Impact Of Eutrophication Research Articles

Freshwater eutrophication: spatially explicit fate factors for nitrogen and phosphorus emissions at the global scale

Spatially explicit freshwater eutrophication indicators in life cycle assessment focus on phosphorus as the sole contributor to such impacts. Nitrogen may also be an ecological limiting factor in freshwater systems, but commonly not modelled. This work aims at filling this gap by consistently developing fate factors (FFs) for both dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP), using the same underlying model of nutrient export by rivers. The present FFs were developed for application to both diffuse emissions from soil and point emissions of nutrients to freshwater. The fate processes modelled include nutrient attenuation from land to stream, in the river network, in artificial reservoirs and lakes and associated with water consumption. FFs were calculated at a river basin resolution with a global coverage and at the country and global scales by means of emission-weighting aggregation and distinguishing agricultural from non-agricultural emissions. River basin-scale FFs range from 7.7 × 10−8 to 330 days for N emissions and from 3.0 × 10−8 to 520 days for P emissions. Fate factors are aggregated at country and global scale with applicability at such scales in mind. Global average FFs (in days) are FFsoil N global = 125; FFfw N global = 257; FFsoil P global = 23; FFfw P global = 247. Comparison of FFs calculated at various scales showed the importance of using FFs at the highest spatial resolution (i.e. river basin). However, the river basin resolution may be too coarse for certain large basins as demonstrated for the Waikato basin in New Zealand, where FFs calculated at the sub-basin scale varied significantly. The characterisation factors represent the potential contribution of N and P to freshwater eutrophication (in Neq and Peq). The N and P components can be aggregated into a single indicator expressed in “algae-equivalent” for co-limited catchments or when the limitation status is unknown. The present fate model for freshwater eutrophication is consistent with and complements recent advances in marine eutrophication impact assessment. Applying these FFs in conjunction with a spatially explicit inventory data of N and P emissions may improve the environmental relevance of freshwater eutrophication impact assessment in LCA. One limitation is the focus on dissolved N and P, as highlighted by a comparison of attenuation factors with a New Zealand-specific hydrological model. The inclusion of particulate and organic N and P from NEWS2 should be part of future freshwater eutrophication FF developments.

Seasonal Variation in Biomass and Production of the Macrophytobenthos in two Lagoons in the Southern Baltic Sea

Baltic coastal lagoons are severely threatened by eutrophication. To evaluate the impact of eutrophication on macrophytobenthos, we compared the seasonal development in macrophytobenthic composition, biomass and production, water column parameters (light, nutrients), phytoplankton biomass and production in one mesotrophic and one eutrophic German coastal lagoon. We hypothesized that light availability is the main driver for primary production, and that net primary production is lower at a higher eutrophication level. In the mesotrophic lagoon, macrophytobenthic biomass was much higher with distinct seasonal succession in species composition. Filamentous algae dominated in spring and late summer and probably caused reduced macrophytobenthic biomass and growth during early summer, thus decreasing vegetation stability. Light attenuation was far higher in the eutrophic lagoon, due to high phytoplankton densities, explaining the low macrophytobenthic biomass and species diversity in every season. Areal net primary production was far lower in the eutrophic lagoon. The “paradox of enrichment” hypothesis predicts lower production at higher trophic levels with increased nutrient concentrations. Our results prove for the first time that this hypothesis may be valid already at the primary producer level in coastal lagoons.

Life cycle assessment of electricity generation from sugarcane bagasse hydrochar produced by microwave assisted hydrothermal carbonization

