Identification and source apportionment of polycyclic aromatic hydrocarbons in ambient air particulate matter of Riyadh, Saudi Arabia

In an effort to assess the occurrence and sources of polycyclic aromatic hydrocarbons (PAHs) in the ambient air of Riyadh, Saudi Arabia, PM₁₀ samples were collected during December 2010. Diagnostic PAH concentration ratios were used as a tool to identify and characterize the PAH sources. The results reflect high PM₁₀ and PAH concentrations (particulate matter (PM)?=?270–1,270 μg/m³). The corresponding average PAH concentrations were in the range of 18?±?8 to 1,003?±?597 ng/m³ and the total concentrations (total PAHs (TPAHs) of 17 compounds) varied from 1,383 to 13,470 ng/m³ with an average of 5,871?±?2,830 ng/m³. The detection and quantification limits were 1–3 and 1–10 ng/ml, respectively, with a recovery range of 42–80 %. The ratio of the sum of the concentrations of the nine major non-alkylated compounds to the total (CPAHs/TPAHs) was 0.87?±?0.10, and other ratios were determined to apportion the PM sources. The PAHs found are characteristic for emissions from traffic with diesel being a predominant source.     

Contamination of the Lake Tahoe Air Basin by High Molecular Weight Petroleum Residues

The atmosphere of the Lake Tahoe air basin is contaminated with high molecular weight (> C₁₂) petroleum hydrocarbons. Aerosol samples were collected by high-volume filtration and the solvent-soluble organic matter was analyzed. The relative concentrations of petroleum residues found were as follows: winter > summer and day > night. This contamination is primarily due to the poorer combustion of diesel and home heating fuels at that altitude and during periods of colder climate.     

Fukushima fallout in Northwest German environmental media

Traces of short- and long-lived fallout isotopes (¹³¹I, ¹³⁴Cs and ¹³⁷Cs) were found in environmental samples collected in Northwest Germany (rain water, river sediment, soil, grass and cow milk) from March to May 2011, following the radioactivity releases after the nuclear accident in Fukushima, Japan. The measured concentrations are consistent with reported concentrations in air, amount of rainfall and expected values applying simple radioecological models. The [¹³⁴Cs]/[¹³⁷Cs] ratio reported for air (about 1) allows for discrimination between “recent” and “old” ¹³⁷Cs. Expected ¹³⁶Cs values fell below the detection limits of the instrumentation, despite large sample masses and long counting times.     

Does the Temporal Resolution of Precipitation Input Influence the Simulated Hydrological Components Employing the SWAT Model?

This study aimed to evaluate the influence of sub‐daily precipitation time steps on model performance and hydrological components by applying the Green and Ampt infiltration method using the Soil and Water Assessment Tool (SWAT). Precipitation was measured at a resolution of 0.1 mm and aggregated to 5‐, 15‐, 30‐, and 60‐min time steps. Daily discharge data over a 10‐year period were used to calibrate and validate the model. Following a global sensitivity analysis, relevant parameters were optimized through an automatic calibration procedure using SWAT‐CUP for each time step. Daily performance statistics were almost equal among all four time steps (NSE ≈ 0.47). Discharge mainly consisted of groundwater flow (55%) and tile flow (42%), in reasonable proportions for the investigated catchment. In conclusion, model outputs were almost identical, showing simulations responded nearly independently of the chosen precipitation time step. This held true for (1) the selection of sensitive parameters, (2) performance statistics, (3) the shape of the hydrographs, and (4) flow components. However, a scenario analysis revealed that the precipitation time step becomes important when saturated hydraulic conductivities are low and curve numbers are high. The study suggests that there is no need in using precipitation time steps <1 h for lowland catchments dominated by soils with a low surface runoff potential if daily flow values are being considered. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.     

EU-wide survey of polar organic persistent pollutants in European river waters

This study provides the first EU-wide reconnaissance of the occurrence of polar organic persistent pollutants in European river waters. More than 100 individual water samples from over 100 European rivers from 27 European Countries were analysed for 35 selected compounds, comprising pharmaceuticals, pesticides, PFOS, PFOA, benzotriazoles, hormones, and endocrine disrupters. Around 40 laboratories participated in this sampling exercise. The most frequently and at the highest concentration levels detected compounds were benzotriazole, caffeine, carbamazepine, tolyltriazole, and nonylphenoxy acetic acid (NPE₁C). Only about 10% of the river water samples analysed could be classified as “very clean” in terms of chemical pollution. The rivers responsible for the major aqueous emissions of PFOS and PFOA from the European Continent could be identified. For the target compounds chosen, we are proposing “indicative warning levels” in surface waters, which are (for most compounds) close to the 90th percentile of all water samples analysed.     

