Historic Trends and Future Prospects of Waste Generation and Recycling in China's Phosphorus Cycle.

Intensified human activities have generated a large amount of phosphorus-containing waste (P waste). Unrecycled P waste is lost to the environment and causes eutrophication, while the increasing phosphate consumption risks the depletion of phosphorus resources. The management of P waste is critical to solving these problems. In this study, we quantified the historic trends of P waste generation and recycling in China. From 1900 to 2015, the annual generation of P waste increased from 1 Mt P to 12 Mt P. Crop farming was the largest P waste source in most years, while P waste from phosphate mining and phosphorus chemical production increased the fastest. The total recycled P waste increased 5-fold, but phosphorus loss increased 26-fold. In 2015, 28% of the P waste was lost on cultivated land, and 21% was lost on nonarable land. The largest phosphorus contributor to inland water changed from crop farming to aquaculture. The full recycling of P waste would have reduced phosphate consumption by more than one-third in 2015. The results of a scenario analysis showed that a healthier diet would greatly increase the generation and loss of P waste, but balanced fertilization could reduce the generation of P waste by 17% and promoting waste recycling could reduce the phosphorus loss by 35%.

Environmental impacts of lithium production showing the importance of primary data of upstream process in life-cycle assessment.

Life-cycle assessment (LCA) emphasizes obtaining primary data from an on-site process to reduce uncertainties. However, data of the upstream process from secondary sources also yield significant uncertainties, which have not been drawn enough attention. This study aims to explore the importance of primary data of the upstream process in LCAs. Here, we choose lithium, a key component of lithium-ion (Li-ion) battery, as a case to present a cradle-to-gate LCA for its production by rock-based technology (LRT). Then, we compare the environmental impacts of lithium by LRT with that by brine-based technology (LBT) and the Li-ion battery using lithium by the two methods. The result shows that the impacts of rock-based lithium production are dominated by the leaching process, which has the highest levels of impacts for 8 of 10 environmental categories. Besides, all 10 impact categories of lithium produced by LRT are much larger than that by LBT, with differences up to 60.4 -fold. We also find that the Li-ion battery pack by rock-based lithium offers a 17-32% increase in acidification and global warming potential relative to that by brine-based lithium. Our results contribute by providing the first mass-produced life-cycle inventory of rock-based lithium and showing the importance of primary data of the upstream process in LCAs.

A physiological concentration of luteolin induces phase II drug-metabolizing enzymes through the ERK1/2 signaling pathway in HepG2 cells.

The flavon luteolin has various health-promoting activities including cardiovascular protection, anti-inflammatory activity and anticancer activity. A serum concentration of about 100 nM luteolin is reached by dietary habit. However, little is known about the function of luteolin over its physiological concentration range. In this study, we investigated whether a physiological concentration of luteolin could activate nuclear factor-erythroid-2-related factor 2 (Nrf2)-mediated expression of phase II drug-metabolizing enzymes in human hepatoma HepG2 cells. Interestingly, less than 1 nM of luteolin could induce phase II drug-metabolizing enzymes, such as GSTs, HO-1, and NQO1. Both 1 and 100 nM luteolin increased expression and activity of ALDH2, which metabolized toxic acetaldehyde into nontoxic acetic acid. Luteolin increased nuclear accumulation of Nrf2 and enhanced the ARE-binding complex through increasing the stability of the Nrf2 protein. Luteolin increased phosphorylation of Nrf2 at Ser40, and MEK inhibitors (U0126 and PD98059) canceled luteolin-induced phosphorylation of Nrf2. Furthermore, luteolin increased modified Keap1. In conclusion, a physiological concentration of luteolin induces the expression of phase II drug-metabolizing enzymes by enhancement of Nrf2 nuclear accumulation through MEK1/2-ERK1/2-mediated phosphorylation of Nrf2, increasing Nrf2 stability and inducing a conformational change of Keap1.

Intensification of phosphorus cycling in China since the 1600s.

