A proficiency testing scheme for aromatic hydrocarbons in air by the manual thermal desorption-GC method: a comparison of laboratory performance with the uncertainty requirements of the European Union Ambient Air Directive

The Workplace Analysis Scheme for Proficiency (WASP) is a proficiency testing scheme for the analysis of occupational hygiene and environmental air samples and is operated in the UK by the Health and Safety Laboratory. Since 1997, WASP has offered samples of benzene, toluene and m-xylene, at environmental levels on Tenax, and has about 35 laboratories participating, mostly from industry, local government and consultancy organisations in the UK. The results reported cover the first 10 rounds of the environmental analytes (1997-1999) and demonstrate the important role of proficiency testing in assessing the quality of laboratory performance. Estimates are obtained for within-laboratory precision and the total variability at each analyte level. The estimates of within-laboratory precision suggest that laboratories have more difficulty analysing toluene and m-xylene than benzene. Linear relationships for the reproducibility relative standard deviation (RSDT) with loading level are evident for the analytes at occupational levels. At environmental levels, the relationship between loading level and reproducibility is much less well defined. The standard deviation for the proficiency testing assessment for all three analytes at the environmental level is 14%, as derived from the benzene data. Expanded uncertainty estimates (k = 1.96), for the analysis of samples since the scheme started, are obtained from the average total variance, and are 27% for benzene, 39% for toluene and 36% for m-xylene. Although the linear trend of performance against round number was not significant at the 95% level of confidence (p = 0.23 for benzene, p = 0.3 for toluene and p = 0.32 for m-xylene), there was a general improvement in RSDT from 26-34% to about 8-13% 10 rounds later. Currently, for a laboratory to meet one of the data quality objectives in the Ambient Air Directive (indicative measurement of benzene, expanded uncertainty +/- 30% or less), it would have to achieve a level of analytical performance to satisfy the category 1 (best performance) limit of better than +/- 8.8%. In the last proficiency testing round, discussed in this paper, only 58% of laboratories obtained performance scores that indicated that they were able to consistently achieve this level of performance.     

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.     

采用能力验证数据评估环境监测结果测量不确定度

测量不确定度评估是实验室检测能力的体现,能力验证是实验室质量控制的有效方法,对环境监测领域实验室采用能力验证数据进行测量结果不确定度评估方法进行了研究。依据Nordtest准则,根据实验室内再现性标准差和测量偏倚,评估了重铬酸钾法测定水中质量浓度为100 mg/L的化学需氧量测量结果的相对不确定度为6.00%。该评估方法避免了ISO GUM评定方法自下而上不确定度评估过程的繁琐,还充分考虑了实验室内外误差的来源,能够促进环境监测结果不确定度评定的一致性。     

Ultrasonic extraction and portable anodic stripping voltammetric measurement of lead in paint, dust wipes, soil, and air: an interlaboratory evaluation

Recent studies have demonstrated the utility of ultrasonic extraction (UE), followed by portable anodic stripping voltammetry (ASV), for the on-site determination of lead in environmental and industrial hygiene samples. The aim of this work was to conduct an interlaboratory evaluation of the UE-ASV procedure, with a goal of establishing estimates of method performance based on results from collaborative interlaboratory analysis. In this investigation, performance evaluation materials (PEMs) with characterized lead concentrations were used for interlaboratory testing of the UE-ASV procedure. The UE-ASV protocol examined has been promulgated in the form of two separate national voluntary consensus standards (one for UE and another for electroanalysis, which includes ASV). The PEMs consisted of characterized and homogenized paints, soils, and dusts (the last of which were spiked onto wipes meeting national voluntary consensus standard specifications), and air filter samples (mixed cellulose ester membrane) generated using characterized paints within an aerosol chamber. The lead concentrations within the PEMs were chosen so as to bracket pertinent action levels for lead in the various sample matrices. The interlaboratory evaluation was conducted so as to comply with an applicable national voluntary consensus standard that can be used to estimate the interlaboratory precision of a given analytical test method. Based on the analytical results reported by the participating laboratories, relative standard deviations (RSDs) for repeatability and reproducibility were computed for three different lead contents of the four PEMs. RSDs for repeatability were 0.019-0.100 for paints; 0.030-0.151 for soils; 0.085-0.134 for dust wipes; and 0.095-0.137 for air filters. RSDs for reproducibility were 0.127-0.213 for paints; 0.062-0.162 for soils; 0.085-0.134 for dust wipes; and 0.114-0.220 for air filters. With the exception of one of the air filter samples and one of the paint samples, the precision estimates were within the +/- 20% precision requirement specified in the US Environmental Protection Agency National Lead Laboratory Accreditation Program (NLLAP). The results of this investigation illustrate that the UE-ASV procedure is an effective method for the quantitative measurement of lead in the matrices evaluated in this study.     

