Grey Water Footprint Research Articles

Environment-food nexus in trout ponds: a developed index by combining grey water footprint and life cycle assessment

Environment-food nexus in trout ponds: a developed index by combining grey water footprint and life cycle assessment

Revealing neglected hotspots for China’s quality-induced water scarcity

A dependable assessment of quality-induced water scarcity (QualWS) is essential for tackling the issue and achieving sustainable development goals. The conventional Emission-based grey water footprint (GWF) may over- or under-estimate QualWS, as it solely focuses on local pollutant emissions while disregarding other influential factors, such as water body self-purification capacity, transboundary water flows and the potential under- or over-estimation of water pollution emissions. To address this limitation, we propose the State-based GWF to reflect the quality status of local water resources accurately. The indicator is applied in annual and monthly QualWS assessments at the provincial scale in China. In 2021, 19 provinces were identified as QualWS hotspots, comprising seven moderate and 12 slight hotspots for at least one pollutant. Notably, the State-based assessment revealed eight previously overlooked hotspots undetected by conventional methods. Furthermore, total phosphorus emerged as the most critical water pollutant, followed by total nitrogen and chemical oxygen demand. Our assessment presents an innovative perspective for understanding QualWS and establishes a scientific basis for effective aquatic environment management.

The water footprint of Spanish Ternera de Navarra PGI beef: Conventional versus novel feeding based on vegetable by-products from the local food industry

CONTEXTIn recent years, livestock farming has been in the spotlight. Meat production is blamed for the pollution of aquifers and rivers, as well as for the large amount of water required to feed livestock. This has highlighted the need to find alternative feeding systems for cattle breeding able to reduce food/feed competition. OBJECTIVEIn this context, the present study compares the water footprint (WF) of conventionally fed beef versus beef fed with vegetable by-products from the local agri-food industry. METHODSTwenty-four entire male young bulls were reared under the Ternera de Navarra Protected Geographic Identification (PGI) in the town of Azoz, in Navarra, Spain. Twelve calves were fattened on a diet based on vegetable by-products and fodder and grain to complement the ration (VBP diet) and the remaining animals were fattened with a traditional diet based on concentrate and straw (conventional or control diet). RESULTS AND CONCLUSIONSOnce the fattening was finished and animals were slaughtered, the results showed a larger green, blue and grey WF in terms of m3 per beef cattle for conventionally fed animals compared to those fed with VBP. However, when looking at the efficiency, the results were mixed. Conventionally fed cattle exhibited lower green and grey WFs but a higher blue WF compared to VBP-fed cattle, with values of 9955 l/kg, 1577 l/kg and 1731 l/kg versus 10,147 l/kg, 1457 l/kg and 1831 l/kg of carcass beef, respectively. SIGNIFICANCEThis means that a by-product-based calf diet can reduce blue water use. However, further research is needed on the indirect water pollution associated with animal-fed crop production.

Long-term global water pollution stress from crops production considering different driving forces

Increasingly intensive crop farming has been aggravating global water pollution. It is significant to retrospectively investigate world's crop production induced water pollution stress, facilitating sustainable agriculture in the future. In this study, nearly 60-yr grey water footprint (GWF) dynamics of global crop farming are examined at multi-scales covering 146 crops in 162 countries, based on a framework coupling GWF assessment with an advanced dynamic decomposition analysis (DDA). Results show that global crop GWF has increased by 1224.1 % in 1961–2018, presenting three stages of GWF growth: an accelerated period of 1961–1980 (P1), a linear period of 1980–1999 (P2), and a decelerated period of 1999–2018 (P3). The spatial and crop-wise patterns of GWF vary for the stages. Crop GWF generally shifts from developed (North America and Europe) to developing (Asia and South America) regions during P1-P2, with crop-wise GWF showing increased proportions in cash crops (Fruits, Vegetables, Oil crops, etc.) for P2-P3 and decreased in food crops (mainly Cereals). China, America, and India exhibit top three national crop GWF amounts and increases (in total 60.3 % of world's GWF growth). Overall, production efficiency and population scale are determinants of growing global crop GWF, with different drivers recognized for the stages. Fertilization level principally drives up world's crop GWF for P1 (50.7 %) while offsets GWF growth in P3 (−8.61 %). Proportion of rural population becomes the main contributor offsetting crop GWF growth especially in P3. Driving pattern of crop GWF evolution varies among continents, countries, and crop categories, as well. Based on these, we recommend optimizing regional/national crop activities expecting to enhance sustainability of global agriculture.

