Environmental Engineering Science最新文献

Accurately identifying microplastics (MPs) poses a challenge because environmental and human activities, like thermal oxidation (common in wildfires, urban fires, and waste burning) and mechanical abrasion (common in riverine and marine environments), chemically modify the plastic structure. Conventional Fourier transform infrared (FTIR) libraries lack the accuracy to identify these plastics because degradation alters their spectra-thermal oxidation adds new peaks, and abrasion causes characteristic peaks to fade. This creates a knowledge gap, leading to MP misidentification and flawed risk assessments for plastic pollution. To address this, we developed a new, environmentally relevant spectral library that significantly improved identification, increasing match rates by 7.3% for thermally oxidized plastics and by 23.8% for mechanically abraded plastics. We did this by subjecting seven commercial polymers (polypropylene [PP], polystyrene, rayon, low-density polyethylene [LDPE], linear low-density polyethylene, high-density polyethylene, and polyethylene terephthalate) to controlled thermal oxidation (100-200°C for 1-24 h) and by exposing PP and LDPE preproduction pellets to 40 days of mechanical abrasion (33 rpm; 3.41 rad s - 1). We then collected attenuated total reflectance (ATR)-FTIR spectra from these altered plastics and incorporated them into two newly developed spectral libraries. We tested these new libraries on 62 environmental MP samples (thermally oxidized) and 15 lab-generated particles (abraded), confirming a significant improvement in identification accuracy. Our findings underscore the importance of incorporating spectra obtained from plastics exposed to environmentally weathering processes into FTIR libraries, which represent a scientific advancement and a practical tool for more accurate MP identification and monitoring in environmental research.

Polyurethane foam equipped passive air samplers (PUF-PAS) are a valuable tool for monitoring atmospheric semi-volatile organic pollutants but are often complicated due to the need for an accurate sampling rate ( $R_s$ ). Here we describe the development and implementation of a web based $R_s$ interface that allows for a user-friendly way of determining and visualizing accurate modelled $R_s$ values. The web interface provides access to the previously published model without the need for proprietary software (MATLAB) or coding experience. The precalculated $R_s$ avoids unnecessary computation time, providing the user with fast results and visualizations of the sampler behavior during deployment. Supported by NASA's MERRA meteorological data at both 2 m and 10 m heights above ground level (AGL), users can determine $R_s$ for any location on the globe. Users can select prepopulated compounds (e.g., polychlorinated biphenyls) or manually enter compounds, enter sample information individually or upload them batch wise, run the model, and export data to a CSV to further integrate with the data analysis workflow. Additionally, an implementation of the same model is available in R, along with scripts to process meteorological data.

In the event of a wide-area release of Bacillus anthracis spores, soils and other outdoor materials will likely become contaminated with the biological agent. Soils may also become contaminated with B. anthracis when livestock or wildlife succumb to anthrax disease. This study was conducted to assess the in situ remediation of soil using steam vapor to inactivate a B. anthracis spore surrogate (Bacillus atrophaeus) inoculated into soil samples. Tests were conducted using small columns (~0.04 m³ of soil) filled with either loam, clay, or a sandy soil. Following steam treatment, the B. atrophaeus spores were recovered from the test and positive control soil samples via liquid extraction and this liquid was subsequently dilution plated to quantify viable spores in terms of colony-forming units. Decontamination efficacy was assessed as a function of soil type, soil depth, soil moisture, soil temperature, and steam exposure time. Results showed that spore inactivation improved with increasing steam exposure time and diminished with depth. The clay soil generally exhibited the highest soil temperatures and correspondingly showed the highest inactivation of spores. Adding moisture to the soil prior to the steam treatment increased heat transfer within the soil column, and sealing the columns to mitigate steam leakage increased spore inactivation. The results showed that a steam mass of 40-50 kg applied per square meter of soil surface was sufficient to inactivate bacterial spores to depths between 7 and 10 cm. With bacterial spores on the soil column surface, a contact time of 15 min with the steam vapor at 99°C was sufficient for complete inactivation. These findings provide a foundation for estimating costs and time requirements for applying steam to the soil surface, and further confirmatory testing at field-scale is suggested.