soils have not been well established, in this study, both, impacted and non-impacted agricultural soils from different regions were considered. The relationships between the concentrations of these elements in soils were also examined. The concentration ranges for copper, arsenic and antimony were 11-530; 2.7-202 and 0.42-11 mg kg(-1) respectively. The copper concentrations in non-polluted soils from the north and central zone of Chile were similar. However, three sites from the north region have copper concentration as higher as 100 mg kg(-1), values that exceed the critical concentration for copper in soils. The concentration of arsenic and antimony in the north soils were higher than in non-impacted ones and, in the case of arsenic, greatly exceeded the world average concentration reported for this element in soils. The highest arsenic and antimony concentrations were found in Calama and Quillagua soils, two different sites in the Loa valley. The arsenic/antimony concentration ratio was higher in Quillagua soil. The high concentrations of three elements determined in impacted soils from region V (Puchuncaví and Catemu valleys) clearly shows the impact produced in this zone by the industrial and mining activities developed in their proximities. At Puchuncaví valley a clear decrease was observed in copper, arsenic and antimony concentrations in soils on the function of the distance from the industrial complex "Las Ventanas", and all concentrations exceeded the reported critical values for this matrix. Instead at Catemu valley, only the copper concentration was higher than this value. Statistically significant correlation was found for Cu-Sb in all soils; more significant Cu-As, Cu-Sb and Sb-As correlations were evaluated for soils from Puchuncaví and Catemu valleys, corroborating that high concentrations of copper, arsenic and antimony in these soils coming from the same pollution sources, the copper industry and the thermoelectric power plant.     

Removing arsenic from groundwater in Cambodia using high performance iron adsorbent

In Cambodia, groundwater has been contaminated with arsenic, and purification of the water is an urgent issue. From 2010 to 2012, an international collaborative project between Japan and Cambodia for developing arsenic-removing technology from well water was conducted and supported by the foundation of New Energy and Industrial Technology Development Organization, Japan. Quality of well water was surveyed in Kandal, Prey Veng, and Kampong Cham Provinces, and a monitoring trial of the arsenic removal equipment using our patented amorphous iron (hydr)oxide adsorbent was performed. Of the 37 wells surveyed, arsenic concentration of 24 exceeded the Cambodian guideline value (50 μg L^?1), and those of 27 exceeded the WHO guideline for drinking water (10 μg L^?1). Levels of arsenic were extremely high in some wells (>1,000–6,000 μg L^?1), suggesting that arsenic pollution of groundwater is serious in these areas. Based on the survey results, 16 arsenic removal equipments were installed in six schools, three temples, two health centers, four private houses, and one commune office. Over 10 months of monitoring, the average arsenic concentrations of the treated water were between 0 and 10 μg L^?1 at four locations, 10–50 μg L^?1 at eight locations, and >50 μg L^?1 at four locations. The arsenic removal rate ranged in 83.1–99.7 %, with an average of 93.8 %, indicating that the arsenic removal equipment greatly lower the risk of arsenic exposure to the residents. Results of the field trial showed that As concentration of the treated water could be reduced to <10 µg L^?1 by managing the As removal equipment properly, suggesting that the amorphous iron (hydr)oxide adsorbent has high adsorbing capacity for As not only in the laboratory environment but also in the field condition. This is one of the succeeding As removal techniques that could reduce As concentration of water below the WHO guideline value for As in situ.     

便携式XRF在污染地块土壤金属元素调查中的应用

研究了便携式X荧光光谱仪（PXRF）测定土壤中砷、铅、铬、铜、锌和镍的性能，评估其检出限、精密度和准确度，探索了土壤水分和粒径对测定结果的影响程度，并与常规实验室分析方法测定结果进行比对。结果表明，PXRF测定土壤中砷、铅、铬、铜、锌和镍的检出限为5~15mg/kg，标准物质测定结果的相对标准偏差（RSD）≤8.6%，相对误差在±15%以内。随着土壤水分含量的增加，各金属元素测定结果均呈下降趋势，而RSD有上升趋势。土壤粒径对测定结果的影响较小，随着土壤粒径减少，各金属元素测定结果的RSD略有下降趋势。PXRF可以简单、快速地测定多种重金属元素，适用于污染地块重金属元素的现场实时监测。     

