Non-vegetated Soil Research Articles

Experimental assessment of potentially toxic metals and nutrient content at various morphological parts of two economic plants grown on spent engine oil (SEO) treated soils

ABSTRACT Metals interact with nutrients in plants grown on spent engine oil (SEO) soils; thus, relationship of metals and nutrients in several morphological parts of economical plants cultivated on SEO soils using a 3 × 4 factorial and a totally randomized design is documented. The polluted-vegetated soils were SEO treated at 0, 2, 4, 8% v/w and planted T. paniculatum and T. fruticosum separately. Before treatment, SEO tested positive for Cd, Zn, Pb, Cr, Cu, Fe and Ni, while at treatment, non-vegetated soils accumulated Pb, Cu, Zn, Ni, Fe. The T. paniculatum on SEO had more Cd among plants. ANOVA indicated significant (P < 0.05) relationship between metals, SEO and treated soils. A Post hoc indicated Fe and Pb levels differed significantly across SEO vegetated soils, while PCA suggests treated plant roots and leaves accumulated more of the toxic metals. These plants parts should not be consumed from SEO-polluted areas.

Evaluation of the potentials of &lt;i&gt;Pennisetium glaucum&lt;/i&gt; and &lt;i&gt;Vigna unguiculata&lt;/i&gt; for phytoremediation of Spent-engine oil contaminated soil

One promising technique for cleaning up soil polluted by spent engine oil is phytoremediation. Particularly in the tropics, where resources can be scarce and the climate is favorable for plant development. Finding plant species that will work well with this technology was the aim of this investigation. The ability of a cereal (Pennisetum glaucum) and a legume (Vigna unguiculata) to remediate soil contaminated with 1%, 2%, 3%, 4%, and 5% (W/V) of spent engine oil was evaluated. After 150 days of incubation, the Total Petroleum Hydrocarbon (TPH) loss in greenhouse studies was calculated. The total petroleum hydrocarbon content of soil that was vegetated with P. glaucum and V. unguiculata was substantially lower than that of non-vegetated soil. Furthermore, a positive association was discovered between the initial TPH and the total petroleum hydrocarbon loss caused by planting P. glaucum. It was also discovered that P. glaucum outperformed V. unguiculata in remediation capacity. These findings suggest that P. glaucum be investigated further, which might lead to a better understanding of how to apply phytoremediation to soils contaminated with spent-engine oil.

Metabarcoding inventory of an arctic tundra soil ecosystem reveals highly heterogeneous communities at a small scale

Biodiversity surveys of Arctic soil ecosystems are limited. Here, we provide a sequence-based inventory of soil fauna from an Arctic tundra ecosystem near the Canadian High Arctic Research Station in Cambridge Bay, Nunavut. Invertebrate communities were extracted at a vegetated and non-vegetated site in three replicates and inventoried using 18S metabarcode sequencing. A total of 361 amplicon sequence variants (ASV) were identified and assigned to the closest matching taxonomic orders, most of which belonged to the Nematoda and Arthropoda. Vegetated soils showed no significantly higher ASV richness relative to non-vegetated soils although they contained a significantly higher diversity of arthropod taxa including insects, mites, and springtails. Most taxa were found only at a single location and even samples from the same site displayed distinct communities, suggesting that belowground species richness in Arctic tundra habitats is highly heterogeneous. Preserving soil biodiversity in a changing Arctic is essential for Inuit communities who rely on intact tundra ecosystems for their health and wellbeing.

