Investigating the distribution of microplastics in soils from e-waste dismantling sites and their adsorption of heavy metals.

Microplastics are characterized by strong hydrophobicity, large specific surface area. In addition to the pollutant they contain, the heavy metals adsorbed on the surface of microplastics can migrate or be transformed with them into the environmental medium, which is potentially harmful to humans. The distribution characteristics of microplastics in contaminated soil at the e-waste dismantling site were studied. The study investigated the adsorption characteristics of polyvinyl chloride (PVC), polypropylene (PP) and acrylonitrile-butadiene-styrene (ABS) on copper (Cu), zinc (Zn) and lead (Pb). It analysed the influence of various factors on the adsorption process of heavy metals, the adsorption law of microplastics on some of the heavy metals in the environment, and the risk of heavy metal release from microplastics to soil. The results showed that ABS and PP were the main microplastics in the contaminated soil. Among them, black, white and transparent microplastics accounted for 89.91%. The shape of microplastics is mainly granular, and microplastics with a particle size of 1-2 mm accounted for the largest proportion. Further studies showed that plastic particles made of ABS, PP and PVC also have the adsorption capacity for different types of heavy metals in soil, and the trends of adsorption capacity are: PP>PVC>ABS. When PP does not reach adsorption equilibrium in the adsorption process, the smaller the particle size and the more added amount, the greater the adsorption capacity. This is because the smaller the particle size of the microplastic is, the more adsorption points it can provide, increasing its ability to adsorb heavy metal ions.

First evidence of occupational and residential exposure to bisphenols associated with an e-waste dismantling site: A case study in China.

Bisphenol A and its structural analogues (BPs) are widely used chemicals in electronics devices. To get insight into the occupational exposure to the full-time employees compared with the residents, urinary BPs in workers dismantling e-waste and in nearby residents were compared. Only 4 BPs among the tested 8 congeners, bisphenol AF (BPAF), bisphenol A, bisphenol S (BPS), and bisphenol F (BPF), were extensively detected with the detection frequencies of 100%, 99%, 98.7%, 51.3%. The median concentration of bisphenol A was 8.48 ng/mL, followed by BPAF (1.05 ng/mL), BPS (0.115 ng/mL), and BPF (0.110 ng/mL). The 4 detected BPs had a median concentration (Σ4BPs) ranging from 0.950 to 64.5 ng/mL in all volunteers, with a median value of 10.2 ng/mL. Result indicated the median concentration of ∑4BPs in worker's urine was significantly higher (14.2 ng/mL) than those in residents in nearby towns (4.52 ng/mL and 5.37 ng/mL) (p < 0.05), suggesting a BPs' occupational exposure risk related to e-waste dismantling. Besides, urinary ∑4BPs' median concentrations for the employees in family workshops (14.5 ng/mL) were significantly higher than those in plants with centralized management (9.36 ng/mL). Among volunteers, higher ∑4BPs were observed in groups of aged above 50 years, males, or body weight under average with no significant correlations. The estimated daily intake of bisphenol A did not exceed the reference dose (50 µg/kg bw/day) recommended by the U.S. Food and Drug Administration. In this research, excess levels of BPs were recorded for the full-time employees in e-waste dismantling sites. Strengthened standards could support public health initiatives for full-time worker protection and reduce take-home BPs to family members.

The Typical Polybrominated Diphenyl Ethers (PBDEs) and Heavy Metals Distributions in a Formal e-Waste Dismantling Site.

Understanding the release of pollutants from the formal e-waste dismantling site could provide the basic information and potential risk to guide the normative regulation of the process. In this study, the distribution of typical polybrominated diphenyl ethers (PBDEs) and heavy metals in a relocating site of a formal e-waste dismantling company was firstly investigated down to the saturated zone, with a maximum depth of 3.0 m. The mean concentrations of Σ13PBDEs were ranged from 2.815 to 7.178 ng/g, with a peak value of 7.178 ng/g in storage area. BDE-209 was the predominant congener of PBDEs in the soil, with the value ranged from 1.688 to 2.483 ng/g. A higher pollution of PBDEs and HMs was presented in the storage area. The risk assessment of PBDEs mostly posed a low environmental risk (RQ ≤ 0.01) and pentaBDE was found to be the most harmful driver for the potential environmental risk.

Characteristics of legacy and novel brominated flame retardants in water and sediment surrounding two e-waste dismantling regions in Taizhou, eastern China.