Microwave assisted hydrothermal carbonization (MAHTC) is a promising strategy for fuel production from sugarcane bagasse. Even though microwave heating has been reported to facilitate product (hydrochar) yield, energy properties and heating efficiency during hydrothermal carbonization (HTC) process, the environmental consequences of MAHTC treatment were still not clear. This study evaluated the environmental impact associated with 1 MJ electricity generation from sugarcane bagasse hydrochar through life cycle assessment (LCA) method, focusing on the critical role of process-based parameters to provide insights for optimization of MAHTC treatment. Specifically, two different allocation factors (energy content and economic value) and five environmental impact categories (climate change, freshwater eutrophication, freshwater ecotoxicity, human toxicity and fossil depletion) were assessed in this study. The LCA results revealed significant contribution of MAHTC process on climate change and fossil depletion because of large energy consumption used to maintain the system at designed temperature. Discharge of liquid phase from MAHTC process resulted in severe eutrophication impact especially when economic value was used as allocation factor. Gas emission from hydrochar combustion caused most toxicity related impacts indicating essential requirement of further investigation to quantify different gaseous composition. Based on LCA results, sensitivity analysis indicated hydrochar yield and carbon content as the top two influential factors on total environmental consequences. Comparison study with other fuel sources were further conducted to identify the influence of substituted energy sources. The overall results suggested MAHTC as promising method for bagasse utilization and energy retention efficiency as important indicator for optimization of MAHTC treatment or the sake of high-quality products and good environmental performance.

The Impact of Climate Change and Eutrophication on Phosphorus Forms in Sediment: Results from a Long-Term Lake Mesocosm Experiment

The Impact of Climate Change and Eutrophication on Phosphorus Forms in Sediment: Results from a Long-Term Lake Mesocosm Experiment

Life cycle assessment of a cement plant in Naypyitaw, Myanmar

Cement production accounts for about 5% of the total anthropogenic CO2 emissions and 12–15% of the global energy use from the industrial sector. The impact on climate change and natural resource depletion are among the key concerns of the cement industry. Cement demand has been growing rapidly in many developing countries due to a booming construction sector spurred by rapid urbanization. Myanmar is one of these countries and has started to privatize its cement industry to meet the growing domestic demand. This study aims to assess the environmental impacts of Ordinary Portland Cement (OPC) production in Myanmar using Life Cycle Assessment (LCA) for the Max Myanmar Cement Plant in Naypyitaw. The LCA examines the entire cement production chain, using two alternative scenarios for fuel substitution. The results suggest that conventional cement production has adverse environmental impacts, with the calcination stage being responsible for most impacts. Calcination accounts for 89%, 95% and 97% of the effect for the climate change, acidification, and eutrophication impact categories respectively. Fuel switching from the coal dominating mix to 100% natural gas can decrease environmental impacts for most mid-point impact categories, such as climate change (68% reduction), acidification potential (83% reduction), and eutrophication potential (96% reduction).

Does Warming Enhance the Effects of Eutrophication in the Seagrass Posidonia oceanica?

Seagrass meadows are disappearing at rates comparable to those reported for mangroves, coral reefs, and tropical rainforests. One of the main causes of their decline is the so-called cultural eutrophication, i.e., the input of abnormal amounts of nutrients derived from human activities. Besides the impact of eutrophication at a local scale, the occurrence of additional stress factors such as global sea warming may create synergisms in detriment of seagrass meadows’ health. In the present study, we aimed to evaluate if plants undergoing chronic cultural eutrophication and plants growing in relatively pristine waters are more (or less) sensitive to heat stress, nutrient load and the combination of both stressors. To address this question, a mesocosm experiment was conducted using Posidonia oceanica collected from two environments with different nutrients load history. Plants were exposed in controlled conditions to high nutrient concentrations, increased temperature and their combination for 5 weeks, to assess the effect of the single stressors and their interaction. Our results revealed that plants experiencing chronic cultural eutrophication (EU) are more sensitive to further exposure to multiple stressors than plants growing in oligotrophic habitats (OL). OL and EU plants showed different morphological traits and physiological performances, which corroborates the role of local pressures in activating different strategies in response to global environmental changes. EU-plants appeared to be weaker during the treatments, showing the greatest percentage of mortality, particularly under increased temperature. Temperature and nutrient treatments showed opposite effects when tested individually and an offset response when combined. The activation of physiological strategies with high energetic expenses to cope with excess of nutrients and other stressors, could affect plants present and future persistence, particularly under eutrophic conditions. Our results represent a step forward in understanding the complex interactions that occur in natural environments. Moreover, unraveling intraspecific strategies and the role of local acclimation/adaptation in response to multiple stressors could be crucial for seagrass conservation strategies under a climate change scenario.

