Total mercury (Hg) concentrations were determined in seven tissues (skeletal muscle, liver, blood, gonad, brain, gill, and heart) of 59 striped bass and four tissues (muscle, liver, blood, and gonad) of 69 largemouth bass, 76 channel catfish, 12 bluegill, and 22 blue tilapia collected from Lake Mead, USA. Mercury levels generally increased according to trophic level and fish length. For striped bass, mean Hg levels (ng g(-1), wet mass) were highest in the liver (531), followed by muscle (309), heart (186), gonad (136), brain (77), gill (52), and blood (36). Similarly, Hg levels in the catfish and tilapia were liver > muscle > gonad > blood. In contrast, largemouth bass and bluegill had the highest levels in muscle, followed by liver, gonad, and blood. Generally, Hg levels were strongly correlated among the tissues, especially for blood/muscle and blood/liver. As the body burden of Hg increased, the concentration in blood and organs increased relative to the concentration in muscle. The trend was most pronounced for the liver. These relationships could form the basis of a predictive model and suggest that blood and muscle (plugs) could be useful for a non-lethal measure of Hg concentration and exposure in fish. For the striped bass, elevated Hg levels in the tissues were also correlated with degree of emaciation. Liver-to-muscle ratios were similar to literature values, except for tilapia with an average ratio of approximately 1.7, which is higher than generally reported for non-piscivores. Finally, this study demonstrates the usefulness of a solid sampling approach in trace element monitoring, especially as pertaining to in vivo analysis, analysis of a large number of samples and reduction of contamination risk.

No abstract

Neither glyphosate nor the GR transgene affect the content of the minerals measured in leaves and seed, harvested seed amino acid composition, or yield of GR soybean. Furthermore, soils with a legacy of GR crops have no effects on these parameters in soybean. © 2017 Society of Chemical Industry.

Total mercury (Hg) concentrations were determined in the skeletal muscle of 339 fish collected during the fall of 1998 and spring of 1999 from Lake Mead, USA, the nation's largest human-made reservoir. Five species of fish representing a range of trophic levels and the lake's principal game fishes were studied. Hg generally increased with trophic level and fish size. Median Hg concentrations (ng/g wet mass) were 277 in striped bass, 168 in channel catfish, 160 in largemouth bass, 75 in bluegill, and 8 in blue tilapia. Overall, fish from Las Vegas Bay and Boulder Basin had the lowest Hg concentrations, possibly a result of biodilution in this biologically productive area. In general, fish-mercury advisories might include a warning about consuming fillet from emaciated fish, based on the finding that Hg concentrations in 59 striped bass (captured during a scarce-food season) correlated inversely ( r = -0.89, p < 0.001) with a fish nutritional-status factor. This is consistent with starvation-concentration, whereby Hg in fish muscle is lost at a slower rate than the muscle mass. The median concentration found for 139 striped bass corresponds to a recommended risk-based consumption limit of three 8-oz. (227-g) meals per month for a 70-kg adult. Finally, this paper serves as a useful archive for future research and long-term studies of Hg in Lake Mead fish.

Screening programs for pediatric lead (Pb) poisoning routinely collect blood by finger stick onto specially designed filter paper (FP) for subsequent laboratory testing. Here, laser ablation inductively coupled plasma time-of-flight mass spectrometry is evaluated as a novel method for the determination of Pb in blood spotted onto FP cards. The method requires no sample pretreatment and may be particularly suitable for rapidly screening a large number of samples. Signal intensity from the ICP-MS strongly correlated (r (2) = 0.996) with Pb target values for five blood cards from a laboratory proficiency testing program. Better precision was obtained by replicate ablation line scans (<15% rsd) compared to a grid of 25 individual ablation spots (>30% rsd). Because <2% of the sample is consumed in the laser ablation analysis, selected samples can also be analyzed by traditional techniques or archived. Lead isotope ratios determined during the same total-Pb analysis appear to be effective for discerning contamination extraneous to the blood sample. Determining that an elevated result was due to contamination may negate the need for retesting with invasive pediatric venipuncture. Some elements monitored along with Pb exhibited signal profiles conducive to potential quantitation (Ca, V, Fe, Cu Zn), whereas others did not (Cr, Mn, Co, Ni, Cd, Hg, Tl, U). Copper, Ca, and V were inversely correlated with Pb (r = -0.89, -0.90, and -0.92, respectively). Scanning electron microscope images revealed surface modality differences between FP spotted with fresh whole blood and reconstituted freeze-dried blood reference material.