Effects of biochar and ligneous soil amendments on greenhouse gas exchange during extremely dry growing season in a Finnish cropland

Organic soil amendments such as manure, biochar and compost are among the most efficient and widely used methods to increase soil carbon sequestration in agricultural soils. Even though their benefits are well known, many wood-derived materials are not yet utilized in Nordic agriculture due to a lack of incentives and knowledge of their effects in the local climate. We studied greenhouse gas exchange, plant growth and soil properties of a clay soil cultivated with oat in southern Finland in an extremely dry year. Two years earlier, the field was treated with three ligneous soil amendments—lime-stabilized fiber from the pulp industry, willow biochar and spruce biochar—which we compared against fertilized and non-fertilized controls. We found that the soil amendments increased porosity and the mean soil water holding capacity, which was most noticeable in plots amended with spruce biochar. There was a trend indicating that the mean yield and overall biomass production were larger in plots with soil amendments; however, the difference to unamended control was seldom significant due to the high variance among replicates. Manual chamber measurements revealed that carbon dioxide and methane exchange rates were reduced most probably by the exceptionally hot and dry weather conditions, but no differences could be found between the amended and unamended treatments. The nitrous oxide emissions were significantly smaller from the vegetated soil amended with willow biochar compared with the unamended control. Emissions from non-vegetated soil, representing heterotrophic respiration, were similar but without significant differences between treatments. Overall, the studied soil amendments indicated positive climatic impact two years after their application, but further research is needed to conclusively characterize the specific effects of organic soil amendments on processes affecting greenhouse gas exchange and plant growth.

Nature-Based Solutions for Restoring an Agricultural Area Contaminated by an Oil Spill.

A feasibility study is presented for a bioremediation intervention to restore agricultural activity in a field hit by a diesel oil spill from an oil pipeline. The analysis of the real contaminated soil was conducted following two approaches. The first concerned the assessment of the biodegradative capacity of the indigenous microbial community through laboratory-scale experimentation with different treatments (natural attenuation, landfarming, landfarming + bioaugmentation). The second consisted of testing the effectiveness of phytoremediation with three plant species: Zea mays (corn), Lupinus albus (lupine) and Medicago sativa (alfalfa). With the first approach, after 180 days, the different treatments led to biodegradation percentages between 83 and 96% for linear hydrocarbons and between 76 and 83% for branched ones. In case of contamination by petroleum products, the main action of plants is to favor the degradation of hydrocarbons in the soil by stimulating microbial activity thanks to root exudates. The results obtained in this experiment confirm that the presence of plants favors a decrease in the hydrocarbon content, resulting in an improved degradation of up to 18% compared with non-vegetated soils. The addition of plant growth-promoting bacteria (PGPB) isolated from the contaminated soil also promoted the growth of the tested plants. In particular, an increase in biomass of over 50% was found for lupine. Finally, the metagenomic analysis of the contaminated soil allowed for evaluating the evolution of the composition of the microbial communities during the experimentation, with a focus on hydrocarbon- oxidizing bacteria.

Efektivitas Pembelajaran Eksploratif tentang Konsep dan Proses Fisika pada Dinamika Harian Iklim Mikro di Permukaan Lahan Bervegetasi dan Tidak Bervegetasi

Explorative learning about the concepts and processes of physics in the daily dynamics of the microclimate on the surface of vegetated and non-vegetated soil is an example of the physics learning process by utilizing the natural surroundings as a learning object. The purpose of this researh was to determine the effectiveness of explorative learning in analyzing the concepts and processes of physics in the daily dynamics of the microclimate on the surface of vegetated and non-vegetated land. This research used a pre-experimental method one group pretest-posttest design. The research subjects are third semester students of Physics Education, Manado State University 2021/2022. Data collection is in the form of observation tables/exploratory fromats. After obtaining the data, the research results were statistically processed using the SPSS 22.0 application for windows. The pretest average result was 47.80 and increased to 89.70 in the posttest average. Obtaining N-Gain scores from student, there are 8 students in the high N-Gain category with a percentage of 80% and 2 students in the medium N-Gain category with a percentage of 20%.&#x0D; The average result of the N-Gain percentage of 10 students is 80.15%. The results of this reseacrh indicate that explorative learning is effectively used in exploring physical concepts and processes in the daily dynamics of the microclimate on vegetated and non-vegetated soil surfaces.

