Surface and building runoff can significantly contribute to the total metal loading in urban runoff waters, with potential adverse effects on the receiving ecosystems. The present paper analyses the corrosion-induced metal dissolution (Fe, Mn, Cr, Ni, Cu) from weathering steel (Cor-Ten A) with or without artificial patinas, exposed for 3 years in unsheltered conditions at a marine urban site (Rimini, Italy). The influence of environmental parameters, atmospheric pollutants and surface finish on the release of dissolved metals in rain was evaluated, also by means of multivariate analysis (two-way and three-way Principal Component Analysis). In addition, surface and cross-section investigations were performed so as to monitor the patina evolution. The contribution provided by weathering steel runoff to the dissolved Fe, Mn and Ni loading at local level is not negligible and pre-patination treatments seem to worsen the performance of weathering steel in term of metal release. Metal dissolution is strongly affected by extreme events and shows seasonal variations, with different influence of seasonal parameters on the behaviour of bare or artificially patinated steel, suggesting that climate changes could significantly influence metal release from this alloy. Therefore, it is essential to perform a long-term monitoring of the performance, the durability and the environmental impact of weathering steel.

Fugitive emissions from natural gas systems are the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S. and contribute to the risk of explosions in urban environments. Here, we report on a survey of CH4 emissions from 100 natural gas leaks in cast iron distribution mains in Metro Boston, MA. Direct measures of CH4 flux from individual leaks ranged from 4.0 – 2.3 × 104 g CH4•day−1. The distribution of leak size is positively skewed, with 7% of leaks contributing 50% of total CH4 emissions measured. We identify parallels in the skewed distribution of leak size found in downstream systems with midstream and upstream stages of the gas process chain. Fixing ‘superemitter’ leaks will disproportionately stem greenhouse gas emissions. Fifteen percent of leaks surveyed qualified as potentially explosive (Grade 1), and we found no difference in CH4 flux between Grade 1 leaks and all remaining leaks surveyed (p = 0.24). All leaks must be addressed, as even small leaks cannot be disregarded as ‘safely leaking.’ Key methodological impediments to quantifying and addressing the impacts of leaking natural gas distribution infrastructure involve inconsistencies in the manner in which gas leaks are defined, detected, and classified. To address this need, we propose a two-part leak classification system that reflects both the safety and climatic impacts of natural gas leaks.

Surface soil samples were collected surrounding two brominated flame retardants (BFRs) manufacturing plants in China in August 2014 and analyzed for 23 polybrominated diphenyl ethers (PBDEs) and 8 novel brominated flame retardants (NBFRs). BDE209 and decabromodiphenylethane (DBDPE) were the predominant compounds in soil with the median levels of 1600 and 560 ng/g dw, respectively. The PBDEs profiles in soil samples were consistent with that of commercial product (comDecaBDE). The percentage contributions to total PBDEs decreased from higher to lower brominated homologues. Lower concentrations of NBFRs (excluding DBDPE) were detected in soil surrounding the two plants, suggesting they are byproducts or degradation products of the manufacturing activities. The concentrations of most BFRs dropped exponentially within 3–5 km of the manufacturing plants, suggesting recent deposition of these compounds to the soil. Directional distribution indicated that PBDEs and DBDPE concentrations were highest in the north direction of Plants 1. Three-day air parcel forward trajectories confirmed that the air parcel was responsible for the higher concentration of BFRs in the soil of north direction of the plant.

Trace element profiling in the incrementally formed dentine of mammalian teeth can be applied to reconstruct temporal variation of incorporation of these elements into the tissue. Using an electron microprobe, this study analysed fluoride distribution in dentine of first and third mandibular molars of free-ranging eastern grey kangaroos inhabiting a high-fluoride area, to assess temporal variation in fluoride uptake of the animals. Fluoride content in the early-formed dentine of first molars was significantly lower than in the late-formed dentine of these teeth, and was also lower than in both, the early and the late-formed dentine of third molars. As early dentine formation in M1 takes place prior to weaning, this finding indicates a lower dentinal fluoride uptake during the pre-weaning compared to the post-weaning period. This is hypothetically attributed to the action of a partial barrier to fluoride transfer from blood to milk in lactating females and a low bioavailability of fluoride ingested together with milk. Another factor contributing to lower plasma fluoride levels in juveniles compared to adults is the rapid clearance of fluoride from blood plasma in the former due to their intense skeletal growth. The combined action of these mechanisms is considered to explain why in kangaroos from high-fluoride areas, the (early-formed) first molars are not affected by dental fluorosis while the (later-formed) third and fourth molars regularly exhibit marked to severe fluorotic lesions.