Quantitative arsenic speciation in two species of earthworms from a former mine site

The relationship between the total arsenic concentration and the chemical speciation of arsenic in two species of earthworm (Lumbricus rubellus and Dendrodrilus rubidus) in relation to the host soil, was investigated for 13 sites of varying arsenic content, including a background level garden soil and a former mine site at the Devon Great Consols, UK. Earthworms were collected with the host soil (As soil concentration range 16-12, 466 mg kg(-1) dry weight) and measured for their total arsenic (concentration range 7-595 mg kg(-1) dry weight) using inductively coupled plasma mass spectrometry (ICP-MS). A methanol-water mixture was used to extract arsenic species from the earthworms prior to determination of the individual arsenic species by a combination of anion and cation exchange high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (HPLC-ICP-MS). A gradient elution anion exchange method is presented whereby nine arsenic species could be measured in one sample injection. Arsenic species were identified by comparison of retention times and sample spiking with known standards and a fully characterised seaweed extract. Arsenic was generally present in the earthworm as arsenate (As(V)) or arsenite (As(III)) and arsenobetaine (AB). Methylarsonate (MA), dimethylarsinate (DMA) and three arsenosugars (glycerol, phosphate, sulfate) were present as minor constituents. These results are discussed in relation to the mechanisms for coping with exposure to soil bound arsenic.     

Effect of fasting on the pattern of urinary arsenic excretion

Millions of people in some of the poorest regions of the world are exposed to high levels of arsenic through drinking contaminated water. It has been reported that development of cancer caused by arsenic exposure in such populations is dependent on dietary and nutritional factors which can modulate arsenic metabolism. Many people in arsenic exposed regions of Bangladesh and India practice fasting for at least one month every year when they refrain from consumption of food and fluid during daylight hours. How such practices may modulate arsenic metabolism has not been previously investigated. This study investigated this issue by determining total arsenic and its species in urine samples from a group of 29 unexposed volunteers at the beginning of the fasting and at the end of approximately 12 h of fasting period. Inductively coupled plasma mass spectrometry (ICP-MS) and high performance liquid chromatography (HPLC) coupled with ICP-MS was used to measure the total arsenic and arsenic speciation in the urine samples, respectively. The mean total levels of arsenic at the beginning of fasting (18.3 microg g(-1) creatinine) and at the end of approximately 12 h of fasting (17.7 microg g(-1) creatinine) did not differ significantly (p > 0.05). However, the percentages of urinary arsenic as the methylated arsenic species methylarsonate (MA) were found to be significantly different (p < 0.05) and this species was observed more frequently at the end of fasting, although its overall concentration was similar. There were no significant differences (p > 0.05) in both the concentrations and percentages of other urinary arsenic species detected, namely arsenobetaine (AB) and dimethylarsinate (DMA). Arsenite (As(III)) and arsenate (As(V)) were also analyzed, but were not detected. We conclude that fasting for a period of 12 h results in a significant increase in the percentage of urinary arsenic as MA, and its frequency of detection in the volunteers at the end of the fasting period is almost nine fold higher. This suggests that metabolism of arsenic is altered by fasting.     

European bee-eater (Merops apiaster) populations under arsenic and metal stress: evaluation of exposure at a mining site

Two populations of the European bee-eater were studied, one living at a reference site and the other at a metal mining site. The concentration of arsenic and 11 metals (Al, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn) was measured in feathers and regurgitated pellets collected at both sites. Cadmium, chromium, mercury, nickel, and lead were at least twofold higher in feathers of birds from the contaminated site than in the reference site, suggesting that this population was exposed to higher metal levels. Similarly, levels of aluminum, arsenic, cadmium, cobalt, chromium, iron, and lead were also at least twofold higher in pellets from the contaminated area. The obtained results suggested that the impacted population of Merops apiaster is at risk due to the exposure to some metals.     