Phytoremediation of heavy metals contaminated soil samples obtained from mechanic workshop and dumpsite using Amaranthus spinosus

This study investigated the potential of Amaranthus spinosus for the remediation of heavy metal contaminated soils a mechanic workshop and refuse dumpsites. The plant was grown in each soil for 12 weeks. The heavy metals were extracted from the samples using HNO3 digestion and analyzed using atomic absorption spectrometry (AAS) equipment (Perkin Elmer Analyst 460). The growth of A. spinosus contributed to an enhanced loss of the heavy metals from the soils. The loss of the heavy metals due to the growth of A. spinosus was more in soils from the refuse dumpsite than in the soils from the mechanic workshop. The rate of heavy metal loss was faster in the soil from mechanic workshop mechanic workshop than in the soil from the dumpsite. The trend of the rate of heavy metals loss was Cu>Zn>Pb>Cd for vegetated soil and Zn>Cu>Pb>Cd for non-vegetated soil. The rate of the heavy metal loss shows it will take lesser time to achieve 100% loss of the heavy metals in the vegetated soil than in the non-vegetated soils. There was no statistical difference between the loss of the heavy metals from the soils of the mechanic workshop and refuse dumpsite (p > 0.05). The results of this study indicated that A. spinosus with BCF values greater than 1 for Zn and Cu suggest that the plant uses hyperaccumaulation as the mechanism of remediation of the metals. The percentage loss of the heavy metals from the soils had a negative correlation with the amounts of heavy metals accumulated in the tissues of the plant, the rate of loss, and the bioconcentration factors. The ability of A. spinosus to be considered for phytoremediation has to be viewed with caution, as the translocation factor index indicates that all the metals investigated in this study were being translocated to the aerial parts of the plant.

The plant rhizosheath–root niche is an edaphic “mini-oasis” in hyperarid deserts with enhanced microbial competition

Plants have evolved unique morphological and developmental adaptations to cope with the abiotic stresses imposed by (hyper)arid environments. Such adaptations include the formation of rhizosheath–root system in which mutualistic plant–soil microbiome associations are established: the plant provides a nutrient-rich and shielded environment to microorganisms, which in return improve plant-fitness through plant growth promoting services. We hypothesized that the rhizosheath–root systems represent refuge niches and resource islands for the desert edaphic microbial communities. As a corollary, we posited that microorganisms compete intensively to colonize such “oasis” and only those beneficial microorganisms improving host fitness are preferentially selected by plant. Our results show that the belowground rhizosheath–root micro-environment is largely more hospitable than the surrounding gravel plain soil with higher nutrient and humidity contents, and cooler temperatures. By combining metabarcoding and shotgun metagenomics, we demonstrated that edaphic microbial biomass and community stability increased from the non-vegetated soils to the rhizosheath–root system. Concomitantly, non-vegetated soil communities favored autotrophy lifestyle while those associated with the plant niches were mainly heterotrophs and enriched in microbial plant growth promoting capacities. An intense inter-taxon microbial competition is involved in the colonization and homeostasis of the rhizosheath zone, as documented by significant enrichment of antibiotic resistance genes and CRISPR-Cas motifs. Altogether, our results demonstrate that rhizosheath–root systems are “edaphic mini-oases” and microbial diversity hotspots in hyperarid deserts. However, to colonize such refuge niches, the desert soil microorganisms compete intensively and are therefore prepared to outcompete potential rivals.

Re-vegetation Improves Soil Quality by Decreasing Soil Conductivity and Altering Soil Microbial Communities: A Case Study of an Opencast Coal Mine in the Helan Mountains.

