Trace metals used as natural markers for discriminating some karstic freshwaters near Trieste (Italy)

Some heavy metals have been determined using voltammetry in freshwaters forming part of a karstic hydrological system (the Timavo River, north of Trieste), during attempts to characterize and discriminate the different sources of the springs. The trace elements can be considered natural markers, with lead appearing to be the most discriminating variable. Non parametric statistics and cluster analysis were used to estimate the significance of the determined parameters with respect to the considered ecosystem.     

Potential impacts of early twenty-first century changes in temperature and precipitation on rainfed annual crops in the Central Andes of Peru

Smallholder agriculture in the Central Andes of Peru is based to large extent on rainfed cropping systems, is exposed to climatic risks and is expected to respond sensitively to increasing temperatures and shifts in the precipitation regime. Here, we examine the potential implications of early twenty-first century climate change scenarios for the cultivation of potato, maize, wheat, barley and broad bean, five annual crops that account for 50 % of the cultivated area in the Department of Cusco and Apurímac and provide the dietary backbone for a large share of the local population. The scenarios disclose a regionally coherent increase in temperature of the order of 1 °C but overall only moderate changes in growing season precipitation by 2030. A simple crop model is used to assess the effects of these changes on crop phenology and development. The results show earlier harvest dates, shorter cropping seasons and, in a few cases, a slightly higher risk of planting failure in the near future. This suggests that a better understanding of changes in the precipitation regime at the onset of the cropping season is required to evaluate short-term needs and possibilities for adaptation. However, as the scenarios are highly uncertain, these conclusions should be verified.     

Short-term impact of olive mill wastewater (OMWW) applications on the physico-chemical and microbiological soil properties of an olive grove in Argentina

The purpose of this work was to investigate the effects of spreading olive oil mill wastewater (OMWW) on soil biochemical parameters and olive production in an organically managed olive orchard. The experiment was carried out with three different doses of OMWW (80, 160 and 500 m³ ha^?1) and a control (untreated soil). Three samplings were done at 10, 30 and 90 days after the administration of the byproduct. OMWW application differentially modified the biochemical properties of the soil analyzed. Organic matter, organic carbon, total nitrogen and extractable phosphorus soil contents increased proportionally with each increasing dose. The values of these parameters decreased gradually with time. Total microbial activity was altered and the OMWW 500 m³ ha^?1 treatment proved to be the most active when compared with the other applied doses. OMWW agricultural application also modified the structure of soil microbial communities, particularly affecting Gram positive and negative bacteria, while fungal biomass did not show consistent changes. Although there was a salinity increase in the treated soil, especially at the highest dose, the productive parameters analyzed (fruit and oil tree^?1) were not affected. In light of the obtained results, we consider that low dose of OMWW could be considered an alternative farming practice for semiarid regions.     

Environmental and lifestyle factors affect benzene uptake biomonitoring of residents near a petrochemical plant

Background

We monitored urinary benzene excretion to examine factors affecting benzene uptake in a sample of the general population living near a petrochemical plant.

Methods

Our study population included 143 subjects: 33 petrochemical plant workers (W) with low level occupational benzene exposure; 30 residents in a small town 2 km from the plant (2kmR); 26 residents in a second small town located 2 to 4 km from the plant (4kmR); and 54 urban residents 25 km from the plant (25kmR). Exposure to benzene was evaluated by personal air sampling during one work-shift for the W group, and from 8.00 to 20:00 for general population subgroups, and by urinary benzene (BEN-U).

Results

Median airborne benzene exposure was 25, 9, 7 and 6 μg/m³ benzene among the W, 2kmR, 4kmR, and 25kmR subgroups, respectively; the highest level was found among the workers, while there was no significant difference among the other groups. Median BEN-U was 2 to 14-fold higher in smokers compared to non-smokers; among non-smokers BEN-U was the highest in W (median 236 ng/L), and lower in the 2kmR (48 ng/L) and 4kmR (63 ng/L) subgroups than in the 25kmR (120 ng/L) subgroup. A multiple linear regression analysis, explaining up to 73% of BEN-U variability, confirmed that active smoking and airborne benzene most strongly affected BEN-U. Among the non-smoking, non-occupationally exposed study subjects, a positive association was found between BEN-U and the distance of residence from the plant. This association was explained by increased exposure to urban traffic emissions in the study group residing at a greater distance from the plant. Environmental tobacco smoke had a marginally positive role.

Conclusion

Among factors affecting benzene uptake in non-occupationally exposed individuals, urban residence contributes to benzene exposure more than residing in close proximity to a petrochemical plant.     

