The rotation of white lupin (Lupinus albus L.) with metal-accumulating plant crops: a strategy to increase the benefits of soil phytoremediation.

Most of the plants employed to remove metals from contaminated soils are annuals and have a seed-to-seed life cycle of a few months, usually over spring and summer. Consequently, for most of the year, fields are not actively cleaned but are completely bare and subject to erosion by water and wind. The objective of this study was to evaluate the benefits of using Lupinus albus as a winter crop in a rotation sequence with a summer crop ideally selected for phytoextraction, such as industrial hemp. Lupin plants were grown in two alkaline soil plots (heavy metal-contaminated and uncontaminated) of approximately 400 m(2) each after the cultivation and harvest of industrial hemp. A smaller-scale parallel pot experiment was also performed to better understand the lupin behavior in increasing concentrations of Cd, Cu, Ni and Zn. White lupin grew well in alkaline conditions, covering the soil during the winter season. In few months plants were approximately 40-50 cm high in both control and contaminated plots. In fields where the bioavailable fraction of metals was low (less than 12%), plants showed a high tolerance to these contaminants. However, their growth was affected in some pot treatments in which the concentrations of assimilable Cu, Zn and Ni were higher, ranging from approximately 40-70% of the total concentrations. The lupin's ability to absorb heavy metals and translocate them to shoots was negligible with respect to the magnitude of contamination, suggesting that this plant is not suitable for extending the period of phytoextraction. However, it is entirely exploitable as green manure, avoiding the application of chemical amendments during phytoremediation. In addition, in polluted fields, white lupin cultivation increased the soil concentration of live bacteria and the bioavailable percentage of metals. On average live bacteria counts per gram of soil were 65×10(6)±18×10(6) and 99×10(6)±22*10(6) before and after cultivation, respectively. The percentages of bioavailable Cu, Pb, Ni, Zn and Cr, which were 5.7±0.7, 5.3±1.7, 1.2±0.1, 12±1.5 and 0.1±0.02%, respectively, before lupin growth, increased to 9.6±1.6, 7±2, 2±0.3, 14±1.5 and 0.1±0.02% after lupin harvest. On the whole, our results indicate that the winter cultivation of white lupin in sequence with a metal-accumulator summer crop can improve the recovery of soil quality during the phytoextraction period. It improves the safety of the area, limiting additional ecological and human health problems, and enhances soil health by avoiding the use of chemical amendments and by increasing the levels of viable microorganisms.

Life on a hilltop: vegetation history, plant husbandry and pastoralism at the dawn of Bergamo-Bergomum (northern Italy, 15th to 7th century bc).

Cores and trenches drilled or dug in religious and secular buildings in the hilltop town of Bergamo (northern Italy) were investigated by means of micro/macrobotanical and pedochemical analysis to unravel the cultural vegetation history of the area during ca. seven centuries across the Bronze-Iron Ages. We explore the predictive power of biological proxies, nutrients, and coupled 14C datings to reveal early phases of human settlement and activity in a modern urban context with low visibility and difficult accessibility. Our records suggest that a farming centre was active on the Bergamo hilltop as early as the 15th century bc. Crop and animal husbandry reached a high point between the 11th-8th century bc. Plant and biogeochemical proxies predict extensive and diversified cereal cropping, flax and grapevine cultivation, as well as herd stalling at a watering pond, free range livestock growing in woodlands, and pastoralism, shown by hay making and overgrazing evidence. The suggestive hypothesis of carding wool is mentioned but is currently untenable. Furthermore, we identified a possible phase of abandonment starting from the 8th century bc, to be further investigated, and in agreement with archaeological data suggesting settlement decline in the 8th-6th century bc. Our research highlights the dedication to pastoralism of the Bergamo hill since prehistoric times. The settlement position was strategic for pastoralists to exploit biological and water resources in space, season and elevation, i.e. from the plain to higher Alpine pastures. Ethnographic examples and Middle Age written sources strongly support this picture.

Polychlorinated biphenyls (PCBs) in air and soil from a high-altitude pasture in the Italian Alps: evidence of CB-209 contamination.

This study analyses the seasonal trend of polychlorinated biphenyls (PCB) concentrations in air and soil from a high-altitude mountain pasture in the Italian Alps. PCB concentrations in soil were generally comparable to background levels and were lower than those previously measured in the same area. Only CB-209 unexpectedly showed high concentrations with respect to the other congeners. GC-MS-MS identification was very clear, rising a new problem of increasing PCB contamination concerning only CB-209, which is not present in commercial mixtures used in the past in Italy and Europe. Considering all of the congeners, seasonal PCB trends were observed both in air and in soil that were related to the temperature and precipitation measured specifically in the study area. Highly significant relationships were found between the temperature-normalised concentrations in soil and the precipitation amounts. A north/south enrichment factor was present only in soil with rapid early summer re-volatilisation kinetics from soil to air and autumn re-deposition events from air to soil. Fugacity ratio calculations confirmed these trends. Surface soils respond rapidly to meteorological variables, while subsurface soils respond much more slowly. Seasonal trends were different for the northern and southern sides of the mountain. A detailed picture of the interactions among temperature, precipitation, mountain aspects and soil features was obtained.

