Comparability of 24-hour composite and grab samples for detection of SARS-2-CoV RNA in wastewater.

Wastewater surveillance is a cost-effective way to monitor pathogen prevalence and transmission patterns in the entire community. Here, we compare 24-hour composite and grab samples collected during September 2020 from several municipalities in New York State to detect SARS-CoV-2. A total of 45 paired samples (90 total samples) from three counties and 14 wastewater treatment plants were available for analysis. The categorical comparison (SARS-CoV-2 genetic material detected and quantifiable, genetic material detected but below the limits of quantification, and genetic material not detected) between the grab and composite samples was quite strong, with 91.1% agreement (kappa P-value < .001). The correlations among the quantifiable grab and composite samples were statistically significant yet modest for SARS2-CoV RNA (Pearson correlation = 0.44, P = .02), crAssphage cDNA (Pearson correlation = 0.36, P = .02), and crAssphage DNA (Pearson correlation = 0.46, P = .002). We found good comparison between grab and 24-hour composite samples for detecting SARS-CoV-2 RNA from municipal wastewater treatment plants. Grab sampling is an efficient and cost-effective method to monitor for the presence of SARS-CoV-2 in the entire community.

Detection of anticancer drugs in wastewater effluents: Grab versus passive sampling.

The occurrence of six anticancer drugs was evaluated in wastewater effluents. Several grab samples from wastewater effluent were collected throughout a year. Capecitabine, cyclophosphamide and ifosfamide were detected at concentrations ranging from 8 to 46 ng·L-1. Capecitabine was detected in all the sampling events whereas cyclophosphamide and ifosfamide were detected less frequently. Additionally, the suitability of using pharmaceutical-polar organic chemical integrative samplers (POCIS) to monitor the target drugs in wastewater effluents was assessed. Capecitabine, ifosfamide and cyclophosphamide were detected with POCIS and showed a linear uptake over 15 days. The sampling rates, determined in situ, were used to estimate time-weighted average concentrations. A good correlation was found between the concentration of capecitabine detected with POCIS deployed during five days (32 ± 1 ng·L-1) and the average concentrations obtained in grab samples. The use of passive samplers has advantages over grab samples: easier analysis, less time and costs associated with the analytical method. Passive samplers also provide a time-weighted information about the concentration of pollutants in the aquatic environment. However, information may be lost when the concentration of the target compounds in wastewater effluents is low and the passive samplers are deployed for a short time.

Combination of passive and grab sampling strategies improves the assessment of pesticide occurrence and contamination levels in a large-scale watershed.

Fifty-one monitoring stations from the Water Framework Directive network (2000/60/CE) were selected in the Adour-Garonne basin (117,650 km2, SW France). These stations were characterized by a diversity of land use, implying different water pesticide contamination profiles. In each, Polar Organic Chemical Integrative Sampler (POCIS) deployment (14 days) and grab water samples (1 per period) were performed 6 times in 2016 in order to obtain contamination levels (29 pesticides monitored). The large amount of data collected during this 1-year monitoring required specific graphical and map processing to compare the information provided by POCIS and grab samples. Graphical projections demonstrated that with POCIS the number of quantified pesticides and the quantification frequencies were higher than with grab samples. Additionally, projections showed that POCIS provided better temporal representativeness of monthly contamination levels. Indeed, the POCIS data showed seasonal trends which were directly linked with the use of each pesticide (application period) and the land use of each sampling site, that was not visible with the grab samples data. Map projections of the measured concentrations, using a common scale for the two sampling strategies, clearly showed the strengths of the POCIS deployment and the link between measured contamination levels, quantified pesticides and land use. Finally, this study shows that the combination of grab sample data (magnitude of contamination peaks) and POCIS data (average concentration over a given period) provided more complete and reliable knowledge of the contamination levels in the Basin than either method alone.

A comparison of sampling methods for seawater microplastics and a first report of the microplastic litter in coastal waters of Ascension and Falkland Islands.

To date there is no gold standard for sampling microplastics. Zooplankton sampling methods, such as plankton and Neuston nets, are commonly used to estimate the concentrations of microplastics in seawater, but their ability to detect microplastics is limited by their mesh size. We compared different net-based sampling methods with different mesh sizes including bongo nets (>500 µm), manta nets (>300 µm) and plankton nets (>200 µm and >400 µm) to 1 litre bottle grabbed, filtered (0.45 µm) samples. Concentrations of microplastics estimated using net-based methods were ~3 orders of magnitude less than those estimated by 1 litre grab samples. Some parts of the world with low human populations, such as Ascension Island and the Falkland Islands, lack baseline data on microplastics. Using the bottle grab sampling method we found that microplastic litter was present at these remote locations and was comparable to levels of contamination in more populated coastal regions, such as the United Kingdom.