Ongoing Laboratory Performance Study on Chemical Analysis of Hydrophobic and Hydrophilic Compounds in Three Aquatic Passive Samplers.

The quality of chemical analysis is an important aspect of passive sampling-based environmental assessments. The present study reports on a proficiency testing program for the chemical analysis of hydrophobic organic compounds in silicone and low-density polyethylene (LDPE) passive samplers and hydrophilic compounds in polar organic chemical integrative samplers. The median between-laboratory coefficients of variation (CVs) of hydrophobic compound concentrations in the polymer phase were 33% (silicone) and 38% (LDPE), similar to the CVs obtained in four earlier rounds of this program.

Field test of the TOXSWA pesticide fate model: Comparison of simulated and observed chlorpyrifos in water, sediment and macrophytes in four stagnant ditches.

TOXSWA is a numerical model describing pesticide behavior in an edge-of-field waterbody. It is widely used to predict exposure in regulatory risk assessment for aquatic ecosystems. Exposure concentrations are predicted based upon pesticide process parameters obtained in standardized laboratory experiments.

Results of WEPAL-QUASIMEME/NORMANs first global interlaboratory study on microplastics reveal urgent need for harmonization.

To survey the conformity and quality of results among laboratories for microplastics determination worldwide, an international laboratory intercomparison and development exercise was organized. The 34 participants were requested to determine the polymer type and number or mass of polymer particles in 12 samples, i.e.

Determination of total dissolved nitrogen in seawater by isotope dilution gas chromatography mass spectrometry following digestion with persulfate and derivatization with aqueous triethyloxonium.

In this study, we propose a novel approach for the determination of total dissolved nitrogen (TDN) in seawater combining high-precision isotope dilution GC-MS with persulfate digestion. A 2 mL sample aliquot was digested with an alkaline solution of persulfate to convert nitrogen containing compounds to nitrate. Digested samples were spiked with NO internal standard and treated with aqueous triethyloxonium to convert the analyte into volatile EtONO.

Inter-laboratory study for the certification of trace elements in seawater certified reference materials NASS-7 and CASS-6.

Certification of trace metals in seawater certified reference materials (CRMs) NASS-7 and CASS-6 is described. At the National Research Council Canada (NRC), column separation was performed to remove the seawater matrix prior to the determination of Cd, Cr, Cu, Fe, Pb, Mn, Mo, Ni, U, V, and Zn, whereas As was directly measured in 10-fold diluted seawater samples, and B was directly measured in 200-fold diluted seawater samples. High-resolution inductively coupled plasma mass spectrometry (HR-ICPMS) was used for elemental analyses, with double isotope dilution for the accurate determination of B, Cd, Cr, Cu, Fe, Pb, Mo, Ni, U, and Zn in seawater NASS-7 and CASS-6, and standard addition calibration for As, Co, Mn, and V.

The influence of vegetation, mesoclimate and meteorology on urban atmospheric microclimates across a coastal to desert climate gradient.

Many cities are increasing vegetation in part due to the potential for microclimate cooling. However, the magnitude of vegetation cooling and sensitivity to mesoclimate and meteorology are uncertain. To improve understanding of the variation in vegetation's influence on urban microclimates we asked: how do meso- and regional-scale drivers influence the magnitude and timing of vegetation-based moderation on summertime air temperature (T), relative humidity (RH) and heat index (HI) across dryland cities? To answer this question we deployed a network of 180 temperature sensors in summer 2015 over 30 high- and 30 low-vegetated plots in three cities across a coastal to inland to desert climate gradient in southern California, USA.

Variation in the urban vegetation, surface temperature, air temperature nexus.

Our study examines the urban vegetation - air temperature (T) - land surface temperature (LST) nexus at micro- and regional-scales to better understand urban climate dynamics and the uncertainty in using satellite-based LST for characterizing T. While vegetated cooling has been repeatedly linked to reductions in urban LST, the effects of vegetation on T, the quantity often used to characterize urban heat islands and global warming, and on the interactions between LST and T are less well characterized. To address this need we quantified summer temporal and spatial variation in T through a network of 300 air temperature sensors in three sub-regions of greater Los Angeles, CA, which spans a coastal to desert climate gradient.

Laboratory performance study for passive sampling of nonpolar chemicals in water.

