1,721,082 research outputs found
How much are we paying for drinking water in (PET) bottles? A global assessment of the hidden costs and potential damage to the environment
No full textPlastic pollution is a global problem of unprecedented magnitude. In particular, marine plastic pollution is one of the biggest environmental problems, mainly due to single-use or disposable plastic waste, such as polyethylene terephthalate (PET) bottles. With the aim of quantifying their post-use fate and types of environmental damage, we have carried out the first global calculation of total stocks and fluxes since 1950, as well as an estimate of the value of ecosystem services lost due to the mismanagement and abandonment of PET bottles in the environment.
The analysis was conducted by collecting and synthesizing published data on the production, use and end-of-life management of PET bottles. The results show that since the start of plastic production in 1950, about 80 % of all PET bottles produced and used have been mismanaged, littered or dumped. Of this, about 8 %, or about 19 Mt, has been lost to oceans and seas, resulting in global damage costs of about USD 8.6 billion, mainly due to the loss of ecosystem services. For a single PET bottle, this corresponds to a hidden cost estimated at around USD 0.02, which is around 100 % of the current average production price of a 500 ml PET bottle
Direct measurement of dissolved dinitrogen to refine reactive modelling of denitrification in agricultural soils
No full textNitrogen fertilizers used in agriculture often cause nitrate leaching towards shallow groundwater, especially in lowland areas where soil permeability, ploughing, clay content, and the flat topography minimizes surface runoff. The introduction of good agricultural practices to reduce the nitrate amount entering the groundwater system is crucial to ameliorate the kinetic control on nitrate denitrification capacity. With this aim, a series of anaerobic mesocosms, consisting of loamy and clay soils and nitrate rich water, were modelled using acetate and natural organic matter as electron donors. Acetate was chosen because it is the main intermediate in many biodegradation pathways of organic compounds, and hence it is a suitable carbon source for denitrification. To account for the spatial variability of soil parameters, the experiments were performed in triplicates. The geochemical code PHREEQC(3) was used to simulate kinetic denitrification, and equilibrium reactions of gas and mineral phases. The reactive modelling results highlighted a rapid acetate and nitrate degradation rate, a rapid production of dissolved inorganic carbon and dinitrogen, and a steady concentration of dissolved iron and sulphate, suggesting that the main pathway of nitrate attenuation is through denitrification; concomitantly excluding the occurrence of other processes leading to nitrate consumption. In the absence of acetate, the loamy soil, poor of natural organic matter, did not allow to complete the denitrification process.This modelling study investigates in detail the relationship between the denitrification process in natural soils, with excess and in limitation of organic substrates, and the occurrence and fate of dissolved dinitrogen analysed with a high precision membrane inlet mass spectrometer. Results demonstrate that modelling nitrate degradation processes as a whole, using geochemical datasets and codes, will improve the estimates of agricultural landscapes denitrification and support better nitrogen management, especially in lowland environments. (C) 2018 Elsevier B.V. All rights reserved
Multi-scale spatio-temporal patchiness of macrozoobenthos in the Sacca di Goro lagoon (Po River Delta, Italy)
No full textContrasting biogeochemical processes revealed by stable isotopes of H2O, N, C and S in shallow aquifers underlying agricultural lowlands
No full textLowland coastal areas as the Po Delta (Italy) are often intensively cultivated and affected by nitrogen imbalance due to fertilizers leaching to groundwater and export via run-off. To address this issue several agricultural best practices have been proposed, like limiting the amount of fertilizers and increasing soil organic matter content. In this study, groundwater samples were analysed for major ions and stable isotopes of H2O, C, N and S using multi-level sampler (MLS) from two contrasting depositional environments, one representative of alluvial plain (AP) and the other representative of a reclaimed coastal plain (RCP). In each site, controlled plots with different agriculture practice including fertilizers and tillage and compost amendment and no tillage were considered in the study. Tracer test results highlight that recharge water infiltrated at the start of the controlled study has not yet reached the saturated zone, thus current groundwater concentrations are representative of former agricultural practices. Stable isotopes show a clear distinction between different sources of nitrogen in both sites, from synthetic fertilizers to sedimentary nitrogen pool and atmospheric input. The main source of sulphate in groundwater is pyrite and fertilizers. Denitrification, sulphate reduction and methanogenesis were involved in the C, N and S cycle in the RCP site characterized by low hydraulic conductivity sediments and high SOM. These processes were not relevant in the AP site characterized by oxic condition and low SOM, but some evidence of denitrification was found in one of the AP sites. High resolution monitoring was a key tool to identify the different redox zones responsible for N, C and S cycling in these aquifers. This study shows that a clear understanding of transit times in the vadose zone is a key prerequisite to evaluate the effect of controlled agriculture practice on the quality of shallow groundwater.Lowland coastal areas as the Po Delta (Italy) are often intensively cultivated and affected by nitrogen imbalance due to fertilizers leaching to groundwater and export via run-off. To address this issue several agricultural best practices have been proposed, like limiting the amount of fertilizers and increasing soil organic matter content. In this study, groundwater samples were analysed for major ions and stable isotopes of H2O, C, N and S using multi-level sampler (MLS) from two contrasting depositional environments, one representative of alluvial plain (AP) and the other representative of a reclaimed coastal plain (RCP). In each site, controlled plots with different agriculture practice including fertilizers and tillage and compost amendment and no tillage were considered in the study. Tracer test results highlight that recharge water infiltrated at the start of the controlled study has not yet reached the saturated zone, thus current groundwater