Evaluation of sediment quality guidelines derived using the screening-level concentration approach for application at uranium operations in Saskatchewan,Canada

Sediment quality guidelines (SQGs) can be derived using different approaches and are commonly used in environmental management, reclamation, and risk assessment. The screening-level concentration (SLC) approach has been used in Ontario, Canada, to derive lowest effect levels (LELs) and severe effect levels for use as SQGs. This approach was adopted by the Canadian Nuclear Safety Commission (CNSC) to set guidelines for metals (As, Cr, Cu, Pb, Mo, Ni, Se, U, and V) and radionuclides (Ra-226, Pb-210, and Po-210) in sediment at northern Saskatchewan uranium mining and milling operations. The SLC approach is based on total metal and radionuclide concentrations in sediment, and corresponding benthic community composition data for a specific sampling site. In this study, sediment chemistry (total metals and radionuclides) and benthic community data from northern Saskatchewan uranium operations were compiled and examined. Results indicate that the CNSC-derived SQGs had limited relationships to observed effects, or lack thereof, on benthic invertebrate communities near uranium operations in Saskatchewan. The LELs were found to correctly align with effects at 95% of the sites that had effects, on a general basis, but on an element-specific basis many of the elements had concentrations at effect sites below their LELs. Furthermore, concentrations of the evaluated elements exceeded at least one LEL at 60% of the no-effect sites. The high number of exceedences of LELs at reference and no-effect sites (false-positives) calls to question the appropriateness of the CNSC-derived SQGs. It is suggested that alternatives to the SLC approach be explored.     

BTX measurements with diffusive samplers in the vicinity of a cokery: comparison between ORSA-type samplers and pumped sampling

In the framework of new European directives in the field of ambient air quality assessment specific requirements for measurement methods for benzene will be defined and have to be met in the future. In a residential area in the vicinity of a cokery a comprehensive monitoring programme for BTX compounds (benzene, toluene, xylenes) was carried out with diffusive samplers. Measurement results from 20 sites show a distinct spatial distribution of benzene concentrations which is caused by the emissions of the plant. Comparisons with two pumped measurement methods reveal excellent agreement in the case of benzene. An assessment of measurement uncertainty for the diffusive method is presented in terms of standard deviations from parallel measurements (precision) and by comparison with a reference method according to national and international standards. Data quality objectives required by an upcoming European directive for benzene can be met by diffusive sampling.     

Evaluation of Three Air Dispersion Models: ISCST2, ISCLT2, and Screen2 for Mercury Emissions in an Urban Area

The goal of this paper is to compare and evaluate the performance of three air quality regulatory models for mercury releases. The models include Industrial Source Complex Short Term model (ISCST2), Industrial Source Complex Long Term model (ISCLT2), and SCREEN2. The evaluation is conducted in multiple point source urban environment using meteorological data, emission inventory and monitoring data for eight stations for the year 1990 to 1992. The performance of the models is evaluated using eight statistical parameters. The comparison of models results for both quarterly and annual averaging periods shows that ISCST2 predictions qualitatively match the observed concentrations; whereas SCREEN2 predicts highest concentrations and ISCLT2 the lowest concentrations. The summary of statistical analysis obtained by using three different methods of observed concentration (Co) and predicted concentrations (Cp) comparison show that the ISCST2 has a better overall performance than ISCLT2 and SCREEN2 models. However, none of the models met the criteria for a reasonable model. Summaries of 95% confidence limits on normalize mean square error (NMSE), geometric mean variance (VG) and geometric mean bias (MG) for each and among model indicate that of the three models, ISCST2 has the best overall performance indicators. Improved model performance may be achieved by incorporating different types of mercury forms into emission rate and air dispersion calculations.     

The application of satellite data for the quantification of mangrove loss and coastal management in the Godavari estuary, East Coast of India

The mangrove formations of Godavari estuary are due to silting over many centuries. The estuary covers an area of 62,000 ha of which dense Coringa mangrove forest spread in 6,600 ha. Satellite sensor data was used to detect change in the mangrove cover for a period of 12 years (1992-2004). It was found that an area of about 1,250 ha of mangroves was destroyed by anthropogenic interference like aquaculture, and tree felling etc. It was found that mangrove's spectral response/digital number (DN) value is much lower than non-mangrove vegetation such as plantation and paddy fields in SWIR band. By taking this as an advantage, spectral data was utilized for clear demarcation of mangroves from nearby paddy fields and other vegetation. Simpson's diversity index, which is a measure of biodiversity, was found to be 0.09, showing mangroves dominance. Ecological parameters like mud-flats/swamps, mangrove cover alterations, and biodiversity status are studied in detail for a period of 12 years. The increase in mangrove front towards coast was delineated using remote sensing data. The major advantages of remote sensing data is monitoring of change periodically. The combination of moderate and high-resolution data provided detailed coastal land use maps for implementing coastal regulation measures. The classification accuracy has been achieved is 90%. Overall, simple and viable measures are suggested based on multi-spectral data to sustain this sensitive coastal ecology.     

