Belowground effects of enhanced tropospheric ozone and drought in a beech/spruce forest (Fagus sylvatica L./Picea abies [L.] Karst)

The effects of experimentally elevated O₃ on soil respiration rates, standing fine-root biomass, fine-root production and δ¹³C signature of newly produced fine roots were investigated in an adult European beech/Norway spruce forest in Germany during two subsequent years with contrasting rainfall patterns. During humid 2002, soil respiration rate was enhanced under elevated O₃ under beech and spruce, and was related to O₃-stimulated fine-root production only in beech. During dry 2003, the stimulating effect of O₃ on soil respiration rate vanished under spruce, which was correlated with decreased fine-root production in spruce under drought, irrespective of the O₃ regime. δ¹³C signature of newly formed fine-roots was consistent with the differing g_s of beech and spruce, and indicated stomatal limitation by O₃ in beech and by drought in spruce. Our study showed that drought can override the stimulating O₃ effects on fine-root dynamics and soil respiration in mature beech and spruce forests.     

Factors affecting on the susceptibility of vetch cultivars to infestation by <Emphasis Type="Italic">Acyrthosiphon pisum</Emphasis> L. (Hemiptera,Aphididae)

Current trends in organic agriculture have led to the need of seeking alternative methods of pest control. For that reason the influence of weather conditions, some morphological and chemical traits of common vetch (Vicia sativa) cultivars–“Liya”, “Loryna”, “Villena”, “Moldavskaya 82” (Moldovan cultivars) and “Obrazets 666” (Bulgarian cultivar), and hairy vetch (V. villosa)–“Violeta” and “Viola” [Moldovan cultivars]) on the dynamic and preference of Acyrthosiphon pisum were determined. Moldovan cultivars belonging to V. sativa were distinguished by lower aphid numbers as they had shorter duration of the flowering period unlike the V. villosa cultivars, where that duration was significantly longer. The plant morphological traits as height, branch, flower and leaflet numbers influenced on the aphid density. The aphid density was affected by branch and leaflet numbers more than by height and flower plant. “Villena” had a shorter vegetative period, lowest flower and leaflet numbers as well as low nitrogen and phosphorus content, which resulted in the lowest A. pisum population. The use of vetch cultivars with some characteristics of tolerance would result in a reduction of losses due to pea aphids. That will provide an environmentally safer option for aphid control.     

Azo Dye Schwarz GRS Bioconversion Under Various Conditions

The transformation of the azo dye Schwarz GRS under anoxic and anaerobic conditions in batch reactor was investigated. The initial dye concentrations varied from 10 to 100 mg/L and the tests were carried either in the presence or absence of a carbon source (glucose). It was found that dye bioconversion was closely related to the glucose consumption. The degradation rates under anaerobic conditions were much higher than the rates under anoxic conditions and they increased with increasing the initial dye concentration. This suggests that the process of transformation of Schwarz GRS is a first order reaction. The highest biotransformation rate obtained was 542 μmol/g d under anaerobic conditions in the presence of glucose.     

Pea weevil damage and chemical characteristics of pea cultivars related to Bruchus <Emphasis Type="Italic">Pisorum</Emphasis> L. tolerance

It was studied the tolerance of five spring pea cultivars to Bruchus pisorum based on the weevil damage and chemical composition of seeds related to pea weevil tolerance. From visibly damaged pea seeds by pea weevil was isolated the parasitoid Triaspis thoracica Curtis (Hymenoptera, Braconidae). Cultivars with a lower protein and phosphorus content had a lower level of damage. The crude protein, crude fiber and phosphorus content in damaged seeds significantly or no significantly was increased. Modus, followed Glyans had emerged as tolerant cultivars against the pea weevil. They had the lowest total damaged seed degree, loss in weight of damaged seeds, values of harmfulness coefficient and lower protein and phosphorus content.     

Enhanced ozone strongly reduces carbon sink strength of adult beech (Fagus sylvatica) - Resume from the free-air fumigation study at Kranzberg Forest

Ground-level ozone (O₃) has gained awareness as an agent of climate change. In this respect, key results are comprehended from a unique 8-year free-air O₃-fumigation experiment, conducted on adult beech (Fagus sylvatica) at Kranzberg Forest (Germany). A novel canopy O₃ exposure methodology was employed that allowed whole-tree assessment in situ under twice-ambient O₃ levels. Elevated O₃ significantly weakened the C sink strength of the tree-soil system as evidenced by lowered photosynthesis and 44% reduction in whole-stem growth, but increased soil respiration. Associated effects in leaves and roots at the gene, cell and organ level varied from year to year, with drought being a crucial determinant of O₃ responsiveness. Regarding adult individuals of a late-successional tree species, empirical proof is provided first time in relation to recent modelling predictions that enhanced ground-level O₃ can substantially mitigate the C sequestration of forests in view of climate change.     