In situ laser-induced fluorescence (LIF) analysis of petroleum product-contaminated soil samples

General considerations of the calibrations of in situ measurements are presented and the concept of using an "average oil" with average analysability for calibration purposes is introduced. The in situ analysis of 30 petroleum product-contaminated soil samples with laser-induced fluorescence (LIF) spectroscopy was performed. Compared to an uncontaminated laboratory reference (LR) soil, 23 soil samples exhibited significantly higher LIF signals, so that these soil samples were classified as contaminated. The repeatability and reproducibility of the in situ LIF analysis were investigated. For the calibration of the LIF data, two LR oils (a fuel oil and a crude oil) were employed. The degree of soil contamination with petroleum products ranged from the limit of detection (LOD) for LIF analysis (ca. 100 ppm), or below, to more than 10,000 ppm. The petroleum product concentrations determined with in situ LIF analysis reveal a reasonable correlation with the results of standard IR analysis after extraction of the contaminated soils.     

Application of portable gas chromatography-photo ionization detector combined with headspace sampling for field analysis of benzene, toluene, ethylbenzene, and xylene in soils

A method based on headspace (HS) sampling coupling with portable gas chromatography (GC) with photo ionization detector (PID) was developed for rapid determination of benzene, toluene, ethylbenzene, and xylenes (BTEX) in soils. Optimal conditions for HS gas sampling procedure were determined, and the influence of soil organic matter on the recovery of BTEX from soil was investigated using five representative Chinese soils. The results showed that the HS-portable-GC-PID method could be effectively operated at ambient temperature, and the addition of 15 ml of saturated NaCl solution in a 40-ml sampling vial and 60 s of shaking time for sample solution were optimum for the HS gas sampling procedure. The recoveries of each BTEX in soils ranged from 87.2 to 105.1 %, with relative standard deviations varying from 5.3 to 7.8 %. Good linearity was obtained for all BTEX compounds, and the detection limits were in the 0.1 to 0.8 μg kg^?1 range. Soil organic matter was identified as one of the principal elements that affect the HS gas sampling of BTEX in soils. The HS-portable-GC-PID method was successfully applied for field determination of benzene and toluene in soils of a former chemical plant in Jilin City, northeast China. Considering its satisfactory repeatability and reproducibility and particular suitability to be operated in ambient environment, HS sampling coupling with portable GC-PID is, therefore, recommended to be a suitable screening tool for rapid on-site determination of BTEX in soils.     

Soil subsampling in environmental sciences: the role of granulometry

Uncertainty associated to analytical results is an issue of major interest for the whole analytical community. A large effort has been made to improve analytical techniques and procedures aimed to achieve a well characterized uncertainty associated with analysis. However, it is becoming increasingly recognised that uncertainty deriving from sampling and subsampling can even dominate the global uncertainty budget. A study on subsampling activities on different soil typologies has been performed by granulometry determinations. The differences between sieving methodologies based on both wet and dry mode have been studied. Subsampling is approached by replicated measurements providing a quantitative assessment of the distribution heterogeneity, a suitable method validation scheme and an empirical determination of uncertainty.     

杭州地区农业土壤中重金属的分布特征及其环境意义

为了分析杭州地区农业土壤重金属的分布特征及其环境意义,通过现场采样和室内分析检测的方法,对杭州市各区县不同作物农业土壤表层土中的Hg、As、Cu、Pb、Cr、Cd 6种重金属元素进行检测,并对其分布特征进行了分析。结果表明,杭州地区农业土壤中除As外,其他5种重金属的平均含量均低于且接近浙江省土壤背景值,个别采样点的重金属含量超过了土壤环境质量国家二级标准。总体上,杭州地区农业土壤处于安全水平。通过重金属的区域分布特征分析表明,余杭区和富阳市农业土壤中重金属平均含量普遍高于其他区域。萧山区和建德市部分农业土壤则存在Cu和Hg含量较高的情况,而淳安县农业土壤中重金属含量差异较大,土壤中出现了As、Cr和Cd含量最大值。不同作物的农业土壤重金属含量存在一定的差异,但不明显。水稻田和蔬菜地的土壤中,重金属含量较其他作物种植类型的土壤中含量高;叶菜类(蔬菜、茶叶)作物土壤中的Cd含量要比根茎类(水稻)、茄果类(水果)及其他作物种植类型的土壤中的含量低。目前杭州地区土壤中6种重金属含量均对作物的直接危害不大,但由于萧山区个别采样点Cu含量严重超标,淳安县土壤中Cd受外源性来源影响也已较明显,需要相关部门加大监管力度,防止污染事件发生。同时,为防止农业土壤中重金属含量进一步升高,需要加大大气降尘监测与治理、废气污染监管与控制治理。     