concentrations are representative of former agricultural practices. Stable isotopes show a clear distinction between different sources of nitrogen in both sites, from synthetic fertilizers to sedimentary nitrogen pool and atmospheric input. The main source of sulphate in groundwater is pyrite and fertilizers. Denitrification, sulphate reduction and methanogenesis were involved in the C, N and S cycle in the RCP site characterized by low hydraulic conductivity sediments and high SOM. These processes were not relevant in the AP site characterized by oxic condition and low SOM, but some evidence of denitrification was found in one of the AP sites. High resolution monitoring was a key tool to identify the different redox zones responsible for N, C and S cycling in these aquifers. This study shows that a clear understanding of transit times in the vadose zone is a key prerequisite to evaluate the effect of controlled agriculture practice on the quality of shallow groundwater. (c) 2019 Elsevier B.V. All rights reserved
L’azoto e il suo cammino nell’ambiente
No full textNegli ultimi cento anni la quantità di azoto circolante nella biosfera è quasi raddoppiata con forti ripercussioni ambientali. Oggi il problema più grave, in ampie aree dell’Europa e del Nord America, riguarda la contaminazione delle acque di falda che ne mette
a rischio il loro uso potabile. Fra le pratiche utili a ridurre il carico di questo elemento si segnalano apporti fertilizzanti corretti e frazionati, una tecnica irrigua a ridotto consumo di acqua, il ripristino di fasce di vegetazione ai bordi degli appezzamenti e lungo i canali
Estuarine macrofauna affects benthic biogeochemistry in a hypertrophic lagoon
No full textCoastal lagoons display a wide range of physico-chemical conditions that shape benthic macrofauna communities. In turn, benthic macrofauna affects a wide array of biogeochemical processes as a consequence of feeding, bioirrigation, ventilation, and excretion activities. In this work, we have measured benthic respiration and solute fluxes in intact sediment cores with natural macrofauna communities collected from four distinct areas within the Sacca di Goro Lagoon (NE Adriatic Sea). The macrofauna community was characterized at the end of the incubations. Redundancy analysis (RDA) was used to quantify and test the interactions between the dominant macrofauna species and solute fluxes. Moreover, the relevance of macrofauna as driver of benthic nitrogen (N) redundancy analysis revealed that up to 66% of the benthic fluxes and metabolism variance was explained by macrofauna microbial-mediated N processes. Nitrification was stimulated by the presence of shallow (corophiids) in combination with deep burrowers (spionids, oligochaetes) or ammonium-excreting clams. Deep burrowers and clams increase ammonium availability in burrows actively ventilated by corophiids, which creates optimal conditions to nitrifiers. However, the stimulatory effect of burrowing macrofauna on nitrification does not necessarily result in higher denitrification as processes are spatially separated
Swoon over the moon: The influence of environmental factors on glass eels entering Mediterranean coastal lagoons
No full textThe European eel (Anguilla anguilla, Linnaeus 1758) is a critically endangered species that completes its life cycle between the freshwaters of Europe (and North Africa) and spawning grounds in the Sargasso Sea. Its marine larvae are planktonic and metamorphose into post-larval glass eels near the coast. The relationship between environmental variables and the migration of glass eels into brackish water and estuaries is not well understood, but has important implications for European eel conservation and management. Using linear mixed effects (LME) models, we investigated the combined role of meteorological (wind direction and strength and rainfall), oceanographical (tide amplitude), astronomical (moon phase and illumination), temporal and water quality variables on the timing and magnitude of glass eel migration from marine to brackish waters in the Comacchio Lagoon, Northern Adriatic Sea. We used this site as a test case because it was historically prominent in glass eel wild harvest for extensive aquaculture in the Mediterranean region. We found that meteorological factors and tide amplitude had a weak effect on the migration of glass eels into the lagoon. On the contrary, astronomical variables strongly influenced glass eel movement, with waxing phases and intermediate illumination enhancing movement towards the lagoon. We also identified at least two distinct migration pulses during our study period, which were not affected by temporal and water quality variables. Temporal and water quality variables affected body size of glass eels, with bigger glass eels caught later in the season. Identifying the importance of environmental variables affecting glass eels recruitment to brackish waters can help promoting eel stocks restoration through local management
Image analysis-based assessment of perfluorooctanoic acid-induced liver pathology in piscine model
No full textSoil conditioners effects on hydraulic properties, leaching processes and denitrification on a silty-clay soil
Full text linkAgricultural landscapes are often affected by groundwater quality issues due to fertilizers leaching. To address this worldwide problem several agricultural best practices have been proposed, like limiting the amount of fertilizers and increasing soil organic matter content. To evaluate if these practices may promote groundwater quality enhancement, vadose zone retention time and complex biogeochemical processes must be known in detail. In this study, sequential undisturbed column experiments were performed to determine the amount of nutrients and heavy metals leached after simulated stormwater events. The column was amended with urea then flushed for two pore volumes, then straw residuals were incorporated and flushed for two pore volumes and finally compost was incorporated and flushed for six pore volumes. Dissolved ions, major gasses and heavy metals were determined in leachate samples. Nitrate and nitrite were leached in the urea treatment producing the highest concentrations, followed by compost and straw residuals. The redox conditions were aerobic in all treatments and pH was circumneutral or slightly basic. Denitrification was low but increased with the addition of straw residuals and compost. Heavy metals were all at very low concentrations except for lead and cadmium, which slightly exceeded threshold limits (10 and 1 μg/L, respectively) in all the treatments. The compost treatment, after three pore volumes, was affected by clay swelling due to sodium dispersion, which in turn provoked a reduction of porosity and hydraulic conductivity
- …
