James V. Cizdziel

Effects of glyphosate on the mineral content of glyphosate-resistant soybeans (Glycine max).

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.

Determination of elements in situ in green leaves by laser ablation ICP-MS using pressed reference materials for calibration

Laser ablation (LA) was used with double focusing sector field inductively coupled plasma mass spectrometry (ICP-MS) for direct elemental analysis of green leaves from seven species of desert plants. Pressed leaf standards (n = 7) were used as matrix matched standards for calibration and quality assurance. Nine elements (Mg, Ca, Mn, Cu, Sr, Cd, Ba, Hg and Pb) were determined in low mass resolution (m/Δm ≈ 400). Data was collected for three ablation line scans starting from near the stem to the tip of the leaf. The 213 nm laser ablation system was operated at the full energy setting (100%), with a repetition rate of 20 Hz, a spot size of 100 μm, and a scan rate of 50 μm min−1. Pressed cellulose was used for estimating detection limits, which were found to vary between 0.04 and 26 μg g−1 for Pb and Ca, respectively. Results suggest that the calibration approach is feasible for some elements (Mg, Ca, Mn, Cu, Sr, Cd, Ba) but problematic for others (Pb, Hg). Although somewhat element dependent, desert willow, autumn sage and brittle bush tended to have the highest concentrations of the elements monitored. Overall, LA-ICP-MS is a useful method for quantifying (in situ) the distribution of many elements in plant leaves.

Mercury concentrations in fish from three major lakes in north Mississippi: Spatial and temporal differences and human health risk assessment

ABSTRACT The goal of this study was to compare total mercury (Hg) concentrations in fish muscle tissue and assess consumption health risks of fish collected from three north Mississippi lakes (Sardis, Enid, and Grenada) that are extensively used for fishing and recreation. Largemouth bass (LMB; n = 64), channel catfish (CC; n = 72), and white crappie (WC; n = 100), which represent a range of trophic levels, were collected during spring 2013 and 2014. Creel data estimated that anglers harvested approximately 370,000 kg of WC, 27,000 kg of CC, and 15,000 kg of LMB from the lakes annually. Median Hg wet weight concentrations were highest in LMB (443 ng/g), followed by CC (211 ng/g) and WC (192 ng/g). Fish-Hg concentrations were lower than those reported in fish >10 years ago. There were significant differences between lakes consistent across species. Grenada length-normalized fish-Hg concentrations were higher than those from Enid and Sardis. Because existing consumption advisories for CC are length based, the lack of relationship between length and Hg concentration indicated that the recommendations may not be sufficiently protective. Further, five different risk assessment paradigms yielded hazard quotient (HQ) values suggesting that existing fish consumption advisories may be insufficient to protect adults and especially children from exposure to Hg.

Elemental Analysis of Desert Varnish Samples in the Vicinity of Coal- Fired Power Plants and the Nevada Test Site Using Laser Ablation ICPMS

Desert varnish is a thin manganese-iron rich dark coating that forms on rocks most often in arid climates. This coating may be up to a few hundred microns in thickness and is thought to grow by approximately one micron per thousand years. Recent research has shown that many elements are incorporated into this coating, and, in spite of its slow growth, it may serve as a passive environmental monitor for recent and historical air pollution. To test this hypothesis, small pieces of varnished rock were probed directly by laser ablation inductively coupled plasma mass spectrometry (LA- ICPMS). Results were obtained for 11 elements (13 isotopes: 9 Be, 107 Ag, 111 Cd, 118 Sn, 121 Sb, 138 Ba, 184 W, 205 Tl, 206 Pb, 207 Pb, 208 Pb, 232 Th, and 238 U) by magnetic sector ICPMS and for 23 elements (25 isotopes: same as before plus 51 V, 52 Cr, 59 Co, 60 Ni, 65 Cu, 66 Zn, 88 Sr, 98 Mo, 115 In, 133 Cs, 197 Au, and 209 Bi) by quadrupole ICPMS. Varnished rock samples were collected mainly in the fallout patterns of two coal-fired power plants and downwind from the Nevada Test Site (NTS). The LA-ICPMS data indicate that many of the elements commonly found in fly ash from coal-fired power plants (e.g., Cr, Co, Ni, Cu, Zn, Cd, Sn, Sb, Tl and Pb) were highly enriched in the rock coatings in relation to the upper continental crust (UCC). For one of the power plants, where tracer plume studies had been carried out, the highest concentrations in the rock varnish coincide with the peak tracer concentration locations. Thus, these elements in rock varnish hold promise for identifying those geographical regions impacted by nearby power plants. Overall, the results indicate that rock varnish can be used as a passive environmental monitor of relatively recent events, and that the trace element fingerprints held in rock varnish may also hold much potential in forensic air pollution studies.