Formation of chlorinated disinfection by-products in viticulture

Background, aim and scope  The use of sodium hypochlorite (HYP) in viticulture results in effluents which are contaminated with halogenated substances. These disinfection by-products (DBPs) can be quantified as group parameter ‘adsorbable organic halogens’ (AOX) and have not been determined in effluents of viticulture yet. The substances that are detected as AOX are unknown. The AOX can be composed of harmless substances, but even toxic contaminants. Thus, it is impossible to assess ecological impacts. The aim of this study is to determine the quantification of AOX and DBPs after the use of HYP. This will be helpful to reduce environmental pollution by AOX. Materials and methods  The potential of HYP to generate AOX was determined in laboratory-scale experiments. Different model solutions were treated with HYP according to disinfection processes in viticulture and conditions of AOX formation in effluents were simulated. AOX were quantified using the flask-shaking method and identified DBPs were investigated by gas chromatography–mass spectrometry. Results  Treatment with HYP resulted in the formation of AOX. The percentage conversion of HYP to AOX was up to 11%. Most important identified DBPs in viticulture are chloroform, dichloroacetic acid and trichloroacetaldehyde. In addition, the formation of carbon tetrachloride (CT), 1,1,1-trichloropropanone, 2,4-dichlorobenzoic acid and 2-chloro-/2,4-dichlorophenylacetic acid was investigated. It was demonstrated that reaction temperature, concentration of HYP and type of organic matter have important influence on the formation of chlorinated DBPs. Discussion  The percentage conversion of HYP to AOX was similar to other published studies. Although a correlation of single compounds and AOX is difficult, chloroform was the predominant AOX. Generation of the volatile chloroform should be avoided due to possible adverse effects. The generation of dichloroacetic acid is of minor importance on account of biodegradation. Trichloroacetaldehyde and 1,1,1-trichloropropanone are weak mutagens and their formation should be avoided. Conclusions  The generation of AOX and chlorinated DBPs can be minimised by reducing the concentrations of the organic materials in the effluents. The removal of organic matter before disinfection results in a decreased formation of AOX. HYP is an effective disinfectant; therefore, it should be used at low temperatures and concentrations to reduce the amount of AOX. If possible, disinfection should be accomplished by the use of no chlorine-containing agents. By this means, negative influences of HYP on the quality of wine can also be avoided. Recommendations and perspectives  Our results indicate that HYP has a high potential to form AOX in effluents of viticulture. The predominant by-products are chloroform, dichloroacetic acid and trichloroacetaldehyde. In further research, wastewaters from a winery and the in- and outflows of two sewage treatment plants were sampled during vintage and analysed. These results will be discussed in a following paper.     

Effects of sterile storage,cation saturation and substrate additions on the degradability and extractability of nonylphenol and phenanthrene in soil

The main objective of this study was to determine the effects of long-term abiotic processes during aging of organic pollutants in soil on their microbial degradability and formation of non-extractable residues. The specific aims of our study were to investigate how the fate of p353-nonylphenol (NP) and phenanthrene (Phe) in soils might be affected by: (i) saturation of soil by cations with different valency (Na⁺, Ca²⁺ or Al³⁺), (ii) addition of organic substrate (wood flour) during incubation period and (iii) different soil moisture levels.     

Analysis of perfluorooctanoate (PFOA) and other perfluorinated compounds (PFCs) in the River Po watershed in N-Italy

C7-C11 perfluorinated carboxylates (PFACs) and perfluorooctansulfonate (PFOS) were analysed in selected stretches of the River Po and its major tributaries. Analyses were performed by solid-phase extraction (SPE) with Oasis HLB cartridges and methanol elution followed by LC-MS-MS detection using 13C-labelled internal standards. High concentration levels ( approximately 1.3 microg l(-1)) of perfluorooctanoate (PFOA) were detected in the Tánaro River close to the city Alessandria. After this tributary, levels between 60 and 337 ng l(-1) were measured in the Po River on several occasions. The PFOA concentration close to the river mouth in Ferrara was between 60 and 174 ng l(-1). Using the river discharge flow data in m3 s(-1) at this point (average approximately 920 m3 s(-1) for the year 2006), a mass load of approximately 0.3 kg PFOA per hour or approximately 2.6 tons per year discharged in the Adriatic Sea has been calculated. PFOS concentration levels in the Po River at Ferrara were approximately 10 ng l(-1).     