环境检测领域能力验证工作的组织及评价方法

介绍了环境检测领域能力验证的基本情况和统计方法，以及当前国内外能力验证计划提供者采用的数据处理方法，分析了该领域能力验证的发展趋势。指出环境检测领域化学分析方面的能力验证计划一般采用参加者结果的中位值或稳健均值作为指定值，采用标准化四分位距或稳健标准偏差作为能力评定标准差，以 z比分数法评价参加者的能力。     

The effects of heavy metal pollution on enzyme activities and basal soil respiration of roadside soils

In this study, soil samples (0-5 cm depth) were taken from ten different roadside fields of intensive traffic regions of Van-Turkey in order to determine the effects of heavy metal pollution on enzymes and microbial activities of soils. Basal soil respiration (BSR), arylsulphatase (ASA), alkaline phosphatase (APA) and urease (UA) enzyme activities, and heavy metal contents (Pb, Cr, Ni, Cd, Fe, Mn, Cu and Zn) of soils significantly changed with 5, 25 and 45 m from the roadside of soil sampling positions. BSR, ASA, APA and UA activities significantly increased while the heavy metal contents generally decreased from the sampling position of 5 m through 25 and 45 m. Significant positive correlations were found among BSR, ASA, APA and UA. Chromium, Mn and Pb contents gave the significant negative correlation with ASA, APA and UA.     

6项环境监测分析方法标准中钴、铬、钼、钛的不确定度分析及其在达标判定中的应用

研究依据测定不确定度的基本理论和ISO 21748：2017《采用重复性、再现性和正确度评估测量不确定度的导则》，提出了基于中国环境监测分析方法标准多家实验室验证中已获得的数据计算合成标准不确定度的方法，将方法标准中规定的重复性、再现性等指标与合成标准不确定度进行了衔接。分析了近年发布的6项水质监测分析方法标准中钴、铬、钼、钛等4种金属元素的相对合成标准不确定度，结果表明：被测量的浓度是影响方法标准测量不确定度的重要因素。对于火焰原子吸收分光光度法（FAAS）和石墨炉原子吸收分光光度法（GAAS），样品浓度为方法标准测定下限3倍左右时，测定结果的相对标准不确定度可保持在15%以下；对于电感耦合等离子体发射光谱法（ICP-AES），样品浓度为方法标准测定下限3~5倍时，测定结果的相对标准不确定度为12%~17%；对于电感耦合等离子体质谱法（ICP-MS），钛元素浓度为测定下限3倍左右时，相对标准不确定度在15%以下，而钴、铬、钼的浓度在测定下限40~100倍以上时，相对标准不确定度在15%以下。6项方法标准可分别用于《地表水环境质量标准》（GB 3838—2002）以及22项水污染物排放标准钴、铬、钼、钛的达标监测。     

Survey of phthalate pollution in arable soils in China

The problem of pollution by phthalates is of global concern due to their widespread occurrence, toxicity and endocrine disruption properties. The contamination by phthalates such as dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) in 23 arable soils throughout China was investigated to evaluate the present pollution situation. The survey results demonstrated that phthalates were ubiquitous pollutants in soils in China. The total concentrations of phthalates differed from one location to another, and ranged from 0.89 to 10.03 mg kg(-1) with a median concentration of 3.43 mg kg(-1). Among the phthalates, DEHP was dominant and detected in all 23 soils. DEP and DBP were also in abundance, and DMP was rarely detected. Similar contamination patterns were observed in all 23 soils. A distinct feature of phthalate pollution in China was that the average concentration in northern China was higher than that in southern China. In addition, a close relationship was observed between the concentration of phthalates in soils and the consumption of agricultural film. The correlation showed that the application of agriculture film might be a significant pollution source of phthalates in arable soils of China. The potential risk of phthalates in soils was assessed on the basis of current guide values and limits.     