Responses of stream zooplankton diversity metrics to eutrophication and temporal environmental variability in agricultural catchments

Eutrophication of rivers and streams in agricultural lands is one of the main threats for biodiversity and ecosystem functions. This study was focused on seven subtropical streams where agriculture is the predominant land use. We tested the hypothesis that (i) eutrophication causes a decrease in taxonomic and functional diversity of zooplankton, leading to potential consequences for the ecosystem integrity. Furthermore, given that the temporal variability in the environmental conditions of each stream may influence the species sorting mechanisms, we also hypothesized that (ii) streams with higher temporal environmental variability have greater taxonomic and functional alpha (α) and temporal beta (βt) diversity measures regardless of the trophic state. Thus, we characterized the streams according to their trophic state and analyzed the zooplankton composition, α and βt by using taxonomic and functional perspectives. We found differences in the zooplankton composition between mesotrophic and eutrophic streams. However, eutrophic streams supported similar taxonomic and functional α diversity and similar taxonomic βt diversity to mesotrophic ones. These results were mainly explained by the occurrence of rare species occupying different temporal niches in eutrophic systems. On the contrary, functional βt diversity was lower in the eutrophic streams, being nestedness the ecological mechanisms underlying the variability in the zooplankton functional groups. Streams with higher temporal environmental variability supported greater α taxonomic diversity. However, the βt diversity metrics showed no correlation with the environmental variability, suggesting that the environmental filters of the studied systems were the overriding determinants of species turnover. Our study suggests that both taxonomic and functional perspectives should be considered to improve our knowledge on the biotic responses to environmental changes. Also, among all metrics analyzed on the zooplankton community, functional βt diversity was the most sensitive indicator of the eutrophication impact.

Environmental and economic assessment of proposed on-site wastewater management system in multi-storey residential building.

In the present study, the concept of 'environmental floors' in the multi-storeyed building is proposed, where separate treatment of greywater by gravity-governed stabilization tank and blackwater by underground Malaprabha digester of the DOSIWAM (Decentralized On-Site Integrated WAste Management) system is carried out. The study evaluates the feasibility of the non-mechanised DOSIWAM system by comparing it with the mechanised activated sludge process (ASP) with the life cycle and cost assessment (LCA and LCCA) method. The LCA was carried out with the SimaPro software using the impact 2002+ method. Both systems served a multi-storeyed (G + 30) building with 890 population equivalent. The LCA results reveal that the non-mechanised DOSIWAM system has three to six times reduced environmental impacts than the ASP system in almost all impact categories. Although DOSIWAMS' weaker removal efficiency dominates in the results of aquatic eutrophication and acidification impact, the latter comparative economical assessment showed to be the most cost-effective alternative due to reduced land use cost, O&M cost, and benefits achieved with energy recovery in the form of biogas. The electricity and chemical consumption in the operation phase caused the highest environmental impact for the ASP system, whereas the production of clinker and steel are responsible for a detrimental impact in the construction phase of the DOSIWAM system.

Regionalization of characterization factor in Brazil: freshwater eutrophication category

Brazil is privileged to have the most important natural resource in its territory, the water. But currently, the increased concentration of phosphorus (P) affects the water quality. It has two main routes to get into aquatic environmental: through the dump of untreated sewage and fertilizers runoff. The P excess may promote eutrophication, a process characterized by microalgae uncontrolled growth, affecting several parameters of freshwater. Due to the great differences at the Brazilian regions, the current Life Cycle Impact Assessment methodologies are not capable to evaluate properly the eutrophication impact in Brazil. The most viable method to obtain a more suitable model is regionalizing it by estimating the characterization factor (CF). Therefore this is the first study that presents a regionalized model to estimate Brazilian CF for freshwater eutrophication. The regionalization was based on the models proposed by Helmes et al. (2012) and Azevedo et al. (2013), which are considered the most complete and suitable models. Due to the lack of data it was possible to calculate the CF for Alto Iguaçu micro watershed and four more subwatersheds: Paraíba do Sul, Parnaíba, Litorânea do Ceará and Litorânea Pernambuco Alagoas. The processes assessment of advection, retention and water use provides valuable information of each region and also results in more realistic Fate Facto (FF), since Brazilian sanitation is completely uneven, and the sewage treatment must be modelled to not overestimated or sub estimated the FF. At Alto Iguaçu is the advection rate is the most relevant and its CF is 7.43 103. m3 .KgP-1 day. For that reason, the same amount of emitted phosphorus promotes a bigger eutrophication potential at Paraíba do Sul and Parnaíba than other basins. Phosphorus income rates estimate is possible to know the origin of its most significant input. Based on this information, financial resources can be better used. This was the first attempt to develop a Brazilian CF and some improvements need to be done. Firstly, new studies ought to concentrate to promote good quality of data, because the unavailability of data was one of the greatest difficulties of this study. Then the regionalized model should be improved modeling treatment of industrial sewage and, finally, CF needs to be calculated for all subwatershed.
 Keywords: Eutrophication. Characterization factor. Freshwater. Brazil. Life Cycle Impact Assessment.

