Sugar beet ( L.) growth reduction caused by hydrochar is related to nitrogen supply

Hydrothermal carbonization allows rapid conversion of biomass into a carbon-rich, lignite-like product (hydrochar). It is assumed to have beneficial effects on soil properties and plant growth, but detailed studies are lacking, especially in the field. The objective of our study was to investigate the effect of hydrochar incorporated into arable soils on soil mineral nitrogen (N) content and sugar beet growth. In 2010-2011, a field and a pot trial were conducted. Hydrochars (field: 10 Mg ha; pot: equivalent to 30 Mg ha) processed from sugar beet pulp (HSP) and beer draff (HBD) were tested against an untreated control. As a second factor, mineral nitrogen (N) fertilizer level (field: 0, 50, 100, 150 kg N ha; pot: 0, 100, 200 mg N kg soil) was varied. In both trials, hydrochars reduced initial sugar beet growth, especially when hydrochar with a high C/N ratio (38, HSP) was combined with a low N fertilizer level; high N supply partly compensated for the reduced seedling growth. Without N fertilization, no extractable N was present at the end of the pot trial in the HSP treatment, whereas in HBD even more N was extracted than in the control. This suggests remineralization of previously immobilized N when hydrochar with a low C/N ratio was applied (16, HBD). In the field, beet yield was equal at the high N fertilizer level in HSP and at all N levels in HBD treatment. Our results suggest that hydrochar can decrease plant-available N due to N immobilization. Other potential causes for the observed early growth reduction need to be studied more in detail.     

Multi-criteria forest road network planning in fire-prone environment: a case study in Serbia

This paper presents a multi-criteria selection of the best forest road network with the aim of achieving effective preventive and timely repressive protection against forest fires. The research was carried out in national park (NP) “Tara” at a site which is under constant threat of fire. Four variants of the forest road network were designed and analyzed against seven criteria, and the best variant was selected using entropy weight coefficients (EWC) method. The importance of these seven criteria was studied by the management of the NP “Tara.” The greatest importance was given to the criteria relating to the cost of construction and maintenance of permanent and temporary roads (47% of the total value of all criteria). The EWC method did not select the variant based on the lowest costs of construction and maintenance as the best option, but the variant whose location was the most suitable for effective defense against forest fires.     

Direct N2O emission from agricultural soils in Poland between 1960 and 2009

Nitrogen fertilization (N) is commonly known as a main source of direct nitrous oxide (N₂O) emission from agricultural soils. An area of 38 % of the total land surface of Poland was covered by agricultural soils in 2009. In this paper, we aimed at analyzing data regarding the land exploitation for 13 selected subareas of Poland between 1960 and 2009. Seven out of the 13 subareas studied are located in the West (area A), and six subareas are located in southeast of Poland (area B). The total area covered by large farms (>20 ha) differed largely, between area A (10.6 %) and area B (0.9 %) in 2009. Both areas varied in terms of the amount of fertilizers used annually, average crop yield and crop structure. Average direct emissions of N₂O from agricultural soils were 1.66 ± 0.09 kg N₂O–N ha^?1 a^?1 for area A, 1.39 ± 0.07 kg N₂O–N ha^?1 a^?1 for area B and 1.46 ± 0.07 kg N₂O–N ha^?1 a^?1 for the whole country between 1960 and 2009.     

Seasonal and spatial variations of Po and Pb activity concentrations in Mytilus galloprovincialis from Croatian coast of the Adriatic Sea

Results of 2 years monitoring of ²¹⁰Po and ²¹⁰Pb activity concentrations in soft tissue of the species Mytilus galloprovincialis from Croatian part of the Adriatic coast are presented. The samples were collected at thirteen coastal stations (some of which are also a part of the Mediterranean Mussel Watch Project) in spring and autumn of 2010 and 2011. The collected mussels were ranging between 4 cm and 6 cm in shell length. After sample pre-treatment lead and polonium were radiochemically separated on Sr resin. ²¹⁰Po was determined by alpha-particle spectrometry and ²¹⁰Pb was determined, via ²¹⁰Bi, by a low-level gas proportional counter. The results of ²¹⁰Po activity concentrations were found to vary between (104 ± 11) and (1421 ± 81) Bq kg⁻¹ dry weight while ²¹⁰Pb activity concentrations were much lower and in range (8.2 ± 5.3)–(94.1 ± 29.8) Bq kg⁻¹ dry weight. Higher ²¹⁰Po and ²¹⁰Pb activity concentrations were determined in spring period. The inter-site differences seen in their activity concentrations can be due to natural background levels of sites. The ²¹⁰Po/²¹⁰Pb activity concentration ratios in all cases exceeded unity for all mussel samples and ranged between 4.0 and 47.9.     