Pollution of intensively managed greenhouse soils by nutrients and heavy metals in the Yellow River Irrigation Region,Northwest China

The present study aimed to assess the potential ecological risk of heavy metals and nutrient accumulation in polytunnel greenhouse soils in the Yellow River irrigation region (YRIR), Northwest China, and to identify the potential sources of these heavy metals using principal component analysis. Contents of available nitrogen (AN), phosphorus (AP), and potassium (AK) in the surface polytunnel greenhouse soils (0–20 cm) varied from 13.42 to 486.78, from 39.10 to 566.97, and from 21.64 to 1,156.40 mg kg^?1, respectively, as well as AP, soil organic matter (SOM) and AK contents tended to increase significantly at the 0–20- and 20–40-cm soil layers. Heavy metal accumulations occurred in the polytunnel greenhouse soils as compared to arable soils, especially at a depth of 20 cm where Cd, Zn and Cu contents were significantly higher than arable soil. Cd and As were found to be the two main polluting elements in the greenhouse soils because their contents exceeded the thresholds established for greenhouse vegetable production HJ333-2006 in China and the background of Gansu province. It has been shown that Cd, Cu, Pb and Zn at the 0–20-cm soil layer were derived mainly from agricultural production activities, whereas contents of Cr and Ni at the same soil layer were determined by ‘natural’ factors and As originated from natural sources, deposition and irrigation water.     

A field screening test for the assessment of concentrations and mobility of potentially toxic elements in soils: a case study on urban soils from Rome and Novi Sad

The increasing demand for environmental pollution control results in the development and use of new procedures for the determination of dangerous chemicals. Simple screening methods, which can be used directly in the field for a preliminary assessment of soil contamination, seem to be extremely advantageous. In our laboratory, we developed and optimized a rapid test for a preliminary evaluation of both the concentration and the mobility of some potentially toxic metals in soils. This screening test consists of a single extraction of the soil sample with a buffer solution, followed by the titration of the extracted solution with dithizone to determine the contents of bi-valent heavy metals (such as Pb, Cu, Zn, and Cd). This screening method was then directly applied in the field during the sampling campaign in the framework of an Italian–Serbian collaborative project, finalized in the study of metal availability in soils. The results obtained in the field with the rapid test were compared with those obtained in the laboratory following the conventional procedure commonly used to evaluate metal bioavailability (diethylenetriaminepentaacetic extraction). Moreover, selected samples were analyzed sequentially in the laboratory using the standardized BCR three-step sequential extraction procedure. The screening test gave results conceptually in good agreement with those obtained via the BCR procedure. These preliminary data show that the proposed screening test is a reliable method for the preliminary rapid evaluation of metal total concentrations and of potential metal mobility in soils, supporting sampling activities directly in the field.     

The contents and forms of solid-phase species of radioactive strontium and cesium in Taiwan soils

This study was to investigate the activities and contents of ¹³⁷Cs in the profiles of selected arable and forest soils in Taiwan and various solid-phase species of ⁸⁵Sr and ¹³⁷Cs in selected arable soils in Taiwan. The gamma (γ) ray spectra of the collected soil samples and some of the soils amended with ⁸⁵Sr and ¹³⁷Cs were measured. The data indicate that the arable soils from Sanhsing series, Sanhsing Township and Chuangwei series, Chuangwei Township, Ilan County, and from Tunglochuan series, Pinglin Township, Taipei County shows significantly higher radioactivity of ¹³⁷Cs (ND − 11.0 ± 0.2 Bq kg⁻¹). Furthermore, the radioactivity of ¹³⁷Cs in the mountain soils (1.24 ± 0.07 − 42 ± 1 Bq kg⁻¹) from Yuanyang Lake Nature Preserve among Ilan, Taoyuan, and Hsinchu Counties is the highest among the investigated mountain forest soils. This may be mainly attributed to the fact that Ilan County is located in the northeastern part of Taiwan and faces the northeastern and northern seasonal winds with lots of precipitation annually from mid-autumn through mid-spring next year and is receiving greater amount of fallouts yearly. Due to longer reaction period (≥3 y) of ¹³⁷Cs with soil components, ¹³⁷Cs was mainly in the forms bound to oxides and to organic matter in the soil amended with ¹³⁷Cs and in the soil contaminated with ¹³⁷Cs. On the contrary, due to shorter reaction period (<60 d) of ⁸⁵Sr with soil components, ⁸⁵Sr was mainly in exchangeable form and partially in the forms bound to carbonates and oxides in the soils amended with ⁸⁵Sr.     

