Multi-element analysis of unfiltered samples in river water monitoring-digestion and single-run analyses of 67 elements.

Routine analysis of inorganic analytes in whole water samples from rivers (unfiltered river water) is rarely reported in scientific publications. However, this sample type is valuable and often used in long-term monitoring, regulation, and catchment element budgets, as it includes the dissolved, colloidal, and particulate fraction in one sample type. Preservation measures are not needed and solid-liquid partitioning can be disregarded, which simplifies automated sampling and storage procedures. In this study, we provide several digestion protocols for whole water samples from rivers and the subsequent multi-element analysis of 67 major, minor, and trace elements: Li, Be, B, Na, Mg, Al, Si, P, S, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Ru, Ag, Cd, In, Sn, Sb, Te, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, Ir, Pt, Au, Hg, Tl, Pb, Bi, Th, U. In the absence of whole water reference materials for inorganic analytes, we introduce simulated whole water samples by suspending sediment reference materials as quality control measures. The applicability for improved routine water quality monitoring was successfully tested on samples from different rivers revealing variations of the element fingerprints over time.

Quantification of 68 elements in river water monitoring samples in single-run measurements.

Triple-quadrupole inductively coupled plasma mass spectrometry (ICP-QQQ-MS) is a unique analytical technique which is, next to speciation analyses, applied for the determination of total element concentrations in several matrices. Due to its wide linear range, short analysis times, and the collision-reaction gas technology, it is capable of addressing a high number of analytes in a single run with sufficient low limits of quantification for river water monitoring. Over the last decades, the focus of the environmental monitoring changed from "traditional" and regulated analytes to elements of possibly rising concern from new applications such as the so-called technology-critical elements (TCE). By widening the analytical window of this method for applications in networks of future river water monitoring, a better understanding of natural transport processes and global biogeochemical element cycles will be established and the total number of methods can be reduced. During method development and validation, certified reference materials, calibration check solutions, and spiked river water samples from 12 major German rivers covering different catchment areas were measured and evaluated with the three cell gases He, H2 and O2. The method delivers a best as possible undisturbed simultaneous determination for 68 out of 71 target analytes with recoveries in an accepted range of 80-120% for river water samples (dissolved fraction; <0.45 µm). After comprehensive evaluation, we offer a novel best-practice multi-element method for river water monitoring with the goal of fostering the exchange and discussion between practitioners in long-term river monitoring. It enables the readers to create their own methods based on the scientific needs to monitor elemental "fingerprints" of rivers and their catchments.

Removal of per- and polyfluoroalkyl substances (PFASs) in a full-scale drinking water treatment plant: Long-term performance of granular activated carbon (GAC) and influence of flow-rate.

Per- and polyfluoroalkyl substances (PFASs) have been ubiquitously detected in drinking water which poses a risk for human exposure. In this study, the treatment efficiency for the removal of 15 PFASs was examined in a full-scale drinking water treatment plant (DWTP) in the City of Uppsala, Sweden, over a period of two years (2015-2017). Removal of the five frequently detected PFASs was influenced by the total operation time of granular activated carbon (GAC) filters, GAC type and surface loading rate. The average removal efficiency of PFASs ranged from 92 to 100% for "young" GAC filters and decreased to 7.0-100% for "old" GAC filters (up to 357 operation days, 29 300 bed volumes (BV) treated). Flow-rates were adjusted in two full-scale GAC filters of different operational age to examine the removal of PFAS and organic matter depending on GAC operational age and operating flow. The decrease in flow-rate by 10 L s-1 from 39 to 29 L s-1 led to an average increase of 14% and 6.5% in total PFAS removal efficiency for an "old" (264 operation days, 21 971 BV treated) and a "young" GAC filter (63 operation days, 5 725 BV treated), respectively. A cost-analysis for various operation scenarios illustrated the dominating effect of treatment goals and costs for GAC regeneration on overall GAC operation costs. The unit costs for GAC filters ranged from 0.08 to 0.10 € m-3 water treated and 0.020-0.025 € m-3 water treated for a treatment goal of 10 ng L-1 and 85 ng L-1, respectively, for ∑11PFAS. Furthermore, it was concluded that prolonging the GAC service life by lowering the flow-rates after reaching the treatment goal could lead to a 26% cost-deduction. The results and methods presented in this study give drinking water providers valuable tools for the operation of a full-scale treatment train for the removal of PFAS in contaminated raw water.