Phosphorus (P) is an essential nutrient for living systems with emerging sustainability challenges related to supply uncertainty and aquatic eutrophication. However, its long-term temporal dynamics and subsequent effects on freshwater ecosystems are still unclear. Here, we quantify the P pathways across China over the past four centuries with a life cycle process-balanced model and evaluate the concomitant potential for eutrophication with a spatial resolution of 5 arc-minutes in 2012. We find that P cycling in China has been artificially intensified during this period to sustain the increasing population and its demand for animal protein-based diets, with continuous accumulations in inland waters and lands. In the past decade, China's international trade of P involves net exports of P chemicals and net imports of downstream crops, specifically soybeans from the United States, Brazil, and Argentina. The contribution of crop products to per capita food P demand, namely, the P directly consumed by humans, declined from over 98% before the 1950s to 76% in 2012, even though there was little change in per capita food P demand. Anthropogenic P losses to freshwater and their eutrophication potential clustered in wealthy coastal regions with dense populations. We estimate that Chinese P reserve depletion could be postponed for over 20 y by more efficient life cycle P management. Our results highlight the importance of closing the P cycle to achieve the cobenefits of P resource conservation and eutrophication mitigation in the world's most rapidly developing economy.

Animal based diets and environment: Perspective from phosphorus flow quantifications of livestock and poultry raising in China.

Identifying the key nodes of the phosphorus flows in animal raising system is fundamental to improve P utilization efficiency and reduce the P contamination. This study established a phosphorus flow analysis model for livestock and poultry raising, depicted P flows for major livestock and poultry under two raising modes, and further analyzed their spatial and temporal distributions. We find that around 15% of P input was transferred into the products, and in P output around 40% lost into the environment in 2015. The P flows have been increasing since 2000, and the main contributor is pigs followed by beef cattle. It should be noticed that P loss from livestock and poultry raising is huge with extensive prospect of recycling in some central provinces of China, and western region where ecological environment is fragile, has a higher P loss rate which need to change the dietary preference and adjust raising structure. As for diets, pork and eggs are better choices than milk or other kinds of meat in terms of reducing the P load, when producing per unit protein or energy. This study contributes to the understanding of P management in husbandry industry, the quantification of environmental loads of animal-based food and the identification of the potential of reducing P loss to realize sustainable utilization of P.

Human Perturbation of the Global Phosphorus Cycle: Changes and Consequences.

The phosphorus (P) cycle is an important Earth system process. While natural P mobilization is slow, humans have been altering P cycle by intensifying P releases from lithosphere to ecosystems. Here, we examined magnitudes of which humans have altered the P cycles by integrating the estimates from recent literatures, and furthermore illustrated the consequences. Based on our synthesis, human alterations have tripled the global P mobilization in land-water continuum and increased P accumulation in soil with 6.9 ± 3.3 Tg-P yr-1. Around 30% of atmospheric P transfer is caused by human activities, which plays a significant role than previously thought. Pathways involving with human alterations include phosphate extraction, fertilizers application, wastes generation, and P losses from cropland. This study highlights the importance of sustainable P supply as a control on future food security because of regional P scarcity, food demand increase and continuously P intensive food production. Besides, accelerated P loads are responsible for enhanced eutrophication worldwide, resulting in water quality impairment and aquatic biodiversity losses. Moreover, the P enrichment can definitely stimulate the cycling of carbon and nitrogen, implying the great need for incorporating P in models predicting the response of carbon and nitrogen cycles to global changes.

Phosphorus Flow Patterns in the Chaohu Watershed from 1978 to 2012.