No abstract

There are conflicting claims as to whether treatment with glyphosate adversely affects mineral nutrition of glyphosate-resistant (GR) crops. Those who have made claims of adverse effects have argued links between reduced Mn and diseases in these crops. This article describes experiments designed to determine the effects of a recommended rate (0.86 kg ha(-1)) of glyphosate applied once or twice on the mineral content of young and mature leaves, as well as in seeds produced by GR soybeans (Glycine max) in both the greenhouse and field using inductively coupled plasma mass spectrometry (ICP-MS). In the greenhouse, there were no effects of either one application (at 3 weeks after planting, WAP) or two applications (at 3 and 6 WAP) of glyphosate on Ca, Mg, Mn, Zn, Fe, Cu, Sr, Ba, Al, Cd, Cr, Co, or Ni content of young or old leaves sampled at 6, 9, and 12 WAP and in harvested seed. Se concentrations were too low for accurate detection in leaves, but there was also no effect of glyphosate applications on Se in the seeds. In the field study, there were no effects of two applications (at 3 and 6 WAP) of glyphosate on Ca, Mg, Mn, Zn, Fe, Cu, Sr, Ba, Al, Cd, Cr, Co, or Ni content of young or old leaves at either 9 or 12 WAP. There was also no effect on Se in the seeds. There was no difference in yield between control and glyphosate-treated GR soybeans in the field. The results indicate that glyphosate does not influence mineral nutrition of GR soybean at recommended rates for weed management in the field. Furthermore, the field studies confirm the results of greenhouse studies.

Much of the seafood that humans consume comes from estuaries and coastal areas where microplastics (MPs) accumulate, due in part to continual input and degradation of plastic litter from rivers and runoff. As filter feeders, oysters (Crassostrea virginica) are especially vulnerable to MP pollution. In this study, we assessed MP pollution in water at oyster reefs along the Mississippi Gulf Coast when: (1) historic flooding of the Mississippi River caused the Bonnet Carré Spillway to remain open for a record period of time causing major freshwater intrusion to the area and deleterious impacts on the species and (2) the spillway was closed, and normal salinity conditions resumed. Microplastics (~25 µm–5 mm) were isolated using a single-pot method, preparing samples in the same vessel (Mason jars) used for their collection right up until the MPs were transferred onto filters for analyses. The MPs were quantified using Nile Red fluorescence detection and identified using laser direct infrared (LDIR) analysis. Concentrations ranged from ~12 to 381 particles/L and tended to decrease at sites impacted by major freshwater intrusion. With the spillway open, average MP concentrations were positively correlated with salinity (r = 0.87, p = 0.05) for sites with three or more samples examined. However, the dilution effect on MP abundances was temporary, and oyster yields suffered from the extended periods of lower salinity. There were no significant changes in the relative distribution of MPs during freshwater intrusions; most of the MPs (>50%) were in the lower size fraction (~25–90 µm) and consisted mostly of fragments (~84%), followed by fibers (~11%) and beads (~5%). The most prevalent plastic was polyester, followed by acrylates/polyurethanes, polyamide, polypropylene, polyethylene, and polyacetal. Overall, this work provides much-needed empirical data on the abundances, morphologies, and types of MPs that oysters are exposed to in the Mississippi Sound, although how much of these MPs are ingested and their impacts on the organisms deserves further scrutiny. This paper is believed to be the first major application of LDIR to the analysis of MPs in natural waters.