Two laboratory performance studies with 21 and 11 participants were carried out for passive sampling of nonpolar chemicals in water, using silicone samplers that were deployed for 7 wk and 13 wk at 2 river sites in the Netherlands. Target analytes were polychlorinated biphenyls, polycyclic aromatic hydrocarbons (PAHs), polybrominated diphenyl ethers (PBDEs), hexachlorobutadiene, hexachlorobenzene, and a number of performance reference compounds (PRCs). Calculation of aqueous concentrations based on prescribed input values and a prescribed uptake model was also included.

Effects of sediment-spiked lufenuron on benthic macroinvertebrates in outdoor microcosms and single-species toxicity tests.

Sediment ecotoxicity studies were conducted with lufenuron to (i) complement the results of a water-spiked mesocosm experiment with this lipophilic benzoylurea insecticide, (ii) to explore the predictive value of laboratory single-species tests for population and community-level responses of benthic macroinvertebrates, and (iii) to calibrate the tier-1 effect assessment procedure for sediment organisms. For this purpose the concentration-response relationships for macroinvertebrates between sediment-spiked microcosms and those of 28-d sediment-spiked single-species toxicity tests with Chironomus riparius, Hyalella azteca and Lumbriculus variegatus were compared. Lufenuron persisted in the sediment of the microcosms.

Effects of linuron on a rooted aquatic macrophyte in sediment-dosed test systems.

Effects of linuron on the sediment-rooted aquatic macrophyte Myriophyllum spicatum L. were studied in sediment-dosed test systems following a proposed guideline with extended test duration. Sediment, pore water, overlying water and macrophyte shoots were sampled weekly for chemical analyses.

Estimating degradation rates in outdoor stagnant water by inverse modelling with TOXSWA: a case study with prosulfocarb.

Background: The regulatory risk assessment of pesticides requires the assessment of exposure of aquatic ecosystems in small surface waters adjacent to agricultural fields. This exposure is predicted using simulation models, for which an important input parameter is the degradation rate in water. In regulatory dossiers, the decline rate in water from outdoor mesocosms is often available, but this rate encompasses more processes than degradation.

Variability in the dynamics of mortality and immobility responses of freshwater arthropods exposed to chlorpyrifos.

The species sensitivity distribution (SSD) concept is an important probabilistic tool for environmental risk assessment (ERA) and accounts for differences in species sensitivity to different chemicals. The SSD model assumes that the sensitivity of the species included is randomly distributed. If this assumption is violated, indicator values, such as the 50% hazardous concentration, can potentially change dramatically.

Effects of a herbicide-insecticide mixture in freshwater microcosms: risk assessment and ecological effect chain.

Effects of chronic application of a mixture of the herbicide atrazine and the insecticide lindane were studied in indoor freshwater plankton-dominated microcosms. The macroinvertebrate community was seriously affected at all but the lowest treatment levels, the zooplankton community at the three highest treatment levels, with crustaceans, caddisflies and dipterans being the most sensitive groups. Increased abundance of the phytoplankton taxa Cyclotella sp.

Fate and effects of the insecticide chlorpyrifos in outdoor plankton-dominated microcosms in Thailand.

The fate and effects of the insecticide chlorpyrifos were studied in plankton-dominated, freshwater microcosms in Thailand. Disappearance rates of chlorpyrifos from the water column in the present study were similar to those in temperate regions. Insecticide accumulation in the sediment was relatively small, with the major part in the top layer (depth, 1.

Responses of zooplankton in lufenuron-stressed experimental ditches in the presence or absence of uncontaminated refuges.

Outdoor experimental ditches were used to evaluate the influence of untreated refuges on the recovery of zooplankton communities following treatment with the fast-dissipating insecticide lufenuron. Each experimental ditch was divided into three sections of the same surface area. The treatments differed in the proportion of ditch (0, 33, 67, and 100% of the surface area) to which the insecticide was applied at the same nominal treatment (3 mug/L).

Impact of triphenyltin acetate in microcosms simulating floodplain lakes. II. Comparison of species sensitivity distributions between laboratory and semi-field.