Water Footprint: A Review Based on Concepts, Methods, and Implications

Water footprint assessment has become a useful method for assessing how much water is used by products and activities related to humans, offering insights into how water resources might be managed sustainably. While agricultural production accounts for the majority of water consumption worldwide, the industrial and residential sectors also use large amounts of water and cause pollution. This review article provides an examination of the approaches and uses of water footprint assessment in a range of industries and geographical areas. The notion of water footprint and its elements green, blue, and grey water footprints as well as the corresponding computation techniques are introduced at the outset of the work. The most recent developments in spatially explicit modelling and life cycle assessment techniques, it examines the development of water footprint assessment procedures. The paper explores the many uses of water footprint assessment, from consumer items and urban water management to industrial operations and agricultural output. It provides case studies and real-world examples that show how water footprint analysis may be applied practically to address issues with pollution, water shortages, and sustainability in various settings. The study also looks at the difficulties and constraints that come with assessing the water footprint, such as methodological uncertainty, data availability, and temporal and geographical variability. It talks about current studies as well as potential paths forward for improving the reliability and usability of water footprint measurement instruments. As a comprehensive and integrated method for measuring and controlling the effects of human-induced water usage on regional and global water resources, this study concludes by highlighting the importance of water footprint assessment. In order to promote sustainable water management practices, it highlights the necessity of multidisciplinary collaboration and stakeholder involvement. Keyword: Water Footprint, Sustainability, Life Cycle Assessment, Spatial Analysis.

A Framework for Assessing Food Baskets Based on Water and Carbon Footprints

The composition of food baskets can significantly influence the water consumption rate and society’s environmental impact. This study evaluates the sustainability of Iran’s food and nutrition security by evaluating five food baskets using water and carbon-footprint indices. These food baskets are the common Iranian food basket (CIFB), the vegetarian food basket (VFB), the Ministry of Health desired food basket (MHDFB), the Swiss Society for Nutrition food basket (SSNFB), and the Mediterranean food basket (MFB). This study also examines the role of Iran’s agricultural sector under the Paris Climate Change Agreement (COP21). The TOPSIS multi-criteria decision-making method was used to identify the most desirable food basket. The results of this study show that the VFB could be the most desirable alternative to the CIFB. Replacing the CIFB with the VFB causes a 10% and 21% lower water and carbon footprint, respectively. From a 30-year perspective (around 2050), choosing the VFB would reduce the blue water footprint by 19.7 BCM and the gray water footprint by 3.6 BCM compared to the CIFB. According to the provisions of COP21 regarding Iran’s voluntary program to reduce greenhouse gas emissions, the agricultural sector will be one of the sources of greenhouse gas emissions that will face an upward trend. Hence, to adhere to this voluntary commitment, these emissions should be reduced by changing the CIFB to the VFB or reducing emissions in other sectors, such as industry. Choosing the VFB can reduce 10.7 million tons of CO2 emissions, which can be a significant step for the agricultural sector in Iran in reducing greenhouse gas emissions. Overall, considering the characteristics of farm products (water and carbon footprints) in Iran, a country located in a semi-arid climate, the VFB is recommended.

Grey water footprint model of heavy metal based on the hazard quotient

The traditional Grey Water Footprint (GWF) model, rooted in the assumption that the hazard of each pollutant is independent, faces a limitation when dealing with heavy metals, whose hazards to aquatic organisms accumulate. The objective of this study is to develop a GWF model that reflects the cumulative threat posed by heavy metals to aquatic organisms, using the Hazard Quotient (HQ) as a foundation. The model comprises three parts: (i) defining the minimum virtual water volume required to control the HQ within the allowable limits, which includes long-term GWF (L-GWF) and short-term GWF (S-GWF); (ii) calculating the hazard level of heavy metal pollution (HHL); and (iii) determining the contribution rates of each heavy metal to L-GWF and S-GWF. The evaluation results of the heavy metal pollution discharged from the Guixi Smelter show that (i) The GWF of heavy metals from the Guixi Smelter decreases dramatically in 2014, with L-GWF and S-GWF of 2.39 and 0.22 billion m3, respectively, which are only 49.9 % and 47.1 % of L-GWF and S-GWF in 2013. (ii) The HHL values in 2012 and 2013 are 1.52 and 1.43, respectively, with a grade of “moderate.” In contrast, the HHL values in 2014 and 2015 significantly decrease to 0.82 and 0.74, respectively, both with a grade of “low”. (iii) The L-GWF contributors of heavy metals in the Guixi Smelter are Cu > Cd > Pb, and the S-GWF contributors are Cu > Pb > Cd > As. (iv) The GWF model based on HQ overcomes the limitations of conventional GWF and provides an effective assessment of the cumulative heavy metal hazards to aquatic organisms.

