Spatiotemporal occurrence and characteristics of microplastics in the urban road dust in a megacity, eastern China

The pervasive issue of microplastics pollution has garnered public attention, yet urban residents remain unaware of the threat within their living spaces. Urban road dust, as primary reservoirs for environmental microplastics, offers an insightful perspective into their occurrence and characteristics. This study investigated microplastics in the urban road dust in Nanjing, a megacity in eastern China, to reveal their spatiotemporal pattern. The abundance of microplastics in the road dust measured 143.3 ± 40.8 particles/m2, with predominant fragments and suspected tire wear particles, particularly those below 100 µm. Significant spatial variations were observed across urban functional zones (P < 0.05), with commercial and heavy industrial areas experiencing the highest microplastic pollution (up to 223.5 particles/m2). Infrared spectroscopy analysis identified 29 polymer types, with polystyrene (PS), polyamide (PA), and polyvinylidene difluoride (PVDF) prevailing. Light industrial zones exhibited slight contamination (mean = 93.4 particles/m2) but with diverse polymer components (24 types). Redundancy analysis and variation partitioning revealed that urban functional zoning, 7-day accumulated precipitation, and monthly PM2.5 primarily influenced the occurrence and characteristics of microplastics in urban road dust (P = 0.001). This study deepened our understanding of microplastics pollution in urban environments, providing novel insights for effective urban environmental management and improvement.

Spatiotemporal variations in the occurrence of Campylobacter species in the Bloukrans and Swartkops rivers, Eastern Cape, South Africa

An increase in the incidence of Campylobacter species in rivers raises concerns on the safety of river water for humans who get exposed to river water. This study examines the spatiotemporal dynamics of Campylobacter species in the Bloukrans and Swartkops rivers, analysing patterns of its occurrence in relation to meteorological conditions, physicochemical parameters, seasons, and sampling sites. Physico-chemical parameters and meteorological conditions were measured during water sampling from various sites along the rivers over a year, while Polymerase Chain Reaction (PCR) was utilised to detect Campylobacter genus-specific genes and selected antibiotic-resistant genes. Campylobacter was detected in 66.67% (Bloukrans River) and 58.33% (Swartkops River). In the Bloukrans River, multi-drug resistance genes cmeA (20%), cmeB (65%), cmeC (10%), were detected while and tetO was detected at 70%. In the Swartkops River, the corresponding prevalence were 28%, 66.67%, 28.56%, and 76%. The study indicates that sampling season did not significantly impact Campylobacter prevalence. However, variation in Campylobacter occurrence exists among different sites along the rivers, reflecting the influence of site proximity to potential contamination sources. The study suggests that Campylobacter infection may be endemic in South Africa, with rivers serving as potential sources of exposure to humans, thereby contributing to the epidemiology of campylobacteriosis.

Identification of core micropollutants of Ergene River and their categorization based on spatiotemporal distribution

Ergene River is heavily utilized for irrigation of fields to grow the main stocks of rice, wheat, and sunflower of Turkey also exported to Europe; therefore, monitoring the river's water quality is crucial for public health. Although the river quality is routinely monitored, the evaluation of pollution based on micropollutants is limited. In this study, we measured 222 organic micropollutants in 300 samples collected from 75 different locations on the Ergene River between August 2017 and May 2018 using direct injection liquid chromatography-tandem spectrometry with optimized scheduled multiple reaction monitoring. In total, 165 micropollutants were detected at a range of concentrations between 1.90 ng/L and 1824.55 μg/L. Sixty-three chemical substances were recurrent micropollutants that were detected at least one location in all seasons. Among them, 41 chemical substances were identified as the core micropollutants of the Ergene River using data-driven clustering methods. Hexa(methoxymethyl)melamine, benzotriazoles, and benzalkonium chlorides were frequently detected core micropollutants with an industrial origin. Besides, diuron, carbendazim, and cadusafos were common pesticides in the river. Core micropollutants were further categorized based on their type of source and environmental behavior using Kurtosis of concentration and load data obtained for each micropollutant. As a result, the majority of the core micropollutants are recalcitrant chemicals either released from a specific source located upstream of the river or have urban and agricultural sources dispersed on the watershed. In this study, we assessed the current state of pollution in the Ergene River at the micropollutant level with a very high spatial resolution and developed a statistical approach to categorize micropollutants that can be used to monitor the extent of pollution and track pollution sources in the river.