Microbial communities constitute a diverse genetic resource pool in the soil and are key indicators of soil health and quality. How re-vegetation affects soil microbial diversity and community composition at the dump of an opencast coal mine is largely unknown. Using high-throughput sequencing, we performed a comparative study of the bacterial and fungal communities from non-vegetated (bare land) soil and from areas re-vegetated by Astragalus laxmannii, Halogeton arachnoideus, and Artemisia desertorum at an opencast coal mine in the Helan Mountains in western China. These results indicated that re-vegetation significantly reduced soil conductivity. The soils re-vegetated by all three plant species showed greater richness of bacterial species than the bare land, and soils re-vegetated with A. desertorum and A. laxmannii showed significantly greater richness of fungal species than bare land. The bacterial and fungal β-diversity values differed significantly between vegetated and non-vegetated soil, and these differences were more pronounced for bacterial communities than for fungal communities. Re-vegetation significantly increased the relative abundances of Proteobacteria and Bacteroidota and decreased the relative abundance of Chloroflexi. The decreasing soil conductivity that occurred with re-vegetation was found to be an important environmental determinant of the soil microbial community. This study provides evidence that re-vegetation may enhance soil quality via decreasing soil conductivity and altering the soil microbial community, and A. laxmannii was found to be a more effective species than H. arachnoideus or A. desertorum with respect to decreasing soil conductivity and altering the soil microbial communities in the Opencast Coal Mine arid region. This work may provide a helpful guideline for selection of plant species for re-vegetation projects.

The relative importance of mercury methylation and demethylation in rice paddy soil varies depending on the presence of rice plants

Neurotoxic methylmercury (MeHg) accumulates in rice grain from paddy soil, where its concentration is controlled by microbial mercury methylation and demethylation. Both up- and down-regulation of methylation is known to occur in the presence of rice plants in comparison to non-vegetated paddy soils; the influence of rice plant presence/absence on demethylation is unknown. To assess the concurrent influence of rice plant presence/absence on methylation and demethylation, and to determine which process was more dominant in controlling soil MeHg concentrations, we maintained six rhizoboxes of paddy soil with and without rice plants. At the peak of plant growth, we simultaneously measured ambient MeHg, ambient inorganic mercury (IHg), and potential rate constants of methylation and demethylation (Kmeth and Kdemeth) in soil using stable isotope tracers and ID-GC-ICPMS. We also measured organic matter content, elemental S, and water-extractable sulfate. We found MeHg concentrations were differentially controlled by MeHg production and degradation processes, depending on whether plants were present. In non-vegetated boxes, MeHg concentration was controlled by Kmeth, as evidenced by a strong and positive correlation, while Kdemeth had no relation to MeHg concentration. These results indicate methylation was the dominant driver of MeHg concentration in non-vegetated soil. In vegetated boxes, Kdemeth strongly and negatively predicted MeHg concentration, indicating that demethylation was the dominant control in soil with plants. MeHg concentration, Kmeth, and % MeHg all had significantly less variance in vegetated than in non-vegetated soils due to a consistent elimination of greater values. This pattern suggests that reduced MeHg production capacity was a secondary control on MeHg concentrations in vegetated soils. We observed no difference in the magnitude or variance of Kdemeth between treatments, suggesting that demethylation was robust to soil chemical conditions influenced by the plant, perhaps because of a wider taxonomic diversity of demethylators. Our results suggest that methylation and demethylation processes could both be leveraged to alter MeHg concentrations in rice paddy soil.

Shifts in Soil Structure, Biological, and Functional Diversity Under Long-Term Carbon Deprivation.

