Bacterial numbers in a pine forest soil in relation to environmental factors

Numbers of soil bacteria stained with acridine orange (AO) or fluorescein diacetate (FDA) were studied for 3 and 2 yr respectively. Three pine forest sites were used and both organic and mineral soil layers were included. Different patterns of fluctuation in bacterial numbers were found each year. Significant correlations were demonstrated between AO-stained bacterial numbers and soil moisture content and between FDA-stained bacteria and the accumulated precipitation during a week before the sampling date. In multiple regression analyses 60–80% of the variation in numbers of AO-stained bacteria could be accounted for by soil moisture and numbers of bacterial-feeding nematodes at the sampling dates, and 30–45% of the variation in numbers of FDA-stained bacteria was accounted for by precipitation.     

Evaluation of porous ceramic cups for monitoring soil-water aluminium in acid soils: comment on a paper by Raulund-Rasmussen (1989)

Following recent observations by Raulund-Rasmussen (1989) implicating A1 contamination of soil solutions isolated by suction-cup samplers, A1 release from porous ceramic cups in acid solutions was investigated. In our studies a flush of Al, followed by a gradual decrease in leaching over successive extractions was observed. The amount of Al released was retarded by the presence of 37 μmol dm^?3 of A1 in solution. Gibbsite solubility controls were not observed; all solutions isolated by the cups were undersaturated with respect to amorphous gibbsite. The cups evaluated in this study are appropriate for sampling acidic soil solution, provided they are suitably pretreated and then equilibrated in the field before use.     

Anthropogenic influences on the global mercury cycle: A model-based analysis

A model of the global Hg cycle is presented and applied to analyze modern Hg budgets and historical changes in deposition. Our modeling suggests that mixing into the ocean interior is a significant sink of Hg and likely has limited any anthropogenically-caused increase in surface ocean Hg concentrations to about 50% above natural levels rather than 200% as has recently been argued. Additionally, both the increase in air pollutants during the industrial era and their recent decrease in North America likely have affected atmospheric Hg scavenging and the resulting records of Hg deposition rates in lake and bog sediments.     

Mercury Values in Urine from Inhabitants of St. Petersburg

The results of 3000 urine analyses are presented. The observational data were obtained for the reference group of school children and adults and for groups of people suffered from indoor mercury pollution. A novel Zeeman atomic absorption spectrometer and cold vapour and piroliz methods were used for determination of total mercury. A background mercury value in urine for St. Petersburg region is determined as 0.5 μg/l. Distributions of mercury concentrations in urine after five accidents are given. There are considerable differences in total mercury distribution for each group, that depend on level of Hg exposure. Peculiar features of the 24-hour rhythm of mercury excretion with urine is used for the treatment of patients, an optimal therapy selection and rehabilitation control.     

Determination of the odor threshold concentrations of iodinated trihalomethanes in drinking water

Iodinated trihalomethanes (ITHMs) have been usually considered the disinfection byproducts suspected of causing medicinal odor episodes in treated water around the world. The odor threshold concentration (OTC) of mixed ITHMs (bromochloroiodo-, bromodiiodo-, chlorodiiodo-, dibromoiodo-, and dichloroiodomethane) which were previously synthesized -- because commercial standards are not available-- were determined by using two sensory techniques: flavor profile analysis (FPA), performed by an experienced panel trained in identifying odors and tastes in water; and gas chromatography coupled with olfactometry (GCO). FPA results gave a theoretical OTCs range from 0.1 to 8.9 microg/L and ITHMs were described as sweet, solvent, and medicinal products. The lowest experimental value (OTC(exp)) obtained from the six ITHMs, 0.03 microg/L, corresponded to iodoform.     

Ecdysteroids of quinoa seeds (Chenopodium quinoa Willd.)

Quinoa (Chenopodium quinoa) is a hardy and nutritious Latin American pseudo-cereal. Studies on the seeds led to the isolation of five ecdysteroids using column chromatography. Their structures were determined as ecdysterone, makisterone A, 24-epi-makisterone A, 24(28)-dehydromakisterone A, and 20,26-dihydroxyecdysone by spectroscopic methods. This study demonstrates that quinoa seeds are a source of ecdysteroids, which were reported to be molting hormones in insects.     

