Assessing Metal Exposure and Leaching from Discarded Cigarette Butts: Environmental Analysis and Integrated Waste Management Approaches.

Cigarette butts, often discarded as litter, are considered a common form of waste, containing a variety of pollutants within this hazardous residue. This study, which was designed to assess the environmental release of certain metals from cigarette butts, investigates a variety of scenarios under varying climatic conditions. Thus, in order to assess the level of metal contamination, samples of cigarette butts were collected in urban areas from seven popular brands in China, smoked artificially, and examined through graphite furnace atomic absorption (GF-AAS). The findings indicated mean concentrations of 1.77 for Cr, 2.88 for Ni, 12.93 for Cu, 24.25 for Zn, and 1.77 µg/g for Pb in the case of newly smoked butts. The emission of each of the metals increases to 8-10% when cigarette butts remain in the environment for an extended period of time. Furthermore, rainfall can accelerate metal leaching, reaching values of 18-20% compared to the controlled scenario. The worst-case scenario releases 2129.31 kg/year of metals into the environment, while the best-case scenario sees a lower release of 844.97 kg/year. The data reflect variations in metal emissions across different scenarios. There was also a strong correlation between cigarette butts in public spaces and cities. This research highlights the need to educate smokers and increase urban maintenance efficiency to reduce this litter and the metals it leaches into the environment.

Historical behaviors of microplastic in estuarine and riverine reservoir sediment.

This study investigates the sedimentation behaviors of microplastics (MPs) within a typical meso-scale river estuary, the Yalu River Estuary (YRE) and its riverine reservoir. It analyzes sediment cores in two habitats of Yalu River, revealing changing MPs abundance over time. Results highlight significant differences in riverine and estuarine MPs deposition. Reservoir sample contains more MPs in fragments. Color variations are notable in estuarine samples but minimal in reservoir sample. After 1980, estuarine cores show an increase in coarser MPs, likely due to growth of aquaculture activities. Although sediment accumulates at 1/10 of the rate in reservoir compared to estuary, MPs in reservoir sediments exceeds estuarine level by over threefold. A possible mechanistic framework is then proposed to discuss the varying MPs behaviors in the two habitats, indicating reservoirs accumulate MPs at a higher rate due to the barrier effect of an upper-stream reservoir, stable hydrodynamics, and weak salinity-induced buoyancy.

Quantifying the influence of urban road surface roughness on heavy metals pollution in road-deposited sediment's accumulation and wash-off.

Surface roughness is an important factor to consider when evaluating the loads of surface runoff caused by road-deposited sediment (RDS) wash-off and creating management solutions for this occurrence in metropolitan areas. Nevertheless, the implications of surface roughness on RDS development and escape remain unclear due to a paucity of experimental evidence distinguishing the significance of surface roughness. This research aimed to differentiate the impact of surface roughness on RDS accumulation and wash-off by employing paired asphalt, rainfall simulation designs, and concrete road surfaces. Our findings indicated that normal asphalt surfaces are typically rougher than typical concrete surfaces because they frequently contain deeper depressions. Compared to concrete surfaces, asphalt surfaces typically retain more RDS, a higher proportion of coarse aggregates, more RDS wash-off loads, and a lower proportion of wash-off. Surface roughness has varying impacts on the RDS motilities of particulates of varying sizes during rainy runoff; nevertheless, the settleable particles (40-150 µm) were more noticeably impacted by it. The first flush effect also seemed to be more pronounced on surfaces with lower roughness. Hence, surface roughness has a significant impact on how RDS builds on and is washed off of various road aspects.