Long-term effects of single potassium fertilization on 137Cs levels in plants and fungi in a boreal forest ecosystem

We examined the long-term effects of a single application of potassium (K) fertilizer (100 kg K ha⁻¹) in 1992 on ¹³⁷Cs uptake in a forest ecosystem in central Sweden. ¹³⁷Cs activity concentrations were determined in three low-growing perennial shrubs, heather (Calluna vulgaris), lingonberry (Vaccinium vitis-idaea) and bilberry (Vaccinium myrtillus), and in four wild fungal species (Cortinarius semisanguineus, Lactarius rufus, Rozites caperata and Suillus variegatus). Uptake of ¹³⁷Cs by plants and fungi growing on K-fertilized plots 17 years after application of the K fertilizer was significantly lower than in corresponding species growing in a non-fertilized control area. The ¹³⁷Cs activity concentration was 21-58% lower in fungal sporocarps and 40-61% lower in plants in the K-fertilized area compared with the control. Over the study period, this decrease in ¹³⁷Cs activity concentration was more consistent in plants than in fungi, although the effect was statistically significant and strongly pronounced in all species. The effect of K fertilization in reducing ¹³⁷Cs activity concentration in fungi and plants decreased over time but was still significant in 2009, 17 years after fertilization. This suggests that application of K fertilizer to forests is an appropriate and effective long-term measure to decrease radiocaesium accumulation in plants and fungi.     

Quantifying sediment-associated metal dispersal using Pb isotopes: Application of binary and multivariate mixing models at the catchment-scale

In this study Pb isotope signatures were used to identify the provenance of contaminant metals and establish patterns of downstream sediment dispersal within the River Maritsa catchment, which is impacted by the mining of polymetallic ores. A two-fold modelling approach was undertaken to quantify sediment-associated metal delivery to the Maritsa catchment; employing binary mixing models in tributary systems and a composite fingerprinting and mixing model approach in the wider Maritsa catchment. Composite fingerprints were determined using Pb isotopic and multi-element geochemical data to characterize sediments delivered from tributary catchments. Application of a mixing model allowed a quantification of the percentage contribution of tributary catchments to the sediment load of the River Maritsa. Sediment delivery from tributaries directly affected by mining activity contributes 42-63% to the sediment load of the River Maritsa, with best-fit regression relationships indicating that sediments originating from mining-affected tributaries are being dispersed over 200 km downstream.     

Managing mercury in the great lakes: an analytical review of abatement policies

Mercury, a toxic metal known to have several deleterious affects on human health, has been one of the principal contaminants of concern in the Great Lakes basin. There are numerous anthropogenic sources of mercury to the Great Lakes area. Combustion of coal, smelting of non ferrous metals, and incineration of municipal and medical waste are major sources of mercury emissions in the region. In addition to North American anthropogenic emissions, global atmospheric emissions also significantly contribute to the deposition of mercury in the Great Lakes basin. Both the USA and Canada have agreed to reduce human exposure to mercury in the Great Lakes basin and have significantly curtailed mercury load to this region through individual and joint efforts. However, many important mercury sources, such as coal-fired power plants, still exist in the vicinity of the Great Lakes. More serious actions to drastically reduce mercury sources by employing alternative energy sources, restricting mercury trade and banning various mercury containing consumer products, such as dental amalgam are as essential as cleaning up the historical deposits of mercury in the basin. A strong political will and mass momentum are crucial for efficient mercury management. International cooperation is equally important. In the present paper, we have analyzed existing policies in respective jurisdictions to reduce mercury concentration in the Great Lakes environment. A brief review of the sources, occurrence in the Great Lakes, and the health effects of mercury is also included.     

Perspective on the Therapeutic Applications of Algal Polysaccharides

Journal of Polymers and the Environment - Algae are an enormous source of polysaccharides and have gained much interest in human flourishing as organic drugs. Algal polysaccharides have aroused...