Heavy metals in road dust pose a significant threat to human health. This study investigated the concentrations, patterns, and sources of eight hazardous heavy metals (Cr, Ni, Cu, Zn, As, Cd, Pb, and Hg) in the street dust of Zhengzhou city of PR China. Fifty-eight samples of road dust were analyzed based on three methods of risk assessment, i.e., Geo-Accumulation Index (I_geo), Potential Ecological Risk Assessment (RI), and Nemerow Synthetic Pollution Index (PI_N). The results exhibited higher concentrations of Hg and Cd 14 and 7 times higher than their background values, respectively. I_geo showed the risks of contamination in a range of unpolluted (Cr, Ni) to strongly polluted (Hg and Cd) categories. RI came up with the contamination ranges from low (Cr, Ni, Cu, Zn, As, and Pb) to extreme (Cd and Hg) risk of contamination. The risk of contamination based on PI_N was from safe (Cu, As, and Pb) to seriously high (Cd and Hg). The results yielded by PI_N indicated the extreme risk of Cd and Hg in the city. Positive Matrix Factorization was used to identify the sources of contamination. Factor 1 (vehicular exhaust), Factor 2 (coal combustion), Factor 3 (metal industry), and Factor 4 (anthropogenic activities), respectively, contributed 14.63%, 35.34%, 36.14%, and 13.87% of total heavy metal pollution. Metal’s presence in the dust is a direct health risk for humans and warrants immediate and effective pollution control and prevention measures in the city.

Based on the different particle sizes of street dust, the potential pollution load of heavy metals from dry and wet atmospheric deposition to surface runoff in different functional areas of Zhengzhou city was estimated by using the rain-scour heavy metal index model. Compared to the EA, IA, and CA areas, RA and PA have a higher potential contribution to heavy metal runoff pollution from Road deposited sediments (RDS) than the other watersheds. Zhengzhou utilized the RDS index model to calculate pollution loads in various areas around Zhengzhou (EA, IA, CA, PA, and RA). In the different land-use areas, the RDS indices for pollutant load (RDS_index,load) and pollutant strength (RDS_{index,strength}) varied greatly, and the RDS _{index strength} values increased. RDS_index,load fell in the following order: IA > RA > PA > EA. Because the RDS index incorporates RDS characteristics such as the amount of RDS, grain sizes present, RDS mobility, and associated metals, the RDS_index,load and RDS_{index,strength} results did not merely match variability in the amounts of RDS found or metal concentrations in the RDS in various land-use areas. Metal’s presence in the dust is a direct health risk for humans and warrants immediate and effective pollution control and prevention measures in the city.

Initially 73 chromium(VI)-resisting bacteria were isolated from nine samples collected from three industrial cities (Kasur, Kalashahkaku, and Sialkot) of Pakistan. Eleven strains with the highest chromium resistance also were selected. Among these highly resistant selected isolates (MTC ≥ 250 mM), AM81 (Cellulosimicrobium cellulans) showed the highest MTC of 375 mM against Cr(VI). Biochemical characterization was used to identify the families of bacteria after initial screening. Four isolates shared origin with Staphylococcaceae — three each with Promicromonosporaceae and Microbacteriaceae, and a single strain was related to Bacillales Family XII incertaesedis. 16S rRNA was used for species identification and found KM2 to be Leucobacter chironomid, KS1W; Microbacterium sp., SIS21 and KSKE42; Staphylococcus saprophyticus, SIS22; Staphylococcus sciuri, SIS51; Staphylococcus xylosus, MWM81, AM81, and KSKE3; Cellulosimicrobium cellulans, MWM82; and Microbacterium paraoxydans, KSKE41 was Exiguobacterium profundum. Strains tolerated the stress of other heavy metals (cadmium, mercury, copper, zinc, arsenic, and manganese) to variable extant along with chromium(VI). Antibiotic susceptibility was found to be more for streptomycin (10 μg ml^-1) and the least susceptibility was observed for kanamycin (30 μg ml^-1).

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.