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

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

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

Structure and Function of the Soil Rhizosphere Fungal Communities in Medicinal Plants—A Preliminary Study

Plants regulate their rhizosphere microbiome, which partly comprises the fungal community. We conducted a study in order to determine the effect that five medicinal plant species (Origanum syriacum, Salvia fruticosa, Teucrium capitatum, Myrtus communis and Pistacia lentiscus) have on the fungal community in their rhizosphere. We measured abiotic parameters and used sequencing to determine the structure of the rhizosphere fungal community, both taxonomically, as phyla and genera, and functionally, as trophic modes. Our data shows that the rhizosphere fungal communities were significantly different, both taxonomically and functionally. The rhizosphere of M. communis had a significant relative abundance of saprotrophs and a lower relative abundance of symbiotrophs than the control soil and the rhizosphere of T. capitatum. The relative abundance of the genus Aureobasidium was significantly higher in the rhizosphere of P. lentiscus than in the control and for all other rhizospheres, but that of S. fruiticosa. The relative abundance of genus Alternaria was lower in the rhizospheres of S. fruticosa and M. communis than in the control soil. Our results highlight the potential use of these plants in agroforestry, as a means to influence the soil fungi population

Soil biogeochemical properties of Angren industrial area, Uzbekistan

The present study examined air pollution effects on soil health applying microbiological parameters. It was carried out near the Angren heavy industry complex in a semiarid region of Uzbekistan. This area was selected in order to establish a national monitoring program for assessing environmental condition of areas remote but downwind from greater emission sources. Moreover, little information exists about how air pollution affects microbiological functioning of soils in semiarid and arid regions of the world, and especially those of Central Asia. Soil samples were collected in May 2005 along a 20-km NE-SW river valley transect downwind from the industrial complex. Soil chemical analyses included electrical conductivity, pH, water soluble Na, Ca, and K, total soluble nitrogen, and mineralizable nitrogen content upon a 1:2 digestion by deionized water. Major elements and heavy metal inventory in solids was measured by X-ray fluorescence and atomic absorption spectrometry. Microbiological ecosystem properties were assessed by biological indicators such as basal respiration (R (B)), microbial biomass related C and N contents, and microbial community functioning coefficients like the metabolic quotient qCO(2). There was a significant spatial dependence and differences for all soil chemical and microbiological parameters tested. The highest contents were found for the relatively volatile metals Zn (a parts per thousand currency sign1,136 mg/kg) and Pb (a parts per thousand currency sign373 mg/kg) in upper soil layers near the power station suggesting that the metal pollutants are derived from local stack emissions. Soil microflora was obviously affected by heavy metals. Significant positive correlations (p a parts per thousand currency signaEuro parts per thousand 0.001) were found between the metal content, R (B), and qCO(2), while a negative one was found for the mineralizable N and C (mic)/C (org) ratio. A high total number of nematodes was found only most distant from the industrial emission sources. The results disclosed remarkable spatial dependence not only of the heavy metal impact onto the soil but also of microbiological soil properties in the study area. The latter suggests bioavailability of the anthropogenic metals in the soil affecting the soil microbial community. This is suggested by less biomass formation and higher qCO(2) values in heavy metal-contaminated compared to less-polluted soil plots. Knowledge of these spatial ecosystem functioning patterns and dependence could be very useful in determining and delineating specific land use and management programs that would be suited and feasible for the highly polluted area. Results of this study can be utilized to develop a monitoring program that may quantify harmful effects on the soil health and impact of any future remediation activities. Studies on the relationship between soil biota and pollution levels have raised the question regarding the status of natural soil microbial health, stressing the importance of background data of environmental conditions, and elucidating the importance of this environmental monitoring approach even in semiarid and arid regions. Soil microbiological parameters, in particular the metabolic quotient qCO(2) as one of the most sensitive bioindicators identified for that region, should clearly become part of the national environmental monitoring program