Quantifying and modelling the dynamics of groundwater balance in unconfined aquifers under a changing climate

The strategic importance of groundwater for water security is increasing under a changing climate, where the projected more frequent and intensive climate extremes could result in a higher vulnerability of surface water compared to groundwater. Nevertheless, groundwater systems are inevitably impacted by climate change directly through changes of replenishment or indirectly through the climate inducing changes in groundwater extraction. It has been reported that a large proportion of aquifers across the world have been experiencing significant groundwater depletion, which in turn poses greater threats not only to human society but also to natural ecosystem. For sustainable groundwater management, one of the essential but challenging hydrogeological missions is to investigate the groundwater dynamics under a changing climate. This research progressively has developed an integrative framework to investigate dynamics of groundwater balance components (including groundwater recharge, discharge and storage) in unconfined aquifers and their connections with climate determinants. The framework combined use of process-based modelling, statistical modelling, hydrograph-based methods and a tracer aided approach to facilitate investigating the dynamics of groundwater balance with consideration of data availability. The methods developed in this research expand the horizon of groundwater research and have been applied to catchments in the Murray-Darling Basin (MDB), the most important agricultural region in Australia that has been suffering from water overallocation for decades. The new findings of this research are expected to contribute to the development of adaption strategies in water resources management and are summarized in the following. (1) This research demonstrates that the combined use of hydrological modelling, hydrograph-based approaches and a tracer-aided approach is applicable to investigate the dynamics of groundwater balance elements in unconfined aquifers at a catchment scale. For the studied catchments in the MDB, catchments with higher precipitation have more recharge and discharge together with higher intra-annual variability. Groundwater storages collectively reach their highest level in winter or early spring, rapidly recede during summer and then continue to be low-level in autumn. (2) This research demonstrates that for the studied catchments, groundwater discharge has decreased significantly and consistently over the past decades and particularly so since the 1990s. The changes in groundwater are strongly associated with climate change and climate variation. Groundwater discharge and storage are found more sensitive to changes in winter precipitation. The decrease in autumn precipitation accounts for 45%-85% of the decrease in groundwater discharge. (3) This research demonstrates that groundwater drought is less resilient but more strongly resistant than precipitation drought. The difference in performance between groundwater drought and precipitation drought narrows down over longer timescales due to a closer relationship between groundwater and precipitation at a longer timescale. Relationships between groundwater drought performance and climate determinants are highly nonlinear and could be distinctly different at different timescales as found by the random forest modelling. (4) This research demonstrates that uncertainties exist in investigating groundwater dynamics owing to the limitation of observations, assumptions in the approaches and the complexity of the groundwater system. The recharge estimates inherit uncertainties from model conceptualization, parameterization and hydrological non-stationarity. The uncertainties from parameterization are comparable with that from model structure. Uncertainties are also discerned in quantifying climate contributions to groundwater reductions based on statistical models without considering hydrological non-stationarity

Growing up with the one-child policy: CEO early-life experiences and corporate investment in China

We examine corporate investment behaviour of Chinese CEOs whose formative years (5–15 years old) overlapped with China’s one-child policy period. We construct alternative measures of CEO early-life experience of gender inequality based on the information on the cities where CEOs lived in their formative years during the one-child policy period. We find that a sample CEO, who experienced greater gender inequality induced by the one-child policy, intends to increase investment, and they invest more than their peers. Moreover, experiencing greater gender inequality, women CEOs are more conservative and risk-averse in investment, and they invest less than their peers. In contrast, men CEOs experiencing greater gender inequality are overconfident and risk-taking in investment, and they invest more than their peers. These results remain robust across a set of tests, including the Generalized Method of Moments (GMM), Difference-In-Difference (DID), and Propensity Score Matching (PSM). We contribute to the debate surrounding China’s one-child policy by providing new evidence on how the one-child policy affects the Chinese economy through its corporate sector

Evaluation of microbe-driven soil organic matter quantity and quality by thermodynamic theory

Microbial communities, coupled with substrate quality and availability, regulate the stock (formation versus mineralization) of soil organic matter (SOM) in terrestrial ecosystems. However, our understanding of how soil microbes interact with contrasting substrates influencing SOM quantity and quality is still very superfi-cial. Here, we used thermodynamic theory principles and Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) to evaluate the linkages between dissolved organic matter (DOM [organic substrates in soil that are readily available]), thermodynamic quality, and microbial communities. We investigated soils from subtropical paddy ecosystems across a 1,000-km gradient and comprising contrasting levels of SOM content and nutrient availability. Our region-scale study suggested that soils with a larger abundance of readily accessible resources (i.e., lower Gibbs free energy) supported higher levels of microbial diversity and higher SOM content. We further advocated a novel phylotype-level microbial classification based on their associations with OM quantities and qualities and identified two contrasting clusters of bacterial taxa: phylotypes that are highly positively correlated with thermodynami-cally favorable DOM and larger SOM content versus those which are associated with less-favorable DOM and lower SOM content. Both groups are expected to play criti-cal roles in regulating SOM contents in the soil. By identifying the associations between microbial phylotypes of different life strategies and OM qualities and quan-tities, our study indicates that thermodynamic theory can act as a proxy for the relationship between OM and soil microbial communities and should be considered in models of soil organic matter preservation. IMPORTANCE Microbial communities are known to be important drivers of organic matter (OM) accumulation in terrestrial ecosystems. However, despite the importance of these soil microbes and processes, the mechanisms behind these microbial-SOM associations remain poorly understood. Here, we used the principles of thermodynamic theory and novel Fourier transform ion cyclotron resonance mass spectrome-try techniques to investigate the links between microbial communities and dissolved OM (DOM) thermodynamic quality in soils across a 1,000-km gradient and comprising contrasting nutrient and C contents. Our region-scale study provided evidence that soils with a larger amount of readily accessible resources (i.e., lower Gibbs free energy) supported higher levels of microbial diversity and larger SOM con-tent. Moreover, we created a novel phylotype-level microbial classification based on the associations between microbial taxa and DOM quantities and qualities. We found two contrasting clusters of bacterial taxa based on their level of association with thermodynamically favorable DOM and SOM content. Our study advan-ces our knowledge on the important links between microbial communities and SOM. Moreover, by identifying the associations between microbial phylotypes of different life strategies and OM qualities and quantities, our study indicates that thermodynamic theory can act as a proxy for the relationship between OM and soil microbial communities. Together, our findings support that the association between microbial species taxa and substrate thermodynamic quality constituted an important complement explanation for soil organic matter preservation

