Environmental consequences of wheat-based crop rotation in potato farming systems in galicia, Spain.

Intensive agricultural farming systems have negative impacts on the ecosystem. Therefore, the use of crop rotation emerges as an opportunity to improve the environmental sustainability of agricultural systems. In the region of Galicia in north-western Spain, potato and wheat are important commodities and essential foods in the diet. Hence, it is interesting to investigate the environmental profile of these crops to improve the understanding of local agrosystems. This study evaluated three agricultural crops managed under a crop rotation system and following a conventional arable farming: the main rotation crop, which is the potato in the first year (cP), followed by a second year of commercial wheat (cW) and autochthonous Galician wheat (GcW) in the third year. The Life Cycle Assessment (LCA) methodology was performed using four types of functional units: in terms of productivity (kg-1); land management (ha-1∙year-1); a financial function (euros €-1 of income from sales) and energetic value (MJ-1). The environmental indicators selected are Climate Change (CC), Particulate Matter (PM), Terrestrial Acidification (TA), Freshwater Eutrophication (FE), Marine Eutrophication (ME), Human Toxicity (HT), Land Use (LU) and Fossil Depletion (FD). The figures show that the GcW has the lowest environmental impact when the functional units refer to land management, financial function and energetic value. However, if analysed in terms of productivity, cP is presented as the best crop due to its comparatively higher yield, reaching a production ratio 10 times higher than wheat. In the specific case of wheat, compared to a previous study in the same region, the environmental impacts are lower when grown in a crop rotation system in contrast to monoculture. This article demonstrates the relevance of using LCA for diverse stakeholders (e.g., farmers, consumers and researchers) to understand the environmental impacts of regional agricultural systems. In addition, it serves as a basis for future work aimed at comparing rotational agricultural systems in this region, integrating economic and social aspects.

Environmental assessment of different biofilters for the treatment of gaseous streams.

Biological techniques have been considered as an interesting alternative to treat gaseous streams from industrial processes. In this work, the performance of biofilters was evaluated from an environmental point of view by using Life Cycle Assessment methodology. More specifically, the potential impacts of four biofilters packed with different organic materials: spherical clay pellets covered with compost, a mixture of coconut fibre and sludge based carbon, peat and heather and pine bark have been quantified. The impact categories considered in this work were: eutrophication, acidification, global warming, photochemical oxidation, malodorous air, human toxicity and marine, terrestrial and freshwater ecotoxicity. From an environmental point of view, the reactor packed with coconut fibre and sludge based carbon appears to be the most suitable alternative since it presented the lowest values in almost all the impact categories assessed. On the other hand, the biofilter packed with clay pellets covered with compost seems to be the most penalized bioreactor providing the highest impacts for six of the nine impact categories evaluated, mainly due to the significant pressure drop achieved in the reactor which led to a considerable increase of energy demand. The reactor packed with coconut fibre and sludge based carbon is also the most beneficial alternative after performing the normalization step. In this case, the alternatives of peat and heather and pine bark are the less favourable ones in terms of photochemical oxidation, which was attributed to the lowest efficiency of methyl isobutyl ketone removal efficiency observed in both configurations. On the other hand, the option of treating off-gases is, in general, more positive and advisable than the direct discharge to the atmosphere.

Benchmarking environmental and operational parameters through eco-efficiency criteria for dairy farms.

Life Cycle Assessment (LCA) is often used for the environmental evaluation of agri-food systems due to its holistic perspective. In particular, the assessment of milk production at farm level requires the evaluation of multiple dairy farms to guarantee the representativeness of the study when a regional perspective is adopted. This article shows the joint implementation of LCA and Data Envelopment Analysis (DEA) in order to avoid the formulation of an average farm, therefore preventing standard deviations associated with the use of average inventory data while attaining the characterization and benchmarking of the operational and environmental performance of dairy farms. Within this framework, 72 farms located in Galicia (NW Spain) were subject to an LCA+DEA study which led to identify those farms with an efficient operation. Furthermore, target input consumption levels were benchmarked for each inefficient farm, and the corresponding target environmental impacts were calculated so that eco-efficiency criteria were verified. Thus, average reductions of up to 38% were found for input consumption levels, leading to impact reductions above 20% for every environmental impact category. Finally, the economic savings arising from efficient farming practices were also estimated. Economic savings of up to 0.13€ per liter of raw milk were calculated, which means extra profits of up to 40% of the final raw milk price.

Anaerobic microbial mobilization and biotransformation of arsenate adsorbed onto activated alumina.

Due to the enactment of a stricter drinking water standard for arsenic in the United States, larger quantities of arsenic will be treated resulting in larger volumes of treatment residuals. The current United States Environmental Protection Agency recommendation is to dispose spent adsorbent residuals from arsenic treatment into non-hazardous municipal solid waste (MSW) landfills. The potential of microorganisms to alter the speciation affecting the mobility of arsenic in the disposal environment is therefore a concern. The purpose of this paper was to evaluate the potential of an anaerobic microbial consortium to biologically mobilize arsenate (As(V)) adsorbed onto activated alumina (AA), a common adsorbent used for treating arsenic in drinking water. Three anaerobic columns (0.27 l) packed with 100 g dry weight of AA containing 0.657 mg adsorbed As(V) (expressed as arsenic) per gram dry weight were continuously flushed with synthetic landfill leachate for 257 days. The fully biologically active column was inoculated with methanogenic anaerobic sludge (10 g volatile suspended solids l(-1) column) and was operated with a mixture of volatile fatty acids (VFA) in the feed (2.5 g chemical oxygen demand l(-1) feed). At the end of the experiment, 37% of the arsenic was removed from the column, of which 48% was accounted for by arsenical species identified in the column effluent. The most important form of arsenic eluted was arsenite (As(III)), accounting for nearly all of the identified arsenic in periods of high mobilization. Additionally, two methylated metabolites, methylarsonic acid and dimethylarsinic acid were observed. Mobilization of arsenic is attributed to the biological reduction of As(V) to As(III) since literature data indicates that As(III) is more weakly adsorbed to AA compared to As(V). Batch and continuous assays confirmed that VFA, present in landfill leachates, served as an electron donating substrate supporting enhanced rates of As(V) reduction to As(III). Two control columns, lacking inoculum and/or VFA in the feed displayed low mobilization of arsenic compared to the fully biologically active column. Therefore, leachates generated in MSW landfills could potentially result in the biologically catalyzed mobilization of arsenic from As(V)-laden drinking water residuals.