Estimation of Environmental Effects of Industrial Tomato Cultivatıon in Field by the Life Cycle Assessment Method

Ülkemizde domates üretimi her bölgede yapılabilirken, ticari anlamda sanayi tipi domates yetiştiriciliği Marmara ve Ege bölgelerinde yoğunlaşmaktadır. Domates üretimi geleneksel yetiştiricilikte sera ve tarla olmak üzere iki farklı şekilde yapılmaktadır. Gelişen teknoloji ile yeni yetiştiricilik şekli olan topraksız tarımda hidroponik domates yetiştiriciliği de üretim şekilleri arasına eklenmiştir. Üretim sistemlerinin farklılaşması ile üretim sistemlerinin girdilerinin farklılaşmasına ve dolayısıyla da çevresel etkilerinin farklılaşmasına neden olmaktadır. Bu çalışma kapsamında ülkemizde, sürdürülebilir domates üretimi ve domates sanayi için, tarla domatesi üretiminin çevresel etkilerinin yaşam döngüsü değerlendirmesi yöntemi kullanılarak ortaya konulması amaçlanmıştır. Çalışmada Bursa bölgesinde tarlada sanayi domatesi üreten bir işletme ele alınmıştır. İşletme ile yapılan görüşmeler sonucunda yaşam döngüsü analizinde kullanılacak olan su tüketimi, üretimin tüm aşamalarındaki enerji tüketimi, kullanılan organik ve kimyasal gübre miktarı, araç kullanımı, araçların yakıt tüketimleri vb. bilgiler toplanmıştır. Girdiler kullanılarak yapılan üretim sonucunda ortaya çıkan son ürünler, domates, emisyonlar, atıklar ve kimyasal gübreden kaynaklanan kimyasallar olarak alınmıştır. Çalışmada üretimin neden olabileceği olası çevresel etki kategorileri seçilerek analiz gerçekleştirilmiştir. Çalışmada küresel ısınma, asidifikasyon, ötrofikasyon, ozon incelmesi, iklim değişimi, ekosistem-arazi kullanımı, ekosistem-toplam, insan zehirlenmesi ve doğal kaynak tüketimi etki kategorileri seçilmiştir. Çalışma sonucunda seçilen etki kategorilerinden ötrofikasyon, alan kullanımı ve toplam ekosistem etkisi kategorilerinde diğerlerine oranla yüksek etki değerleri elde edilmiştir. Tarlada domates yetiştiriciliğinde uygulanan kimyasal ve organik gübre miktarlarının yüksek olması çevresel etkileri ötrofikasyona kaydırmaktadır. Sonuç olarak yetiştiricilerin arazilerine uygulayacakları kimyasal ve organik gübre miktarlarına son derece dikkat etmeleri ve toprağın ve bitkinin gereksinimini ile uygulama döneminde meteorolojik şartları da gözeterek uygun miktarları arazilerine uygulamalıdır.

Mechanisms behind bottom-up effects: eutrophication increases fecundity by shortening the interspawning interval in stickleback

Anthropogenic eutrophication is altering aquatic environments by promoting primary production. This influences the population dynamics of consumers through bottom-up effects, but the underlying mechanisms and pathways are not always clear. To evaluate and mitigate effects of eutrophication on ecological communities, more research is needed on the underlying factors. Here we show that anthropogenic eutrophication increases population fecundity in the threespine stickleback (Gasterosteus aculeatus) by increasing the number of times females reproduce—lifetime fecundity—rather than instantaneous fecundity. When we exposed females to nutrient-enriched waters with enhanced algal growth, their interspawning interval shortened but the size of their egg clutches, or the size of their eggs, did not change. The shortening of the interspawning interval was probably caused by higher food intake, as algae growth promotes the growth of preferred prey populations. Enhanced female lifetime fecundity could increase offspring production and, hence, influence population dynamics. In support of this, earlier studies show that more offspring are emerging in habitats with denser algae growth. Thus, our results stress the importance of considering lifetime fecundity, in addition to instantaneous fecundity, when investigating the impact of human-induced eutrophication on population processes. At a broader level, our results highlight the importance of following individuals over longer time spans when evaluating the pathways and processes through which environmental changes influence individual fitness and population processes.