Understanding historical patterns of phosphorus (P) cycling is critical for sustainable P management and eutrophication mitigation in watersheds. This study built a bottom-up model using the substance flow analysis approach to quantify P cycling in the Chaohu watershed during 1978-2012. We found that P flows have been intensified, with a 5-fold increase of annual P inputs to sustain the expanding intensive agriculture. Annually, most P inputs (75%) were stored within the watershed, which caused accelerating buildup of legacy P in cultivated land (from 4.9 Gg to 6.5 × 10(2) Gg), uncultivated land (from 2.1 Gg to 1.3 × 10(2) Gg) and surface water (from 3.7 Gg to 2.6 × 10(2) Gg) during 1978-2012. The main legacy P sources include fertilizer application for cultivated land, phosphogypsum abandonment for uncultivated land, respectively. The animal husbandry contributed about 63-66% of total P inputs to surface water. The contribution of animal food-P increased greatly during 1978-2012, from 7% to 24% and from 1% to 8% for urban and rural residents, respectively. This work demonstrates principle for the buildup of legacy P at the watershed-scale, and advances the knowledge of sustainable P management, such as improving agricultural technologies to reduce fertilizer application.

Luteolin modulates expression of drug-metabolizing enzymes through the AhR and Nrf2 pathways in hepatic cells.

Drugs, xenobiotics including environmental pollutants, and certain food components modulate expression of drug-metabolizing enzymes. An aryl hydrocarbon receptor (AhR) possesses possible expression of phase I and phase II enzymes directly by binding of its ligands such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) and indirectly by regulating expression of nuclear factor-erythroid-2-related factor 2 (Nrf2). Previous our result demonstrated that luteolin, a natural flavonoid existing in vegetables and herbs, competed the binding of TCDD to AhR. In the present study, we investigated the effect of luteolin on the expression of drug-metabolizing enzymes through the AhR and Nrf2 pathways. Luteolin inhibited TCDD-induced protein expression of phase I enzyme cytochrome P450 1A1 (CYP1A1), phase II enzymes NAD(P)H: quinone oxidoreductase-1 (NQO1) and glutathione-S-transferase P1 (GSTP1) in HepG2, Hepa1c1c7 and RL-34 cells in a dose-dependent manner. Luteolin suppressed TCDD- and tert-butylhydroquinone-induced Nrf2 protein by decreasing its stability in HepG2 cells. In tert-butylhydroquinone treated cells, luteolin dose-dependently inhibited NQO1, GSTP1 and aldo-keto reductases (AKRs). Of these, protein expression of CYP1A1 and GSTP1 was mainly dominated by the AhR pathway, while that of NQO1 and AKRs was by the Nrf2 pathway. In conclusion, luteolin inhibits expression of phase I and phase II drug-metabolizing enzymes by modulating the AhR and Nrf2 pathways.

Black soybean seed coat polyphenols prevent B(a)P-induced DNA damage through modulating drug-metabolizing enzymes in HepG2 cells and ICR mice.

Black soybean seed coat is a rich source of polyphenols that have been reported to have various physiological functions. The present study investigated the potential protective effects of polyphenolic extracts from black soybean seed coat on DNA damage in human hepatoma HepG2 cells and ICR mice. The results from micronucleus (MN) assay revealed that black soybean seed coat extract (BE) at concentrations up to 25µg/mL was non-genotoxic. It is noteworthy that BE (at 4.85µg/mL) and its main components, procyanidins (PCs) and cyanidin 3-glucoside (C3G), at 10µM significantly reduced the genotoxic effect induced by benzo[a]pyrene [B(a)P]. To obtain insights into the underlying mechanism, we investigated BE and its main components on drug-metabolizing enzyme expression. The results of this study demonstrate that BE and its main components, PCs and C3G, down-regulated B(a)P-induced cytochrome P4501A1 (CYP1A1) expression by inhibiting the transformation of aryl hydrocarbon receptor. Moreover, they increased expression of detoxifying defense enzymes, glutathione S-transferases (GSTs) via increasing the binding of nuclear factor-erythroid-2-related factor 2 to antioxidant response elements. Collectively, we found that PCs and C3G, which are the main active compounds of BE, down-regulated CYP1A1 and up-regulated GST expression to protect B(a)P-induced DNA damage in HepG2 cells and ICR mice effectively.

Prediction of atherosclerosis using machine learning based on operations research.