The characteristics of size distribution of suspended particulates in the air for sulphates and selected metals in different areas and seasons

The characteristics of the distribution of particles by size were investigated for sulphates and selected metals (Pb, Fe, Mn, and Cu) in the air in two urban and an industrial area during the winter and summer periods using an Andersen cascade impactor.In the case of metals, but not sulphates, the character of the area affected the value of mass median diameter. Lowest values were obtained in a sparsely populated urban area, whereas in a densely populated urban area and in the industrial area the values were higher.In the industrial area a high correlation coefficient was found between sulphate and manganese, and between sulphate and lead, as well as a high value of the equivalent Mn²⁺/SO _inf4 ^sup2- ratio for the total sample. It may therefore be assumed that in the industrial area manganese produces a catalytic effect on SO₂ conversion to sulphate. Among the investigated metals lead stands out as a dominant cation which binds to the sulphate ion in the industrial and densely populated areas.     

Triethoxysilyl-substituted aminoethanethiol ligands for zinc and cadmium complexes and aminoethanethiol-modified silica gel. Evaluation of the corresponding supported molecular trap for metallic pollutant uptake (Cd2+, Hg2+ and Pb2+)

The reaction of 2-[3-(triethoxysilyl)propylamino]ethanethiol (LH, a) and 1-methyl-2-[3-(triethoxysilyl)propylamino]ethanethiol (LH, b) with ZnX2 and CdX2 (X = Cl, Br, I, NO3) in tetrahydrofuran (THF) or CH2Cl2 gives several complexes depending on the experimental conditions. Elemental analyses, IR, Raman, 13C[1H], 1H NMR and mass spectroscopies indicated the formation of mononuclear and dinuclear complexes. In the absence of NEt3 as proton quencher, the protonated ligands react in their zwitterionic form giving dinuclear [M(LH)X2]2 [M = Zn (1), Cd (2); LH = a, b; X = Cl, Br, I] or mononuclear M(NO3)2(LH)2 [M = Zn (5), Cd (6); LH = a] complexes. In both cases, coordination occurs through the S atoms, the ligands acting as terminal and bridging species. With NEt3, the deprotonated ligands are chelated through their N and S atoms and bridging occurs through the S atoms in [MLX]2 [M = Zn (3), Cd (4); LH = a; X = Cl, Br] complexes. The LH ligand is chemically grafted onto silica, the procedure optimized and the resulting material characterized by 13C and 29Si cross-polarization, magic-angle spinning (CP-MAS) NMR and DRIFT. This material is evaluated as a supported molecular trap for binding heavy metals (Cd2+, Hg2+, Pb2+) in aqueous solution. In both batch and column processes, it appears that Hg2+ and Pb2+ are trapped more than Cd2+, but in all cases values lower than those allowed were obtained.     

Laboratory and field comparison of measurements obtained using the available diffusive samplers for ozone and nitrogen dioxide in ambient air

This study presents an evaluation of the extent of differences between measurements performed by O(3) and NO(2) diffusive samplers and by the reference methods for diffusive samplers commercially available. The tests were performed in an exposure chamber under extreme conditions of controlling factors and under field conditions. For NO(2), the results of the laboratory experiments showed that most of the diffusive samplers were affected by extreme exposure conditions. The agreement between the samplers and the reference method was better for the field tests than for the laboratory ones. The estimate of the uptake rate for the exposure conditions using a model equation improved the agreement between the diffusive samplers and the reference methods. The agreement between O(3) measured by the diffusive samplers and by the reference method was satisfactory for 1-week exposure. For 8-hour exposures, the diffusive samplers with high uptake rates quantified better the O(3) concentration than the samplers with low uptake rates. As for NO(2), the results of the O(3) field tests were in better agreement with the reference method than the ones of the laboratory tests. The field tests showed that the majority of diffusive samplers fulfils the 25% uncertainty requirement of the NO(2) European Directive and the 30% uncertainty requirement of the O(3) European Directive for 1-week exposure.     

