Evaluation of virtual water trade in the Yellow River Delta, China

Water conservation potential of energy-intensive industries under clean energy and electricity substitution: A case study of nine provinces along the Yellow River Basin

Energy-intensive industries in China are generally water-intensive. In the context of clean energy and electricity substitution driven by the carbon peaking goal, few studies have examined changes in industrial water resources in this development. To address this knowledge gap, a new framework is proposed for quantitatively analyzing industrial water conservation pathways. This study focuses on the nine provinces in the Yellow River Basin (YRB). It employs a bottom-up approach to estimate the overall water consumption of the power and steel industries, which are two key components of both energy-intensive and water-intensive sectors. Subsequently, decomposition analysis was used to identify the key factors affecting inter-annual water consumption changes. Based on the above information, indicators are established to quantify the potential for water conservation, and scenario analysis is utilized to measure and evaluate the water conservation potential of the study area. The results show that the total water consumption for power generation in nine provinces is projected to reach 5.13 billion m3 by 2030, with an average water consumption factor of 0.97 m3/MWh. Simultaneously, the total water consumption for steelmaking is expected to be 820 million m3, with an average water consumption factor of 2.89 m3/t. The increase in water consumption can be decoupled into scale, structure, and intensity effects, which have positive, negative, and negative impacts, respectively. By 2030, the nine provinces have the potential to conserve up to 4.57 billion m3 of water through clean energy and electricity substitution, traditional technology improvement, and inter-regional transmission. These results will contribute to the future coordinated management of energy and water resources.

Optimal water resource allocation considering virtual water trade in the Yellow River Basin

Water can be redistributed physically and virtually. We explored water allocation optimization to mitigate water stresses by constructing a physical-virtual dual water system and optimizing the 1987 Yellow River water allocation scheme. We calculated the virtual water volume, identified the virtual in-basin, out-of-basin, and export water volumes, and compared the total regional water demand (i.e., combined physical and virtual water volumes) with regional water planetary boundaries to optimize basin water allocation schemes. Virtual water accounted for > 90% of the total regional demands, whereas physical flows did not significantly impact them. Moreover, allocation quotas for Qinghai and Inner Mongolia should be reduced by 0.113 and 1.005 billion m3, respectively, for sustainability. Furthermore, improving the efficiency of water-intensive sectors and limiting virtual water outflows from heavy industry to out-of-basin sectors are vital to water intensification. Increased attention should be directed toward physical-virtual water demands than the current focus on supply-oriented water allocation.

Occurrence and health risk assessment of phthalates in a typical estuarine soil: A case study of the various functional areas of the Yellow River Delta

In recent years, the extensive distribution of phthalates (PAEs) in soils has attracted increasing attention. In this study, the concentrations of six types of PAEs were measured in five dissimilar regions of the Yellow River Delta (YRD), and regional differences, pollution characteristics and health risks of PAEs pollution were investigated. The detection rate of PAEs was 100 %, and the concentration range of Σ6PAEs was 0.709-9.565 mg/kg, with an average of 3.258 ± 2.031 mg/kg. There were different spatial distribution differences of PAEs in soils of the YRD, with residential living, chemical industrial, and crop growing areas being the main areas of PAEs distribution. It was worth noting that di (2-ethylhexyl) phthalate (DEHP) and dibutyl phthalate (DBP) are prominent contributors to PAEs in soils of the YRD. Correlation analyses showed that soils physicochemical properties such as SOM, TN and CEC were closely correlated to the transport and transformation of PAEs. Use by petrochemical industries, accumulation of plasticizers, additives (derived from cosmetics, food, pharmaceutical), fertilizers, pesticides, plastics, and atmospheric deposition are the principal sources of PAEs in the YRD. A health risk assessment showed that the health risk caused by non-dietary intake of PAEs was low and considered acceptable. PAEs pollution in the YRD soil is particularly noteworthy, especially for the prevention and control of DEHP and DBP pollution. This study provides basic data for an effective control of soil PAEs pollution in the YRD, which is conducive to the sustainable development of the region.

Study on the fundraising of horizontal ecological compensation under efficiency and fairness: a case study of the Yellow River Basin in China

How to raise the ecological compensation fund for the Yellow River Basin is one of the key difficulties for executing the ecological compensation mechanism and ensuring the high-quality development of the entire basin. This paper, which is based on systems theory, analyzes the social-economic-ecological compound system of the Yellow River Basin. It makes the point that the goals of human-water harmony, ecological compensation efficiency improvement, and coordinated regional development should be achieved in raising ecological compensation funds. Guided by the raising targets, a two-layer fundraising model based on efficiency and fairness is constructed for ecological compensation. The upper-level model is built to calculate the ecological compensation efficiency of each compensation subject from an input-output perspective. The initial fundraising scheme was further determined to implement the efficiency principle. Within the framework of sustainable development theory, the lower-level model adheres to the fairness principle based on efficiency. The social-economic development level of the compensation subject is considered to discriminate and optimize the initial scheme. Additionally, the two-layer model was utilized to conduct an empirical analysis with the data of the Yellow River Basin from 2013 to 2020. The results show that the optimized fundraising scheme is in line with the actual development level of the Yellow River Basin. This study can provide a reference for the fundraising of horizontal ecological compensation and promote the sustainable development of the whole basin.