Malondialdehyde and heavy metal concentrations in tissues of wild boar (Sus scrofa L.) from central Croatia

The aim of this research was to assess the degree of heavy metal (cadmium, lead and mercury) contamination of wild boars from central Croatia and thereby conduct further tests to connect the contamination to oxidative stress occurrence. The highest cadmium concentration was noticed in the kidneys of older boars, the lead concentration was approximately the same in the liver and kidneys, but it was much higher than the concentration in the muscles, while the highest mercury concentration was measured in the kidneys of all wild boars. The correlation between the malondialdehyde (MDA) and the heavy metal concentrations was higher in tissue samples taken from younger animals (1 to 3 years of age) than in the tissue samples taken from older animals (5 to 6 years of age). In the kidneys of all wild boars there was a statistically significant connection between the MDA and cadmium concentration; in the kidneys of younger wild boars there was a statistically significant connection between the MDA and lead concentration. Further research on this topic should focus on MDA potential to find its use, not only as a contamination biomarker in the area of ecotoxicology, but also in the evaluation of the hygienic acceptability of animal products.     

Cadmium effects on the fitness-related traits and antioxidative defense of Lymantria dispar L. larvae

Cadmium, like many other pollutants, is nondegradable and can be accumulated by Lymantria dispar at a level that affects fitness components, physiology, and development, which could indicate presence of environment pollution by heavy metals. The cadmium effect on fitness-related traits in the third, fourth, fifth, and sixth instar of L. dispar L. was determined. Furthermore, activities of the following antioxidative defense components after the larvae had been fed on the artificial cadmium-supplemented diet (50 μg Cd/g dry food) were assessed: superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APOX), total glutathione amount (GSH), glutathione-S-transferase (GST), glutathione reductase (GR), and the amount of free sulfhydryl (SH) groups. Statistically significant delay of development in the fourth, fifth, and sixth instar and decrease of the larval mass in the third and fourth instar were estimated after the exposure to cadmium through food in comparison to the control. There were no changes in SOD activity of cadmium-treated larvae. Significantly lower CAT, APOX, and GR activities were recorded in the third, fifth, and in the third instar, respectively. At the same time, higher activity was recorded in the sixth instar, while GST activity was higher in the third. GSH content was significantly lower during all instars after treatment but the amount of SH groups was higher in older larvae. The strategy of antioxidative defense and the adjustment or modulation of fitness-related traits in presence of cadmium was dependent on the age of larvae in L. dispar, which might be used in early metal risk assessment in Lepidoptera and other insects.     

Enzymatic biomarkers as indicators of dietary cadmium in gypsy moth caterpillars

Heavy metals damage the structure, chemistry, and function of cells, including enzyme systems inside them. Variation in the profile of biochemical biomarkers in prevalent species should be used for assessing environmental contamination. The present study pays attention to the phosphatases present in the midgut of gypsy moth fourth instar caterpillars, which had been exposed to short- and long-term cadmium intake at 10 and 30 μg Cd/g dry food. Chronic cadmium ingestion significantly inhibited the activity of all examined phosphatases, while only the activity of lysosomal phosphatase was acutely decreased. Total acid phosphatase activity recovered from both long-term cadmium treatments within 3 days. The low index of phenotypic plasticity was connected to high variability of plasticity. Dependence of phosphatase isoforms on genotype and duration of cadmium treatment was determined. We concluded that, with further investigations, profiling of total acid phosphatase activity, as well as the lysosomal fraction can be used as a biomarker for acute sublethal metal toxicity.     

