Trace Metal Incorporation in Otoliths of Black Bream (Acanthopagrus butcheri Munro), an Indicator of Exposure to Metal Contamination

Otoliths of black bream (Acanthopagrus butcheri) collected from the Swan River Estuary were analysed by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) to measure concentrations of 14 trace metals. Trace metal concentrations in the otoliths may be related to the environmental exposure history of fish to contamination. The following metal isotopes were investigated: aluminium (²⁷Al), calcium (⁴⁴Ca), manganese (⁵⁵Mn), iron (⁵⁷Fe), copper (⁶⁵Cu), zinc (⁶⁶Zn), strontium (⁸⁸Sr), cadmium (¹¹¹Cd), tin (¹²⁰Sn), barium (¹³⁸Ba), mercury (²⁰²Hg), lead (²⁰⁸Pb) and the metalloids arsenic (⁷⁵As, ⁷⁷As) and selenium (⁸²Se). Significant differences in otolith trace metal composition were found between sampling sites. Lead and ⁵⁷Fe were consistently lower in downstream fish relative to upstream fish, while ⁸⁸Sr varied with the salinity gradient in the urban estuary. Lead and ⁵⁷Fe followed similar patterns within the otoliths, and appeared to provide the best discriminatory power for relating otolith metal concentration to the environmental history of the fish.     

Evaluation of 28 balm and lemon balm (<Emphasis Type="Italic">Melissa officinalis</Emphasis>) accessions for content and composition of essential oil and content of rosmarinic acid

Lemon balm (Melissa officinalis L.) is a well-known aromatic and medicinal plant. Because of its proven sedative, spasmolytic and antiviral effects, it is often used in watery or alcoholic extracts for self-medication or pharmaceutical purposes. Its therapeutic effect is due to the content of essential oil and rosmarinic acid. A set of 28 balm accessions was evaluated for the variability of essential oil content and composition and the content of rosmarinic acid. For analysis of secondary metabolites distillation, gas chromatography and high performance liquid chromatography was used. The content of essential oil in the first cut of the years 2009 and 2010 varied in this study in a range between 0.02 and 0.48% and in the second cut between 0.01 and 0.72%. The rosmarinic acid content of the collection ranged in the year 2009 for the first cut from 3.99 to 8.78% and in the second cut from 2.45 to 6.78%. Ploidy was determined for all accessions and two cytotypes were found: diploid 2n = 2x = 32 (15 accessions), tetraploid 2n = 4x = 64 (13 accessions). Via statistical analyses two chemotypes of essential oil were found: chemotype citral and chemotype germacrene D.     

Content and composition of essential oil and content of rosmarinic acid in lemon balm and balm genotypes (<Emphasis Type="Italic">Melissa officinalis</Emphasis>)

Lemon balm (Melissa officinalis L.) is used since ancient times because of its sedative, spasmolytic and antiviral effects. Its therapeutic impact is due to the content of essential oil and rosmarinic acid. A set of 68 M. officinalis genotypes was evaluated for content and composition of essential oil and the content of rosmarinic acid. For all genotypes the level of ploidy was determined. The 68 genotypes were clone plants grown and evaluated for two years at Quedlinburg. For analysis of secondary metabolites distillation, gas chromatography and high performance liquid chromatography was used. The content of essential oil varied in this study in ranges from 0.03 to 0.33% for the second cut 2010 and 0.01–0.35% for the second cut 2011. The rosmarinic acid content ranged in the year 2010 from 3.67 to 7.55% and in the year 2011 from 4.92 to 8.07%. Via statistical analyses two chemotypes of essential oil were found: chemotype citral and chemotype β-caryophyllene oxide. Ploidy was determined for all genotypes and two cytotypes were found: diploid 2n = 2x = 32 (62 of 68 genotypes) and triploid 2n = 3x = 48 (6 of 68 genotypes).     

Improved effectiveness and efficiency in measuring soil enzymes as universal soil quality indicators using microplate fluorimetry

We tested the relevance of the microplate fluorimetric (F) assay for five enzymes in contrasting land uses, including woodland, grassland, cultivated and contaminated lands, as compared to the standard spectrophotometric (P) method. Enzymatic activity measured by the P method ranged from 0 to 56.04 nmol-pNP g^?1 min^?1 (median = 4) while the F method revealed lower values ranging from 0 to 6.22 nmol-MUB g^?1 dry soil min^?1 (median = 1). The values obtained by the P method were around 8 times higher than those revealed by the F method. However, the F method revealed significant differences in enzyme activity in orchard parcels (land use with low variations in soil properties). We concluded that the F method improves the effectiveness and the efficiency of measuring universal soil quality indicators using enzymes.     

Changes in humus forms and soil N pathways along a 130-year-old pure beech forest chronosequence

Introduction   

We investigated changes in humus morphology and soil potential net N mineralization pathways along a pure beech even-aged forest chronosequence, composed of four stages (15, 65, 95, and 130 years old) on Luvisol.     

Sensory characteristics and volatile profiles of parsley ( Petroselinum crispum [Mill.] Nym.) in correlation to resistance properties against Septoria Blight ( Septoria petroselini )

Sixteen different genotypes of parsley, including two cultivars, six populations, and eight inbred lines, were investigated regarding their sensory characteristics in relation to the volatile patterns and resistance to Septoria petroselini . The sensory quality was determined by a combination of profile analysis and preference test, whereas the volatile patterns were analyzed by headspace-SPME-GC of leaf homogenates with subsequent nontargeted data processing to prevent a possible overlooking of volatile compounds. The more resistant genotypes are characterized by several negative sensory characteristics such as bitter, grassy, herbaceous, pungent, chemical, and harsh. In contrast, the contents of some volatile compounds correlate highly and significantly either with resistance (e.g., hexanal and α-copaene) or with susceptibility (e.g., p-menthenol). Some of these compounds with very strong correlation to resistance are still unidentified and are presumed to act as resistance markers.     

Sources of spatial and temporal variability of inorganic nitrogen in pure and mixed deciduous temperate forests

We investigated the influence of tree canopy composition and structure on the spatial and temporal variability of (i) concentrations of inorganic N (NH₄⁺ and NO₃⁻) and (ii) net N-mineralization and net nitrification, within the temperate forest floor. We compared a pure European beech stand (PS) with a mixed beech-hornbeam one (MS). Three sampling areas were chosen in each stand. Within the PS, the tree locations represented a decreasing gradient of light intensity reaching the forest floor. Within the MS they represented a gradient in the amount of hornbeam leaves present in the litter. In the field NH₄⁺ and NO₃⁻ concentrations were measured in the upper mineral soil (UMS) and the overlying organic layers (OL and OF+OH). Field exposures using buried bags were carried out on UMS over 1 year to measure in situ net N-mineralization and net nitrification. Potential net N-mineralization and net nitrification were investigated in summer with UMS, OL and OF+OH incubated at 28 °C for 28 days in the laboratory. We hypothesize that with the presence of a mull-forming species (hornbeam) within a stand dominated by a moder-forming one (European beech), (i) the spatial and (ii) temporal patterns of soil inorganic N concentrations, net N-mineralization and net nitrification would be different in the two stands. Our main results show that tree species composition has an influence on both spatial and temporal patterns of nitrification. The PS exhibited its highest peaks of UMS NO₃⁻ concentration and net nitrification in spring and early summer while they were highest in the MS in winter. Furthermore, PS exhibited a higher rate of net nitrification than MS. We discuss this unexpected result and suggest that dissolved organic C may be the controlling factor for net nitrification in the MS.