"Water-Carbon" redistribution caused by China's interprovincial grain transportation

Water resource and carbon emission involved in grain production in mainland China are redistributed among provinces as the grain was transported in recent years. This study first calculated the water consumption and carbon emission during the growth of grain crops based on the water-carbon footprint theory, and then used the social-equity method to calculate the inter-regional grain virtual water and virtual carbon flow. Finally, the regional and national trends in water saving and carbon emission reduction were calculated based on the spatial and temporal differences in grain planting among provinces. In terms of virtual water-carbon, from 2000 to 2017, the amount of the inter-provincial grain virtual water flow increased from 717.4 × 10⁸ m³ to 1472.6 × 10⁸ m³. Heilongjiang and Guangdong are the provinces with the largest amount of grain virtual water outflow (670.9 × 10⁸ m³) and inflow (402.8 × 10⁸ m³) in 2017, respectively. And the total inter-provincial grain virtual carbon flow increased from 2362.7 × 10⁴ t CO₂e to 12,680.6 × 10⁴ t CO₂e. Grain transport leads to water saving and carbon emission reduction, the amount of water saving increased from 25.6 × 10⁸ m³ to 77.0 × 10⁸ m³ and the carbon emission reduction increased from 2.4 × 10⁴ t CO₂e to 847.4 × 10⁴ t CO₂e from 2000 to 2017. Based on research results and from the perspective of socio-hydrology combined with water saving and carbon emission reduction, the regions could optimize the integration of water saving, carbon emission reduction, and sustainable development based on coordinating the grain planting structure according to their own climatic condition, soil and water resource condition, and socioeconomic condition.

Pollution characteristics and health risk assessment of phthalate esters in agricultural soil of the Yellow River Delta, China

A total of 100 agricultural soil samples, collected in the Yellow River Delta, China, were analyzed for six U.S. Environmental Protection Agency priority phthalate esters (PAEs), focusing on the characteristics of PAEs contamination and potential health risks. The detection frequencies of ∑₆PAEs were 100%, where the concentration ranged from 1.087 to 14.391 mg·kg^-1, with a mean value of 4.149 mg·kg^-1. The most abundant PAEs were di(2-ethylhexyl) phthalate (DEHP) and di-n-butyl phthalate (DnBP). The areas with higher contents of ∑₆PAEs are distributed in the western and central parts of the Yellow River Delta region and around Laizhou Bay. PAEs in the Yellow River Delta agricultural soil were attributed to pollutant emissions from petrochemical industries, plasticizers or additives, fertilizers, and pesticides. The non-carcinogenic risk of human exposure to PAEs in agricultural soils is relatively low, but the non-carcinogenic risk is higher in children than in adults, and children are a sensitive group. Under the dietary route, both DEHP and ∑₂PAEs (BBP, and DEHP) pose some degree of carcinogenic risk to both local adults and children. Efforts must be made to enhance the prevention and control of PAEs contamination of agricultural soils in the Yellow River Delta region to reduce the potential risk to humans.

Optimization and Benefit Analysis of Grain Trade in Belt and Road Countries

Grain trade in Belt and Road (B&R) countries shows a mismatch between the volume and direction of grain flows and actual demand. With economic and industrial development, the water crisis has intensified, which poses a great challenge to the security of world grain supply and demand. There are few studies on the reconstruction of grain trade relations from the perspective of grain economic value. In this paper, a linear optimization model considering opportunity cost is proposed to fill the gap, and it is compared and analyzed with the optimization model considering only transportation cost. The grain supply and demand structures in both optimization results show characteristics of geographical proximity and long-tail distribution. Furthermore, the economic and water resource benefits resulting from the two optimal configurations are compared and analyzed. It is found that the economic benefits generated by grain trade in B&R countries with the consideration of opportunity cost not only cover transportation costs but also generate an economic value of about 130 trillion US dollars. Therefore, considering opportunity cost in grain trade is of great significance for strengthening cooperation and promoting the economic development of countries under the B&R framework. In terms of resource benefits, the grain trade with consideration of opportunity cost saves nearly 28 billion cubic meters of water, or about 5% of the total virtual water flow. However, about 72 billion cubic meters of water is lost for the grain trade with consideration of transportation cost. This study will help to formulate and adjust policies related to the "Belt and Road Initiative" (B&R Initiative), so as to maximize the economic benefits while optimizing the structure of grain trade and alleviating water scarcity pressures.