The second‒order rate constants (k) of hydroxyl radical (·OH) with polychlorinated biphenyls (PCBs) in the gas phase are of scientific and regulatory importance for assessing their global distribution and fate in the atmosphere. Due to the limited number of measured k values, there is a need to model the k values for unknown PCBs congeners. In the present study, we developed a quantitative structure–activity relationship (QSAR) model with quantum chemical descriptors using a sequential approach, including correlation analysis, principal component analysis, multi−linear regression, validation, and estimation of applicability domain. The result indicates that the single descriptor, polarizability (α), plays an important role in determining the reactivity with a global standardized function of lnk = −0.054 × α ‒ 19.49 at 298 K. In order to validate the QSAR predicted k values and expand the current k value database for PCBs congeners, an independent method, density functional theory (DFT), was employed to calculate the kinetics and thermodynamics of the gas‒phase ·OH oxidation of 2,4′,5-trichlorobiphenyl (PCB31), 2,2′,4,4′-tetrachlorobiphenyl (PCB47), 2,3,4,5,6-pentachlorobiphenyl (PCB116), 3,3′,4,4′,5,5′-hexachlorobiphenyl (PCB169), and 2,3,3′,4,5,5′,6-heptachlorobiphenyl (PCB192) at 298 K at B3LYP/6–311++G**//B3LYP/6–31 + G** level of theory. The QSAR predicted and DFT calculated k values for ·OH oxidation of these PCB congeners exhibit excellent agreement with the experimental k values, indicating the robustness and predictive power of the single–descriptor based QSAR model we developed.

From November 2014 to October 2015, the concentrations of volatile organic compounds (VOCs), O3 and NOx were simultaneously monitored by using online instruments at the air monitoring station belonged to Tianjin Environmental Protection Bureau (TEPB). The results indicated that VOCs concentrations were higher in autumn and lower in spring, while O3 concentrations were higher in summer, and lower in winter. The diurnal variations of VOCs and NOx (NO2 plus NO) showed opposite tendency comparing to that of O3. The concentrations of alkanes were higher (the average of 18.2 ppbv) than that of aromatics (5.3 ppbv) and alkenes (5.2 ppbv), however, the alkenes and aromatics made larger contributions to ozone because of their high reactivity. Tianjin belonged to the VOC-limited region during most of seasons (except summer) according to the VOC/NOx ratios (the 8:1 threshold). The automobile exhaust, industrial emission, liquefied petroleum gas/natural gas (LPG/NG), combustion, gasoline evaporation, internal combustion engine emission and solvent usage were identified as major sources of VOCs by Positive Matrix Factorization (PMF) model in Tianjin, and the contributions to VOCs for the entire year were 23.1%, 19.9%, 18.6%, 10.6%, 8.7%, 5.4% and 4.7%, respectively. The conditional probability function (CPF) analysis indicated that the contributing directions of automobile exhaust and industrial emission were mainly affected by source distributions, and that of other sources might be mainly affected by wind direction. The backward trajectory analysis indicated that the trajectory of air mass originated from Mongolia, which reflected the features of large-scale and long-distance air transport, and that of beginning in Jiangsu, Shandong and Tianjin, which showed the features of small-scale and short-distance. Tianjin, Beijing, Hebei and Northwest of Shandong were identified as major potential source-areas of VOCs by using potential source contribution function (PSCF) and concentration-weighted trajectory (CWT) models.