Decoupling Agricultural Grey Water Footprint from Economic Growth in the Yellow River Basin

Decoupling agricultural economic growth from agricultural water pollution is of great importance to regional sustainable development. It is necessary to further explore the decoupling state and key driving factors connecting agricultural water pollution and agricultural economic growth on the basis of accurate measurement of agricultural water pollution. Accordingly, taking the Yellow River Basin (YRB) as the research object, this study combined the water footprint theory, the Logarithmic Mean Divisia Index (LMDI) model and the Tapio decoupling model (TDM) to conduct an in-depth decoupling analysis of the connection between the agricultural grey water footprint (AGWF) and agricultural economic growth in the YRB. Specifically, this study first calculated the AGWF of the YRB during 2016–2021 and objectively evaluated the water resource utilization in this region based on the AGWF. Then, the LMDI model was used to explore the driving factors of the AGWF in the YRB. Finally, the decoupling states between the AGWF and its driving factors with agricultural GDP (AGDP) were studied using the TDM. The main results are as follows: (1) The overall AGWF in the YRB showed a decreasing trend and a slow increase, decreasing by 5.39% in 2021 compared to 2016. (2) The primary promoting factor and inhibiting factor of AGWF reduction are the efficiency effect and agricultural economic effect, respectively. (3) The decoupling states of the AGWF and AGDP presented strong decoupling (SD) and then weak decoupling (WD) in the YRB during the research period. The decoupling states between the agricultural grey water footprint intensity (AGWFI) and AGDP changed from expansive negative decoupling (END) to SD. The decoupling state of population and AGDP remained SD. This study will contribute to alleviating agricultural water pollution in the YRB and help policymakers in water-stressed countries to formulate agricultural water management policies.

Effects of new-type urbanization on resource pressure: Evidence from a water-energy-food system perspective in China

To address the resource and environmental challenges posed by rapid urbanization, China has devised and executed the strategy of new-type urbanization (NU). This study aims to discuss the effects of NU on resource pressure in view of the water-energy-food (WEF) system. Taking 30 provinces in China from 2006 to 2020 as samples, this paper firstly establishes a comprehensive evaluation indicator system of NU from the population, economic, spatial, social and eco-environmental dimensions, and assesses the level of NU using the entropy weight method. Secondly, this paper uses the gray water footprint as a measurement indicator, innovatively integrating water quality into the WEF system for assessing WEF system pressure (WEFSP). Finally, the impact of NU on WEFSP is explored based on the panel fixed effects model. The findings revealed: (1) There is an inverted “U-shaped” relationship between NU and WEFSP, and China's current level of NU has exceeded the Environmental Kuznets Curve (EKC) threshold. (2) The impact of NU on WEFSP exhibits significant regional heterogeneity, with a significant impact in the eastern region. (3) NU consistently exacerbates regional water stress when water quality is considered, indicating that sustainable urban water management practices are essential. (4) The subdimensions of NU indicate that population and social urbanization are important factors that exacerbate the WEFSP, while economic and spatial urbanization reduce the WEFSP. The research results help to clarify the impact of NU on the WEFSP and provide a reference for the timely adjustment and optimization of NU policies to achieve effective resource management and regional sustainable development.