A total of 51 water and 43 sediment samples were collected from the locations surrounding the two e-waste dismantling zones in Taizhou, the Fengjiang resource recycling industrial zone (FJ, shut down in 2017) and the Taizhou resource recycling base (TZ, newly constructed in recent years). The concentrations of polybrominated diphenyl ethers (PBDEs) ranged from 1.7 to 44 ng/L in water and from not detected (nd) to 7100 ng/g in sediment. Novel brominated flame retardants (NBFRs) ranged from 0.29 to 1.6 ng/L in water, and from nd to 5300 ng/g in sediment. The levels of PBDEs and NBFRs in the water were comparable between FJ and TZ, while their concentrations were higher in the sediment from FJ than those from TZ. The levels of BDE-28, BDE-153, pentabromotoluene (PBT), pentabromobenzene (PBB), ∑PBDEs and ∑BFRs in the water from FJ or TZ were found to be significantly negatively associated with the distance from the zone center. However, in the sediments from FJ and TZ, the BFRs levels did not decrease from the center to the outer regions. BDE-209 and decabromodiphenyl ethane (DBDPE) were predominant in the sediments and the ratio of DBDPE/BDE-209 were as high as 5.6 (mean: 0.97). The mass burden of PBDEs, BDE-209, DBDPE, 1,2-bis(2,4,6-tribromophenoxy) ethane (BTBPE), and HBB in the riverine sediments in Luqiao District was 829, 787, 363, 85, and 61 kg, respectively. The ecological risk assessment revealed that BDE-99 posed an unacceptable risk to aquatic life at 86% of the locations. The hazard quotients for penta-BDE, BDE-209, and HBB exceeded one for 30%, 28%, and 2.3% of the sediment samples, respectively.

Insight Into Microbial Community Aerosols Associated With Electronic Waste Handling Facilities by Culture-Dependent and Culture-Independent Methods.

Airborne microorganisms in the waste associated environments are more active and complex compared to other places. However, the diversity and structure of airborne bacteria in waste-associated environments are still not clearly understood. The purpose of this study was to assess airborne bacterial community in electronic waste dismantling site and a waste transfer station based on culture-dependent and culture-independent methods. A total of 229 isolates were obtained from four airborne sites collected from residential area, electronic industrial park, and office area in or near an electronic waste dismantling site and a waste transfer station in Southern China in the morning, afternoon, and evening. Most of the isolates were isolated from air for the first time and 14 potentially novel species were identified by Sanger sequencing. Bacterial communities in waste-associated bioaerosols were predominated by Proteobacteria and Bacteroidetes. Abundant genera (>1%) included Paracaedibacteraceae (uncultured EF667926), Ralstonia, Chroococcidiopsis, Chitinophagaceae (uncultured FN428761), Sphingobium, and Heliimonas. One-third of the species in these genera were uncultured approximately. Differences community structure existed in airborne bacterial diversity among different sampling sites. These results showed that waste-associated environments have unique bacterial diversity. Further studies on such environments could provide new insights into bacterial community.

Concentration profiles, source apportionment and risk assessment of polycyclic aromatic hydrocarbons (PAHs) in dumpsite soils from Agbogbloshie e-waste dismantling site, Accra, Ghana.

The concentrations of eighteen (18) polycyclic aromatic hydrocarbons (PAHs), including the 16 USEPA's priority PAHs as well as two alkyl-substituted naphthalenes were determined in dumpsite soils collected from different sampling sites within the Agbogbloshie e-waste dismantling site in Accra, Ghana. Following their isolation with ultrasonic-assisted extraction technique, the concentrations of the PAHs were determined by gas chromatography mass spectrometry (GC-MS). Loss-on-ignition (LOI) method was employed for the determination of total organic carbon (TOC) of the soil samples. The mean Σ18PAHs obtained were 3006, 5627, 3046, 5555, and 7199 ng g(-1) dry weight (dw) for sampling sites A (mosque), B (dismantling site), C (residential house/police station), D (personal computer repairers' shop) and E (e-waste open burning area), respectively. In all cases, the prevalence of phenanthrene, fluoranthene and pyrene was generally observed across the sampling sites. In this study, PAHs with two to three rings and four to six rings exhibited strong positive correlations, whereas BbF and BkF showed weak positive and negative correlations with other PAHs investigated. With the exception of BbF and BkF, all the PAHs had moderate to strong positive correlations with the TOC. Benzo[a]pyrene equivalent (BaPeq) concentration is a useful indicator of the carcinogenic potency of environmental matrices and these ranged between 111 and 454 ng g(-1), which are generally below the 'safe' level of 600 ng g(-1) established for the protection of the environment and human health. Interestingly, the seven carcinogenic PAHs were the major contributors to the BaPeq concentrations accounting between 97.7 and 98.3 %. Despite the minimal risk to cancer via exposure to the investigated dumpsite soil as indicated in the present study, the prolonged exposure to these pollutants via various exposure pathways may result in increased risk to cancer over time. The application of several methodological approaches for PAH source apportionment, including the use of molecular diagnostic ratios, mostly implicated pyrogenic processes as the main sources of PAHs into the investigated dumpsite soils. Furthermore, their compositional profiles across the sampling sites also suggest similar sources of PAHs into the dumpsite soil.