Understanding the evolution of aerosols in the atmosphere is of great importance for improving air quality and reducing aerosol-related uncertainties in global climate simulations. Here, a unique haze episode at a regional receptor site near the East China Sea was examined as a case study of the aging process of atmospheric aerosols during transport. An increase in photochemical age from 5 h to more than 25 h and a progressive increase in the fitted mean particle diameter from 70 nm to approximately 300 nm were observed. According to the pollution features and meteorology conditions involved, pollution accumulation (PA), sea breeze (SB), and land breeze (LB) periods were identified. Concentrations of black carbon (BC), hydrocarbon-like organic aerosols (HOA), semi-volatile oxidized organic aerosols (SV-OOA), and nitrate increased by 7-fold up to 39-fold when the air masses passed through Taizhou, a nearby city. In addition, nitrate and SV-OOA dominated the aerosol composition in the urban outflow plumes (52% and 18%, respectively), yet they gradually decreased in concentration during transport. In contrast, sulfate and the low-volatile oxidized organic aerosols (LV-OOA) exhibited more regional footprints and potentially have similar formation mechanisms. The atomic oxygen-to-carbon (O/C) ratio also increased from 0.45 to 0.9, thereby suggesting that rapid formation of highly oxidized secondary organic aerosols (SOA) occurred during transport. Overall, these results provide valuable insight into the evolution of the chemical and physical features of aerosol pollution during transport and also highlight the need for regulatory controls of nitrogen oxides, sulfur dioxide, and VOCs to improve air quality on different scales.

Approximately 40% of the volume of domestic sewage generated in the São Paulo State is untreated and released into water bodies, causing serious pollution problems that affect the water quality and especially the suspended sediments transported by rivers. Thus, this paper investigates the seasonal influence on the origin and fluxes of Cu, Co, Cr, Zn, Cd, Ni, Sc and particulate organic matter (POM) in sediments transported by a disturbed watershed in the São Paulo State, i.e. the Sorocaba River basin. POM was characterized using particulate organic carbon, particulate organic nitrogen, C:N ratio and δ13C and δ15N stable isotopic composition. Eight sample collections of fine suspended sediments (FSS) were carried out at the mouth of the Sorocaba River from July 2009 to May 2010. During the study period, the discharge rate followed the seasonal variation trend of the past 25 years. Zn was the most abundant trace element in the FSS, followed by Cr, Cu, Ni, Co, Sc and Cd. There was a higher concentration of trace elements during the dry season, except for Sc and Co, which did not vary seasonally. The POM showed the same trend, with higher concentrations during the dry season. The calculated enrichment factors and geoaccumulation index indicated that most of the trace elements are of geogenic origin, except for Zn, which showed significant anthropogenic contributions (55%). The elemental and isotopic analysis of C and N and C:N ratio indicated that the anthropogenic origin of POM found in the FSS is related mainly to domestic sewage (97%), while the significant correlation found between the concentrations of Zn and POM indicates that the main anthropogenic source of Zn is related to this domestic sewage. The FSS load transported during the study period was of 373,194 t y−1, of which 87% occurred during the rainy season.

PBDEs and heavy metals are two major contaminants at e-waste disposal sites, but their combined effects remain largely unexplored. In the present study, the transcriptomic profiles of zebrafish larvae were examined after acute exposure of embryos to 200 μg/L BDE-209, 20 μg/L lead (Pb) or their mixture (Mix). Stimulation of steroidogenic pathway and vitellogenesis in the BDE-209 and Mix treatments indicated the estrogenic activities of BDE-209, while Pb antagonized those estrogenic effects in the Mix treatment. Increased heart rates were observed in zebrafish exposed to the Pb and Mix treatments. The cardiac dysfunction probably resulted from the promotion of angiogenesis, increased adrenergic drive and induction of the formation of blood clot. Furthermore, the Pb and Mix treatments activated neuroendocrine regulation of the pituitary in a positive feedback loop, via the thyrotropin-releasing hormone receptor, thus increasing thyroid hormone production self-adaptively. Overall, the interaction between BDE-209 and Pb led to synergistic and antagonistic effects on gene transcriptions, with concerted contribution from their individual toxicological properties.

The fungicide tebuconazole (TBZ) is used to repress fungal growth in golf greens and ensure their playability. This study determined the degradation and sorption of TBZ applied as an analytical grade compound, a commercial fungicide formulation or in combination with a surfactant product in thatch and soils below two types of greens (USGA and push-up greens) in 12-cm vertical profiles covered by three different types of turf grass. Only minor TBZ degradation was observed and it was most pronounced in treatments with the commercial fungicide product or in combination with the surfactant compared to the analytical grade compound alone. A tendency for higher TBZ sorption when applied as the formulated product and lowest sorption when applied as a formulated product in combination with the surfactant was observed, with this effect being most distinct on USGA greens. No correlation between occurrence of degradation and soil depth, green type or grass type was observed. Sorption seemed to be the main process governing the leaching risk of TBZ from the greens and a positive correlation to the organic matter content was shown. In light of these findings, organic matter content should be taken into consideration during the construction of golf courses, especially when following USGA guidelines.