Persistence of phenols in aquatic microcosms receiving chronic inputs of coal-derived oil

The environmental fate of constituent phenols of a coal-derived oil spilled intermittently on water was evaluated in aquatic microcosms. Phenols dissolved rapidly from the oil into the water, and initially accumulated with sequential oil additions. The major process removing phenols from the microcosms was microbial degradation-other processes were negligible in comparison. After phenols attained maximum concentrations in the first 28 days of the study, degradation rates exceeded input rates in all microcosms during the second 28 days the study and total phenol concentrations decreased. Significant differences were apparent in the rates of degradation of various alkylphenol isomers and isomer groups, but no compounds were observed to be refractory. Upon discontinuation of oil inputs at day 56, dissolved phenols disappeared within several weeks. Microcosm exposure history and the presence of other phenol isomers affected the rate of removal of individual isomers, complicating prediction of the rate of removal of individual toxicants.     

Method Dependency in the Measurement of BTEX Levels in Contaminated Soil

Environmental consultants and analytical laboratories are increasingly realizing the importance of analytical method selection and validation for the reliable measurement of soil contamination. Aromatic hydrocarbons (BTEX) is one class of environmentally significant soil contamination for which testing is required by regulatory authorities in most industrialized countries. Unfortunately, in most guidelines there is a lack of direction for the selection of a testing method for BTEX and, in practice, any one of a variety of methods may be employed. The fact that these may not all yield comparable results is a source of much frustration in the industry and there is a paucity of published research into this problem. In a number of carefully controlled experiments, the method dependency of measured BTEX levels in contaminated soil samples has been investigated. Three commonly employed methods, namely, (methanol extraction) purge-and-trap/gas chromatography with mass selective detection (P&T/GCMSD), headspace/GCMSD and dichloromethane (DCM) extraction/gas chromatography with flame ionization detection (GCFID) have been compared in the analysis of 109 gasoline-contaminated soil samples collected from station sites in Melbourne, Australia. Measurable BTEX concentrations were recorded in 92% of the samples using P&T/GCMSD, 59% using DCM/GCFID, and 40% using headspace/GCMSD. Correspondingly, the magnitudes of the recovered concentrations were significantly higher by P&T/GCMSD than by DCM/GCFID, which in turn were significantly higher than the magnitudes determined by headspace/GCMSD. These trends are evident for both clay and sandy soils. These studies clearly demonstrate that, for the three commonly employed methods described, measured BTEX levels are extraction and analytical method dependent in at least two different soil types.     

Phytochemical stability and color retention of copigmented and processed muscadine grape juice

Muscadine (Vitis rotundifolia) grape juice was assessed for color and phytochemical stability as influenced by anthocyanin copigmentation with a water-soluble rosemary extract, fortification with ascorbic acid, and processing by heat or high hydrostatic pressure (HHP). The roles of polyphenolic cofactors in the presence and in the absence of ascorbic acid were assessed as a means to improve the overall processing stability of the juice. Addition of rosemary extract from 0 to 0.4% (v/v) readily formed copigment complexes with anthocyanins and resulted in concentration-dependent hyperchromic shifts from 10 to 27% that corresponded to increased antioxidant activity. The presence of ascorbic acid was generally detrimental to juice quality, especially in the presence of rosemary extract, and resulted in overall anthocyanin, ascorbic acid, and antioxidant activity losses. Although thermal and high-pressure processing methods were detrimental to juice quality, HHP resulted in greater losses after processing, likely due to action from residual oxidase enzymes. Although physicochemical attributes were enhanced by copigmentation with rosemary extract, methods to inactivate residual enzymes should be addressed prior to copigmentation to prevent degradation of anthocyanins in the presence of ascorbic acid.     

Zigzag survey designs in line transect sampling

Zigzag survey lines are frequently used in shipboard and aerial line transect surveys of animal populations. Analysis proceeds assuming that coverage probability through the survey region is uniform. We show that the two types of zigzag design that are in wide use do not generally have this property, and explore the degree of bias in abundance estimates that can be anticipated. We construct a zigzag design for convex survey regions that has even coverage probability with respect to distance along a design axis. We also provide Horvitz-Thompson estimators that allow coverage probability to vary by location through the survey region.     

Where nothing stands still: quantifying nomadism in Australian arid-zone birds

Landscape Ecology - Nomadism is a movement strategy in response to non-seasonal environmental variability. Knowledge of nomadic species movements is poor but is necessary to understand life...     