Soil organic matter is composed of a variety of carbon (C) forms. However, not all forms are equally accessible to soil microorganisms. Deprivation of C inputs will cause changes in the physical and microbial community structures of soils; yet the trajectories of such changes are not clear. We assessed microbial communities using phospholipid fatty acid profiling, metabarcoding, CO2 emissions, and functional gene microarrays in a decade-long C deprivation field experiment. We also assessed changes in a range of soil physicochemical properties, including using X-ray Computed Tomography imaging to assess differences in soil structure. Two sets of soils were deprived of C inputs by removing plant inputs for 10 years and 1 year, respectively. We found a reduction in diversity measures, after 10 years of C deprivation, which was unexpected based on previous research. Fungi appeared to be most impacted, likely due to competition for scarce resources after exhausting the available plant material. This suggestion was supported by evidence of bioindicator taxa in non-vegetated soils that may directly compete with or consume fungi. There was also a reduction in copies of most functional genes after 10 years of C deprivation, though gene copies increased for phytase and some genes involved in decomposing recalcitrant C and methanogenesis. Additionally, soils under C deprivation displayed expected reductions in pH, organic C, nitrogen, and biomass as well as reduced mean pore size, especially in larger pores. However, pore connectivity increased after 10 years of C deprivation contrary to expectations. Our results highlight concurrent collapse of soil structure and biodiversity following long-term C deprivation. Overall, this study shows the negative trajectory of continuous C deprivation and loss of organic matter on a wide range of soil quality indicators and microorganisms.

Soil water dynamics based on a contrastive experiment between vegetated and non-vegetated sites in a semiarid region in Northwest China

Vegetation plays an active role in soil water dynamics and water balance in groundwater-soil-plant-atmosphere continuum systems. Therefore, we characterized soil water transport at depths of 0–4.0 m induced by root water uptake (RWU) at a groundwater-dependent Salix site during the whole growth stage and compared the results with those from a non-vegetated soil site, in the semiarid Ordos basin of China. The results showed that: during the whole experimental period, evapotranspiration at the vegetated site was more than twice evaporation at the bare site, indicating that the transpiration exceeded the evaporation and was the main output of soil water. For the bare site, the increase of soil water storage in the lysimeter was 97.9 mm in total, accounting for 27.5% of the precipitation, with 16.8% of rainfall as retention in the shallow vadose zone and 10.7% of rainfall as seepage below 150 cm depth. Conversely, in the vegetated site, rainfall-driven soil water was mainly consumed by vegetation, and the decrease of soil water storage was 254.4 mm in total, with no seepage being observed. Although the root system as the preferred channel improved the soil infiltration capacity, it did not mean that the deep soil water recharge increased. The infiltrated rainfwater could not offset the water consumption of the root system. An exponential normal composite RWU model obtained by the reverse method showed that the water deficit soil layers caused by RWU changed the soil water flow field and blocked soil water interchange. Consequently, deep soil water and groundwater could not be replenished by precipitation. Our results emphasize ascertaining the hydrodynamic processes of vegetation in semiarid regions and help to strike a balance between vegetation restoration and groundwater management.

Evaluation of reduction of external load of total phosphorus and total suspended solids for rehabilitation of urban lakes

Urban lakes provide important services to cities, but they suffer from en-vironmental problems, mainly resulting from degradation of the watershed. Rehabilitation of degraded lakes is based on the recovery of water quality and reduction of external pollution, the latter usually taking priority. The Lagoa da Pampulha (LP) is an artificial lake located in Belo Horizonte, Minas Gerais - Brazil, that has suffered eutrophication and silting for decades and has been undergoing rehabilitation for some years. The objective of this study was to evaluate the importance of sanitary, environmental and urban improvements implemented in the LP watershed. For this purpose, total phosphorus (TP) and total suspended solid (TSS) loads transported to LP, between 2016 and 2017, obtained from hydrological and water quality monitoring data, were estimated. Additionally, simulations were carried out using the Storm Water Management Model (SWMM) to evaluate TP and TSS loads in hypothetical scenarios. The conservative scenario proposed a reduction of 50 % in sanitary sewage discharge to water courses and an increase of 30 % and 10 % in the urban area and non-vegetated soil, respectively, in the watershed. In an op-timistic scenario, a reduction of 95 % in sewage discharge and a reduction of 50 % in non-vegetated soils was proposed. According to the results obtained, between October 2016 and September 2017, about 38 tons of TP and 3000 tons of TSS were transported into LP. The results of the SWMM simulations indicated high loads entering the lake, ranging from about 23,000 to 13,000 ton/year for TP and from 3200 to 2400 ton/year for TSS, in actual and optimistic scenario respectively. Despite presenting significant reductions, of up to 60 % for TP and 25 % for TSS, the loads transported to LP remained high even in the most optimistic scenario, indicating that implementation of the evaluated improvements only not sufficient to guarantee rehabilitation of the lake, and must be associated with other measures.

