Polycyclic aromatic hydrocarbons (PAHs) in soils of an industrial area in semi-arid Uzbekistan: spatial distribution, relationship with trace metals and risk assessment

The concentrations, composition patterns, transport and fate of PAHs in semi-arid and arid soils such as in Central Asia are not well known. Such knowledge is required to manage the risk posed by these toxic chemicals to humans and ecosystems in these regions. To fill this knowledge gap, we determined the concentrations of 21 parent PAHs, 4,5-methylenephenanthrene, 6 alkylated PAHs, and biphenyl in soils from 11 sampling locations (0–10, 10–20 cm soil depths) along a 20-km transect downwind from the Almalyk metal mining and metallurgical industrial complex (Almalyk MMC), Uzbekistan. The concentrations of Σ29 PAHs and Σ16 US-EPA PAHs were 41–2670 ng g$^{-1}$ and 29–1940 ng g$^{-1}$, respectively. The highest concentration of Σ29 PAHs occurred in the immediate vicinity of the copper smelting factory of the Almalyk MMC. The concentrations in topsoil decreased substantially to a value of ≤ 200 ng g$^{-1}$ (considered as background concentration) at ≥ 2 km away from the factory. Low molecular weight PAHs dominated the PAH mixtures at less contaminated sites and high molecular weight PAHs at the most contaminated site. The concentration of Σ16 US-EPA PAHs did not exceed the precautionary values set by the soil quality guidelines of, e.g., Switzerland and Germany. Similarly, the benzo[a]pyrene equivalent concentration in soils near the Almalyk MMC did not exceed the value set by the Canadian guidelines for the protection of humans from carcinogenic PAHs in soils. Consequently, the cancer risk due to exposure to PAHs in these soils can be considered as low

A sensitive soil biological indicator to changes in land-use in regions with Mediterranean climate

The demand for reliable indicators to quantify soil health has increased recently. We propose and test the use of soil microbial functional diversity as an indicator of multifunctional performance in agriculturally important areas. Agricultural fields in the Mediterranean and semiarid regions of Israel were selected as test sites and measured in Spring and Autumn seasons. Measurements included microbial parameters, basic soil abiotic properties and biological responses to agricultural management relative to measures of a natural ecosystem. Using a canonical correlation analysis we found that soil moisture was the most important basic soil property with different responses in Spring and Autumn. In Spring, it had a strongly negative relation with microbial biomass (MB), community level physiological profiling (CLPP) and the Shannon-Weaver index H', while in Autumn it had a strong relation with CLPP. We further show a significant interaction between CLPP and climate for land-use type "orchards". CLPP measured in the autumn season was thus identified as a useful and rapid biological soil health indicator, recommended for application in semiarid and Mediterranean agricultural regions. Apart from obtaining a better understanding of CLPP as the soil indicator, the study concludes that CLPP is well suited to differentiate between soils in different climates, seasons and land use types. The study shows a promising direction for further research on characterizing soil health under a larger variety of conditions.</p

Functional Diversity of Soil Microbial Communities in the Vicinity of Panicum urvilleanum and Neosparton aphyllumin a Semi-arid Environment at La Payunia Provincial Reserve, North Patagonia

Vegetation cover is an important factor in soil microbial community composition and activity. We compared the effects of dominant plantspecies cover in a semi-arid scrub environment in northern Patagonia. We compared indicators of a microbial community and activity under areas of Panicum urvilleanumand Neosparton aphyllumin La Payunia Provincial Reserve, Argentina. Soil parameters differed in their physicochemical components, playing an important role determining soil biotic compartments. Microbial community biomass and CO2 evolution react to changes in substrate availability determined by plant cover and soil pedological components. Our study showed that soil heterogeneity – plant cover – grazing activity interplay may be a main factor affecting soil microbial community function and is accountable to nutrient supply and soil stability. The high utilization of carboxylic acids, carbohydrates, and amino acids, and the difference in the ratio between them - are difficult to explain. The effect of plant cover, water-holding capacity, organic matter, pH, and soil properties on a soil microbial community could improve our understanding of the latter in low-production grazing areas. Better understanding of the patterns of soil characteristics and activity can facilitate environmental monitoring of the effects of wild guanaco (Lama guanicoe) populations, enhancing effective reserve management practices.Fil: Carmanchahi, Pablo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Panebianco, Antonella. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Jun, Yu. Chinese Academy of Sciences; República de China. Bar-Ilan University; IsraelFil: Suárez, Adriana. Universidad Nacional del Comahue. Asentamiento Universidad San Martín de Los Andes; ArgentinaFil: Gregorio, Pablo Francisco. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Sherman, Chen. Bar-Ilan University; IsraelFil: Steinberger, Yosef. Bar-Ilan University; Israe

