Peroxy acetyl nitrate (PAN) is a key component of photochemical smog and plays an important role in atmospheric chemistry. Though it has been known that PAN is produced via reactions of nitrogen oxides (NOx) with some volatile organic compounds (VOCs), it is difficult to quantify the contributions of individual precursor species. Here we use an explicit photochemical model – Master Chemical Mechanism (MCM) model – to dissect PAN formation and identify principal precursors, by analyzing measurements made in Beijing in summer 2008. PAN production was sensitive to both NOx and VOCs. Isoprene was the predominant VOC precursor at suburb with biogenic impact, whilst anthropogenic hydrocarbons dominated at downtown. PAN production was attributable to a relatively small class of compounds including NOx, xylenes, trimethylbenzenes, trans/cis-2-butenes, toluene, and propene. MCM can advance understanding of PAN photochemistry to a species level, and provide more relevant recommendations for mitigating photochemical pollution in large cities.

The chemical composition of Beijing aerosol was measured during summer and winter. Two distinct episodes were identified. Water-soluble potassium (K+) increased significantly during the firework episode in winter with an episode to non-episode ratio of 4.97, whereas the biomass burning (BB) episode in summer was characterized by high episode to non-episode ratios of levoglucosan (6.38) and K+ (6.90). The BB and firework episodes had only a minor influence on the water-soluble OC (organic carbon) to OC ratio. Based on separate investigations of episode and non-episode periods, it was found that: (i) sulfate correlated strongly with both relative humidity and nitrate during the typical winter period presumably indicating the importance of the aqueous-phase oxidation of sulfur dioxide by nitrogen dioxide, (ii) oxalate and WSOC during both winter and summer in Beijing were mainly due to secondary formation, and (iii) high humidity can significantly enhance the formation potential of WSOC in winter.

Northern peatlands are increasingly threatened by climate change and industrial activities. This study examined the impact of simulated droughts on pore water chemistry at six peatlands in Sudbury, Ontario, that differ in copper (Cu), nickel (Ni) and cobalt (Co) contamination, including a site that had been previously limed. All sites responded similarly to simulated drought: pore water pH declined significantly following the 30 day drought and the decline was greater following the 60 day drought treatment. The decline in pore water pH was due to increasing sulphate concentrations, whereas nitrate increased more in the 60 day drought treatment. Decreases in pH were accompanied by large increases in Ni and Co that greatly exceeded provincial water quality guidelines. In contrast, dissolved organic carbon (DOC) concentrations decreased significantly following drought, along with concentrations of Cu and Al, which are strongly complexed by organic acids.

Polar organic chemical integrative samplers (POCIS) were used to estimate atrazine contamination at 24 stream/river sites located across a watershed with land use ranging from 6.7 to 97.4% annual crops and surface water nitrate concentrations ranging from 3 to 5404 μg/L. A gradient of atrazine contamination spanning two orders of magnitude was observed over two POCIS deployments of 28 d and was positively correlated with measures of agricultural intensity. The metabolite desisopropyl atrazine was used as a performance reference compound in field calibration studies. Sampling rates were similar between field sites but differed seasonally. Temperature had a significant effect on sampling rates while other environmental variables, including water velocity, appeared to have no effect on sampling rates. A performance reference compound approach showed potential in evaluating spatial and temporal differences in field sampling rates and as a tool for further understanding processes governing uptake of polar compounds by POCIS.

Runoff and rainfall quality was compared between an aged intensive green roof and an adjacent conventional roof surface. Nutrient concentrations in the runoff were generally below Environmental Quality Standard (EQS) values and the green roof exhibited NO3− retention. Cu, Pb and Zn concentrations were in excess of EQS values for the protection of surface water. Green roof runoff was also significantly higher in Fe and Pb than on the bare roof and in rainfall. Input–output fluxes revealed the green roof to be a potential source of Pb. High concentrations of Pb within the green roof soil and bare roof dusts provide a potential source of Pb in runoff. The origin of the Pb is likely from historic urban atmospheric deposition. Aged green roofs may therefore act as a source of legacy metal pollution. This needs to be considered when constructing green roofs with the aim of improving pollution remediation.

The spatial and temporal patterns of water quality in Kuwait Bay have been investigated using data from six stations between 2009 and 2011. The results showed that most of water quality parameters such as phosphorus (PO4), nitrate (NO3), dissolved oxygen (DO), and Total Suspended Solids (TSS) fluctuated over time and space. Based on Water Quality Index (WQI) data, six stations were significantly clustered into two main classes using cluster analysis, one group located in western side of the Bay, and other in eastern side. Three principal components are responsible for water quality variations in the Bay. The first component included DO and pH. The second included PO4, TSS and NO3, and the last component contained seawater temperature and turbidity. The spatial and temporal patterns of water quality in Kuwait Bay are mainly controlled by seasonal variations and discharges from point sources of pollution along Kuwait Bay’s coast as well as from Shatt Al-Arab River.