Risk management strategies to cope with climate change in grassland production: an illustrative case study for the Swiss plateau

In this paper, we assess climate change impacts on an intensively managed grassland system at the Swiss Plateau using the process-based grassland model PROGRASS. Taking the CO₂ fertilization into account, we find increasing yield levels (in the range of 10–24%) and sharp increases in production risks for an illustrative climate change scenario that suggests a marked increase in temperature and decrease in summer rainfall. Climate change–induced increases in the coefficients of variation of grassland yields are in the range of 21 and 50%. This finding underpins that additional risk management strategies are needed to cope with climate-change impacts on grassland production. The outputs from the grassland model are evaluated economically using certainty equivalents, i.e., accounting for mean quasi rents and production risks. To identify potential risk management strategies under current and future climatic conditions, we consider adjustments of production intensity and farm-level yield insurance. The impact of climate change on production intensities is found to be ambiguous: farmers’ will increase intensity under unconstrained production conditions, but will decrease production intensity in the presence of a cross-compliance scheme. Our results also show that the considered insurance scheme is a powerful tool to manage climate risks in grassland production under current and future conditions because it can reduce the coefficients of variation of quasi rents by up to 50%. However, we find that direct payments tend to reduce farmers’ incentives to use such insurance scheme.     

Modification of soil humic matter after 4 years of compost application

Two soil plots, 1 ha each, were amended yearly for 4 years, respectively, with 35.8 and 71.6 Mg ha(-1) yr(-1) of mature compost (CM) obtained from food and vegetable residues. The compost, amended soils, and a control soil plot after 4 years (S4), were analyzed for humin (HUC), humic acid (HAC), fulvic acid (FAC), and non-humic carbon (NHC) content. Compared to S4, the amended soil contained more humified C (HAC, FAC and HUC) and less NHC. Further evidence of the effect of compost on soil organic matter was obtained by the analysis of the humic acid (HA) fractions isolated from both the compost and the soils. These were characterized by elemental analyses and Diffuse Reflectance Infrared Fourier Transformed spectroscopy. The HAs isolated from CM and from S4 were significantly different. The HAs isolated from the amended plots were more similar to HA isolated from CM than to HA isolated from S4. The experimental data of this work indicate that the compost application may affect significantly the soil organic matter composition, and that the approach used in this work allows one to trace the fate of compost organic matter in soil.     

Isolation of the stable fraction (the core) of the humic acid

Humic acid consists of a recalcitrant (unhydrolysed fraction) (the core) and labile (hydrolysable fraction) fraction. Core-humic acid (core-HA) isolation was performed by treating source material with apolar and polar solvents (organic solvents+acid hydrolysis) before alkaline extraction. Leonardite, soil Ah horizont and dry blood were chosen for this study because of their different origin and degree of humification. Chemical analysis (elemental analysis, total acidity, E(4):E(6)), spectroscopic analysis (DRIFT and (1)H NMR), and complete mass balance were used to investigate the effect of purifying humic acids. The results obtained showed that purification produced a slight modification of Leonardite humic acids as was expected for these highly humified organic matrices. On the other hand, about 500 g kg(-1) of soil humic acids were lost by purification. The fractions lost mainly consisted of carbohydrates. Dry blood showed the presence of humic acids that contrasted with its origin, thus indicating the limitations of the common analytical methods used for HA extraction. Nevertheless, in practice, purification caused the complete disappearance (914 g kg(-1) of HA was lost) of these HAs. The results obtained in this work suggest that the HA fraction isolated (named core-HA) effectively represents the HA structure proposed by the existing literature, since the purification proposed was able to eliminate the adsorbed organic molecules (interference materials) coating the HA structure.     

Compost effect on soil humic acid: A NMR study

The humic acid (HA) fraction of a food and vegetable residues compost (CM) was taken as indicator to trace the fate of CM organic matter in four years CM amended soil. (1)H and (13)C NMR spectroscopy were used to investigate the nature of the HA isolates from CM, control soil (S(4)) and amended soil. The result indicated a significant structural difference between CM HA and S(4) HA, and supported the presence of both HA fractions in soil at the end of the amendment trials. However, the nature and content of CM HA in soil did not fully explain the increase of soil cation exchange capacity (CEC) after amendment. All CM humic fractions (i.e., fulvic acid, humic acid and humin) were found to contribute to the change of the soil organic matter composition. It is concluded that although CM HA is a suitable indicator of the survival of compost organic matter in soil during amendment, all three humic fractions should be monitored and analyzed to fully understand changes in the composition and properties of amended soil.     

An improved index for monitoring metal pollutants in surface sediments

An approach for defining the quality of surface sediments of limited areas in terms of heavy metal contents is proposed. Sediments were taken on a bi‐dimensional mapping, for checking possible different sources of pollution in the case study, a harbour zone. Non residual metals were determined by ICP‐AES in cold diluted hydrochloric acid leachates of sediments. An “enrichment factor”;, r, can be computed for each metal: metals with r values exceeding unity can be considered as indicators of metal pollution. A “total enrichment factor”;, R, was proposed in order to assess the degree of pollution of sediments for each site. R is an adimensional value that accounts for the presence of metals that exceed threshold values determined by background concentrations.