Bacterial seed endophyte community of annual plants modulated by plant photosynthetic pathways

International audienceClimate change is predicted to have adverse impacts on terrestrial ecosystems and uncertainties exist on how these systems will respond. Terrestrial plant ecosystems can be divided by how they fix atmospheric carbon- C3, C4 and CAM photosynthesis pathways. However, as for now, no clear answers could be given regarding the future global repartition of the C3, C4 and CAM plants. As seeds are the reproductive and dispersal unit of the plants and endophytes play a central role in their preservation; here it is suggested that a better knowledge regarding the seeds endophytic community is needed when studying the future repartition of C3, C4 and CAM plant seeds. Bacterial endophyte communities inhabiting seeds belonging to C3, C4 and CAM annual plants were analysed by culture-dependent methods and 16S rRNA gene sequencing. Results indicated there were differences in the relative abundance of bacterial phyla within and across all photosynthetic pathways. Indicating some level of niche partitioning, and each of the three photosynthetic pathways could be characterized by a specific endophytic composition of Firmicutes, corresponding to the adaptation capacity of each group. We successfully identified resistant species of endophytes in the Firmicutes phylum of C4 and CAM plant seeds. Those bacteria are known for being involved in thermal regulation and plant protection through enzymes and antibiotic synthesis and match the strong adaptation capacity of C4 and CAM plants. Overall, this study suggests that there is a plant-mediated selection of the seed microbiome and these symbionts could potentially confer additional benefits to the seed

Figure 2 in Changes in a soil microarthropod community in the vicinity of dominant tree species under trampling management at the Safari Zoological Center, Israel

Figure 2 The abundance (individuals per 10 g dry soil substrate; mean ± SD) of soil microarthropod taxa extracted from core samples at different treatment sites at the Safari Zoological Center, Israel, December 2013. OE = open places under enclosure, OT = open places under trampling; EE =E. camaldulensis canopy habitat under enclosure, ET =E. camaldulensis canopy habitat under trampling, TE = T. aphylla canopy habitat under enclosure, TT =T. aphylla canopy habitat under trampling, CE = C. sempervirens canopy habitat under enclosure, CT =C. sempervirens canopy habitat under trampling. Different letters within the same group represent significance at p<0.05.Published as part of Liu, Rentao, Meller, Roy & Steinberger, Yosef, 2019, Changes in a soil microarthropod community in the vicinity of dominant tree species under trampling management at the Safari Zoological Center, Israel, pp. 33-45 in Acarologia 59 (1) on page 40, DOI: 10.24349/acarologia/20194308, http://zenodo.org/record/448766

Figure 3 in Changes in a soil microarthropod community in the vicinity of dominant tree species under trampling management at the Safari Zoological Center, Israel

Figure 3 The taxon richness, Shannon index, Simpson index, and Evenness index (mean ± SD) of soil Acari at different treatment sites at the Safari Zoological Center, Israel, December 2013. OE = open places under enclosure, OT = open places under trampling; EE = E. camaldulensis canopy habitat under enclosure, ET =E. camaldulensis canopy habitat under trampling, TE =T. aphylla canopy habitat under enclosure, TT =T. aphylla canopy habitat under trampling, CE =C. sempervirens canopy habitat under enclosure, CT =C. sempervirens canopy habitat under trampling. Different letters represent significance at p<0.05.Published as part of Liu, Rentao, Meller, Roy & Steinberger, Yosef, 2019, Changes in a soil microarthropod community in the vicinity of dominant tree species under trampling management at the Safari Zoological Center, Israel, pp. 33-45 in Acarologia 59 (1) on page 41, DOI: 10.24349/acarologia/20194308, http://zenodo.org/record/448766

