Effects of mycorrhizae and fertilizer amendments on zinc tolerance of plants

In soils containing elevated levels of zinc, plant growth may be impaired because of Zn interference with P uptake by plants and because of detrimental effects of Zn toxicity itself. Because mycorrhizal fungi are known to improve uptake of plant P, the beneficial effects of mycorrhizal symbiosis on Zn tolerance of Andropogon gerardii Vitm. were assessed in soil amended with various levels of Zn and P. In the absence of P amendment, mycorrhizal fungi stimulated plant growth, but the degree of benefit depended on the inoculum source and the soil Zn level. Mycorrhizal fungi from a Zn contaminated site were more effective in increasing plant biomass at higher levels of Zn in the soil, whereas plant growth at lower levels of soil Zn was greater with mycorrhizal fungi from a non-contaminated site. Mycorrhizal fungus inoculation had no effect on shoot Zn concentration; however, inoculation significantly improved the plant P nutrition and therefore resulted in a high shoot P/Zn concentration ratio at all the soil Zn levels. To a certain extent, addition of P to the soil alleviated the Zn toxicity that had inhibited plant growth, but plant biomass tended to decrease with increasing soil Zn levels. Although P amendment improved P uptake, it also resulted in increased shoot Zn uptake.     

A new approach for biological online testing of stack gas condensate from municipal waste incinerators

A biological testing system for the monitoring of stack gas condensates of municipal waste incinerators has been developed using Euglena gracilis as a test organism. The motility, velocity and cellular form of the organisms were the endpoints, calculated by an image analysis system. All endpoints showed statistically significant changes in a short time when organisms were exposed to samples collected during combustion situations with increased pollutant concentrations. The velocity of the organisms proved to be the most appropriate endpoint. A semi-continuous system with E. gracilis for monitoring stack gas condensate is proposed, which could result in an online system for testing stack gas condensates in the future.     

Kin structure and the swarming behavior of the honey bee Apis mellifera

Summary Experimental hives obtained from cordovan queens that were instrumentally inseminated with semen from one cordovan and one Italian drone were set up and allowed to swarm. Cordovan provides a resessive genetic marker system (cuticle color) so that the workers from the cordovan and Italian male lines are distinguishable. Our results show that these patrilineal worker groups segregate non-randomly during colony fission and this segregation cannot be explained by observed age structure. Evidence of innate kin recognition in bees has been previously established. We argue that kin recognition could be responsible for the observed non-random grouping of kin during swarming.     

Field bioassessments for selecting test systems to evaluate military training lands in tallgrass prairie. Ecosystem health. V

Ecosystem responses to physical or chemical stress may vary from changes in single organisms to alteration of the structure and function of the ecosystem. These responses to stress cannol be predicted exactly. Ecosystems repeatedly exposed to physical and/or chemical stress can be used to study the separate and combined environmental effects of stress. Such studies also allow the development of procedures to select test systems for the analysis of stress in ecosystems. A preliminary field survey of six military training sites at Fort Riley, Kansas, USA, was conducted to identify and verify ecological test systems for evaluating ecosystem responses to physical and/or chemical stress. Comparisons of these data with data collected concurrently from Konza Prairie Research Natural Area reference sites showed that soil microarthropods, some species of macroarthropods, small mammals, and native earthworm species were negatively affected by stress. In contrast, plant species diversity, plant foliage biomass, soil mycorrhizae, and many soil characteristics were within the boundaries of nominal variations observed on “pristine” Konza Prairie. Introduced European earthworms appeared to be positively affected by training activities. This study provided a test of systematic procedures to support impact analysis, ecological toxicology, and ecosystem risk assessments. This is paper IX in D. J. Schaeffer's “Environmental Audit” series.     

Optimizing Human Intestinal Enteroids for Environmental Monitoring of Human Norovirus

Human noroviruses (HuNoV) are the leading cause of gastrointestinal illness and environmental monitoring is crucial to prevent HuNoV outbreaks. The recent development of a HuNoV cell culture assay in human intestinal enteroids (HIEs) has enabled detection of infectious HuNoV. However, this complex approach requires adaptation of HIEs to facilitate HuNoV replication from environmental matrixes. Integrating data from 200 experiments, we examined six variables: HIE age, HIE basement membrane compounds (BMC), HuNoV inoculum processing, HuNoV inoculum volume, treatment of data below limit of detection (LOD), and cutoff criteria for determining positive HuNoV growth. We infected HIEs with HuNoV GII.4 Sydney positive stool and determined 1.4 × 10³ genome equivalents per HIE well were required for HuNoV replication. HIE age had minimal effect on assay outcomes. LOD replacement and cutoff affected data interpretation, with lower values resulting in higher estimated HuNoV detection. Higher inoculum volumes lead to minimal decreases in HuNoV growth, with an optimal volume of 250uL facilitating capture of low concentrations of HuNoVs present in environmental isolates. Processing of HuNoV inoculum is valuable for disinfection studies and concentrating samples but is not necessary for all HIE applications. This work enhances the HuNoV HIE cell culture approach for environmental monitoring. Future HIE research should report cell age as days of growth and should clearly describe BMC choice, LOD handling, and positive cutoff.

     

Thermal Inactivation of Human Norovirus Surrogates

We investigated the thermal inactivation profiles of murine norovirus (MNV), Hepatitis A virus (HAV), and feline calicivirus (FCV), which are surrogates for the study of human noroviruses. Thermal inactivation of MNV and FCV were evaluated at 37, 50, and 60°C and HAV at 37, 50, 60, and 70°C. All viral surrogates were relatively stable at 37°C. MNV and FCV decimal reduction times (D-values) at 50°C were statistically significantly different (P < 0.05) with MNV being more stable. Both surrogates had comparable, low D-values at 60°C. HAV had significantly higher (P < 0.05) D-values than both MNV and FCV at 50 and 60°C. Overall, the infectivity assay results indicate that HAV is resistant to thermal inactivation while MNV is moderately resistant and FCV is least resistant.     

Nitrogen isotope composition of ammonium in PM2.5 in the Xiamen,China: impact of non-agricultural ammonia

Environmental Science and Pollution Research - Since NH3 is a significant precursor to ammonium in PM2.5 and contributes significantly to atmospheric nitrogen deposition but largely remains...     

A diagnostic comparison of measured and model-predicted speciated VOC concentrations

This study compares speciated model-predicted concentrations (i.e., mixing ratios) of volatile organic compounds (VOCs) with measurements from the Photochemical Assessment Monitoring Stations (PAMS) network at sites within the northeastern US during June–August of 2006. Measurements of total non-methane organic compounds (NMOC), ozone (O₃), oxides of nitrogen (NO_x) and reactive nitrogen species (NO_y) are used for supporting analysis. The measured VOC species were grouped into the surrogate classes used by the Carbon Bond IV (CB4) chemical mechanism. It was found that the model typically over-predicted all the CB4 VOC species, except isoprene, which might be linked to overestimated emissions. Even with over-predictions in the CB4 VOC species, model performance for daily maximum O₃ was typically within ±15%. Analysis at an urban site in NY, where both NMOC and NO_x data were available, suggested that the reasonable ozone performance may be possibly due to compensating overestimated NO_x concentrations, thus modulating the NMOC/NO_x ratio to be in similar ranges as that of observations.