Estimation of the contributions of long range transported aerosol in East Asia to carbonaceous aerosol and PM concentrations in Seoul, Korea using highly time resolved measurements: a PSCF model approach

The contributions of long range transported aerosol in East Asia to carbonaceous aerosol and particulate matter (PM) concentrations in Seoul, Korea were estimated with potential source contribution function (PSCF) calculations. Carbonaceous aerosol (organic carbon (OC) and elemental carbon (EC)), PM(2.5), and PM(10) concentrations were measured from April 2007 to March 2008 in Seoul, Korea. The PSCF and concentration weighted trajectory (CWT) receptor models were used to identify the spatial source distributions of OC, EC, PM(2.5), and coarse particles. Heavily industrialized areas in Northeast China such as Harbin and Changchun and East China including the Pearl River Delta region, the Yangtze River Delta region, and the Beijing-Tianjin region were identified as high OC, EC and PM(2.5) source areas. The conditional PSCF analysis was introduced so as to distinguish the influence of aerosol transported from heavily polluted source areas on a receptor site from that transported from relatively clean areas. The source contributions estimated using the conditional PSCF analysis account for not only the aerosol concentrations of long range transported aerosols but also the number of transport days effective on the measurement site. Based on the proposed algorithm, the condition of airmass pathways was classified into two types: one condition where airmass passed over the source region (PS) and another condition where airmass did not pass over the source region (NPS). For most of the seasons during the measurement period, 249.5-366.2% higher OC, EC, PM(2.5), and coarse particle concentrations were observed at the measurement site under PS conditions than under NPS conditions. Seasonal variations in the concentrations of OC, EC, PM(2.5), and coarse particles under PS, NPS, and background aerosol conditions were quantified. The contributions of long range transported aerosols on the OC, EC, PM(2.5), and coarse particle concentrations during several Asian dust events were also estimated. We also investigated the performance of the PSCF results obtained from combining highly time resolved measurement data and backward trajectory calculations via comparison with those from data in low resolutions. Reduced tailing effects and the larger coverage over the area of interest were observed in the PSCF results obtained from using the highly time resolved data and trajectories.     

Development of a sampling method for the simultaneous monitoring of straight-chain alkanes, straight-chain saturated carbonyl compounds and monoterpenes in remote areas

Studies have shown that biogenic compounds, long chain secondary compounds and long lifetime anthropogenic compounds are involved in the formation of organic aerosols in both polluted areas and remote places. This work aims at developing an active sampling method to monitor these compounds (i.e. 6 straight-chain saturated aldehydes from C6 to C11; 8 straight-chain alkanes from C9 to C16; 6 monoterpenes: α-pinene, β-pinene, camphene, limonene, α-terpinene, & γ-terpinene; and 5 aromatic compounds: toluene, ethylbenzene, meta-, para- and ortho-xylenes) in remote areas. Samples are collected onto multi-bed sorbent cartridges at 200 mL min(-1) flow rate, using the automatic sampler SyPAC (TERA-Environnement, Crolles, France). No breakthrough was observed for sampling volumes up to 120 L (standard mixture at ambient temperature, with a relative humidity of 75%). As ozone has been shown to alter the samples (losses of 90% of aldehydes and up to 95% of terpenes were observed), the addition of a conditioned manganese dioxide (MnO(2)) scrubber to the system has been validated (full recovery of the affected compounds for a standard mixture at 50% relative humidity--RH). Samples are first thermodesorbed and then analysed by GC/FID/MS. This method allows suitable detection limits (from 2 ppt for camphene to 13 ppt for octanal--36 L sampled), and reproducibility (from 1% for toluene to 22% for heptanal). It has been successfully used to determine the diurnal variation of the target compounds (six 3 h samples a day) during winter and summer measurement campaigns at a remote site in the south of France.     

Simplification and validation of a large volume polyurethane foam sampler for the analysis of persistent hydrophobic compounds in drinking water

