Environmental biogeochemistry of mercury in Antarctic ecosystems

Polar regions are recognized as important sinks for long-range transport and deposition of Hg derived from natural and anthropogenic sources at lower latitudes. In previous studies we found enhanced Hg accumulation in soils, mosses and lichens from ice-free areas of Victoria Land facing the Terra Nova Bay coastal polynya. This study extends research to the distribution of organic C, total N, S, Hg, Al and Fe in surface soils, cyanobacterial mats and short sediment cores from four lacustrine ecosystems, each with different environmental characteristics and varying distances from the polynya. Results show that planktonic and benthic mats from lakes, along with mosses in the watershed, are the main sinks for Hg in summer meltwater. The C-normalized Hg concentrations in short sediment cores were higher in samples from lakes more exposed to marine aerosols from the coastal polynya. Reactive halogens in the aerosol promote the oxidation and deposition of atmospheric Hg in coastal ecosystems. The analysis of sediment cores did not reveal increasing Hg concentrations in recent sediments, except in the Lake 14 at Edmonson Point. The latter ice-free area is unaffected by the polynya and the increase in Hg concentrations in surface sediments could be due to local changes in lake water level and S biogeochemistry. Although change in sea ice coverage may enhance the role of Antarctic coastal ecosystems as sink in the global Hg cycle, our results seem to exclude possible risks for Antarctic terrestrial and freshwater organisms.     

Use of electronic nose technology to measure soil microbial activity through biogenic volatile organic compounds and gases release

Gas and volatile organic compounds (VOCs) release in soil is known to be linked to microbial activity and can differently affect the life of organisms in soil. Electronic noses (E-noses) are sensing devices composed of sensor arrays able to measure and monitor gases and VOCs in air. This is the first report on the use of such a sensing device to measure specifically microbial activity in soil. In the present study, γ-irradiated sterilised soil was inoculated with Pseudomonas fluorescens. To be sure for a rapid microbial growth and activity, two pulses of nutrient solution with organic and inorganic C, N, P and S sources were added to soil and the resulting microcosms were incubated for 23 d. During the incubation, respiration and enzyme activities of acid phosphatase, β-glucosidase, fluorescein diacetate hydrolase and protease, were measured, and microbial growth as global biomass of vital cells based on substrate-induced respiration (SIR-C_mic) and enumeration of viable and culturable cells by means of dilution plate counts (CFU) were also monitored. Concurrently, VOCs and/or gas evolution in the headspace of the soil microcosms were measured through the E-nose, upon their adsorption on quartz crystal microbalances (QCMs) comprising the sensory device. The E-nose typically generated an odorant image (olfactory fingerprint) representative of the analysed samples (soils) and resulting from the concurrent perception of all or most of the analytes in headspace, as it commonly happens when several selective but not specific sensors are used together (array). The basic hypothesis of this study was that different soil ecosystems expressing distinct microbial metabolic activities, tested through respiration and enzyme activities, might generate different olfactory fingerprints in headspace. Furthermore, the possibility to detect several substances at the same time, released from the soil ecosystems, possibly deriving from both abiotic and biotic (microbial metabolism) processes provides an “odorant image” representative of the whole ecosystem under study. The E-nose here used succeeded in discriminating between inoculated and non-inoculated ecosystems and in distinguishing different metabolic and growth phases of the inoculated bacteria during incubation. Specifically, E-nose responses were proved highly and significantly correlated with all hydrolytic activities linked to the mobilisation of nutrients from soil organic matter and their cycling, with CO₂ fluxes (respiration and presumed heterotrophic fixation) and with P. fluorescens population dynamics during exponential, stationary and starvation phases measured by SIR-C_mic and CFUs. Interestingly, the E-nose successfully detected soil microbial activity stimulated by nutrient supply, even though none of the catalytic activities tested directly produced VOCs and/or gases. The E-nose technology was then proved able to supply a real holistic image of microbial activity in the entire gnotobiotic and axenic soil ecosystems.     

Consumer Preferences for Farmed Seafood: An Italian Case Study

ABSTRACT

European consumers prefer wild over farmed aquatic food and consider it healthier and tastier. Consumers are increasingly paying attention to sustainability and welfare of farmed fish. Such expectations might be met by organic certification, but this represents a cost for the producer. It is crucial to know consumer habits about farmed aquatic food consumption and willingness to pay for certification. Data about Italian consumers’ preferences regarding farmed organic aquatic food were collected by an online questionnaire. A total of 8,657 answers were analyzed, patterns associated with demographics were investigated, and the degree of correlation among answers was calculated. The majority (75%) of family units buy less than 2 kg of farmed aquatic food per month, spending on average 20–50 €. About 40% never consume organic aquaculture products because of lack of knowledge, unavailability, and high price. Slightly over half (55%) of consumers, regardless of age, sex, and area, were willing to pay a premium price for organic-certified aquatic food, seen as antibiotic free, traceable, and sustainable. Organic food in general is well known, and distrust is the main reason that consumers avoid it, while organic aquatic food is still in its infancy, and lack of knowledge is associated with low consumption.     

Losses of sediment,organic matter,and nutrients in the Argentinean Pampas through rainfall simulation experiments

Journal of Soils and Sediments - Runoff caused by rainfall events contributes to the watercourses pollution through the export of OM, nutrients, and sediments from soils. This study aimed to assess...     