Rock Varnish: A Passive Forensic Tool for Monitoring Recent Air Pollution and Source Identification

Abstract Rock varnish samples were collected near three point sources of air pollution to determine if the varnish contained a record of recent air pollution. Samples were collected as follows: downwind of the Nevada Test Site (NTS); in the fallout pattern of the shuttered Mohave Power Plant, located in Laughlin, Nevada; and, near the operating Reid-Gardner Power Plant, just east of Las Vegas, Nevada. Analysis of the NTS rock varnish shows 240Pu/239Pu mass ratios as low as 0.0592 ± 0.0003 and 241Pu/239Pu ratios as low as 0.00063 ± 0.00004, compared to worldwide values of 0.18 ± 0.01 and 0.009 ± 0.002, respectively, clearly indicating that the varnish can be used as a forensic tool for identifying the source of air pollution, in this case the NTS. The samples collected in the plumes of the coal-fired power plants contain thorium and uranium, and have 232Th/238U mass ratios from 1 to 30, and concentrations from 5 to 755 ppm for Th and 1 to 578 ppm for U. The highest concentrations of these elements occur together at locations that implicate the power plants; however, additional samples would be required to demonstrate unequivocally that the power plants are the sources. Overall, it is apparent that rock varnish can be utilized as a passive monitor to investigate recent air pollution.

Gill Histopathologies Following Exposure to Nanosilver or Silver Nitrate

Fish gill is the site for many crucial physiological functions. It is among the first sites of xenobiotic exposure, and gill histopathological alterations may be detected soon after toxicant exposure. Silver (Ag) is one of the most toxic metals to aquatic organisms mainly due to its ability to disrupt ionic regulation. The goal of this study was to determine the effect of ionic and nanoscale Ag on fathead minnow gills by examining gill histology and Na+/K+-ATPase immunoreactivity. Fathead minnows were exposed to two measured concentrations of silver nitrate (AgNO3: 1.3 or 3.7 μg/L as Ag+), citrate silver nanoparticles (citrate-AgNP: 15 or 39 μg/L), and polyvinylpyrrolidone-AgNP (PVP-AgNP) (AgNP: 11 or 50 μg/L). Circulatory disturbances were the most prevalent gill alterations detected and were significantly increased in all Ag treatment groups compared to control. AgNO3 (1.3 μg/L) was the only treatment that significantly elevated the number of total mucous goblet cells present. In all other Ag treatments, the percent of degenerated goblet cells was significantly increased compared to control. When the sum of all histopathological abnormalities (weighted index) was calculated, all Ag groups displayed a significantly higher index, with citrate-AgNP having the highest toxicity (index of 10 ± 0.32 versus 2.4 ± 0.6 in controls). Gill Na+/K+-ATPase immunoreactivity was decreased by Ag. These results indicated that both AgNO3 and AgNP created similar disruptions in gill structure and ionic regulation, possibly due to the ionic Ag portion of each treatment.

Temporal patterns of atmospheric mercury species in northern Mississippi during 2011–2012: Influence of sudden population swings

Gaseous elemental mercury (GEM), gaseous oxidized mercury (GOM) and particulate bound mercury (PBM) were measured on the University of Mississippi campus from July 2011 to June 2012. It is believed to be the first time that concentrations of atmospheric mercury species have been documented in northern Mississippi, and at a location with relatively large and sudden swings in population. The mean concentration (±1 SD) of GEM was 1.54±0.32 ng m(-3); levels were lower and generally more stable during the winter (1.48±0.22) and spring (1.46±0.27) compared with the summer (1.56±0.32) and fall (1.63±0.42). Mean concentrations for GOM and PBM were 3.87 pg m(-3) and 4.58 pg m(-3), respectively; levels tended to be highest in the afternoon and lowest in the early morning hours. During the fall and spring academic semesters concentrations and variability of GOM and PBM both increased, possibly from vehicle exhaust. There were moderate negative correlations with wind speed (all species) and humidity (GOM and PBM). Backward air mass trajectory modeling for the ten highest peaks for each mercury species revealed that the majority of these events occurred from air masses that passed through the northern continental US region. Overall, this study illustrates the complexity of temporal fluctuations of airborne mercury species, even in a small town environment.