The use of a large volume polyurethane foam (PUF) sampler was validated for rapid extraction of persistent organic pollutants (POPs), such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), in raw water and treated water from drinking water plants. To validate the recovery of target compounds in the sampling process, a (37)Cl-labeled standard was spiked into the 1st PUF plug prior to filtration. An accelerated solvent extraction method, as a pressurized liquid extractor (PLE), was optimized to extract the PUF plug. For sample preparation, tandem column chromatography (TCC) clean-up was used for rapid analysis. The recoveries of labeled compounds in the analytical method were 80-110% (n = 9). The optimized PUF-PLE-TCC method was applied in the analysis of raw water and treated potable water from seven drinking water plants in South Korea. The sample volume used was between 18 and 102 L for raw water at a flow rate of 0.4-2 L min(-1), 95 and 107 L for treated water at a flow rate of 1.5-2.2 L min(-1). Limit of quantitation (LOQ) was a function of sample volume and it decreased with increasing sample volume. The LOQ of PCDD/Fs in raw waters analyzed by this method was 3-11 times lower than that described using large-size disk-type solid phase extraction (SPE) method. The LOQ of PCDD/F congeners in raw water and treated water were 0.022-3.9 ng L(-1) and 0.018-0.74 ng L(-1), respectively. Octachlorinated dibenzo-p-dioxin (OCDD) was found in some raw water samples, while their concentrations were well below the tentative criterion set by the Japanese Environmental Ministry for drinking water. OCDD was below the LOQ in the treated drinking water.     

乌鲁木齐市水磨河水质状况评价与污染成因分析

利用单因子指数法和综合污染指数法,对乌鲁木齐市水磨河4个监测断面水质情况进行了评价。结果表明:搪瓷厂泉为超标水体;七纺桥为Ⅴ类水体,达到农业灌溉用水要求;联丰桥断面、米泉桥断面为劣Ⅴ类水体,没有达到农业灌溉用水要求。生活源和工业源化学需氧量、氨氮等污染物的排入对水体产生了严重影响,造成水体重污染。     

Evaluation Score and Interpretation Index for the Ecological Quality of Running Waters in Central and Northern Hellas

The present study aims at creating an evaluation system for the quality of running waters, based on the analysis of benthic macroinvertebrate records from Hellenic rivers (473 samples from 8 river basins). The proposed evaluation system (Hellenic Evaluation Score and its Interpretation Index) may be used for waters sampled with the cost effective semi-quantitative sampling method of “3 min kick-sweep” and requires benthic macroinvertebrates to be identified to the taxonomic level of family. Though resulting from a modification of the Spanish score BMWP, it differs from it in the following characteristics: a) it includes the relative abundance of benthic macroinvertebrates and b) it takes into consideration the habitat diversity of the studied site, classifying it as “poor” or “rich”, based on some parameters of the System B of the Water Framework Directive (2000/60/EU). Its interpretation is also based on a five-scaled classification system, consistent with the provisions of the same Directive.     

Evaluation of diffusive samplers and photoionisation detectors for measuring very short peak exposures in the workplace

The extent to which very short peak widths, peak frequency, sampling time and post-sampling/pre-capping time impact upon occupational exposure measurements of toluene has been investigated using diffusive tubes. Additionally, the effect of the width of the peak on the estimation of peak maximum concentration and time-weighted average (TWA) concentration from real-time instruments (photoionisation detectors-PIDs) was also studied, and their responses modelled. No clear differences were perceived between diffusive and pumped tube results. Mean biases of -5 to +6% were recorded but no trend could be distinguished with respect to any of the variables examined; the main source of uncertainty was attributed to analytical uncertainty. The diffusive tubes can therefore be used to measure short term transient toluene concentrations (e.g. 5 s duration) over short (15 min) exposure periods. The two slower responding PIDs (t50 = 4 s) underestimated the maximum concentration of short term peaks having durations less than 10 s. The other three PIDs (t50 < or = 2 s) only significantly underestimated the maximum concentration of short term peaks having durations of 2 s and below. Pulse duration appeared to affect the PID's estimation of peak height more than peak area (TWA concentration).     

Comparison of Numerical and Experimental Results for the Evaluation of the Depollution Effectiveness of Photocatalytic Coverings in Street Canyons

Towards the aim of improving the air quality in the urban environment via the application of innovative TiO₂ based photocatalytic coverings, a field campaign took place within the frame of the EU PICADA project () to asses the expected depollution efficiency of such materials under realistic conditions. Furthermore, extensive numerical modeling was performed via the application of the RANS CFD code for microscale applications MIMO, in an effort to asses the sensitivity of the developing flow field and the corresponding dispersion mechanism and hence of the depollution efficiency of the PICADA products on a wide range of factors, with most notably the length of the street canyon, the thermal exchange between the heated street canyon walls and the air and the approaching wind direction. For the needs of the PICADA project a new, simple module had to be implemented into MIMO to be able to model the removal of NO_x from a street canyon whose walls have been treated with a photocatalytic product. The model simulations results presented in this paper, show that MIMO is indeed capable of predicting the effectiveness of the photocatalytic products in question. At the same time, they reveal a strong dependence of the developing flow and concentration fields inside the field site street canyon configuration on most of the aforementioned factors with most notably the direction of the approaching wind.

