Effect of Distance to Orthogonal Buffer Zone Boundary on Contaminant Detection Well Layout at Solid Waste Impoundment

A modeling investigation examined the effect of nearby buffer zone (property) boundaries on passive groundwater monitoring networks at a hypothetical landfill. Network designs considered the unknown location of a small point source in the landfill's liner, contaminant concentrations simulated in groundwater, and the need to detect a contaminant before its concentration at a buffer zone boundary reached a certain threshold. Several buffer zone boundaries were considered, ranging from 6 m to 51 m downgradient of the landfill's downgradient corner. Monitoring wells in each network were located 5 m downgradient of the landfill's downgradient boundaries. Both the minimum number of wells, and the rate of increase in number of wells, increased with proximity of the landfill's downgradient corner to the buffer zone boundary. Based on out-comes of this study, landfill designers should consider a possible need for many closely-spaced detection wells for small potential point sources and close buffer zone boundaries.

Nanozyme-Based Biosensors for Exogenous Contaminant Detection in Foods

: Abstract Food safety arising from exogenous contaminants has become a global concern. The development of simple, rapid and sensitive methods for effective detection and management of trace levels of exogenous contaminants has emerged as a hotspot, as well as the important priorities in food industry. Nanozymes that are defined as the emerging enzyme-like nanomaterials with robust catalytic activity, simple preparation, high stability, and low cost have been widely used in construction of biosensors for detection of hazardous contaminants in foods, greatly accelerating the advancement of food safety assay. In this review, we comprehensively summarize the recent advances of nanozyme-based biosensors, such as colorimetric, electrochemical, photoelectrochemical and surface-enhanced Raman spectroscopy-based sensors, over the past five years for the detection of various exogenous contaminants including mycotoxins, heavy metals, pesticides, antibiotics, pathogens and microcystins in foods. Beyond a highlight of the advantages and limitations in real-world application, we critically propose the current challenges and future trends of these biosensors for exogenous contaminant detection in foods to guarantee their quality and safety.