Ecological risk assessment of surface sediments of Çardak Lagoon along a human disturbance gradient

Lagoons are the hotspot ecosystems whose sustainability should be secured using the ecological assessment indicators. This study aimed to quantify the surface sediment metal distributions of Çardak Lagoon in the Marmara region of Turkey, to characterize their natural and anthropogenic sources and transport mechanisms and to assess their potential ecological risks. The surface sediment samples were collected from 11 stations using Van Veen grab, while for the background values to be determined, core sampling was used from two stations. The analyses of multiple elements, total organic carbon, carbonate, and chlorophyll degradation by-products were carried out to characterize sediments. Enrichment factor and the indices of potential ecological and toxic risks were applied to assess the ecological status of the surface sediments. The operation of the gold mine in the close vicinity was found to be responsible for the enrichment of Au and Hg in the lagoon sediments. Cd, Tl, Sb, and Sr were the other elements responsible for the enrichment. The potential risk levels of the lagoon varied between the low and significant levels. The riskiest elements were found to be Hg and Cd which in turn pointed to the mining and agricultural activities as the most dominant human disturbance. The toxic risk index of Çardak Lagoon was estimated to range from 5.21 to 11.00, with a low mean value of 7.98. The C:N ratio range of 8.52 to 134.93 (a mean of 29.07) indicated that the organic C source was mostly of the terrestrial origin, in particular, from the surrounding agricultural lands.

Compositional Changes in Foliage Phenolics with Plant Age, a Natural Experiment in Boreal Forests

The composition of plant secondary metabolites (PSMs) extensively impacts ecosystem functioning. It is vital that we understand temporal patterns in the plants' allocation of resources to PSMs, particularly those influenced by human activity. Existing data are insufficient in the long-term perspective of perennial plants (age or ontogeny). We analysed phenolic concentrations in foliage from birch (Betula pubescens Ehr.) considered to be undamaged and growing on 5, 10 and 15 years old clear-cuts in two boreal forest landscapes in Norway, sampled at the peak of the growing season. In sum, low molecular weight phenolic concentrations decreased with age. Apart from one apigenin glycoside, the low molecular weight phenolics co-varied similarly at all ages, suggesting a lack of temporal compound-specific prioritisation of this group. In contrast, the concentration of MeOH-soluble condensed tannins increased with age. The compositional shift fits well with several hypotheses that may provide proximate explanations for age patterns in PSM allocations, including both resource constraints and external pressures. Regardless of these explanations, our study adds an important perennial perspective (plant age) to temporal PSM patterns already well-known in boreal plant phenology (foliage age).

Vermi-modification of ruminant excreta using Eisenia fetida

Present investigation aims on the vermicomposting of the excreta of different ruminants to convert it into manure employing earthworm species, Eisenia fetida. A total of 11 feedstocks (FS₁-FS₁₁) with different ratios were prepared from the excreta of different ruminants, viz., sheep, cow, buffalo, and goat. Semi-composted feedstocks were fed to E. fetida for 90 days under laboratory conditions. Vermicomposting enhanced the nutrient contents of ruminant excreta and converted it into odor-free and homogenous vermicompost. The growth of E. fetida was significant in all the feedstocks, but largest biomass gain was achieved in buffalo excreta followed by [sheep + buffalo] > [goat + buffalo] and [cow + buffalo] feedstocks. Highest fecundity (782 ± 23.3) was also recorded in buffalo excreta followed by [goat + buffalo] excreta feedstock (484.6 ± 15.7). In vermicomposted feedstocks, total organic carbon and organic matter was lesser, while NPK and heavy metals were higher as compared to raw feedstocks. C/N ratios of vermicomposts ranged from 15.37 to 38.56, which indicate a good level of maturity and stabilization of feedstocks.

Effects of elevated carbon dioxide and arbuscular mycorrhizal infection on Trifolium repens

Trifolium repens L. cv. aran was grown for 58 d at ambient (350 μol mol(-1) ) and elevated (700 μol mol(-1) ) atmospheric CO2 , wish and without the arbuscular mycorrhizal fungus Glomus mosseae (Nicol. & Gerd.) Gerd. & Trappe cv. YV. Plant biomass, mycorrhizal infection, non-structural carbohydrates, C, N and P content were examined. Elevated CO2 (a) significantly increased above- and below-ground biomass, (b) decreased specific leaf area and specific root length, (c) decreased tissue %N and increased the C:N ratio, and (d) significantly increased total non-structural carbohydrates. Inoculating T. ripens with Glomus mosseae (a) significantly increased above- and below-ground biomass. (b) increased the total root length and total leaf area, and (c) significantly decreased tissue of Evidence of an increased influence of mycorrhiza on the P nutrition of T. repens at elevated CO2 was found in the 22%, increase in leaf total P (P < 005) of mycorrhizal plants grown at elevated CO2 compared with non-mycorrhizal plants. No significant interactions were found between CO2 and mycorrhiza treatments. The proportion of T. repens root length colonized by Glomus mosseae was not affected by CO2 concentration. The percentage mycorrhizal infection was 29% at ambient CO2 and 35%, et al elevated CO2 . However, exposure to elevated CO2 significantly increased the total mycorrhizal foot length from 3.4 to 6.1 m per plant. The results show little evidence that the role of arbuscular mycorrhiza in the growth and nutrition of T. repens would increase if atmospheric CO2 were to increase as predicted.