Seasonal distribution and diversity of ground-active arthropods between shrub microhabitats in the Negev Desert, Israel

<p>We examined the ground-active arthropods using pitfall trapping beneath <i>Hammada scoparia</i> and <i>Zygophyllum dumosum</i> shrubs and in adjacent open spaces in wet winter, short spring, dry and hot summer, and autumn in the Negev Desert, Israel. The activity abundance of ground-active arthropods was 244, 424, and 506 individuals trap⁻¹ in open spaces and beneath <i>H. scoparia</i> and <i>Z. dumosum</i> shrubs, and was 134, 448, 414, and 178 individuals trap⁻¹ in winter, spring, summer, and autumn, respectively. The activity abundance and richness of predators and phytophages were found to exhibit an inconsistent pattern between shrub microhabitats throughout seasonality. In contrast, the activity abundance and richness of omnivores indicated contrasting pattern between summer and other seasons. Likewise, total abundance was found to exhibit a similar pattern to taxa richness and Shannon index between shrub microhabitats only in summer. There was a consistent pattern of diversity indices between shrub microhabitats observed in both winter and autumn. However, no significant (<i>P</i> > 0.05) differences in activity abundance and diversity indices were found between shrub microhabitats in spring. The Sørensen index between open spaces and <i>H. scoparia</i> and <i>Z. dumosum</i> canopy microhabitats, and that between the latter two microhabitats were found to be 0.26, 0.29, and 0.19 in winter, 0.53, 0.48, and 0.48 in spring, 0.47, 0.45, and 0.52 in summer, and 0.57, 0.56, and 0.78 in autumn, respectively. It was suggested that seasonality could mediate the activity abundance and diversity distribution of ground-active arthropods between shrub microhabitats in the Negev Desert.</p

Vertical Distribution of the Free-Living Amoeba Population in Soil under Desert Shrubs in the Negev Desert, Israel

A field study was designed to examine the effect of desert shrubs on the dynamics of free-living amoebae in arid soil. Soil samples from 0- to 50-cm depths were collected at 10-cm intervals in each of the four seasons. The vertical distributions of the four main morphological types of amoebae, grouped according to their mobility, and of small flagellate populations were measured under the canopies of Hammada scoparia and Atriplex halimus, shrubs belonging to the chloride-absorbing xerohalophytes. The result obtained from the field study demonstrated that the total number of protozoa was significantly higher during the wet seasons (winter and spring) than during the dry seasons. The protozoan population was more diverse under the canopy of H. scoparia during the wet seasons, reaching 8,000 individuals per 1 g of dry soil, whereas during the dry seasons, the populations were higher under the canopy of A. halimus, with a mean of 250 individuals. The protozoan population in the deeper layers (40 to 50 cm) was found to be as active as that in the upper layers, demonstrating that, in the desert, soil columns below 20 cm are fertile and worth studying. The type 1 amoebae (e.g., Acanthamoeba and Filamoeba spp.) were the most abundant throughout the study period, and their numbers were significantly higher than those of the other amoeba types

Effect of Soil Aggregate Size on Vineyard Bacterial Communities under Organic and Conventional Agro-Managements

Soil microorganisms are an indispensable component of natural ecosystems and play an important role in agro-management ecosystems. However, the function of soil microbial communities is still a black box. The present study aimed to investigate the effect of organic and conventional agro-management practices in a vineyard on the soil’s bacterial community and its composition in three different soil aggregate sizes using functional profiles derived using 16S rDNA metagenomics analysis for elucidating the metabolic capabilities of soil microbial communities. Soil samples were compared in terms of community composition and functionality. A clear distinction was found between the two managements. The soil samples contained 12 phyla and 45 orders, where Proteobacteria was the most common phylum in all treatments. Twenty-three functional profiles were obtained for both treatments and three aggregate sizes, showing similarity in their function, suggesting that functionality is due to the community’s composition and environmental conditions. The results indicate that organic farming systems have a beneficial effect on microbial diversity and encourage ecosystem multifunctionality