Assessing impacts of the Ecological Retreat project on water conservation in the Yellow River Basin

The Ecological Retreat (ER) project significantly impacts water conservation functions in the Yellow River Basin (YRB). However, studies on the impact and benefit of different ER modes on ecological water effects still lack systematic and integral disclosure. In our study, CNLUCC (China land use/cover data sets) and the Markov transition matrix were used to simulate land pattern changes from 2000 to 2018. Water yield was chosen as an indicator of water conservation to explore the impact of the ER project by using the water yield module of the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model. After the ER project, the land pattern changed significantly because massive cropland was transformed into forest and grassland. Thus, the total water yields of the YRB increased by 46.32 × 10³ hm³ from 2000 to 2018, and the overall water yield benefit was 12.39% larger than the water loss. Forest rehabilitation (FR) showed the highest average water yield capacity, while grassland restoration (GR) exhibited the most incredible total water conservation benefit. Wetland recovery (WLR) manifested a great capacity to improve average water yield, but its total benefit was far less than FR and GR, while waterbody recovery (WBR) showed a negative impact. The results indicate that FR and GR were effective restoration methods, and WLR showed great potential to improve water yield. By using the random forest and principal components analysis, precipitation (PRE), evaporation (AET and ET₀), and variation of forest and grassland proved to be the most critical driving indicators affecting water yield changes. Additionally, the correlation and sensitivity between root depth (R_depth) and water yield indicate that increasing R_Depth can also enhance water conservation. The ER project provides a valuable restoration model for water yield and water conservation benefits. The results can provide theoretical support for eco-hydrology and land ecological restoration studies.

Watershed Ecohydrological Processes in a Changing Environment: Opportunities and Challenges

Basin ecohydrological processes are essential for informing policymaking and social development in response to growing environmental problems. In this paper, we review watershed ecohydrology, focusing on the interaction between watershed ecological and hydrological processes. Climate change and human activities are the most important factors influencing water quantity and quality, and there is a need to integrate watershed socioeconomic activities into the paradigm of watershed ecohydrological process studies. Then, we propose a new framework for integrated watershed management. It includes (1) data collection: building an integrated observation network; (2) theoretical basis: attribution analysis; (3) integrated modeling: medium- and long-term prediction of ecohydrological processes by human–nature interactions; and (4) policy orientation. The paper was a potential solution to overcome challenges in the context of frequent climate extremes and rapid land-use change.

Agricultural Water Utilization Efficiency in China: Evaluation, Spatial Differences, and Related Factors

Agricultural water utilization efficiency (AWUE) reflects the rational utilization of water resources in agricultural production. Improving AWUE is important for both improving the levels of agricultural production and reducing consumption of water resources, and it is significant to explore the spatial differences between different cities and regions and the various factors related to AWUE, both theoretically and practically. The AWUE of totally 281 cities at the prefecture level or above in China between 2003 and 2018 was evaluated using the super-efficiency slacks-based measure (SBM). The spatial differences in AWUE were simulated by exploratory spatial data analysis (ESDA), and the various factors affecting AWUE were simulated using the graphical statistical tool, Geodetector. The results of this study are as follows: (1) The mean value of AWUE across the country was merely 0.23 when it registered a record high in 2018, indicating that the AWUE in China was low; (2) AWUE showed significant spatial differences judging from the results of ESDA, and the low-low type was the principal spatial type, which was distributed mainly in the North China Plain and the Loess Plateau; and (3) agricultural technology was the main factor affecting AWUE.

Decline of virtual water inequality in China's inter-provincial trade: An environmental economic trade-off analysis

The trade-off between economic growth and environmental conservation is a significant factor in national environmental management. Previous studies have revealed that there are substantial water resources embodied in the inter-regional trade of China, but there is a scarcity of studies analyzing the cost-benefit inequality in trade, which should be considered when developing water resource allocation and conservation policies. The aim of the present study was to fill the gap in existing research by constructing a novel virtual water inequality index based on the net transfers of virtual water and value added between trading provinces. The results of the present study reveal that the virtual water trade of China accounts for about a third of the annual water use thereof and tends to flow from interior developing provinces to coastal developed provinces. Over 70% of consumption-based water consumption of richer provinces (Beijing, Tianjin and Shanghai) is imported from other regions; however, approximately 60% of the value added triggered by the final consumption of said regions is retained within the region. When trading with rich provinces, several developing provinces with rich water resources, such as Xinjiang and Heilongjiang, not only incur net water outflows but also suffer a negative balance of value added, thereby resulting in the occurrence of virtual water inequality. However, with the coordinated development of China's economy, the problem of virtual water inequality in China's inter-provincial trade has been alleviated to some extent. Advocating water pricing system reform to reflect local water scarcity is suggested, especially in arid regions. Additionally, a virtual water compensation scheme considering cost-benefit inequality in trade may also be a practical solution.