The microbial community and the nirS- and nirK-encoding denitrifiers in the intertidal sediments along Laizhou Bay in China were studied using pyrosequencing and real-time quantitative PCR (qPCR), respectively. There were three primary intertidal zones: Laizhou (La), Weifang Harbor (We), and Dongying (Do). Significant differences in composition and abundances at the different taxonomic levels were observed among the three bacterial communities. The qPCR results indicated that the nirS gene abundance varied from 8.67×105 to 5.68×106copies/gwet weight (ww), whereas the nirK gene abundance varied from 1.26×105 to 1.89×106copies/gww. The canonical correlation analysis (CCA) indicated that the sand percentage was the most important factor in shaping the bacterial community followed by silt percentage, NO2−, TOC, DO, pH, and clay percentage, whereas the clay percentage, pH, NO3−, DO, NO2−, TOC, silt percentage, and sand percentage were the most important factors associated with regulating the abundance of nirS- and nirK-encoding denitrifiers.

Large amounts of waste water are discharged from the Jeddah Metropolitan Area into the Red Sea. Daily loads of total nitrogen (TN) and phosphorus (TP) amount to 6564kg and 2241kg, respectively, comprising 83% of dissolved inorganic nitrogen and 33% of dissolved phosphate. Steep gradients prevail nearshore, ranging from 2000μMTN and 250μMTP in the hypertrophic city lagoons to 6μMTN and 0.4μMTP in the adjacent oligotrophic water. Sewage inputs from Al Khumra, Jeddah’s main outfall, cause a widespread but moderate increase in surface nutrient concentrations due to the submerged diffuser. The nutrient pool in the oligotrophic water is dominated by dissolved organic and particulate forms, with nitrate frequently below the detection limit, indicating rapid transformation of inorganic nutrients. N:P ratios, as well as half-saturation constants for phytoplankton growth, suggest that nitrogen is the limiting factor restricting primary production in the area.

Urban fugitive dust samples were collected to determine the chemical profiles of fugitive dust over Xi'an. Seventy eight samples were collected and divided into categories of paved road dust, construction dust, cement dust, and soil dust. Eighteen elements, including Na, Mg, Al, Si, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Ba, and Pb, and eight water–soluble inorganic ions, including Na+, Mg2−, Ca2−, NH4−, F−, Cl−, NO3− and SO42−, were measured. The most abundant elements in these urban dust samples were Al, Si, Ca, and Fe. Al, Si, K, and Ti and showed strong positive correlations with each other, indicating they are typical dust trace elements. In contrast, elements of Ca, Zn, As, and Pb had negative correlations to crustal elements. Si/Al, K/Al, Ti/Al, Mn/Al, and Fe/Al ratios varied insignificantly among these four samples types; these ratios are similar to the properties of loess, desert, and Gobi soil dust reported in previous studies. A significantly higher Ca/Al ratio was dominant in the chemical profile of the cement samples. In addition, high Pb/Al and Zn/Al ratios were detected in comparison with those in the Gobi soil, desert soil, and loess soil samples, which indicated that Pb/Al and Zn/Al ratios can be considered as markers of urban dust. To t a l water–soluble ions occupied only a small fraction (<5%) in the urban fugitive soil samples indicating that most of the materials in the fugitive dust were insoluble. Ca2+ and SO42− were the most abundant ions in all samples. Most of the Ca and K in the fugitive soil samples were in insoluble phases, which differ significantly in comparison with combustion sources. A strong correlation was observed between Ca2+ and estimated CO32− levels indicating that most of Ca2+ was in the form of CaCO3 rather than other calcium minerals in Xi’an fugitive dust.

This paper presents a study on black carbon and ionic species concentrations in PM10, sampled from the urban area of Makassar in the Province of South Sulawesi, Indonesia. The samples were collected on a weekly basis within a period of one year from February 2012 to January 2013. Results showed that the mean concentration of PM10 black carbon was 2.01±0.93μg/m3, while ionic species concentrations were found in descending order; SO42−>NO3−>Cl−>NH4+, with mean concentrations of 1.44±1.04μg/m3, 1.11±1.06μg/m3, 0.87±0.91μg/m3, 0.49±0.64μg/m3, respectively. Black carbon concentration was higher during the dry months, which may be attributed to uncontrolled biomass burning during hot and dry weather conditions. Similarly, SO42− and NH4+ concentrations were higher during the dry month seasons. On the contrary, Cl− concentration was higher during the wet months, influenced by the marine environment surrounding the area.