Single cell protein production from food waste using purple non-sulfur bacteria shows economically viable protein products have higher environmental impacts

Landfilling of food waste in the United States is a source of unutilized resources and environmental risks. As cities look to divert food waste from landfills, microorganisms may hold the answer. Purple non-sulfur bacteria are a group of microorganisms that can treat and extract resources from food waste to produce a protein supplement for animal feed. This study includes a life cycle assessment to compare four food waste management scenarios: purple non-sulfur bacteria production offsetting soybean meal production, purple non-sulfur bacteria production offsetting fishmeal and carotenoid production, anaerobic digestion, and landfilling (status quo). Purple non-sulfur bacteria offsetting soybean meal production resulted in significantly reduced environmental impacts compared to landfilling. Specifically, the eutrophication impact, land use, and water use for the soybean meal offset scenario were 141 kg N equivalents/day, 96 ha, and 120,000 L/day lower than landfilling, respectively. However, the low value of soybean meal limits the economic viability of this scenario. When high-value fishmeal and carotenoids were the offset products, there was an increase in value of $0.023/kg FW treated over landfill disposal of food waste. Offset fishmeal and carotenoids are not without environmental tradeoffs, most significantly with respect to eutrophication and global warming. This study then demonstrated that determining maximal growth rates to a PNSB photobioreactor, growing PNSB microorganisms on sunlight, and identifying the degree to which PNSB carotenoids can replace carotenoids in fish food were plausible lines of research to improve environmental and/or economic viability of the process. The life cycle assessment developed here can inform decision making for food waste management and guide research to improve purple non-sulfur bacteria production.

Eutrophication as a driver of microbial community structure in lake sediments.

Lake sediments are globally important carbon sinks. Although the fate of organic carbon in lake sediments depends significantly on microorganisms, only few studies have investigated controls on lake sedimentary microbial communities. Here we investigate the impact of anthropogenic eutrophication, which affects redox chemistry and organic matter (OM) sources in sediments, on microbial communities across five lakes in central Switzerland. Lipid biomarkers and distributions of microbial respiration reactions indicate strong increases in aquatic OM contributions and microbial activity with increasing trophic state. Across all lakes, 16S rRNA genes analyses indicate similar depth-dependent zonations at the phylum- and class-level that follow vertical distributions of OM sources and respiration reactions. Yet, there are notable differences, such as higher abundances of nitrifying Bacteria and Archaea in an oligotrophic lake. Furthermore, analyses at the order-level and below suggest that changes in OM sources due to eutrophication cause permanent changes in bacterial community structure. By contrast, archaeal communities are differentiated according to trophic state in recently deposited layers, but converge in older sediments deposited under different trophic regimes. Our study indicates an important role for trophic state in driving lacustrine sediment microbial communities and reveals fundamental differences in the temporal responses of sediment Bacteria and Archaea to eutrophication.

Permeability is the Critical Factor Governing the Life Cycle Environmental Performance of Drinking Water Treatment Using Living Filtration Membranes.