Influence of Mining and Vegetation Restoration on Soil Properties in the Eastern Margin of the Qinghai-Tibet Plateau.

Mining causes serious destruction of the surface morphology and soil structure of lands, and vegetation restoration on post-mining lands provides an effective way for soil and water conservation. To determine the influence of mining and vegetation restoration on soil properties in the eastern margin of the Qinghai-Tibet Plateau, four land sites, including two vegetation restoration sites (restorated by Elymus nutans and Picea crassifolia, respectively), one non-vegetated mining site and one native grassland site, were selected. Fifty-two topsoil (0–10) samples were collected from these four sites, and then soil properties, trace metals and soil enzyme activities were analyzed. The results showed that there was an increase in soil pH (>8.0) after mining, while vegetation restoration decreased the soil pH compared with native grassland; the soil organic matter and total nitrogen in the site restored with E. nutans increased by 48.8% and 25.17%, respectively, compared with the site restored with P. crassifolia. The soil enzyme activities decreased after mining, and there were no significant increases in urease, phosphatase, β-glucosidase and β-1,4-N-acetylglucosaminidase activities after five years of restoration. In addition, the contents of soil trace metals (cadmium, chromium, mercury, lead and zinc) after mining were lower than the Chinese threshold (GB 15618/2018), but the content of arsenic in non-vegetated soil and P. crassifolia-restored soil exceeded the threshold by 22.61 times and 22.86 times, respectively. Therefore, As-contaminated land areas should be accurately determined and treated in a timely way to prevent arsenic from spreading, and plant species with tolerance to alkaline soil should be selected for vegetation restoration on post-mining lands.

Bioremediation of PAH-contaminated shooting range soil using integrated approaches

Serious contamination of polycyclic aromatic hydrocarbons (PAHs) occurs at outdoor shooting ranges due to the accumulation of clay target fragments containing coal tar or petroleum pitch. These contaminated sites are characterized with high-molecular-weight PAHs that are low in bioavailability and recalcitrant to bioremediation. We evaluated the effectiveness of different remediation strategies, used individually or in combinations, to decontaminate PAHs in a shooting range soil. The treatments included vegetation with bermudagrass [Cynodon dactylon (L.) Pers] or switchgrass [Panicum virgatum]), bioaugmentation of Mycobacterium vanbaalenii PYR-1, and addition of surfactants (Brij-35, rhamnolipid biosurfactant, or Brij-35/sodium dodecyl sulfate mixture). The initial total PAH concentration in the shooting range soil was 373 mg/kg and consisted of primarily high-molecular-weight PAHs (84%). Planting of bermudagrass and switchgrass resulted in 36% and 27% ∑16PAH reduction compared to the non-vegetated control, respectively. Bermudagrass enhanced soil dehydrogenase activity and both vegetation treatments also increased polyphenol oxidase activity. Bioaugmentation of M. vanbaalenii PYR-1 had a significant effect only on the dissipation of high-molecular-weight PAHs, leading to a 15% decrease (∑10PAH) compared to the control. In the non-vegetated soil, Brij-35/sodium dodecyl sulfate mixture increased PAH degradation compared to the no surfactant control. The increased PAH biodegradation in the vegetated and bioaugmented treatments improved lettuce [Lactuca sativa] seed germination, suggesting reduced toxicity in the treated soils. Phytoremediation using bermudagrass or switchgrass with bioaugmentation of M. vanbaalenii PYR-1 was an effective in situ remediation option for shooting range soils with heavy PAH contamination.