Respiration Index Determination: Dynamic And Static Approaches

Forty-five organic matrices of different types and origin were subjected to the test for the determination of biological stability by means of dynamic respirometric measurement (DRI) and static respirometric measurement (SRI). The results obtained from the comparison between the two indexes indicated that the SRI, compared with the DRI, underestimates the consumption of oxygen by the biomasses and consequently their rate of biological stability by a factor equal to 2. From the analysis of the data it is possible to define the biological stability as DRI<1000 mgO₂kg^?1VSh^?1. The DRI data were correlated with the temperatures of the biomasses showing a linear correlation (R²=0.81, p<0.01) only for stable matrices while for nonstable matrices no significant correlation is found.     

Determination of Biological Stability by Oxygen Uptake on Municipal Solid Waste and Derived Products

A new scientific apparatus and method are proposed for determining biological stability by oxygen uptake (respiration index, RI), on municipal solid waste (MSW) and derived products. For measuring the RI, a dynamic approach (with continuous aeration) was demonstrated to be more effective than the static approach (without aeration). The validity of the method was tested by comparing carbon losses calculated using both respirometric (carbon losses_resp) and analytical data (carbon losses_anal) during four trials performed on MSW and products derived from it. Carbon losses (expressed as g kg^?1C_i, in which C_i represents initial carbon content) were: 219.0 and 248.0, 67.9 and 57.1, 39.6 and 36.4, and 250.7 and 280.3, using respirometric and analytical data alternately for Trials 1,2,3, and 4. The comparison between respirometric data using continuous or no aeration showed, for the latter, an underestimation of RI of between 70% and 90% that was more evident for unstable biomass leading to more similar values when stabilization occurred. The scientific apparatus proposed made it possible to measure oxygen uptake under autothermal conditions and avoid problems connected with the use of a preset temperature, biomass temperature being a consequence of the microbial activity, as is also suggested by the significant linear regression of T versus RI (R² = 0.84, 0.73, 0.82, and 0.90 for the four trials, respectively). The methods proposed could be used with advantage in the future for biological stability measurements, above all for heterogeneous material such as MSW and its products, thus obtaining respirometric data that better reflect what happens during an aerobic process.     

Dourine Reemergence in Italy

In 2011, five outbreaks of dourine were originally reported in Italy. The outbreaks occurred in two regions of southern Italy. From June to December 2011, a surveillance plan has been carried out in Italy to estimate the prevalence and geographical distribution of dourine infection in the equine population. Finally, two other new outbreaks were reported, and seven outbreaks were confirmed. This article describes the results of the surveillance plan, also taking into consideration the prevalence of infection observed in the different types of equine premises.     

A field study of the impact of different irrigation practices on herbicide leaching

Agricultural practices, such as subsurface drainage, irrigation and tillage, may significantly affect pesticide leaching and, consequently, the risk of groundwater contamination. The aim of the present study was to investigate the impact of different irrigation systems on herbicide leaching to shallow groundwater through direct monitoring at the field scale in northern Italy over a 3-year period. Concentrations of the herbicide terbuthylazine (TBA) and its metabolite desethylterbuthylazine (DES) were monitored on 10 farms cropped with maize and irrigated by sprinkler, basin and border systems. Considering the results grouped according to the different irrigation systems, the mean TBA and DES concentrations was lower than the arbitrary non-health based legal limit of 0.1 μg/L using sprinkler and border systems, while it was 0.19 and 0.30 μg/L respectively for TBA and DES using basin systems.However, since many factors other than the irrigation systems can contribute to pesticide leaching and in a field study it is impossible to discriminate between all the different variables, the concentrations of both compounds were simulated with and without irrigation using the model MACRO 5.1 in order to gain a deeper understanding of the role of irrigation on leaching. First, the groundwater table depth, which was measured daily in all fields, was used to calibrate the model and thus achieve a good soil hydrology calibration. To assess the performance of the model the root mean squared error (RMSE) was used. RMSE ranged from 0.2 to 0.5 m, showing that a satisfactory hydrology calibration was obtained. Afterward, the solutes were modelled and the results showed that under non-irrigated conditions, concentrations of both compounds would be very low. These findings validate the hypothesis that careful selection of agricultural practices, such as the type of irrigation, can reduce pesticide leaching.     

ULTRASONOGRAPHIC FINDINGS IN 38 HORSES WITH SEPTIC ARTHRITIS/TENOSYNOVITIS

Septic arthritis/tenosynovitis in the horse can have life‐threatening consequences. The purpose of this cross‐sectional retrospective study was to describe ultrasound characteristics of septic arthritis/tenosynovitis in a group of horses. Diagnosis of septic arthritis/tenosynovitis was based on historical and clinical findings as well as the results of the synovial fluid analysis and/or positive synovial culture. Ultrasonographic findings recorded were degree of joint/sheath effusion, degree of synovial membrane thickening, echogenicity of the synovial fluid, and presence of hyperechogenic spots and fibrinous loculations. Ultrasonographic findings were tested for dependence on the cause of sepsis, time between admission and beginning of clinical signs, and the white blood cell counts in the synovial fluid. Thirty‐eight horses with confirmed septic arthritis/tenosynovitis of 43 joints/sheaths were included. Degree of effusion was marked in 81.4% of cases, mild in 16.3%, and absent in 2.3%. Synovial thickening was mild in 30.9% of cases and moderate/severe in 69.1%. Synovial fluid was anechogenic in 45.2% of cases and echogenic in 54.8%. Hyperechogenic spots were identified in 32.5% of structures and fibrinous loculations in 64.3%. Relationships between the degree of synovial effusion, degree of the synovial thickening, presence of fibrinous loculations, and the time between admission and beginning of clinical signs were identified, as well as between the presence of fibrinous loculations and the cause of sepsis (P ≤ 0.05). Findings indicated that ultrasonographic findings of septic arthritis/tenosynovitis may vary in horses, and may be influenced by time between admission and beginning of clinical signs.