BACKGROUND: Atherosclerosis is one of the major reasons for cardiovascular disease including coronary heart disease, cerebral infarction and peripheral vascular disease. Atherosclerosis has no obvious symptoms in its early stages, so the key to the treatment of atherosclerosis is early intervention of risk factors. Machine learning methods have been used to predict atherosclerosis, but the presence of strong causal relationships between features can lead to extremely high levels of information redundancy, which can affect the effectiveness of prediction systems. OBJECTIVE: We aim to combine statistical analysis and machine learning methods to reduce information redundancy and further improve the accuracy of disease diagnosis. METHODS: We cleaned and collated the relevant data obtained from the retrospective study at Affiliated Hospital of Nanjing University of Chinese Medicine through data analysis. First, some features that with too many missing values are filtered out of the 34 features, leaving 25 features. 49% of the samples were categorized as the atherosclerosis risk group while the rest 51% as the control group without atherosclerosis risk under the guidance of relevant experts. We compared the prediction results of a single indicator that had been medically proven to be highly correlated with atherosclerosis with the prediction results of multiple features to fully demonstrate the effect of feature information redundancy on the prediction results. Then the features that could distinguish whether have atherosclerosis risk or not were retained by statistical tests, leaving 20 features. To reduce the information redundancy between features, after drawing inspiration from graph theory, machine learning combined with optimal correlation distances was then used to screen out 15 significant features, and the prediction models were evaluated under the 15 features. Finally, the information of the 5 screened-out non-significant features was fully utilized by ensemble learning to improve the prediction superiority for atherosclerosis. RESULTS: Area Under the Receiver Operating Characteristic (ROC) Curve (AUC), which is used to measure the predictive performance of the model, was 0.84035 and Kolmogorov-Smirnov (KS) value was 0.646. After feature selection model based on optimal correlation distance, the AUC value was 0.88268 and the KS value was 0.688, both of which were improved by about 0.04. Finally, after ensemble learning, the AUC value of the model was further improved by 0.01369 to 0.89637. CONCLUSIONS: The optimal distance feature screening model proposed in this paper improves the performance of atherosclerosis prediction models in terms of both prediction accuracy and AUC metrics. Code and models are available at https://github.com/Cesartwothousands/Prediction-of-Atherosclerosis.

Environmental impacts of hydrometallurgical recycling and reusing for manufacturing of lithium-ion traction batteries in China.

Recycling lithium-ion batteries from electric vehicles is considered an important way to tackle the future supply risks of virgin materials, but the actual environmental impact of traction battery recycling is controversial. This study conducted a process-based life cycle assessment to quantify the environmental impacts of hydrometallurgical recycling of two common lithium-ion traction batteries (lithium nickel manganese cobalt oxide and lithium iron phosphate battery) and reusing materials in their manufacturing in China. The results show that recycling can cause net environmental benefits of the two traction battery types for the considered impact categories, but the net benefits for direct recycling technology are higher because of fewer requirements of chemicals and energy. Reusing recovered materials in battery manufacturing would reduce the impacts in comparison to no recycling, but the reduction potential of greenhouse gas emission and energy demand is not significant. Sensitivity analysis shows that recycling benefits are highly dependent on recovering efficiency and electricity used for manufacturing and recycling. Comprehensive management strategies are necessary to improve the end-of-life traction battery management, such as using carbon-free energy sources, designing batteries with less metal, and developing recycling technology using fewer chemicals. This study contributes by offering transparent life cycle inventory for hydrometallurgical recycling lithium-ion traction batteries and providing scientific knowledge to improve their sustainable management.

Advancing greenhouse gas emission factors for municipal wastewater treatment plants in China.