Aided Phytoremediation to Clean Up Dioxins/Furans-Aged Contaminated Soil: correlation between microbial communities and pollutant dissipation.

To restore and clean up polluted soils, aided phytoremediation was found to be an effective, eco-friendly, and feasible approach in the case of many organic pollutants. However, little is known about its potential efficiency regarding polychlorinated dibenzo-p-dioxins and furans-contaminated soils. Thus, phytoremediation of aged dioxins/furans-contaminated soil was carried out through microcosm experiments vegetated with alfalfa combined with different amendments: an arbuscular mycorrhizal fungal inoculum (Funneliformis mosseae), a biosurfactant (rhamnolipids), a dioxins/furans degrading-bacterium (Sphingomonas wittichii RW1), and native microbiota. The total dioxins/furans dissipation was estimated to 23%, which corresponds to 48 ng.kg−1 of soil, after six months of culture in the vegetated soil combined with the four amendments compared to the non-vegetated soil. Our findings showed that the dioxins/furans dissipation resulted from the stimulation of soil microbial enzyme activities (fluorescein diacetate hydrolase and dehydrogenase) and the increase of bacterial abundance, richness, and diversity, as well as fungal diversity. Amplicon sequencing using Illumina MiSeq analysis led to identification of several bacterial (Bacillaceae, Sphingomonadaceae) and fungal (Chaetomium) groups known to be involved in dioxins/furans degradation. Furthermore, concomitant cytotoxicity and dioxins/furans concentration decreases were pointed out in the phytoremediated soil. The current study demonstrated the usefulness of combining different types of amendments to improve phytoremediation efficacy of aged dioxins/furans-contaminated soils.

Phytoremediation of Heavy Metals in Spent Engine Oil-polluted Soil by Senna alata L.

Senna alata L. was used to remediate heavy metals in soil polluted with spent engine oil (SEO). One hundred and twenty polythene bags filled with 20 kg of soil each were separated into parts A and B. Part A contained S. alata seedlings while part B had no plant. They were set up in completely randomized design. To simulate spillage, 0.15% v/w, 0.75% v/w and 3.75% v/w concentrations of SEO were used to pollute soil planted with seeds of S. alata, 57 days after planting. These treatments were repeated in soil without seeds. Control had no pollution. Heavy metal analyses of SEO, vegetated and non-vegetated soil, leaves, stems and roots of S. alata were determined using Flame Atomic Absorption Spectroscopy, 106 days after pollution. Vegetative and reproductive parameters were also determined. Copper, Lead, Zinc, Iron and Aluminium were detected in SEO. Concentrations of heavy metals in vegetated soils were significantly (P

2500 years of anthropogenic and climatic landscape transformation in the Stymphalia polje, Greece