High heterogeneity in soil composition and quality in different mangrove forests of Venezuela

Mangrove forests play an important role in biogeochemical cycles of metals, nutrients, and C in coastal ecosystems. However, these functions could be strongly affected by the mangrove soil degradation. In this study, we performed an intensive sampling characterizing mangrove soils under different types of environment (lagoon/gulf) and vegetation (Rhizophora/Avicennia/dead mangrove) in the Venezuelan coast. To better understand the spatial heterogeneity of the composition and characteristics of the soils, a wide range of the soil attributes were analyzed. In general, the soils were anoxic (Eh < 200 mV), with a neutral pH and low concentration in toxic metals; nevertheless, they varied widely in the soil and its quality-defining parameters (e.g., clay contents, total organic carbon, Fe, Al, toxic trace metals). It is noteworthy that the mangroves presented a low Fe_Pyrite content due to a limitation in the Fe oxyhydroxide contents, especially in soils with higher organic C content (TOC > 15%). Finally, the dead mangrove showed significantly lower amounts of TOC and fibers (in comparison to the well-preserved mangrove forest), which indicates that the C pools in mangrove soils are highly sensitive also to natural impact, such as ENSO.     

Improvement of the BCR three step sequential extraction procedure prior to the certification of new sediment and soil reference materials

The Standards, Measurements and Testing Programme (formerly BCR) of the European Commission proposed a three-step sequential extraction procedure for sediment analysis, following extensive expert consultations and two interlaboratory studies. This scheme was recently used to certify the extractable trace element contents of a sediment reference material (CRM 601). Although this procedure offers a means to ensure the comparability of data in this field, some difficulties concerning the interlaboratory reproducibility still remain, and a new project is currently being conducted to determine the causes of poor reproducibility in the extraction scheme. The final objective of the project is the certification of new sediment and soil reference materials for their extractable contents of Cd, Cr, Cu, Ni, Pb and Zn. This paper presents the results of a small-scale interlaboratory study, which aimed to test a revised version of the extraction schemes by comparing the original and the modified protocols using the CRM 601 sample. This work offers an improvement to the BCR sequential extraction procedure through intercomparison exercises. This improved procedure will allow the obtaining of CRMs to validate analytical data in the analysis of soils and sediments, and it will also facilitate comparability of data in the European Union.     

Spatial variability of soil total and DTPA-extractable cadmium caused by long-term application of phosphate fertilizers, crop rotation, and soil characteristics

Increasing cadmium (Cd) accumulation in agricultural soils is undesirable due to its hazardous influences on human health. Thus, having more information on spatial variability of Cd and factors effective to increase its content on the cultivated soils is very important. Phosphate fertilizers are main contamination source of cadmium (Cd) in cultivated soils. Also, crop rotation is a critical management practice which can alter soil Cd content. This study was conducted to evaluate the effects of long-term consumption of the phosphate fertilizers, crop rotations, and soil characteristics on spatial variability of two soil Cd species (i.e., total and diethylene triamine pentaacetic acid (DTPA) extractable) in agricultural soils. The study was conducted in wheat farms of Khuzestan Province, Iran. Long-term (27-year period (1980 to 2006)) data including the rate and the type of phosphate fertilizers application, the respective area, and the rotation type of different regions were used. Afterwards, soil Cd content (total or DTPA extractable) and its spatial variability in study area (400,000 ha) were determined by sampling from soils of 255 fields. The results showed that the consumption rate of di-ammonium phosphate fertilizer have been varied enormously in the period study. The application rate of phosphorus fertilizers was very high in some subregions with have extensive agricultural activities (more than 95 kg/ha). The average and maximum contents of total Cd in the study region were obtained as 1.47 and 2.19 mg/kg and DTPA-extractable Cd as 0.084 and 0.35 mg/kg, respectively. The spatial variability of Cd indicated that total and DTPA-extractable Cd contents were over 0.8 and 0.1 mg/kg in 95 and 25 % of samples, respectively. The spherical model enjoys the best fitting and lowest error rate to appraise the Cd content. Comparing the phosphate fertilizer consumption rate with spatial variability of the soil cadmium (both total and DTPA extractable) revealed the high correlation between the consumption rate of P fertilizers and soil Cd content. Rotation type was likely the main effective factor on variations of the soil DTPA-extractable Cd contents in some parts (eastern part of study region) and could explain some Cd variation. Total Cd concentrations had significant correlation with the total neutralizing value (p?<?0.01), available P (p?<?0.01), cation exchange capacity (p?<?0.05), and organic carbon (p?<?0.05) variables. The DTPA-extractable Cd had significant correlation with OC (p?<?0.01), pH, and clay content (p?<?0.05). Therefore, consumption rate of the phosphate fertilizers and crop rotation are important factors on solubility and hence spatial variability of Cd content in agricultural soils.     

