Screening of metallic pollution in complex environmental samples through a transcriptomic fingerprint method

Characterizing waste ecotoxicity is labourious because of both the undefined nature of environmental samples and the diversity of contaminants that can be present. With regard to these limitations, traditional approaches do not provide information about the nature of the pollution encountered. To improve such assessments, a fluorescent library of 1,870 transcriptomic reporters from E. coli K12 MG1655 was used to report the ecotoxic status of environmental samples. The reliability of the approach was evaluated with 6 metallic pollutants (As, Cu, Cd, Hg, Pb, Zn) used alone and in mixture in pure and complex matrices. A total of 18 synthetic samples were used to characterize the specificity of the resulting metallic contamination fingerprints. Metallic contamination impacted 4.5 to 10.2% of the whole transcriptomic fingerprint of E. coli. The analysis revealed that a subset of 175 transcriptomic reporters is sufficient to characterize metallic contamination, regardless of the nature of the sample. A statistical model distinguished patterns due to metallic contamination and provided information about the level of toxicity with 93–98% confidence. The use of the transcriptomic assessment was validated for 17 complex matrices with various toxicities and metal contaminants, such as activated sludge, wastewater effluent, soil, wood and river water. The presence of metals and their associated toxicity, which seems linked to their bioavailabilities, were thereby determined. This method constitutes a possible tool to screen unknown complex samples for their metallic status and identify those for which a deeper characterization must be achieved by the use of traditional biosensors and analytical methods.

Characterization and Removal of Metallic Contamination in H2O and H2O2 Using Single Particle Inductively Coupled Plasma Mass Spectrometry

Metallic contamination is a major challenge in multiple semiconductor processes, including photolithography and wet etch and cleans (WEC). Though there are several contributors to metallic contamination, significant efforts have focused on improving the incoming quality of process chemicals, especially commodity chemicals. Another key contributor to on-wafer metallic contamination is water (H2O), which is used to dilute most aqueous chemicals. Single Particle Inductively Coupled Plasma Mass Spectroscopy (SP-ICP-MS), a technique relying on time-based resolution of pulses generated during a standard ICP-MS analysis, is used to aid the understanding of metal particle contamination in water and process chemicals.In this paper, we studied water and 30% Hydrogen Peroxide (H2O2), two of the most widely used chemicals across all WEC processes. We used a high purity grade of 30% H2O2, further diluted to a typical use concentration (5% by volume) using two grades of Deionized Water (unfiltered and filtered) where the concentration of metallic particles was the key variable. The metals studied included Iron (Fe), Chromium (Cr), Zinc (Zn), Titanium (Ti), Nickel (Ni) and Aluminum (Al), representing some of the most commonly observed metallic contaminants in H2O2 and water. After analyzing the distribution of contaminants in the chemicals, filters were introduced into the system to observe the impact of filtration on metal removal. The importance of filtration on the overall quality of the diluted process chemical was demonstrated by using a Polysulfone (PS) membrane to filter the lower grade Deionized Water (DIW).

Metallic Contamination of the Muscles of Three Fish Species from the Moulouya River (Lower Moulouya, Eastern Morocco)

This study introduces a spatiotemporal evaluation of the metallic contamination with three trace metals (mercury, lead, and cadmium) in the muscles of three fish species (Lepomis macrochirus, Barbus callensis, and Barbus nasus), of which the samples were taken from three stations in the Moulouya River: the confluence of the Moulouya River and the Sebra River (station 1), the neighbourhood of the farms in the region of Aklim downstream from confluence of Lakhmis river (station 2), and the level of ancient bridge of Ras El Ma-Moulouya (station 3), during the period from July 2017 to May 2018. The results have allowed us to highlight rather high contents of lead and mercury in the fish muscles, mainly in station 1, which receives domestic and industrial discharges. The contents of cadmium in all fish species in different stations are very low. Moreover, all concentrations assessed in different fish species do not exceed the maximum limit recommended by European Community (EC) Commission Regulation No. 1881/2006.