Prevalence of Microplastics in the Eastern Oyster Crassostrea virginica in the Chesapeake Bay: The Impact of Different Digestion Methods on Microplastic Properties

This study aimed to determine the microplastic prevalence in eastern oysters (C. virginica) in three sites in the Chesapeake Bay in Virginia and optimize the digestion methods. The digestion results illustrate that the lowest recovery rate and digestion recovery were related to enzymatic, enzymatic + hydrogen peroxide (H2O2), and HCl 5% treatments, while the highest digestion recovery and recovery rate were observed in H2O2 and basic (KOH) treatments. Nitric acid digestion resulted in satisfying digestion recovery (100%), while no blue polyethylene microplastics were observed due to the poor recovery rate. In addition, nitric acid altered the color, changed the Raman spectrum intensity, and melted polypropylene (PP) and polyethylene terephthalate (PET). In order to determine the number of microplastics, 144 oysters with an approximately similar size and weight from three sites, including the James River, York River, and Eastern Shore, were evaluated. Fragments were the most abundant microplastics among the different microplastics, followed by fibers and beads, in the three sites. A significantly higher number of fragments were found in the James River, probably due to the greater amount of human activities. The number of microplastics per gram of oyster tissue was higher in the James River, with 7 MPs/g tissue, than in the York River and Eastern Shore, with 6.7 and 5.6 MPs/g tissue.

Leaching of ilmenite to produce titanium based materials: a review

Naturally available ilmenite mineral is being used as a starting material to produce titanium based products that have wide applications. Transformation of ilmenite to different titanium based materials by strong and weak acid, and base digestion, is discussed. Effects of temperature, concentration of acid/base, reaction time on dissolution of ilmenite are extensively reviewed. Characterization of the starting materials, intermediates and the products by x-ray diffraction, thermogravimetry, brunauer–emmett–teller surface area analysis, and scanning electron microscopy are presented. Further, advantages and disadvantages associated with the digestion methods are discussed.

Strategies for Rapid Identification of Acinetobacter baumannii Membrane Proteins and Polymyxin B’s Effects

Acinetobacter baumannii, especially multidrug resistant Acinetobacter baumannii, is a notable source of pressure in the areas of public health and antibiotic development. To overcome this problem, attention has been focused on membrane proteins. Different digestion methods and extraction detergents were examined for membrane proteome sample preparation, and label-free quantitative and targeted proteome analyses of the polymyxin B-induced Acinetobacter baumannii ATCC 19606 membrane proteome were performed based on nano LC-MS/MS. Ultracentrifugation of proteins at a speed of 150,000×g, digestion by trypsin, filter-aided sample preparation, and detergents such as lauryldimethylamine-N-oxide were proved as a fast and effective way for identification of membrane proteome by nano LC-MS/MS. Upon treatment with polymyxin B, expression levels of 15 proteins related to membrane structure, transporters, cell surface, and periplasmic space were found to be significantly changed. Furthermore, targeted proteome was also used to confirm these changes. A relatively rapid membrane proteome preparation method was developed, and a more comprehensive view of changes in the Acinetobacter baumannii membrane proteome under polymyxin B pressure was obtained.

Development of Optimal Digesting Conditions for Microplastic Analysis in Dried Seaweed Gracilaria fisheri

Currently, research on the accumulation of microplastics (MPs) in the marine food web is being highlighted. An accurate and reliable digestion method to extract and isolate MPs from complex food matrices has seldom been validated. This study aimed to compare the efficacy of MP isolation among enzymatic-, oxidative-, and the combination of two digestion methods on red seaweed, Gracilaria fisheri. The dried seaweed sample was digested using three different methods under various conditions using enzymes (cellulase and protease), 30% H2O2, and a combination of enzymes and 30% H2O2. The method possessing the best digestion efficiency and polymer recovery rate of MPs was selected, and its effect on spiked plastic polymer integrity was analyzed by Raman spectroscopy. As a result, the enzymatic method rendered moderate digestion efficiency (59.3–63.7%) and high polymer recovery rate (94.7–98.9%). The oxidative method using 30% H2O2 showed high digestion efficiency (93.0–96.3%) and high polymer recovery rate (>98%). The combination method was the most effective method in terms of digestion efficiency, polymer recovery rate, and expenditure of digestion time. The method also showed no chemical changes in the spiked plastic polymers (PE, PP, PS, PVC, and PET) after the digestion process. All the spiked plastic polymers were identifiable using Raman spectroscopy.

