Occurrence, distribution, and risk assessment of quinolone antibiotics in municipal sewage sludges throughout China.

A nationwide study of the occurrence, distribution, potential drivers, and ecological risks of 24 quinolone antibiotics (QNs) in 74 Chinese sludge samples from 48 wastewater treatment plants (WWTPs) was conducted. In domestic sludge, the ∑QNs concentrations were  3rd-generation QNs > 4th-generation QNs > 1st-generation QNs. Meanwhile, abundant veterinary and human/veterinary quinolones (

Synergistic interactions of fine particles and radiative effects in modulating urban heat islands during winter haze event in a cold megacity of Northeast China.

Severe air pollution and urban heat islands (UHI) intensity (UHII) are two challenging problems that have attracted wide attention in populated cities. However, previous studies mostly focused on the relationship between fine particulate matter (PM2.5) and UHII, but how UHII responds to the interactions between radiative effects (direct effect (DE), indirect effect (IDE) with slope and shading effects (SSE)) and PM2.5 during heavy pollution is still unclear, especially in the cold region. Therefore, this study explores the synergistic interactions between PM2.5 and radiative effects in influencing UHII during a heavy pollution event in the cold-megacity of Harbin-China. Hence, we designed four scenarios: non-aerosol radiative feedback (NARF), DE, IDE, and combined effects (DE + IDE + SSE) in December 2018 (clear-episode) and December 2019 (heavy-haze-episode) using numerical modeling. The results showed that the radiative effects influenced the spatial distribution of PM2.5 concentration leading to a mean drop in 2-m air-temperature by approximately 0.67 °C (downtown) and 1.48 °C (satellite-town) between the episodes. The diurnal-temporal variations revealed that the daytime and nighttime UHIIs were strengthened in the downtown during the heavy-haze-episode, while a reverse effect was observed in the satellite-town. Interestingly, during the heavy-haze-episode, the considerable difference between excellent and heavily polluted PM2.5 levels showed a decrease in UHIIs (1.32 °C, 1.32 °C, 1.27 °C, and 1.20 °C) due to the radiative effects (NARF, DE, IDE, and (DE + IDE + SSE)), respectively. In assessing other pollutants' interactions with the radiative effects, PM10 and NOx had a considerable impact on the UHII during the heavy-haze episode while O3 and SO2 were discovered to be very low in both episodes. Moreover, the SSE has uniquely influenced UHII, especially during the heavy-haze-episode. Therefore, insight from this study provides an understanding of how UHII responds uniquely in the cold region, which in turn could help to formulate effective policies and co-mitigation strategies for air pollution and UHI problems.

Understanding the inter-city causality and regional transport of atmospheric PM2.5 pollution in winter in the Harbin-Changchun megalopolis in China: A perspective from local and regional.

Harbin-Changchun megalopolis (HCM) is the typical cold urban agglomeration in China, where PM2.5 pollution is still serious in winter against the backdrop of continuous improvement in annual air quality in China. To further understand interactions of atmospheric pollution among HCM cities, inter-city causality and regional transport of PM2.5 in the winter in the HCM were comprehensively investigated by using convergent cross mapping (CCM) and CMAQ-BFM methods. CCM analysis results suggest strong bidirectional causal relationships between cities in the HCM, and the causality during polluted episodes were significantly larger than that during clean period. In addition, the influence on local PM2.5 from the HCM western cities were larger than that from cities in the southeast. Inter-city and regional transport contributions results demonstrated that although local emission were the largest contributors among 14 sub-regions for most HCM cities, interactions among cities were strong. Regional transport (42.8%-77.4%) largely contributes to HCM cities' PM2.5 concentrations. Among three regions outside the HCM, NMG (including part of inner Mongolia and Baicheng city in Jilin, 9.1%) was the largest contributor to the PM2.5 concentration in the whole HCM, followed by JLS (including Liaoning Province, Tonghua and Baishan cities in Jilin province, 5.1%) and HLJ (including cities of Heihe, Yichun, Jiamusi, Hegang, Shuangyashan, Jixi, Qitaihe in the Heilongjiang province, 3.8%). Regional transport contribution to the most HCM cities increased significantly from excellent to heavily polluted days. Furthermore, close relationships between transport paths/intensity and wind direction/speed in studied region suggests that we can quantitatively guide the regional joint emergency prevention and control before and during heavily polluted events based on regional weather forecasts in the future.

Seasonal variation characteristics of inhalable bacteria in bioaerosols and antibiotic resistance genes in Harbin.

Bioaerosols have received extensive attention due to their impact on climate, ecological environment, and human health. This study aimed to reveal the driving factors that structure bacterial community composition and the transmission route of antibiotic resistance genes (ARGs) in PM2.5. The results showed that the bacterial concentration in spring (8.76 × 105 copies/m3) was significantly higher than that in summer (1.03 × 105 copies/m3) and winter (4.74 × 104 copies/m3). Low temperatures and air pollution in winter negatively affected bacterial concentrations. Keystone taxa were identified by network analysis. Although about 50 % of the keystone taxa had low relative abundances, the strong impact of complex interactions between keystone taxa and other taxa on bacterial community structure deserved attention. The bacterial community assembly was dominated by stochastic processes (79.3 %). Interactions between bacteria and environmental filtering together affected bacterial community composition. Vertical gene transfer played an important role in the transmission of airborne ARGs. Given the potential integration and expression of ARGs in recipients, the human exposure risk due to high concentrations of ARGs and mobile genetic elements cannot be ignored. This study highlights human exposure to inhalable bacterial pathogens and ARGs in urban areas.

Light-absorption and fluorescence fingerprinting characteristics of water and methanol soluble organic compounds in PM2.5 in cold regions of Northeast China.

High-performance liquid chromatography-size exclusion chromatography and excitation-emission matrix (EEM) fluorescence spectroscopy were used to analyze the seasonal variations and potential sources of molecular weight (MW) separated light-absorbing chromophores and fluorophores of water-soluble organic compounds (WSOC) and methanol-soluble organic compounds (MSOC) in PM2.5 in cold areas of northern China. The results showed that the light-absorbing organics in MSOC had larger weight-average MW (Mw) (3.19 kDa) and number-average MW (Mn) (1.13 kDa) compared with WSOC (Mw: 1.41 kDa, Mn: 0.692 kDa). The light-absorption of organics showed a trend of winter>spring>autumn>summer and increased on air pollution days. Three fluorescent components including humic-like, protein-like, and terrestrial humic-like components in WSOC were extracted by parallel factor analysis (PARAFAC). Fluorophores in WSOC were dominated by humic-like and terrestrial humic-like components (67.7%). Three fluorescent components extracted from MSOC were low oxidation humic-like, polycyclic aromatic hydrocarbon (PAH)-like, and protein-like components respectively. It is worth noting that compared with WSOC, MSOC may have a higher human health risk due to the presence of PAH-like components. The combination of PARAFAC and self-organizing map had the potential to identify potential sources of fluorophores. It provided a new perspective for comprehensively exploring the characteristics of fluorophores in aerosols. This study provided a reference for further understanding the chemical composition and optical properties of organic aerosols in the cold regions of northern China.