Grey water footprint for evaluating Zefta wastewater treatment plant: a case study

ABSTRACT The numbers of wastewater treatment plants (WWTP) in Egypt are increasing, yet the general level of pollution associated with wastewater discharge after treatment has not been evaluated. Grey water footprint (GWF) was used to assess the effluent discharges from Zefta WWTP. GWF, before and after treatment, was calculated and followed up to determine its impact on the receiving freshwater body. 150 samples were collected and analysed for BOD5 to determine the optimum operating conditions. Averages values were DO = 2.2, SV30 = 500, SVI = 167, SA = 9.3 d, MLVSS = 2392 mg/L, f/m = 0.16, MLSS in RAS = 7922 mg/L, WAS = 140 m3/d and the HRT = 12 h. The removal efficiency of COD and TSS in the primary settling tank reached 39% and 69%, respectively. Average calculations of removal efficiency percentile reached 90-93%. Average freshwater quantities required to reduce pollutants in the receiving body stream were seasonally determined for Zefta WWTP as 5.3 × 107 m3/year. The average influent BOD5 was 376 mg/L, it was reduced to 47 mg/L in the effluent, wherever the Cmin is 6 mg/L and Cnat is 10 mg/L. Statistical analysis has shown a significant direct relation between ΔWFG,mef and WFG,ref reached 0.952 and a significant inverse relation with Cef −0.982. WFG,T has shown a significant direct relation with Cr 0.974. WFG,T– ref has shown a significant direct relation with Cr as 0.971 and WFG,T as 0.803. It can be concluded that ΔWF is effective in evaluating the efficiency of wastewater treatment and its effect on the quality of receiving water bodies.

New approach to domestic grey water footprinting: country-scale accounting using statistical methods in Türkiye

ABSTRACT This study aimed to develop an approach for country-scale domestic grey water footprint (GWFdomestic) accounting and examine spatio-temporal differences using statistical methods. In this scope, the GWFdomestic was calculated as the amount of water required to reduce the total nitrogen concentrations of domestic wastewater released into receiving media from 81 cities in Türkiye. GWFdomestic values were estimated based on the data on wastewater amount and applied wastewater treatment process. GWFdomestic was calculated by dividing the pollutant load of discharged water by the critical concentration in the surface water. The empirical results showed that (a) the produced wastewater amount increased up to 125 m3/year in some cities. (b) GWFdomestic values showed a difference between 330 and 1,900 depending on the level of treatment, and the average value was about 750 m3/ca.year. (c) A total of 81 cities were grouped under four categories, and applied water treatment technology was the main characteristic of this classification. (f) GWFdomestic has not statistically significantly changed over time in a large part of the country. It can be concluded that country-scale GWFdomestic accounting can assist water managers in developing prevention measures by analyzing spatio-temporal differences in the water footprint of domestic discharges.

Multi-Objective Optimization of the Planting Industry in Jiangsu Province and Analysis of Its “Water-Energy-Carbon” Characteristics

The modern development of the planting industry needs to not only ensure food supply but also to consider social and environmental issues. This poses higher demands for rational planning of planting structures to achieve green development while meeting demands and conserving resources. Therefore, this paper takes Jiangsu Province as a representative case, accounting for and analyzing the water footprint, energy consumption, and carbon emissions of seven major crops. Based on this analysis, a multi-objective planning model is established to explore the optimization of its planting structure. The results show that: (1) from 2010 to 2020, the overall water footprint of these seven crops in Jiangsu Province initially increased and then decreased, while energy consumption showed a fluctuating upward trend; (2) carbon emissions from planting in Jiangsu Province initially increased and then fluctuated downward over time, and exhibited significant spatial clustering characteristics, with overall emissions being higher in northern Jiangsu, followed by central Jiangsu, and then southern Jiangsu; (3) the optimization results indicate that economic benefits increased by 4.06%, while the carbon emission and grey water footprints decreased by 3.78% and 7.62%, respectively, resulting in comprehensive improvements in economic and ecological benefits. This study can provide theoretical support for adjusting the planting structure in crop-producing areas and promoting the green and sustainable development of the planting industry.

Application of a water-energy-carbon coupling index to evaluate the long-term operational stability of the anaerobic-anoxic-oxic-membrane bioreactor (A2/O-MBR) process under the influence of rainstorms

