Determination of trace element concentrations in natural freshwaters: How low is “low”, and how low do we need to go? (original) (raw)
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Water Research, 2001
Abstract}Ground-water sampling techniques were modified to reduce random low-level contamination during collection of filtered water samples for determination of trace-element concentrations. The modified sampling techniques were first used in New Jersey by the US Geological Survey in 1994 along with inductively coupled plasma-mass spectrometry (ICP-MS) analysis to determine the concentrations of 18 trace elements at the one microgram-per-liter (mg/L) level in the oxic water of the unconfined sand and gravel Kirkwood-Cohansey aquifer system. The revised technique tested included a combination of the following: collection of samples with flow rates of about 2 L per minute, (2) through acid-washed single-use disposable tubing and (3) a single-use disposable 0.45-mm pore size capsule filter, (4) contained within portable glove boxes, (5) in a dedicated clean sampling van, (6) only after turbidity stabilized at values less than 2 nephelometric turbidity units (NTU), when possible. Quality-assurance data, obtained from equipment blanks and split samples, indicated that trace element concentrations, with the exception of iron, chromium, aluminum, and zinc, measured in the samples collected in 1994 were not subject to random contamination at 1 mg/L.
H2Open Journal, 2018
Despite the fact that the increased use of elements linked to the Anthropocene is frequently assumed to lead to an increase in the concentrations of the elements in surface waters, temporal trends of trace element (TE) concentrations have rarely been checked. A temporally extended, traceable dataset of TE concentrations in the waters of Lake Geneva, Switzerland (1996-2015) has been used here to explore methodological and data treatment issues that arise when attempting to rigorously determine temporal trends in freshwater TE concentrations. The trace elements studied (Cd, Co, Gd, Mo, Pb, Sb, Sr) have been chosen to cover a wide range of chemical and utilisation conditions. We show that detecting temporal trends from monitoring program data is feasible, even when trends are weak, provided that rigorous data treatment methods are applied. Aspects related to the effect of data quality are discussed in detail. However, ascertaining the statistical significance of any trends calculated remains a difficult issue. With the exception of Co and Sr, that show no significant changes, and Pb, that shows a general decrease, concentrations in lake waters of the trace elements considered have increased significantly, particularly between 2006 and 2015.
Environmental Reviews, 2019
The concentrations of trace elements (TEs) in large boreal rivers can fluctuate markedly due to changing water levels and flow rates associated with spring melt and variable contributions from tributaries and groundwaters, themselves having different compositions. These fluctuating and frequently high concentrations create regulatory challenges for protecting aquatic life. For example, water quality criteria do not account for changes in flow regimes that can result in TE levels that may exceed regulatory limits, and neither do they account for the markedly different lability and bioaccessibility of suspended solids. This review addresses the geochemical and biological processes that govern the lability and bioaccessibility of TEs in boreal rivers, with an emphasis on the challenges posed by the colloidal behaviour of many TEs, and their relationship to the dissolved fraction (i.e., <0.45 μm in size). After reviewing the processes and dynamics that give rise to the forms and beha...
The Analyst, 1998
Reference Water Samples (SRWSs) were analyzed for numerous trace constituents, including Al, As, B, Ba, Be, Bi, Br, Cd, Cr, Co, Cu, I, Fe, Pb, Li, Mn, Mo, Ni, Rb, Sb, Se, Sr, Te, Tl, U, V, Zn and major elements (Ca, Mg, Na, SiO 2 , SO 4 , Cl) by inductively coupled plasma mass spectrometry and inductively coupled plasma atomic emission spectrometry. In addition, 15 USGS SRWSs and National Institute of Standards and Technology (NIST) standard reference material (SRM) 1641b were analyzed for mercury using cold vapor atomic fluorescence spectrometry. Also USGS SRWS Hg-7 was analyzed using isotope dilution-inductively coupled plasma mass spectrometry. The results were compared with the reported certified values of the following standard reference materials: NIST SRM 1643a, 1643b, 1643c and 1643d and National Research Council of Canada Riverine Water Reference Materials for Trace Metals SLRS-1, SLRS-2 and SLRS-3. New concentration values for trace and major elements in the SRWSs, traceable to the certified standards, are reported. Additional concentration values are reported for elements that were neither previously published for the SRWSs nor traceable to the certified reference materials. Robust statistical procedures were used that were insensitive to outliers. These data can be used for quality assurance/quality control purposes in analytical laboratories.
Aquatic Geochemistry, 1996
and Zn in the shallow Dutch ground water were studied. Data were extracted from the data base of the Dutch National Ground Water Quality Monitoring Network, a network set up to monitor the diffuse contamination. The network contains over 350 sites at a low density of about 1 per 100 km2. The sites are sampled once a year at two depths (approx. 10 and 25 m below surface). A two-step multivariate statistical approach was used, in which the major element chemistry was used to define water types. Within each water type, trace element behavior could be coupled to distinct geochemical processes: dilution, acidification and weathering, carbonate dissolution, oxidation/reduction, and ion exchange. In recently infiltrated acid rain water in low buffering capacity sands, the anthropogenic influence indirectly caused mobilization of Al (median 430 pg/l), Cd (0.6 &l), Co (14 pg/l), Cu (2.7 ,&l), Ni (16 &l), Y (11 &l), and Zn (50 pg/l). In carbonate bearing sediments the acidification is neutralized, and the mentioned trace elements remain immobile. Arsenic and Cr have higher concentrations levels in ground waters with a slightly reducing character and are possibly governed by the dissolution of iron-manganese hydroxides. Boron, Li, and Sr have high concentrations (respectively 875, 80, 2700 pg/l) in the water type related to a seawater source. Strontium is related to carbonate dissolution in all other water types (medians ranging from 100 to 1000 pg/l). Barium shows a complex behaviour. It is concluded that the high Al, Cd, Co, Cr, Ni, and Zn concentrations are anthropogenically induced. High Ba and Cr concentrations are inferred to be due to natural processes.
Analytica Chimica Acta, 2003
The multivariate statistical techniques principal component analysis (PCA), Q-mode factor analysis (QFA), and correspondence analysis (CA) were applied to a dataset containing trace element concentrations in groundwater samples collected from a number of wells located downgradient from the potential nuclear waste repository at Yucca Mountain, Nevada. PCA results reflect the similarities in the concentrations of trace elements in the water samples resulting from different geochemical processes. QFA results reflect similarities in the trace element compositions, whereas CA reflects similarities in the trace elements that are dominant in the waters relative to all other groundwater samples included in the dataset. These differences are mainly due to the ways in which data are preprocessed by each of the three methods.