Evaluation of the effectiveness of red mud-supported catalysts in combination with ozone and TiO<Subscript>2</Subscript> in the treatment of solution containing benzene,toluene, and xylene

Ozone and a Fe²⁺/TiO₂-based catalyst were examined in the degradation of a synthetic solution of benzene toluene and xylene (BTX) in an advanced oxidation process (AOP). The catalyst beads were made from the slurry waste of aluminum production process, by inserting the TiO₂ content and subsequent calcination. The reduction of the BTX concentration load was monitored by the reduction of chemical oxygen demand (COD) and BTX concentration. Different levels were used on factors: pH, time of treatment, initial concentration of BTX, and percentage of TiO₂. The process was conducted in a bubble column reactor with the insertion of catalyst beads. A response surface methodology technique (CCD) was used to build a model based on COD reduction results. The model was optimized using the normal-boundary intersection (NBI) algorithm to maximize COD reduction and minimize the variance attributed to the process. Optimization led to COD reductions of 80% in 2 h of experiment. Correlation analysis of coefficient models from experimental data R²_adj was 0.9966, showing a good fit of model data. In the optimized conditions, the possible increase of the biodegradability ratio of the BTX solution, through the biochemical oxygen demand (BOD) and COD, was also analyzed. Under pre-treatment conditions, the BOD/COD ratio was 0.13. After the treatment, it increased to 0.56.

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Evaluation of an alternate method for sampling benthic macroinvertebrates in low-gradient streams sampled as part of the National Rivers and Streams Assessment

Benthic macroinvertebrates are sampled in streams and rivers as one of the assessment elements of the US Environmental Protection Agency’s National Rivers and Streams Assessment. In a 2006 report, the recommendation was made that different yet comparable methods be evaluated for different types of streams (e.g., low gradient vs. high gradient). Consequently, a research element was added to the 2008–2009 National Rivers and Streams Assessment to conduct a side-by-side comparison of the standard macroinvertebrate sampling method with an alternate method specifically designed for low-gradient wadeable streams and rivers that focused more on stream edge habitat. Samples were collected using each method at 525 sites in five of nine aggregate ecoregions located in the conterminous USA. Methods were compared using the benthic macroinvertebrate multimetric index developed for the 2006 Wadeable Streams Assessment. Statistical analysis did not reveal any trends that would suggest the overall assessment of low-gradient streams on a regional or national scale would change if the alternate method was used rather than the standard sampling method, regardless of the gradient cutoff used to define low-gradient streams. Based on these results, the National Rivers and Streams Survey should continue to use the standard field method for sampling all streams.     

Evaluation of the NIOSH draft method 5525 for determination of the total reactive isocyanate group (TRIG) for aliphatic isocyanates in autobody repair shops. National Institute for Occupational Safety and Health

This paper evaluates the performance of the NIOSH draft method 5525 for analysis of monomeric and TRIG aliphatic isocyanates in autobody repair shops. It was found that an optimized pH gradient enhanced noticeably the resolution and, therefore, identification of aliphatic isocyanates. Samples proved to be very stable for at least a year when stored at -13 degrees C in the freezer, and no major stability problems were found for the MAP reagent. The detector response factor RSD for selected MAP ureas was 40% in the fluorescence (FLD), 3% in the UV at 254 nm (UV254), and 1% in the UV at 370 nm (UV370). The mean FLD/UV254 and UV254/UV370 detector response ratios of standards were 31.7 (RSD = 37.8) and 17.1 (RSD = 5.4), respectively. The FLD/UV254 ratio in bulks varied from 0.41 to 1.97 times the HDI monomer ratio. The mean UV254/UV370 ratio in bulks was 16.1 (range 14.1 to 19.2, N = 38). Mean (range) recovery of 92 (91.2-93.2)% was found for the N3300 (isocyanurate) spiked on 25 mm quartz fiber filters in the range 0.07 to 2.2 microg NCO ml(-1). Mean (range) recovery for impingers was 100.7 (91.7-106.0)% for N3300 in the concentration range of 0.018 to 2.5 microg NCO ml(-1) and 81.0 (76.1-89.1)% for IPDI in the concentration range of 0.016 to 1.87 microg NCO ml(-1). Analytical method precision was 3.4% and mean bias 7.4% (range = 0-25%). The NIOSH draft method 5525 provides flexibility, enhanced sensitivity and specificity, powerful resolution, and very small compound-to-compound variability in the UV254, resulting in a more reliable identification and quantification of aliphatic isocyanates.