Active moss biomonitoring of small-scale spatial distribution of airborne major and trace elements in the Belgrade urban area

In urban environments, human exposure to air pollutants is expected to be significantly increased, especially near busy traffic streets, street canyons, tunnels, etc. where urban topography and microclimate may additionally cause poor air conditions giving rise to pollution hotspots. As a practical and cost-effective approach, active moss biomonitoring survey of some major and trace element air pollution was performed in the Belgrade street canyons and city tunnel in 2011 with the aim to evaluate possibility of using Sphagnum girgensohnii moss bags for investigation of the small-scale vertical and horizontal distribution patterns of the elements. In five street canyons, the moss bags were hung at heights of about 4, 8 and 16 m, during 10 weeks, and also, for the same time, the moss bags were exposed in the tunnel, in front of and out of it. After the exposure period, the concentrations of Al, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sr, V and Zn in the moss were determined by inductively coupled plasma optical emission spectrometry. According to the results, in all street canyons, the vertical distribution patterns of the moss elements concentration (Al, Ba, Co, Cr, Cu, Ni, Pb, Sr, V and Zn) showed statistically significant decrease from the first to the third heights of bags exposure. In the tunnel experiment, from inner to out of the tunnel, for Al, Ba, Cd, Co, Cr, Cu, Fe, K and Zn, decreasing trend of concentrations was obtained. Significantly higher concentration of the elements was pronounced for the tunnel in comparison with the street canyons. The results indicate that the use of S. girgensohnii moss bags is a simple, sensitive and inexpensive way to monitor the small-scale inner city spatial distribution of airborne major and trace element content.     

The electronic properties of trimethylnaphthalenes as properties for the prediction of biodegradation rates: ab initio and DFT study

There is little information on trimethylnaphthalenes (TMNs) which are constituents of diesel fuel and bitumen emissions. In this study, a theoretical investigation of the electronic properties of all trimethylnaphthalene (TMN) isomers and their relation to biodegradation are presented. Equilibrium geometries, ionization potentials (IPs), electron affinities (EAs), dipole moments and electronic dipole polarizabilities of TMN isomers calculated by ab initio and Density Functional Theory (DFT) methods are reported. Polarizability and dipole moment computations have been performed in gas and in water solution using the polarizable continuum model (PCM). The results obtained show that the IP value varies little along the series of isomers while averaged static dipole polarizabilities (〈α〉) increase on passing from α,α,α-TMN to β,β,β-TMN isomers. This indicates that the binding affinity between TMNs and active site of bacterial enzymes is mainly determined by dispersive and inductive effects. Therefore, the computed polarizability values of TMNs can be used as predictors of the rates of biodegradation of TMNs.     

The sensitivity of soil enzymes,microorganisms and spring wheat to soil contamination with carfentrazone-ethyl

Herbicides pose a significant threat to the natural environment, in particular in soils that are most exposed to plant protection agents. Prolonged herbicide use leads to changes in soil metabolism and decreases soil productive potential. In this study, the influence of carfentrazone-ethyl (CE) on the microbiological and biochemical properties of soil and the yield of Triticum aestivum L. was evaluated. Carfentrazone-ethyl was applied to sandy loam (pH_KCl – 7.0) in doses of 0.000, 0.264, 5.280, 10.56, 21.18, 42.24, 84.48 and 168.96 µg kg^?1 DM soil. Soil samples were subjected to microbiological and biochemical analyses on experimental days 30 and 60. Carfentrazone-ethyl disrupted the biological equilibrium in soil by decreasing the abundance and biodiversity of soil-dwelling microorganisms, the activity of soil enzymes, the values of the biochemical activity indicator and spring wheat yields. Carfentrazone-ethyl had the most adverse effects when applied in doses many fold higher than those recommended by the manufacturer. The toxic effects of CE were also determined by its soil retention time. Soil treated with CE was characterized by higher counts of oligotrophic bacteria, organotrophic bacteria, bacteria of the genus Azotobacter, actinomycetes and fungi on day 60, and spore-forming oligotrophic bacteria on day 30. The activity of dehydrogenases, urease, alkaline phosphatase and β-glucosidase was higher on day 30 than on day 60.