Living Filtration Membranes (LFMs) are a water filtration technology that was recently developed in the lab (Technology Readiness Level 4). LFMs have shown filtration performance comparable with that of ultrafiltration, far better fouling resistance than conventional polymer membranes, and good healing capabilities. These properties give LFMs promise to address two significant issues in conventional membrane filtration: fouling and membrane damage. To integrate environmental considerations into future technology development (i.e., Ecodesign), this study assesses the life cycle environmental performance of drinking water treatment using LFMs under likely design and operation conditions. It also quantitatively ranks the engineering design and operation factors governing the further optimization of LFM environmental performance using a global sensitivity analysis. The results suggest that LFMs' superior fouling resistance will reduce the life cycle environmental impacts of ultrafiltration by 25% compared to those of a conventional polymer membrane in most impact categories (e.g., acidification, global warming potential, and carcinogenics). The only exception is the eutrophication impact, where the need for growth medium and membrane regeneration offsets the benefits of LFMs' fouling resistance. Permeability is the most important factor that should be prioritized in future R&D to further improve the life cycle environmental performance of LFMs. A 1% improvement in the permeability will lead to a ∼0.7% improvement in LFMs' environmental performance in all the impact categories, whereas the same change in the other parameters investigated (e.g., LFM lifespan and regeneration frequency) typically only leads to a <0.2% improvement.

Fishmeal partial substitution within aquafeed formulations: life cycle assessment of four alternative protein sources

Fed aquaculture has long been based on fishmeal (FM) as the main protein source for carnivorous species, but when its demand and price began increasing, both researchers and the industry started to search for alternative protein sources to meet the challenge of securing aquafeed. Consequently, this study has recourse to life cycle assessment (LCA) methodology to identify any critical points and improvement strategies in the current production of four partial substitutes for FM namely dried microalgae biomass from Tetraselmis suecica (DMB_TETRA) and Tisochrysis lutea (DMB_TISO); insect meal (IM) from Hermetia illucens larvae; and poultry by-product meal (PBM). System boundaries are from the cradle to the mill gate, thus including the production phase (and the related upstream activities) and the subsequent biomass processing into unpackaged dried meal. One tonne of protein content was chosen as functional unit. The inventory was based on foreground data provided by the industry and complemented by background data sourced from the Ecoinvent v 3.4 and Agribalyse® v 1.3 LCI databases. The environmental effects were assessed considering five impacts namely global warming (kg CO2 eq.), acidification (kg SO2 eq.) and eutrophication (kg PO43− eq.) estimated via the CML-IA method, plus cumulative energy use (MJ) and water use (m3 m−2 month−1). Two alternative scenarios per production chain were considered in order to increase the robustness of the results. The performance-based ranking indicated the PBM and IM scenarios as the most sustainable options. Both microalgal systems scored the worst performances in four impacts out of five, with eutrophication impact as the only exception. The nutrients provided to poultry and insects (i.e. the feed) as well as to microalgae (the carbon source and the fertilizers) were the main contributors to impacts, together with energy consumption. Despite being cultivated with identical technologies, the two microalgae showed different performances due to their different annual yields and to different consumable goods, water and energy consumptions. The results provided a ranking of these four partial FM substitutes and allowed to make useful considerations on how to improve their environmental sustainability. To this regard, the impacts of IM and DMB production could be reduced by improving nutrient efficiency and reducing energy needs. On the other hand, PBM production is already optimized and is not expected to change substantially in the future years.

Exploring the role of spatial and stoichiometric heterogeneity in the top-down control in eutrophic planktonic ecosystems

Understanding the impact of eutrophication on the dynamics of aquatic food webs, remains a long-term challenge in ecology. Mathematical models generally predict the destabilisation of such webs, under increasing eutrophication levels, with large oscillations of species densities that can result in their extinction. This is at odds with a number of ecological observations that show stable dynamics even for high nutrient loads. The apparent discrepancy between theory and observations is known as the Rosenzweig’s ‘paradox of enrichment’ and various solutions to the problem have been proposed over the years. In this study, we explore the stabilisation of dynamics of a tri-trophic plankton model in a eutrophic environment which occurs as a result of interplay of space heterogeneity, ecological stoichiometry, and food taxis of predators. We build a variety of models of increasing complexity, to explore various scenarios of phytoplankton growth, zooplankton food-dependent vertical movement, and different stoichiometric limitations of zooplankton. We show that the synergy among the vertical gradient in phytoplankton growth, phytoplankton structuring in terms of their stoichiometric ratio, and food-dependent vertical movement of zooplankton, would result in a postponing of destabilisation of eutrophic systems as compared to a well-mixed system. Our approach reveals a high complexity of the bifurcation structure of the system when key model parameters, such as the degree of eutrophication and light shading, are varied. We find coexistence of limit cycles and stable equilibria and that the possibility of multiple attractors in the system can result in hysteresis phenomena when the nutrient load is manipulated. These results are relevant and should be taken into account in lake restoration programs.