In the context of global climate change, sudden rainstorms and typhoons induce fluctuations in hydraulic shocks to wastewater treatment plants (WWTPs) in coastal areas, causing two challenges of stable effluent quality and low-carbon operation. We established a quantitative evaluation method for resistance of wastewater treatment processes to hydraulic shocks based on the water-energy-carbon nexus using operational data from a WWTP in southeast coastal China from July 2018 to December 2022. The effects of hydraulic shocks on the operational stability of the anaerobic-anoxic-oxic-membrane bioreactor (A2/O-MBR) process were analyzed following five steps. The results showed that the gray water footprint (GWF) of the process was 9.3% lower than that of the A2/O process. The energy footprint (ENF) and carbon footprint (CF) were approximately 2.1 times and 1.7 times higher than those of the A2/O process, respectively. The resistance to hydraulic shocks of the A2/O-MBR process is approximately 5.5 times higher than that of the A2/O process. In conclusion, the A2/O-MBR process exhibits higher process operational stability when subjected to hydraulic shocks, which is more conducive to the efficient and stable operation of WWTPs in rainstorm and typhoon-prone areas. The evaluation methodology provides qualitative technical support for selecting upgrading processes for WWTPs in different regions.

A holistic approach for performance evaluation of wastewater treatment plants: integrating grey water footprint and life cycle impact assessment.

Wastewater treatment plants (WWTPs) have positive and negative impacts on the environment. Therefore, life cycle impact assessment (LCIA) can provide a more holistic framework for performance evaluation than the conventional approach. This study added water footprint (WF) to LCIA and defined ϕ index for accounting for the damage ratio of carbon footprint (CF) to WF. The application of these innovations was verified by comparing the performance of 26 WWTPs. These facilities are located in four different climates in Iran, serve between 1,900 and 980,000 people, and have treatment units like activated sludge, aerated lagoon, and stabilization pond. Here, grey water footprint (GWF) calculated the ecological impacts through typical pollutants. Blue water footprint (BWF) included the productive impacts of wastewater reuse, and CF estimated CO2 emissions from WWTPs. Results showed that GWF was the leading factor. ϕ was 4-7.5% and the average WF of WWTPs was 0.6 m3/ca, which reduced 84%, to 0.1 m³/ca, through wastewater reuse. Here, wastewater treatment and reuse in larger WWTPs, particularly with activated sludge had lower cumulative impacts. Since this method takes more items than the conventional approach, it is recommended for integrated evaluation of WWTPs, mainly in areas where the water-energy nexus is a paradigm for sustainable development.

Identifying synergistic solutions for the food-energy-water nexus via plastic film mulching cultivation

Food security, water scarcity, and excessive fossil energy use pose considerable challenges to sustainable agriculture. To understand how rain-fed farming systems on the Loess Plateau, China, reconcile yield increases with ecological conservation, we conducted an integrated evaluation based on the denitrification-decomposition (DNDC) model, agricultural statistics data using the Food-Energy-Water (FEW) nexus indicator. The results showed that maize yields with ridge-furrow plastic film mulching (PFM) were 3479, 8942, and 11,124 kg ha−1 under low (50 kg N ha−1), medium (200 kg N ha−1), and high (350 kg N ha−1) nitrogen (N) fertilizer rates, respectively, and that PFM increased yield and water use efficiency (WUE) by 110–253 % and 166–205 % compared to using no mulching (control, CK), respectively. Plastic film mulching also increased net energy (126–436 %), energy use efficiency (81–578 %), energy productivity (100–670 %), and energy profitability (126–994 %), and nitrogen fertilizer, compound fertilizer, and diesel fuel consumption by agricultural machinery were the main energy inputs. The PFM system reduced water consumption during the maize growing season and the green water footprint and gray water footprint decreased by 66–74 % and 44–68 %, respectively. The FEW nexus indicator, based on a high production at low environmental cost scenario, was greater under the PFM system and had the widest spatial distribution area at the medium-N application rate. Among the environmental factors, the nexus indicator was negatively correlated with precipitation (−0.37), air temperature (−0.36), and the aridity index (−0.36), but positively correlated with elevation (0.17). Our results suggest that the PFM system promotes resource-saving while increasing yields and moves dryland agriculture in an environmentally friendly direction, thus promoting the sustainable development of agroecosystems.