Lacustrine sediments generally record landscape development in the lake's catchment area controlled by palaeoclimatic and human induced changes. To improve our understanding on the anthropogenic and climatic influences on landscape development in Southern Greece for the last 2500 years, we report a 2 m-long, continuous high-resolution sedimentary record from shallow Lake Stymphalia (Peloponnese, Greece). Our proxies record climatically as well as anthropogenically induced landscape changes, influencing the lake area and lake depth.The Classical-Hellenistic era reflects a moderate, stable Mediterranean climate with low sedimentation rates. The parallel existence of the highly populated, major ancient city of Stymphalos, on the contemporary lake edge, doesn't seem to have caused lasting alterations in the record. The construction of the Hadrianic Aqueduct in the Roman era, ca. 130 AD, however causes an influential transformation in the lake development. It has a lasting effect on the lake hydrology as well as the vulnerability of this ecosystem. During Late Roman times, 5th to 6th century cal AD, the abandonment of the aqueduct combined with cooler climate conditions allows lake levels to recover. A phase of very high climatic instability was identified for the subsequent Early Byzantine (EB) period, during the 7th and 8th century cal AD. For this period, the later phase of the Late Antique Little Ice Age (LALIA), our proxies indicate further cooling and highly fluctuating water availability in a rather small lake area. The Middle Byzantine (MB) Period (9th-12th century AD) is characterized by an over fivefold increase in sedimentation rates. Since local population was still well below Classical levels, we explain this singular period through an interaction of modest increase in land use but marked by careless management of deforested areas, warm and wet climatic conditions during the Medieval Warm Period and long-term effects of vulnerability caused by the aqueduct construction. Probably during this phase, the lake level rose through unparalleled sedimentary infill to flood and bury a significant part of the Lower Town of the abandoned ancient city. The Late Byzantine Period (13th and 14th century AD) sees core evidence for erosion of established, non-vegetated soils (high magnetic susceptibility), in a period of almost total depopulation. In the subsequent Ottoman era (late 15th – early 19th centuries AD) local settlement made only slight recovery, the climatic conditions seem less stable during the Little Ice Age (LIA) and the lake seasonally and later periodically starts to dry up, cumulating in a longer dry phase at the end of the 19th century AD, when agricultural activity on the polje floor was possible. The conclusion conforms with recent modelling of environmental change, critical of mono-causation, rather focussing on complex interactions of human and natural factors in the inception of landscape transformation.

Assessment of Certain Plant Species degrading Total Petroleum Hydrocarbons in Contaminated Soil

Biological techniques, especially phytoremediation, have long been recognized as cost-effective and environment friendly to eliminate pollutants from soil. This article is based on a study conducted to assess the capability of alfalfa, ryegrass and white clover to remove total petroleum hydrocarbons (TPHs) from soil. The presence of petroleum contamination significantly decreased germination percentage and rate along with biomass of alfalfa and white clover compared to uncontaminated soil. With regards to ryegrass, there was no significant difference in seed germination percentage and biomass, although the presence of petroleum decreased seed germination rate. The results indicated that these plants had effect on TPHs remediation; and removal of TPH from soil was directly related to density levels and time. Therefore, alfalfa and ryegrass in their highest density levels reduced the maximum concentration of TPHs at the end of the experiment by almost 64.41% and 60.36%, respectively, whereas only slight changes were observed in non-vegetated soil.

Bacterial communities in the rhizosphere of different populations of the Ni-hyperaccumulator Alyssum serpyllifolium and the metal-excluder Dactylis glomerata growing in ultramafic soils

Compare bacterial communities in non-vegetated soils and in the rhizosphere of Ni-hyperaccumulating or Ni-excluding plants from four serpentine sites of the Iberian Peninsula. Bacterial communities in non-vegetated soil and in rhizosphere of Alyssum serpyllifolium, and Dactylis glomerata, were analysed using denaturing gradient gel electrophoresis (DGGE) of 16S rRNA gene fragments of the total bacterial community and of Alphaproteobacteria, Actinobacteria and Streptomycetaceae. Rhizosphere bacterial communities of, either the hyperaccumulators or the excluder plants, were significantly different from communities in non-vegetated soils, especially for Alphaproteobacteria and Actinobacteria. The main differences between the rhizobacterial communities of the hyperaccumulator and of the excluder corresponded to Alphaproteobacteria profiles. Communities in non-vegetated soil were significantly influenced by intrinsic soil properties while in rhizosphere soil these factors were replaced by parameters related to nutrient availability. Members of the genera Blastococcus, Geodermatophilus, Modestobacter, Rhodococcus, Pseudonocardia, Devosia and Hyphomicrobium were detected in the rhizosphere of the Ni-hyperaccumulating plants. Bacterial communities significantly differed between hyperaccumulator and excluder rhizosphere and non-vegetated soil. Actinobacteria of the Geodermatophilaceae family and Alphaproteobacteria of the Hyphomicrobiaceae family predominated in the rhizosphere profiles of the Ni-hyperaccumulators. Alphaproteobacteria could participate in the tolerance of Poaceae to trace elements in ultramafic soils.