Measuring the energy and environmental indices for apple (production and storage) by life cycle assessment (case study: Semirom county, Isfahan, Iran)

Assessment of energy and environmental indices is a common method for estimation the sustainable production in different sectors of agriculture. Considering the area under apple cultivation in Semirom county located in Isfahan province, the present study aimed to investigate the status of energy consumption and emission the environmental pollutants through life cycle assessment for apple production and storage in 2017–2018 cropping season. Required data were collected through questionnaire and interview with apple growers. Based on the results, the average of total required energy input and the yield of apple orchard were obtained as 116,505 ​MJha−1 and 34,951 ​kgha−1, respectively. For post-harvest operations, the average of total energy inputs was estimated as 15,727 ​MJ ​t−1. In apple orchard, the contribution of fuel, pesticides and transportation to total energy input were 58%, 12% and 11%, respectively, while in post-harvest section, the share of apple baskets and electricity in total energy input were 50% and 46%, respectively. Assessment of energy indices showed that energy ratio, energy productivity, specific energy and energy net-added were 0.72, 0.3 ​kgMJ−1, 3.33 ​MJ ​kg−1 and -32621 ​MJha−1, respectively. Based on the results obtained from environmental impact assessment of apple, the highest normalized pollution in apple orchard was related to Eutrophication and Freshwater aquatic ecotoxicity impact categories with the amount of 473×10−9 and 137×10−9, respectively, while in post-harvest operations, Marine aquatic ecotoxicity and Acidification impact categories had highest amounts as 0.0802×10−9 and 0.0121×10−9, respectively. Based on the results, diesel fuel and manure with the share of 97% of total emissions were identified as the environmental hotspots in apple orchard.

Soil N2O emissions, N leaching and marine eutrophication in life cycle assessment – A comparison of modelling approaches

Nitrogen fertilisation is an essential part of modern agriculture, providing food for a growing human population, but also causing environmental impacts when reactive nitrogen (N) is released to the environment. The amount and impact of these emissions are difficult to quantify in life cycle assessment (LCA), due to their site-dependent nature. This study compared seven models for direct soil nitrous oxide (N2O) emissions, seven models for N leaching and five characterisation models for marine eutrophication impact assessment, selected to represent medium-effort options for accounting for spatial variation in emissions and impact assessment. In a case study, the models were applied to wheat cultivation at two Swedish sites to estimate climate and marine eutrophication impact. Direct N2O emissions estimated by the models varied by up to five-fold at one of the sites and contributed 21–56% of the total climate impact. Site-dependent models gave both lower and higher N2O emissions estimates than the site-generic Tier 1 model from the Intergovernmental Panel on Climate Change (IPCC). Estimated N leaching also varied by up to fivefold at one of the sites and contributed 47–93% of the total eutrophication potential, depending on model choice. All site-dependent models estimated lower N leaching than the site-generic IPCC Tier 1 model. Marine eutrophication impact estimates varied by almost an order of magnitude depending on characterisation model choice. The large variation between models found in this study highlights the importance of model choice for N emissions and marine eutrophication impact assessment in LCA of crop cultivation. Due to the divergence of model outcomes and different limitations of some of the models, no general recommendations on choosing soil N2O emissions model, N leaching model or characterisation model for marine eutrophication could be given.

Comparing Machine Learning Approaches for Predicting Spatially Explicit Life Cycle Global Warming and Eutrophication Impacts from Corn Production

Agriculture ranks as one of the top contributors to global warming and nutrient pollution. Quantifying life cycle environmental impacts from agricultural production serves as a scientific foundation for forming effective remediation strategies. However, methods capable of accurately and efficiently calculating spatially explicit life cycle global warming (GW) and eutrophication (EU) impacts at the county scale over a geographic region are lacking. The objective of this study was to determine the most efficient and accurate model for estimating spatially explicit life cycle GW and EU impacts at the county scale, with corn production in the U.S.’s Midwest region as a case study. This study compared the predictive accuracies and efficiencies of five distinct supervised machine learning (ML) algorithms, testing various sample sizes and feature selections. The results indicated that the gradient boosting regression tree model built with approximately 4000 records of monthly weather features yielded the highest predictive accuracy with cross-validation (CV) values of 0.8 for the life cycle GW impacts. The gradient boosting regression tree model built with nearly 6000 records of monthly weather features showed the highest predictive accuracy with CV values of 0.87 for the life cycle EU impacts based on all modeling scenarios. Moreover, predictive accuracy was improved at the cost of simulation time. The gradient boosting regression tree model required the longest training time. ML algorithms demonstrated to be one million times faster than the traditional process-based model with high predictive accuracy. This indicates that ML can serve as an alternative surrogate of process-based models to estimate life-cycle environmental impacts, capturing large geographic areas and timeframes.