Bioethanol from poplar clone Imola: an environmentally viable alternative to fossil fuel?

BACKGROUND: Environmental issues, e.g. climate change, fossil resource depletion have triggered ambitious national/regional policies to develop biofuel and bioenergy roles within the overall energy portfolio to achieve decarbonising the global economy and increase energy security. With the 10 % binding target for the transport sector, the Renewable Energy Directive confirms the EU's commitment to renewable transport fuels especially advanced biofuels. Imola is an elite poplar clone crossed from Populus deltoides Bartr. and Populus nigra L. by Research Units for Intensive Wood Production, Agriculture Research Council in Italy. This study examines its suitability for plantation cultivation under short or very short rotation coppice regimes as a potential lignocellulosic feedstock for the production of ethanol as a transport biofuel. A life cycle assessment (LCA) approach was used to model the cradle-to-gate environmental profile of Imola-derived biofuel benchmarked against conventional fossil gasoline. Specific attention was given to analysing the agroecosystem fluxes of carbon and nitrogen occurring in the cultivation of the Imola biomass in the biofuel life cycle using a process-oriented biogeochemistry model (DeNitrification-DeComposition) specifically modified for application to 2G perennial bioenergy crops and carbon and nitrogen cycling. RESULTS: Our results demonstrate that carbon and nitrogen cycling in perennial crop-soil ecosystems such as this example can be expected to have significant effects on the overall environmental profiles of 2G biofuels. In particular, soil carbon accumulation in perennial biomass plantations is likely to be a significant component in the overall greenhouse gas balance of future biofuel and other biorefinery products and warrants ongoing research and data collection for LCA models. We conclude that bioethanol produced from Imola represents a promising alternative transport fuel offering some savings ranging from 35 to 100 % over petrol in global warming potential, ozone depletion and photochemical oxidation impact categories. CONCLUSIONS: Via comparative analyses for Imola-derived bioethanol across potential supply chains, we highlight priority issues for potential improvement in 2G biofuel profiling. Advanced clones of poplar such as Imola for 2G biofuel production in Italy as modelled here show potential to deliver an environmentally sustainable lignocellulosic biorefinery industry and accelerate advanced biofuel penetration in the transport sector.

Background levels of polybrominated diphenyl ethers (PBDEs) in soils from Mount Meru area, Arusha district (Tanzania).

This study investigates the contamination by 13 polybrominated diphenyl ether (PBDE) congeners in an altitudinal soil transect on Mt. Meru area, Northern Tanzania. A ∑13PBDEs mean concentration of 386±200 pg/g d.w. (4900±3500 pg ∑13PBDEs/g soil organic matter - SOM) was measured, pointing out that, in a prevalently agricultural area from the southern hemisphere, PBDE contamination can be even higher than in similar semi-remote environment of industrialized country of the northern one. The Mt. Meru PBDE pattern of contamination was characterized by the prevalence of intermediate brominated congeners (tetra- and penta-BDEs). Among the detected compounds, BDE-47 was the main congener, followed by BDE-99, BDE-190 and BDE-100. The distribution of PBDEs confirmed that organic carbon had a substantial impact on their accumulation in Tanzanian soils. The altitudinal profile of PBDEs (log TOC-normalized concentrations) fitted a second order polynomial model with altitude, with an initial concentration decrease, interpreted as a dilution effect from local/regional sources, and a following consistent increase with altitude according to the cold condensation theory. Evidences of distillation effect among PBDE congeners were also observed.

Highly spatially- and seasonally-resolved predictive contamination maps for persistent organic pollutants: development and validation.

A reliable spatial assessment of the POPs contamination in soils is essential for burden studies and flux evaluations. Soil characteristics and properties vary enormously even within small spatial scale and over time; therefore soil capacity of accumulating POPs varies greatly. In order to include this very high spatial and temporal variability, models can be used for assessing soil accumulation capacity in a specific time and space and, from it, the spatial distribution and temporal trends of POPs concentrations. In this work, predictive contamination maps of the accumulation capacity of soils were developed at a space resolution of 1×1m with a time frame of one day, in a study area located in the central Alps. Physical algorithms for temperature and organic carbon estimation along the soil profile and across the year were fitted to estimate the horizontal, vertical and seasonal distribution of the contamination potential for PCBs in soil (Ksa maps). The resulting maps were cross-validated with an independent set of PCB contamination data, showing very good agreement (e.g. for CB-153, R(2)=0.80, p-value≤2.2·10(-06)). Slopes of the regression between predicted Ksa and experimental concentrations were used to map the soil contamination for the whole area, taking into account soil characteristics and temperature conditions. These maps offer the opportunity to evaluate burden (concentration maps) and fluxes (emission maps) with highly resolved temporal and spatial detail. In addition, in order to explain the observed low autumn PCB concentrations in soil related to the high Ksa values of this period, a dynamic model of seasonal variation of soil concentrations was developed basing on rate parameters fitted on measured concentrations. The model was able to describe, at least partially, the observed different behavior between the quite rapid discharge phase in summer and the slow recharge phase in autumn.