Monitoring of arsenic in aquatic plants, water, and sediment of wastewater treatment ponds at the Mae Moh Lignite power plant, Thailand

Mae Moh is a risky area for arsenic contamination caused by the effluent from biowetland ponds in Mae Moh lignite-fuelled power plant. The objective of this study was to investigate the arsenic concentrations of Mae Moh biowetland ponds and determine the main factors which are important for arsenic phytoremediation in the treatment system. The result revealed that arsenic concentrations in the supernant were in the range of less than 1.0 μg As L^???1 to 2.0 μg As L^???1 while those in the sediment were in the range of 25–200 μg As kg soil^???1. Both values were below the Thailand national standard of 0.25 mg As L^???1 for water and 27 mg As kg soil^???1 for the soil. Arsenic accumulation in the biomass of 5 aquatic plants at the biowetland ponds ranged from 123.83 to 280.53 mg As kgPlant^???1. Regarding the result of regression analysis (R ²?= 0.474 to 0.954), high concentrations of organic matter and other soluble ions as well as high pH value in the sediment could significantly enhance the removal of soluble arsenic in the wetland ponds. From the regression equation of accumulated arsenic concentration in each aquatic plant, Eichhornia crassipes (Mart.) Solms. (R ²?= 0.954), Ipomoea aquatica Forsk. (R ²?= 0.850), and Typha angustifolia (L.) (R ²?= 0.841) were found to be preferable arsenic removers for wastewater treatment pond in the condition of low Eh value and high content of solid phase EC and phosphorus. On the other hand, Canna glauca (L.) (R ²?= 0.749) appeared to be favorable arsenic accumulator for the treatment pond in the condition of high Eh value and high concentration of soluble EC.     

便携式XRF测定仪在土壤检测中的应用及其影响因素

研究了便携式X射线荧光光谱仪(PXRF)的仪器性能,评估了其检出限、准确度及精密度,并和常规实验室检测方法比对进一步评估其性能,分析两者间的相关性和差异性。进一步探究了影响PXRF测定的2个最主要因素(土壤含水量和粒径)。结果表明:PXRF具备良好的仪器性能,8种元素的检出限为0.62～8.01 mg/kg,除Cd和Hg外,精密度均低于7%,准确度范围为-7.5%～11.1%。Pb、Cr、Cu、Zn、Ni、As的PXRF测定值与常规实验室方法测定值有良好的相关性,特别是Cu、Zn,相关系数可达0.873、0.832,而Cd和Hg的相关性则较弱。土壤含水量和土壤粒径会影响PXRF的测定性能,鲜样测定检测值普遍小于干样,0.15、2 mm粒径下检测值具有较强的相关性。研究旨在为PXRF的现场应用提供 参考,该方法可应用于初步监测和应急监测,实现土壤重金属元素的快速测定。     

Lead,cadmium, arsenic and zinc in the ecosystem surrounding a lead smelter

A lead smelter has been operating at Belledune in the province of New Brunswick, in eastern Canada, since 1966. This paper presents data on the concentrations of the four primary metals emitted from the smelter — lead, cadmium, arsenic and zinc — which were measured in the terrestrial environment near the smelter and the concentrate transport route. Deposition of these metals to the snowpack and the uptake by grass forage are discussed in relation to non-regulatory guidelines, toxicity and atmospheric emissions. A 1992 snowpack transect survey extending 0.5–40 km northwest, southeast and south of the smelter revealed lead concentrations of 2–3193 ppb, cadmium <0.10–49.7 ppb, arsenic <3.0–72.0 ppb, and zinc 3–401 ppb. Deposition estimates within this zone for lead were between 0.046 and 20.1 kg/ha/yr, cadmium <0.007 and 313 g/ha/yr, arsenic <0.016 and 453 g/ha/yr and zinc 0.020 and 2.52 kg/ha/yr. Concentrations of these metals in the snowpack were highest within 3 km of the smelter and were detectable at greater distances SE of the smelter. Lead was dispersed greater distances from the smelter than cadmium or arsenic. Snowpack samples collected within 5–20 m of the railway contained 140–7270 ppb of lead, 0.4–36.9 ppb of cadmium, <3.0–72.0 ppb of arsenic and 41–13100 ppb of zinc. Grass forage sampled within 0.6–16 km of the smelter contained lead 5–152 ppm, cadmium 0.10–4.1 ppm, and zinc 22–154 ppm. Highest concentrations of lead, cadmium and zinc in grass forage were found were found within 2.2 km of the smelter. Grass forage collected within 10–70 m of the railway contained lead 13–288 ppm, cadmium 0.4–1.3 ppm and zinc 98–831 ppm.