Lack of transgene and glyphosate effects on yield, and mineral and amino acid content of glyphosate‐resistant soybean

BACKGROUND There has been controversy as to whether the glyphosate resistance gene and/or glyphosate applied to glyphosate-resistant (GR) soybean affect the content of cationic minerals (especially Mg, Mn and Fe), yield and amino acid content of GR soybean. A two-year field study (2013 and 2014) examined these questions at sites in Mississippi, USA. RESULTS There were no effects of glyphosate, the GR transgene or field crop history (for a field with both no history of glyphosate use versus one with a long history of glyphosate use) on grain yield. Furthermore, these factors had no consistent effects on measured mineral (Al, As, Ba, Cd, Ca, Co, Cr, Cs, Cu, Fe, Ga, K, Li, Mg, Mn, Ni, Pb, Rb, Se, Sr, Tl, U, V, Zn) content of leaves or harvested seed. Effects on minerals were small and inconsistent between years, treatments and mineral, and appeared to be random false positives. No notable effects on free or protein amino acids of the seed were measured, although glyphosate and its degradation product, aminomethylphosphonic acid (AMPA), were found in the seed in concentrations consistent with previous studies. CONCLUSIONS 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.

Simultaneous determination of mercury and organic carbon in sediment and soils using a direct mercury analyzer based on thermal decomposition–atomic absorption spectrophotometry

The purpose of this work was to study the feasibility of using a direct mercury analyzer (DMA) to simultaneously determine mercury (Hg) and organic matter content in sediment and soils. Organic carbon was estimated by re-weighing the sample boats post analysis to obtain loss-on-ignition (LOI) data. The DMA-LOI results were statistically similar (p<0.05) to the conventional muffle furnace approach. A regression equation was developed to convert DMA-LOI data to total organic carbon (TOC), which varied between 0.2% and 13.0%. Thus, mercury analyzers based on combustion can provide accurate estimates of organic carbon content in non-calcareous sediment and soils; however, weight gain from moisture (post-analysis), measurement uncertainty, and sample representativeness should all be taken into account. Sediment cores from seasonal wetland and open water areas from six oxbow lakes in the Mississippi River alluvial flood plain were analyzed. Wetland sediments generally had higher levels of Hg than open water areas owing to a greater fraction of fine particles and higher levels of organic matter. Annual loading of Hg in open water areas was estimated at 4.3, 13.4, 19.2, 20.7, 129, and 135 ng cm(-2) yr(-1) for Beasley, Roundaway, Hampton, Washington, Wolf and Sky Lakes, respectively. Generally, the interval with the highest Hg flux was dated to the 1960s and 1970s.

Elemental fingerprinting of soils using ICP-MS and multivariate statistics: A study for and by forensic chemistry majors

Students in an instrumental analysis course with a forensic emphasis were presented with a mock scenario in which soil was collected from a murder suspects car mat, from the crime scene, from adjacent areas, and from more distant locations. Students were then asked to conduct a comparative analysis using the soils elemental distribution fingerprints. The soil was collected from Lafayette County, Mississippi, USA and categorized as sandy loam. Eight student groups determined twenty-two elements (Li, Be, Mg, Al, K, Ca, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Cs, Ba, Pb, U) in seven samples of soil and one sample of sediment by microwave-assisted acid digestion and inductively coupled plasma-mass spectrometry (ICP-MS). Data were combined and evaluated using multivariate statistical analyses. All eight student groups correctly classified their unknown among the different locations. Students learn, however, that whereas their results suggest that the elemental fingerprinting approach can be used to distinguish soils from different land-use areas and geographic locations, applying the methodology in forensic investigations is more complicated and has potential pitfalls. Overall, the inquiry-based pedagogy enthused the students and provided learning opportunities in analytical chemistry, including sample preparation, ICP-MS, figures-of-merit, and multivariate statistics.