Estimations of greenhouse gas (GHG) emissions from municipal wastewater treatment plants (MWTPs) remain significant uncertainties in China owing to a lack of reliable emission factors (EFs). This study developed a framework to obtain multi-level (technology, province, and nation) GHG EFs of MWTPs using a database containing 3107 MWTPs in China and published site-specific monitoring data. Results show that GHG EFs of different technologies range widely from 180.0 to 615.7 g CO2-eq/t wastewater, and significant differences are also observed among different provinces in China (190.5-600.3 g CO2-eq/t wastewater), which are generally lower than the previous estimates. It confirms the importance of more detailed technology classification and considering the technological disparity of different provinces in refining GHG estimations of MWTPs. To test the feasibility of the developed EFs, we compared GHG emissions from MWTPs based on multi-level EFs at different spatial and temporal scales. Similar estimation results imply that selecting corresponding EF depending on the availability of activity data would simplify GHG estimations of MWTPs without sacrificing much accuracy. This study contributes a set of well-developed EFs to improve the estimates of GHG emissions from MWTPs, and also offers a method to develop GHG EFs for other sectors.

A new dietary guideline balancing sustainability and nutrition for China's rural and urban residents.

Diets have important but often complex implications for both environmental quality and nutrition. We establish a production-oriented life cycle model to quantify and compare the farm-to-gate environmental impacts and food nutritional qualities underlying rural and urban diets in China from 1980 to 2019, a period of rapid urbanization and socioeconomic changes. The environmental impacts of rural diets were generally higher than those of urban diets, but this gap reduced after 2000. Environmental and nutritional values varied considerably across the 31 Chinese provinces due to their different food intakes and dietary structures. Dietary changes coinciding with urbanization increased greenhouse gas emissions, eutrophication potential, and nutritional quality, but decreased energy consumption and acidification potential. Based on our results, we propose a new dietary guideline to mitigate environmental impacts and improve nutritional quality.

Assessment of end-of-life electric vehicle batteries in China: Future scenarios and economic benefits.

A better understanding of the waste of end-of-life batteries from electric vehicles (EVs) is a basis for their sustainable management. This study aims to estimate the waste of end-of-life EV batteries during 2006-2040 in China and to analyze the opportunities and challenges of subsequent utilization, based on a developed numerical model, real market data, and elaborately developed scenarios. The result shows that end-of-life batteries would increase from 0.1 to 7.8 thousand tons during 2012-2018, and then to 1500-3300 thousand tons in 2040. Of the waste streams, around 50% are estimated to be metal materials, representing great opportunities for battery recycling for material recovery. Economically, battery recycling for energy storage is estimated to create more economic benefits compared with that for material recovery solely (147.8 versus 76.9 billion US dollars). However, the supply of end-of-life batteries can hardly meet the demand for renewable energy storage in the near future, and a spatial mismatch of the supply and demand of energy storage capacity exists between the eastern and western regions in China. Accordingly, this study highlights national coordination for the rational layout of the collection, disassembly, and remanufacture facilities for the second use of end-of-life EV batteries in China.

Phosphorus footprint in China over the 1961-2050 period: Historical perspective and future prospect.

The phosphorus footprint (PF) is a novel concept to analyze human burdens on phosphorus resources. However, research on PF approach is still limited, and current several PF studies include incomplete phosphorus sources and have limited quantitative interpretation about the drivers of PF changes, which can help understand future trends of PF. This study develops a more comprehensive PF model by considering crop, livestock and aquatic food, and non-food goods, which covers the mainly phosphorus containing products consumed by human. The model is applied to quantify China's PF from 1961 to 2014, and the results of the model are also used to analyze the factors driving the PF changes and explored China's PF scenarios for 2050 using an econometric analysis model (STIRPAT). The result shows that China's PF increased over 11-fold, from 0.9 to 10.6 Tg between 1961 and 2014. The PF of livestock food dominated China's PF, accounting for 57% of the total in 1961 and 45% in 2014. The key factors driving the increase in China's PF are the increase in population and urbanization rate, with contributions of 38% and 33%, respectively. We showed that in the baseline scenario, China's PF would increase by 70% during 2014-2050 and cause the depletion of China's phosphate reserves in 2045. However, in the best case scenario, China's PF would decrease by 15% in 2050 compared with that in 2014, and it would have 50% of current phosphate reserve remaining by 2050. Several mitigation measures are then proposed by considering China's realities from both production and consumption perspective, which can provide valuable policy insights to other rapid developing countries to mitigate the P footprint.