Germanium accumulation and toxicity in barley

The accumulation of germanium (Ge) by barley (Hordeum vulgare cv. ‘Arivat') grown at various Ge and pH levels was investigated because Ge is an industrially important metal and bioaccumulation of Ge is a potentially useful means of concentrating this trace metal. Six‐day‐old barley seedlings were grown in perlite and nutrient solution adjusted to a pH of 4.5, 6.0, or 7.5 supplemented with 20, 40,60, or 80 μM Ge for seven days. The plants were divided into roots and shoots after harvesting; the dry weight and Ge content of the individual organs were measured, as was the peroxidase activity in the distal 1 cm of the primary leaves. Barley seedlings accumulated Ge in the roots and shoots; the shoots accumulated Ge linearly as medium Ge concentration increased. The dry weight of the organs was not affected, although necrosis was observed in the primary leaves of the seedlings treated with Ge concentrations greater than 20μM. Peroxidase activity in the primary leaves also increased as the Ge levels in the medium increased which indicated that elevated levels of Ge stimulated leaf senescence. These results demonstrate that barley plants can take up Ge and suggest that Ge is not toxic at the levels that might occur in areas where Ge is normally mined.     

Forage Yield and Soil Characteristics Under Various Crops in Alaska

Forage crops and soil attributes were evaluated for 4 years at three sites in Alaska. Annual herbage yields usually exceeded 5 Mg ha^-1 on neutral soils at Fairbanks (64°52' W) and on moderately acidic soils at Point MacKenzie (61°24' N, 150°3' W). Strongly acidic, droughty soils at Delta Junction (63°55' N, 145°20' W) produced low yields for all crops. Soil pH decreased significantly over 4 years under N-fertilized grasses at Delta Junction and under alfalfa and N-fertilized barley at Fairbanks. Soil organic C and N and microbial biomass C showed no differences among treatments at the end of the study. Wet aggregate stability did not vary significantly among crops but was lower for fallow. The results of this study indicated a high potential for use of perennial forage legumes at some locations in Alaska. The lack of large differences in most soil parameters indicates slow responsiveness to management by some commonly used soilquality indicators under subarctic conditions.     

An aboveground–belowground assessment of ecosystem properties associated with exotic annual brome invasion

Exotic annual brome invasion has been well studied in western North American rangelands, particularly for Bromus tectorum L. invasion in sagebrush (Artemisia tridentata) grasslands. We examined both aboveground and belowground properties in native sagebrush grassland and adjacent areas dominated by exotic annual bromes (B. tectorum L. and Bromus japonicus Thunb.) to better understand the fundamental ecological differences between native and invaded areas. Field sites were located in north central Wyoming, USA, and plots were established in areas that had been historically subject to wildfire and either (1) recolonized by native sagebrush grassland vegetation or (2) invaded by exotic annual bromes. We employed measures of vegetation community structure as well as soil physical, chemical, and microbiological properties. Plots with greater than 20 % exotic annual brome cover had significantly less cover of all native vegetation functional groups resulting in lower richness and evenness than native plots. Invaded plots also had low diversity plant communities that were continuous and uniform across space. Soils beneath invaded plant communities had higher infiltration rates, higher levels of total nitrogen, and a lower C/N ratio than the native soils. Invaded soils also had 90–96 % lower abundance of all soil microbial groups measured by phospholipid fatty acid. We conclude that areas dominated by exotic annual bromes display different aboveground and belowground properties compared to the native community, and these changes possibly include spatial and temporal shifts in soil resources and organic matter processing.     

Detection of virulence to septoria tritici blotch (STB) resistance conferred by the winter wheat cultivar Cougar in the Irish Zymoseptoria tritici population and potential implications for STB control

Septoria tritici blotch (STB) caused by the fungal pathogen Zymoseptoria tritici continues to be the most economically destructive disease of winter wheat throughout Ireland. Due to the widespread development of fungicide resistance in the Irish Z. tritici population, integrated strategies to control STB are increasingly necessary. A key component of such strategies will be the deployment of winter wheat cultivars with improved levels of STB resistance. Unfortunately, due to the nature of Z. tritici, such resistances are at risk of being overcome by the pathogen. In late summer 2020, foci of STB were observed across a range of winter wheat cultivars under evaluation for recommendation in Ireland. Common amongst these was the cultivar Cougar in each of their pedigree. To determine if the foci observed in 2020 resulted from strains virulent to Cougar, isolate collections were established and virulence screens conducted on Cougar and a range of the cultivars currently under evaluation. These confirmed the presence of Cougar-virulent strains in the Irish Z. tritici population, and that this virulence affects not just Cougar, but also cultivars derived from it. Although the foci observed in 2020 were in both fungicide-untreated and -treated plots, there was no evidence that these strains are more sensitive or resistant to fungicides compared to the wider Irish Z. tritici population, with moderate resistance to the SDHIs and azoles dominating. Combined, the present study confirms the need to ensure a diversity of control measures for STB, including ensuring a range of STB resistances are used.