Potential of the Biomass of Plants Grown in Trace Element-Contaminated Soils under Mediterranean Climatic Conditions for Bioenergy Production

Phytomanagement of trace element-contaminated soils combines sustainable soil remediation with the use of plant biomass for different applications. Consequently, phytostabilization using plant species useful for bioenergy production has recently received increasing attention. However, the water requirement of most of these species is a limitation for their use under Mediterranean climatic conditions. In this work, eight plant species growing naturally in mine soils contaminated by trace elements were evaluated for their use as bioenergy crops using thermochemical (combustion) and biochemical (anaerobic digestion) methods. The higher heating values of the biomass of the plants studied were all within a narrow range (16.03–18.75 MJ kg−1), while their biochemical methane potentials ranged from 86.0 to 227.4 mL CH4 (g VS)−1. The anaerobic degradation was not influenced by the presence of trace elements in the plants, but the mineral content (mainly Na) negatively affected the potential thermal energy released by combustion (HHV). The highest annual energy yields from biogas or combustion could be obtained by the cultivation of Phragmites australis and Arundo donax, followed by Piptatherum miliaceum. Both options can be considered to be suitable final destinations for the biomass obtained in the phytostabilization of trace element-contaminated soils and may contribute to the implementation of these remediation techniques in Mediterranean areas.

Efficiency of two digestion methods in determining the presence of metals (Cd, Cu, Cr, Pb and Zn) in geopropolis produced by Melipona scutellaris

This study evaluates the efficiency of acid extraction and total digestion to determine the presence of metals in geopropolis produced by the stingless bee Melipona scutellaris. Geopropolis samples were collected at five meliponaries in the city and in the metropolitan region of Salvador, Bahia State, Brazil. The sample treatment methods comprised acid extraction and total digestion. The Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) technique was used to quantify Cd, Cu, Cr, Pb, and Zn. Geopropolis samples submitted to both digestion methods showed statistical differences. For both methods, Cr and Zn showed the highest concentrations, while those of Cd were the lowest. The Cr concentration for determination by total digestion was 37.53 mg/kg, while for acid extraction it was 32.90 mg/kg. For Zn, the concentration was 17.65 mg/kg and 8.85 mg/kg for total digestion and acid extraction, respectively. The total digestion method showed the highest concentrations of the metals evaluated; however, acid extraction (USEPA 3050b) is a more straightforward procedure for metal evaluation in geopropolis samples and presented values that support the use of geopropolis as a bioindicator. The acid extraction method USEPA 3050b, in combination with detection using ICP OES, showed efficiency in analyses carried out to determine metals in geopropolis.

Sample preparation method for metal(loid) contaminant quantitation in rodent hair collected in Yuma County, Arizona

Yuma County, Arizona, is a large agricultural hub of the USA located in the southwestern corner of Arizona on the USA-Mexico border. Year-round use of agrichemicals at a massive scale along with the influx of aquatic contaminants in the Colorado River led to significant levels of environmental pollution and hence exposure risks for people and wildlife. Although hair is a recognized biomarker for metal exposure, there is no universal hair preparation protocol. This study evaluated two digestion methods for metal quantitation using inductively coupled plasma-mass spectrometry (ICP-MS) and three methods for mercury quantitation using cold vapor-atomic absorption spectroscopy (CV-AAS), both employing certified reference materials. The “overnight” and “heating” digestion methods were suitable for ICP-MS, while only the heating method was suitable for CV-AAS. These validated methods will be useful for a variety of human and wildlife assessments of toxic metal(loid) exposure.