Regio- and stereoselective isomerization of hexabromocyclododecanes (HBCDs): kinetics and mechanism of gamma- to alpha-HBCD isomerization

Hexabromocyclododecanes (HBCDs) are high production volume chemicals (>20000 ty(-1)) used as flame retardants for plastics and textiles. Lately, we reported on the stereoselective isomerization of beta-HBCDs. Herein we present insights into the mechanism and kinetics of (+)gamma- to (+)alpha- and of (-)gamma- to (-)alpha-HBCD isomerization. Only two of the six bromine atoms migrated, indicating that rearrangements of gamma- to alpha-HBCDs are regio- and stereoselective as well. The apparent first-order isomerization rate constants increased from 0.0013 to 0.0031 to 0.0070 min(-1) at 120, 130, and 140 degrees C, respectively, corresponding to half-lives of 540, 230, and 99 min. Thus, a thermal treatment of materials containing gamma-HBCDs at temperatures >100 degrees C may induce the formation of alpha-HBCDs and, hence, may alter the diastereomeric ratio of a HBCD mixture. The inversion of vicinal dibromides in like-configurations (RR/SS) prevailed, whereas unlike-configurations (RS/SR) were not affected. An intramolecular, stereoselective migration of neighboring bromine atoms via a four-center transition state would explain the observed stereoisomer pattern and first-order kinetics. Despite the fact that vicinal dibromides in HBCDs prefer synclinal (gauche) conformations, antiperiplanar (staggered) conformations are assumed to facilitate concerted 1.2-shifts of both bromine atoms. A conformation analysis revealed that under kinetic control, only those bromine atoms in the more flexible part of the molecules are migrating, whereas those in the conserved triple-turn motive were not affected. Thus, this structural motive, common to all alpha-, beta-, and gamma-HBCDs, is more rigid and less reactive than the flexible part, containing the reacting dibromides in like-configurations.     

From traditional to modern fee systems

This paper deals with the environmentally important issue regarding how best to motivate citizens to reduce their individual waste production. The paper discusses the pros and cons of the various financial incentives incorporated into the waste charging mechanism, pay-as-you-throw (PAYT). Pay-as-you-throw breaks with the tradition of paying for waste services through general blanket taxes or levies in the form of flat rates in that households are required to pay individually adjusted fees in the same way as water and electricity bills are calculated on an individual consumption basis. This difference is achieved through the interplay of three principal components which mark the technical implementation of PAYT: identification as a vehicle to attain accountability, measurement of the generated waste and/or corresponding services, and unit pricing as the basis for individual charges proportional to the extent of the obtained services. However, any motivating factor for inducing citizens to dispose of their recyclable discards and residual waste must be supported by a well developed collection infrastructure, good media information and an appropriate, transparent charging policy. Of particular importance is the use of a multi-tiered charge model, i.e., the charging of a fixed minimum fee plus certain variable components payable in respect of the service structure. The introduction of a basic charge, albeit reducing the intensity of the incentives created by the PAYT system, ensures that certain fixed costs for the provision of waste services will be covered independently from the actual waste developments and, at the same time, minimises the temptation to attempt to bypass the system. Such an arrangement for the waste charges neither contradicts the principle of pay-as-you-throw nor does it impair the waste diversion for which it is implemented. Waste statistics and figures representing the waste charging situation in Germany indicate that there is a relatively good correlation between the level of recycling and the amount of perceived financial motivation provided by PAYT. Waste stream developments in areas using such charging schemes generally suggest that the reduction goals are being achieved. Single figures on decreasing quantities of collected residual waste, however, say little about the actual efficiency of differentiated waste charging models and deliver little in the way of reasoned explanation as to why the diffusion of variable rate pricing is progressing painstakingly slowly. To evaluate the success, feasibility and problems of PAYT schemes, one needs to consider the various ways for technically implementing this approach in practice, and must take a broader look into the wide spectrum of available waste services and into more factors that influence their efficiency and acceptance. Urban structure settings assume a particular importance here as do the specific goals of social policy which, among others, are reflected in the charging mechanisms applied. Practical experience, however, shows that solutions can be found which allow most of the concerns and area specifics to be accommodated and waste streams to be influenced in the desired way. Aside from this, positive effects as to waste collection efficiency can also be achieved, which contribute towards long-term environmental improvements and countervail the incremental costs of implementing PAYT.