Environmental variables affecting the distribution of POPs on Mt. Meru, Tanzania.

Tanzania is an equatorial country characterized by warm temperatures, which should increase the volatilization of persistent organic pollutants (POPs), but this scenario could be different in mountainous areas like Mount Meru, a volcano situated in the East African Rift (Tz). We collected soil samples along an altitudinal transect upto 4577 m a.s.l., reporting the first data about POP contamination in this area (DDX, HCHs, HCB and PCBs). The DDX contamination pattern in Mt. Meru shows levels slightly higher than those of other remote places with a strong increase in the metabolites/DDT historical trend, which is different from DDX, PCBs, HCHs and particularly HCB as this shows very low contamination levels. Back trajectory analysis allowed a discussion about putative contamination sources, while analysis of the environmental features (climatic and pedological) allowed us to discriminate their relative importance. The distribution of POPs shows a strong correlation with soil organic matter and vegetation. SOM-normalization evidenced altitudinal dependence according to cold condensation for PCBs and HCHs, while DDX are present in larger amounts in the agricultural area at the volcano foot. OM-normalized concentrations suggested also a possible role of the OM composition on the POPs' distribution.

Meteorological and pedological influence on the PCBs distribution in mountain soils.

Polychlorinated biphenyls (PCBs) are a threat to environmental and human health due to their persistence and toxicological effects. In this paper, we analyse some meteorological and organic-matter-related effects on their distribution in the soils of an Alpine environment that is not subject to direct contamination. We collected samples and measured the contamination of 12 selected congeners from three soil layers (O, A1 and A2) and from North-, plain- and South-facing slopes on six different dates spanning the entire snowless portion of the year. We recorded the hourly air and soil temperatures, humidity and rainfall in the study period. We found evidence that PCBs contamination in soils varies significantly, depending on sampling date, layer and aspect. The observed seasonal trend shows an early summer peak and a rapid decrease during June. The layer effect demonstrates higher dry-weight-based concentrations in the O layer, whereas the differences are much smaller for SOM-based concentrations. Different factors caused significantly higher concentrations in northern soils, with a N/S enrichment factor ranging from 1.8 to 1.5 during the season. The southern site has significantly more rapid early-summer re-volatilisation kinetics (half-time of 16d for South, 25d for North).

Seasonal changes and temperature-dependent accumulation of polycyclic aromatic hydrocarbons in high-altitude soils.

Polycyclic Aromatic Hydrocarbons (PAHs) are a major group of pollutants whose occurrence in the environment is mainly of anthropogenic origin. In this paper, we examine the effect of topographical slope exposure on PAH contamination and seasonal change in PAH concentrations in soils. We collected soil samples on three dates in 2007 (early May, end of July and beginning of November) from south- and north-facing aspects at 1900 m a.s.l. in the central Italian Alps. We found greater PAH contamination in soils from a north-facing slope than in those from a south-facing slope at all seasons. We calculated North-South Enrichment Factors as the ratio between the concentrations measured in soils from northern and southern aspects. These ratios ranged from 1.4 to 1.9 for lighter PAHs (from 2 to 4 rings). These values are consistent with theoretical calculations based on temperature-specific octanol-air partition coefficients (predicted North-South Enrichment Factors range from 1.6 to 2.0). For heavier PAHs (from 5 to 6 rings), smaller differences were observed between soils from northern and southern aspects, due to the gas/particle distribution of these compounds. We also found consistent differences in normalised PAH concentrations across the three sampling periods. The majority of compounds showed a significant decreasing trend from the beginning of May to the end of July, due to the annual cycles of physical processes (deposition vs. volatilisation) and biological processes (uptake and/or biotransformation). Only a few compounds showed different trends, presumably due to season-specific local emission sources.

Preferential retention of POPs on the northern aspect of mountains.

Soils are the main reservoirs of POPs in mountain ecosystems, but the great variability of the concentrations, also at small scale, leaves some uncertainties in the evaluation of environmental burdens and exposure. The role of the aspect of the mountain side and the seasonal variation in the contamination levels was analysed by means of several soil samples taken from central Italian Alps. A greater contamination content was present in northern soils with a mean ratio between the north vs. south normalised concentration of around a factor of 2 (North-South Enrichment Factor). Experimental factors agreed with theoretical calculations based on temperature-specific calculated K(sa) values. From May to November consistent differences in normalised concentrations up to 5-fold were observed. A dynamic picture of the POP contamination in high altitudinal soils is derived from the data in this work, with spring-summer half-lives between 60 and 120 days for most of the compounds.