SI-traceable certification of Cu, Cr, Cd and Pb in sediment and fly ash candidate reference materials

Many fields in environmental analytical chemistry deal with very low limits and thresholds as set by governmental legislations or transnational regulations. The need for the accuracy, comparability and traceability of analytical measurements in environmental analytical chemistry has significantly increased and total uncertainties are even asked for by accreditation bodies of environmental laboratories. This paper addresses achieving these goals to guarantee accuracy, quality control, quality assurance or validation of a method by means of certified reference materials. The assessment of analytical results in certified reference materials must be as accurate as possible and every single step has to be fully evaluated. This paper presents the SI-traceable certification of Cu, Cr, Cd and Pb contents in geological and environmentally relevant matrices (three sediments and one fly ash sample). Certification was achieved using isotope dilution (ID) ICPMS as a primary method of measurement. In order to reduce significantly the number of analytical steps and intermediate samples a multiple spiking approach was developed. The full methodology is documented and total uncertainty budgets are calculated for all certified values. A non-element specific sample digestion process was optimised. All wet chemical digestion methods examined resulted in a more or less pronounced amount of precipitate. It is demonstrated that these precipitates originate mainly from secondary formation of fluorides (essentially CaF2) and that their formation takes place after isotopic equilibration. The contribution to the total uncertainty of the final values resulting from the formation of such precipitates was in general < 0.1% for all investigated elements. Other sources of uncertainty scrutinised included the moisture content determination, procedural blank determination, cross-contamination from the different spike materials, correction for spectral interferences, instrumental background and deadtime effects, as well as the use of either certified values or IUPAC data in the IDMS equation. The average elemental content in the sediment samples was 30-130 micrograms g-1 for Pb, 0.5-3 micrograms g-1 for Cd and 50-70 micrograms g-1 for Cu. Cr was measured in one sample and was about 60 micrograms g-1. The concentrations in the fly ash sample were up to 2 orders of magnitude higher. Expanded uncertainty for the investigated elements was about 3% (coverae factor k = 2) except for Cr, (measured by high resolution ICPMS), for which the expanded uncertainty was about 7% (k = 2).     

Characterization and environmental implications of nano- and larger TiO(2) particles in sewage sludge, and soils amended with sewage sludge

Titanium dioxide (TiO(2)) is the most extensively used engineered nanoparticle to date, yet its fate in the soil environment has been investigated only rarely and is poorly understood. In the present study, we conducted two field-scale investigations to better describe TiO(2) nano- and larger particles in their most likely route of entry into the environment, i.e., the application of biosolids to soils. We particularly concentrated on the particles in the nano-size regime due to their novel and commercially useful properties. First, we analyzed three sewage sludge products from the US EPA TNSSS sampling inventory for the occurrence, qualitative abundance, and nature of TiO(2) nano- and larger particles by using analytical scanning electron microscopy and analytical (scanning) transmission electron microscopy. Nano- and larger particles of TiO(2) were repeatedly identified across the sewage sludge types tested, providing strong evidence of their likely concentration in sewage sludge products. The TiO(2) particles identified were as small as 40 nm, and as large as 300 nm, having faceted shapes with the rutile crystal structure, and they typically formed small, loosely packed aggregates. Second, we examined surface soils in mesocosms that had been amended with Ag nanoparticle-spiked biosolids for the occurrence of TiO(2) particles. An aggregate of TiO(2) nanoparticles with the rutile structure was again identified, but this time TiO(2) nanoparticles were found to contain Ag on their surfaces. This suggests that TiO(2) nanoparticles from biosolids can interact with toxic trace metals that would then enter the environment as a soil amendment. Therefore, the long-term behavior of TiO(2) nano- and larger particles in sewage sludge materials as well as their impacts in the soil environment need to be carefully considered.