Emerging contaminants in wastewater – results of Joint Danube Survey 4 evaluated via the grey water footprint

Emerging contaminants in wastewater – results of Joint Danube Survey 4 evaluated via the grey water footprint

Grey water footprint of crop in Riau Province

The escalating severity of the water problem poses a potential threat to the prospects of sustainable development in the future. The grey water footprint is an indicator of the need for fresh water to mix and dilute pollutants and maintain air quality according to water quality standards. The evaluation of the grey water footprint (GWF) serves as a valuable measure in the mitigation and management of water contamination. The main objective of this study is to determine the grey water footprint associated with crop production along the Kampar Watershed and develop strategies to mitigate pollution levels. The grey water footprint is calculated using a water footprint assessment method. The finding show that the grey water footprint of rice farming (17.01 m3/ton) is larger than the maize (9.51 m3/ton), this indicate that necessary to improve water management on rice and maize agriculture. The water footprint performance scores of rice and corn plants are both in the poor category with scores of 11.93 and 45 respectively. To improve grey water performance and reduce air pollution, it can be done by using fertilizer according to plant needs, replacing inorganic fertilizer with organic fertilizer, implementing practices conventional tillage and maintain soil moisture.

The role of Kampar watershed in achieving sufficient rice production and sustaining agriculture

Abstract Agriculture is the largest global water consumer, crucial to understanding its impact on watersheds. This study was conducted in the Kampar watershed in Riau province, covering Kampar and Pelalawan regencies. It assesses the watershed's suitability for meeting agricultural water needs, particularly for rice cultivation. The study utilizes quantitative methods, applying the Penman–Monteith technique and benefit transfer analysis to measure the water footprint of agriculture. Key indicators include blue, green, and gray water footprints. The water footprint in the Kampar watershed is 173.84 m3/t, with rice cultivation in the Kampar regency having 57.96 m3/t blue, 32.19 m3/t green, and 14.52 m3/t gray water footprints. In the Pelalawan regency, the values were 41.09 m3/t blue, 25.59 m3/t green, and 2.49 m3/t gray water footprints. The findings suggest a significant need for ample water usage from surface and groundwater in both Kampar and Pelalawan regencies for rice cultivation. Regarding the water availability in each district: Kampar regency has 1,063,281,652 m3/year and Pelalawan regency has 987,542,991 m3/year. This surplus in the Kampar watershed ensures sufficient water for rice cultivation in both districts, especially in the Kampar regency. These hold promising further agricultural development in the Riau province.

A fuzzy logic evaluation of synergies and trade-offs between agricultural production and climate change mitigation

This study introduces a trade-off evaluation system, the Σommit index, which considers four components: crop yield, soil carbon stock changes, direct and indirect nitrous oxide emissions, and nitrate-nitrogen leaching across alternative agronomic case scenarios, i.e., combinations of management practices within specific pedo-climatic conditions. The four trade-off components have been estimated by combining standard equations and emission factors from the Guidelines for National Greenhouse Gas Inventories, complemented with Grey Water Footprint accounting Guidelines and other meta-analyses. The Σommit index has been developed using a harmonised dataset of ∼1.8 million agronomic case scenarios, leveraging fuzzy logic to aggregate the trade-off components into a value ranging from 0 (bad) to 1 (good). It has been tested under three narratives reflecting stakeholders' sustainability priorities (young farmers, agrochemical companies, EU Common Agricultural Policy paying agency), using alternative weighting schemes derived from expert opinion. Adding organic matter input, intermediate N fertilisation (50–150 kg ha−1), no-tillage, winter cereal cultivation, and irrigation for summer cereals have consistently achieved higher performance across all narratives. When assigning a higher weight to soil carbon stock changes, a broader range of Σommit index values emerged, while assigning higher importance to crop yield has led to a narrower evaluation. We openly release the dataset of agronomic case scenarios, along with the scripts to replicate the methodology and an interactive dashboard to inspect the results. These resources are meant to be used by different stakeholders (e.g., policymakers, Common Agricultural Policy payment agencies, farms, agrochemical industry) as a complement to the Intergovernmental Panel on Climate Change methodology to improve current understanding and awareness of environmental trade-offs and synergies in agricultural management.

Water footprint assessment of mining and processing of gold in Turkey

ABSTRACT This study aims to identify critical points by calculating the water footprint (WF) of a mine and assessing the environmental impact of this water usage. Utilising the Water Footprint Assessment (WFA) methodology for critical points and the Life Cycle Assessment (LCA) methodology for environmental impact, results reveal that, among the identified hotspots, the highest blue water footprint is associated with the lost return flow, measuring 260.61 m3/kg Au. Regarding the grey water footprint, arsenic exhibits the highest value, measuring 1.777 m3/kg Au. Among the five impact categories, climate change human health emerges as the most environmentally affected category.