Life cycle assessment of organic and conventional non-Bt cotton products from Mali

Cotton is the most produced natural fibre in the world, with an annual output of 23 million t of lint in the period 2000–2013. Africa produced in average 6% of that output, and despite being a relatively minor contributor to global cotton supply chains, it has been estimated that a large percentage of the continent’s population depends on cotton cultivation for their livelihood. Most published cotton LCAs focused on the main global producers (India, China, USA), a few consider African cotton, and none to date Malian cotton. This work presents an LCA of the Malian cotton sector, consisting of an agricultural phase and ginning operations, in contrast with other African and global cotton LCAs. The goal of the study is to assess the absolute and relative environmental impacts of Malian cotton, per agricultural production system type, including the processing of seed cotton in ginning plants to produce cotton fibre bales (cradle to processing plant gate). Inventories were built for the two initial phases in the production cycle of cotton fibre, namely, the agricultural phase and the ginning phase. The main agricultural production system types were identified, according to distinctive differences in yields and technical processes―such as phytosanitary strategies―as well as the main processes performed in ginning plants. Operational data, representing the period 2002–2010, were provided by the Malian Company for the Development of Textiles (CMDT). It included yields and input and their uncertainty data. Direct field emissions of the agricultural phase were estimated following the AGRIBALYSE methodology, adapted when necessary to tropical conditions (e.g. a modified version of the Indigo-N model set was used to estimate N losses). Impact assessment was based on the European-sanctioned ILCD 2011 Midpoint+ v1.0.9, May 2016 method. Sensitivity was explored with scenarios and uncertainty data was propagated with Monte Carlo. The agricultural phase of cotton production in Mali differs from that of the largest producing countries, in that it is non-irrigated and non-mechanised and that non-Bt varieties are used. Instead, Malian cotton is rainfed―thus produced during the rainy season, from April/May to October/November―in rotation with maize or sorghum, manual work is prevalent up to the harvest, ploughs are towed by animals, and local varieties are grown (mainly STAM 59A and NTA 90-5). Malian yields were in the order of 400 kg lint/ha in the period 2001–2018, corresponding to ~ 1 t seed cotton/ha. The dominant production system, conventional agriculture, was sub-classified into three sub-types based on the phytosanitary strategy followed: calendar (81%), threshold control (15%) and targeted (4%). An average conventional system type was also constructed, as a production-weighted average of calendar, targeted and threshold. An existing marginal production of organic (0.5‰) cotton was also modelled. Organic cotton products (seed cotton, lint and cottonseed) feature lower impacts than conventional both per t and per ha (except for the toxicity, climate change and eutrophication impact categories), despite comparatively lower yields, due to lower input intensity. A single score–based contribution analysis confirms that, for conventional cotton, pesticide application is the main contributor to impacts, followed by mineral fertilisers. For organic cotton, the main drivers of impacts are natural pesticides and organic fertilisation. The overwhelming contribution of pesticides is largely due to the provision of organophosphorus compounds, specifically the insecticide profenofos. Moreover, the ginning phase contributed very little to the overall impacts (up to 3%). When data uncertainty is considered, the impacts per t of lint are always lower for organic cotton. Impacts were generally larger for conventional than from organic cotton. The main hotspots are related to pesticide use, and therefore, efforts should focus on that factor, despite pesticide inputs being already relatively lower than elsewhere. Climate change indicators for Malian cotton products were compared with literature values, having similar orders of magnitude. Malian cotton production features lower yields than the main global producers do, which is mainly due to low soil fertility and, to a lesser extent, to its dependence on rainwater. A shift towards organic cotton would be desirable only if the yield gap can be overcome.