Nutritional Status of Pollen and Needles of Diverse Pinus Sylvestris Populations Grown at Sites with Contrasting Pollution

Pollen may serve as a biological indicator for air pollution stress in plants. However, knowledge of pollen mineral composition and its relationship to environmental and genetic factors is very limited. We studied the concentrations of macro- and micronutrients in pollen and needles for seven European Scots pine (Pinus sylvestris L.) populations grown in two 15-yr-old provenance plantations with contrasting pollution levels. One site was located near a phosphate fertilizer factory, and the other in an area free of acute air pollution. We also tested the relationship between tree age and pollen nutrient composition by sampling 60-yr-old trees of local origin in both sites. No population differences were found in nutrient concentrations in pollen. However, there were significant differences among populations in needle concentrations of K, Mg and Zn, as well as significant site x population interaction for Mn concentration. In pollen, populations at the polluted site had significantly higher concentrations of S, Mn, Al, Na, Cu, Ni and Cd, and lower Zn. Average concentrations of S, P, Mn and Cd was lower in pollen of 60-yr-old than 15-yr-old Scots pine trees. Pollen concentrations of P, K, Ca, Mg, Fe and B were similar between sites and not related to the concentration of these elements in needles. Therefore, by analyzing the chemical composition of pollen it is not possible to detect any nutritional disorders for P, K, Ca and Mg in plants, and it seems unlikely that nutrient analyses of pollen have an advantage over analyses of foliage as a bioindicator of pollution. However, enhanced accumulation by pollen of such elements as Al, S, Mn, Cu, Ni and Cd at the polluted site may adversely affect pollen function.     

Biomass Fly Ash as Foliar Fertilizer for Hybrid Aspen Trees: Nutrient Uptake,Growth Response,and Compatibility with Nitrogen Fertilizer

Biomass ash is an important and potentially useful by-product of the bioenergy industry. As a “proof of concept” for using biomass fly ash as a foliar fertilizer, we tested (i) whether the nutrients in the ash were absorbed by hybrid aspen trees, (ii) whether the ash affected tree growth, and (iii) whether the ash was compatible with nitrogen foliar fertilizer. Four foliar treatments (water [control], ash suspended in water, nitrogen fertilizer solution, and ash suspended in nitrogen fertilizer solution) were evaluated. Several nutrients in the fly ash were absorbed by hybrid aspen both in the greenhouse and in the field; however, this absorption did not significantly affect tree growth in either setting. Nitrogen fertilization was associated with significantly higher tree growth in the greenhouse; inclusion of the fly ash with the nitrogen fertilizer solution did not significantly alter this growth response.     

Long-Term Fertilizer Use Altered Soil Microbial Community Structure but Not α-Diversity in Subtropical Southwestern China

Eurasian Soil Science - Despite the general consensus that fertilizer is the most important driver of the evolution of soil microbial communities, the specific effects of long-term fertilizer use...     

Crop response of drought-tolerant and conventional maize hybrids in a semiarid environment

In the High Plains, corn (Zea mays L.) is an important commodity for livestock feed. However, limited water resources and drought conditions continue to hinder corn production. Drought-tolerant (DT) corn hybrids could help maintain high yields under water-limited conditions, though consistent response of such hybrids is unverified. In this two-year study, the effects of three irrigation treatments were investigated for a DT and conventional maize hybrid, Pioneer AQUAMax P0876HR and Pioneer 33Y75, respectively. In 2013, the drier of the 2 years, irrigation amounts and crop water use (ET_c) were greater for the conventional hybrid, but grain water use efficiency (WUE) and harvest index were significantly greater for the DT hybrid. In 2014, grain yields and WUE were not significantly different between hybrids. However, irrigation amounts, ET_c and biomass yields were greater for the conventional hybrid. Results from both years indicate that the DT hybrid required less water to maximize grain yield as compared to the conventional hybrid. Producing relatively high yields with reduced amounts of water may provide a means for producers to continue corn production in a semiarid environment with declining water supplies.