The study objectives were to shed light on the types of freshwater organism that are sensitive to triphenyltin acetate (TPT) and to compare the laboratory and microcosm sensitivities of the invertebrate community. The responses of a wide array of freshwater taxa (including invertebrates, phytoplankton and macrophytes) from acute laboratory Single Species Tests (SST) were compared with the concentration-response relationships of aquatic populations in two types of freshwater microcosms. Representatives of several taxonomic groups of invertebrates, and several phytoplankton and vascular plant species proved to be sensitive to TPT, illustrating its diverse modes of toxic action.

Impact of triphenyltin acetate in microcosms simulating floodplain lakes. I. Influence of sediment quality.

Floodplain lakes in the Rhine-Meuse delta of the Netherlands vary considerably in levels of sediment-bound toxicants. Microcosm experiments were done to compare the ecological impact of the fungicide triphenyltin acetate (TPT) between test systems with clean or polluted sediments (10 microcosms each). Differences in sediment quality affected the structure of the aquatic communities that developed in the microcosms.

Aquatic risk assessment of a realistic exposure to pesticides used in bulb crops: a microcosm study.

The fungicide fluazinam, the insecticide lambda-cyhalothrin, and the herbicides asulam and metamitron were applied to indoor freshwater microcosms (water volume approximately 0.6 m3). The treatment regime was based on a realistic application scenario in tulip cultivation.

Comparing aquatic risk assessment methods for the photosynthesis-inhibiting herbicides metribuzin and metamitron.

Three different risk assessment procedures are described that aim to protect freshwater habitats from risks of the photosynthesis-inhibiting herbicides metribuzin and metamitron. These procedures are (1) the first-tier approach, based on standard toxicity tests and the application of an assessment factor, (2) the Species Sensitivity Distribution (SSD) approach, based on laboratory tests with a wider array of species and the application of a statistical model to calculate the HCx (the Hazardous Concentration for x% of the species), and (3) the model ecosystem approach, based on the evaluation of treatment-related effects in field enclosures. A comparison of the risk assessment procedures reveals that the first-tier approach is the most conservative for metamitron and metribuzin, and that HC5 values (and even HC10 values) based on acute EC50 values of algae and aquatic vascular plants may be used to derive maximum permissible concentrations for single applications.

Association of impedance cardiography parameters with changes in functional and quality-of-life measures in patients with chronic heart failure.

Assessment and prognosis of chronic heart failure is often difficult due to a lack of objective and easily obtainable parameters that accurately reflect disease status. This study was conducted to determine whether impedance cardiography (ICG) parameters were associated with changes in functional and quality-of-life measures in chronic heart failure patients. Retrospective chart review identified 64 patients (73% male, aged 73+/-13 years) with paired ICG measurements followed for 180+113 days.

The effects of a pesticide mixture on aquatic ecosystems differing in trophic status: responses of the macrophyte Myriophyllum spicatum and the periphytic algal community.

The effects of a pesticide mixture (asulam, fluazinam, lambda-cyhalothrin, and metamitron) on aquatic ecosystems were investigated in 20 outdoor aquatic microcosms. Ten of the microcosms simulated mesotrophic aquatic ecosystems dominated by submerged macrophytes (Elodea). The others simulated eutrophic ecosystems with a high Lemna surface coverage (Lemna).

Fate of the insecticide lambda-cyhalothrin in ditch enclosures differing in vegetation density.

Use of the insecticide lambda-cyhalothrin in agriculture may result in the contamination of water bodies, for example by spray drift. Therefore, the possible exposure of aquatic organisms to this insecticide needs to be evaluated. The exposure of the organisms may be reduced by the strong sorption of the insecticide to organic materials and its susceptibility to hydrolysis at the high pH values in the natural range.

Effects of an extract of oystercatcher (Haematopus ostralegus) eggs from the Zeehavenkanaal in The Netherlands, and of its major contaminant, hexachlorobenzene, on the chicken embryo.

Oystercatchers (Haematopus ostralegus) foraging on the canal 'Zeehavenkanaal' in the Netherlands have been shown to accumulate appreciable amounts of contaminants, especially hexachlorobenzene. The present study was performed to assess the embryotoxic effects of the present contaminants. To this end, a two step approach was followed.

Effects of a mixture of two insecticides in freshwater microcosms: I. Fate of chlorpyrifos and lindane and responses of macroinvertebrates.

Effects of chronic application of a mixture of the insecticides chlorpyrifos and lindane were studied in indoor freshwater microcosms. The exposure concentrations (based on 0, 0.005, 0.