A compact NaI(Tl) with avalanche photodiode gamma spectrometer for in situ radioactivity measurements in marine environment

Development of a high energy resolution and wide dose rate range portable gamma-ray spectrometer

In this paper, a portable gamma-ray spectrometer for real-time and in-situ gamma-ray detection applications is presented. By combining a quasi-hemispherical CdZnTe (CZT) semiconductor detector and a Geiger-Muller (GM) counter together, a wide dose rate range is achieved, ranging from 0.1 μSv/h to 100 mSv/h with a relative error of less than 10%. The GM counter is used to measure dose rate from 1 mSv/h to 100 mSv/h. With CZT, the spectrometer can provide a high energy resolution spectrum for nuclide identification and a high precision dose rate at low dose rates. The full width half maximum (FWHM) resolution is 2.2% at 662 keV below 70 μSv/h and is better than 3.3% at 3.8 mSv/h. The weight of the spectrometer is 3.2 kg for handheld and the runtime is up to 12 h without charging. For preliminary applications, the spectrometer was used to measure the gamma radiation around the Back-n white neutron beam line at China Spallation Neutron Source and around the steam generator in the nuclear power plant at Daya Bay Nuclear Power Station.

Enrichment and dissemination of bacterial pathogens by microplastics in the aquatic environment

Microplastic pollution and associated impacts in the aquatic environment are spreading at an alarming rate worldwide. Plastic waste is increasing in the environment, and microplastics (MPs) are becoming a growing issue because they serve as vectors for pathogen transmission. This is the first comprehensive review that specifically addresses MPs as a source and vector of pathogenic bacteria, mainly associated with genera Vibrio, Pseudomonas, Acinetobacter, and so on, which are discovered to be more abundant on the aquatic plastisphere than that in the surrounding wastewater, freshwater, and marine water ecosystems. The horizontal gene transfer, chemotaxis, and co-selection and cross-selection could be the potential mechanism involved in the enrichment and dissemination of bacterial pathogens through the aquatic plastisphere. Further, bacterial pathogens through aquatic plastisphere can cause various ecological and human health impacts such as disrupted food chain, oxidative stress, tissue damages, disease transmission, microbial dysbiosis, metabolic disorders, among others. Last but not least, future research directions are also described to find answers to the challenging questions about bacterial pathogens in the aquatic plastisphere to ensure the integrity and safety of ecological and human health.