The chemical profiling of Salvia plebeia during different growth periods and the biosynthesis of its main flavonoids ingredients

Salvia plebeia (Lamiaceae) is a valuable medicinal plant widely distributed across Asia and Oceania. However, the composition and accumulation patterns of its active ingredients in different organs during the growth and their biosynthetic mechanism remain unknown. Therefore, we conducted metabolite profiling, transcriptomic analysis, and biological functional verification to explore the distribution, accumulation, and biosynthesis mechanisms of flavonoids in S. plebeia. We identified 70 metabolites including 46 flavonoids, 16 phenolic acids, seven terpenoids, and one organic acid, of which 21 were previously unreported in S. plebeia. Combining metabolomic-transcriptomic analysis and biological functional verification, we identified the key genes involved in biosynthesis of its main active ingredients, hispidulin and homoplantaginin, including SpPAL, SpC4H, Sp4CL2, Sp4CL5, SpCHS1, SpCHI, SpFNS, SpF6H1, SpF6OMT1, SpF6OMT2, SpUGT1, SpUGT2, and SpUGT3. Using the identified genes, we reconstructed the hispidulin and homoplantaginin biosynthesis pathways in Escherichia coli, and obtained a yield of 5.33 and 3.86 mg/L for hispidulin and homoplantaginin, respectively. Our findings provide valuable insights into the changes in chemical components in different organs of S. plebeia during different growth and harvest stages and establishes a foundation for identifying and synthesizing its active components

Intermediate role of gut microbiota in vitamin B nutrition and its influences on human health

Vitamin B consists of a group of water-soluble micronutrients that are mainly derived from the daily diet. They serve as cofactors, mediating multiple metabolic pathways in humans. As an integrated part of human health, gut microbiota could produce, consume, and even compete for vitamin B with the host. The interplay between gut microbiota and the host might be a crucial factor affecting the absorbing processes of vitamin B. On the other hand, vitamin B supplementation or deficiency might impact the growth of specific bacteria, resulting in changes in the composition and function of gut microbiota. Together, the interplay between vitamin B and gut microbiota might systemically contribute to human health. In this review, we summarized the interactions between vitamin B and gut microbiota and tried to reveal the underlying mechanism so that we can have a better understanding of its role in human health

Mapping the Distribution of Water Resource Security in the Beijing-Tianjin-Hebei Region at the County Level under a Changing Context

The Beijing-Tianjin-Hebei (Jingjinji) region is the most densely populated region in China and suffers from severe water resource shortage, with considerable water-related issues emerging under a changing context such as construction of water diversion projects (WDP), regional synergistic development, and climate change. To this end, this paper develops a framework to examine the water resource security for 200 counties in the Jingjinji region under these changes. Thus, county-level water resource security is assessed in terms of the long-term annual mean and selected typical years (i.e., dry, normal, and wet years), with and without the WDP, and under the current and projected future (i.e., regional synergistic development and climate change). The outcomes of such scenarios are assessed based on two water-crowding indicators, two use-to-availability indicators, and one composite indicator. Results indicate first that the water resources are distributed unevenly, relatively more abundant in the northeastern counties and extremely limited in the other counties. The water resources are very limited at the regional level, with the water availability per capita and per unit gross domestic product (GDP) being only 279/290 m3 and 46/18 m3 in the current and projected future scenarios, respectively, even when considering the WDP. Second, the population carrying capacity is currently the dominant influence, while economic development will be the controlling factor in the future for most middle and southern counties. This suggests that significant improvement in water-saving technologies, vigorous replacement of industries from high to low water consumption, as well as water from other supplies for large-scale applications are greatly needed. Third, the research identifies those counties most at risk to water scarcity and shows that most of them can be greatly relieved after supplementation by the planned WDP. Finally, more attention should be paid to the southern counties because their water resources are not only limited but also much more sensitive and vulnerable to climate change. This work should benefit water resource management and allocation decisions in the Jingjinji region, and the proposed assessment framework can be applied to other similar problems.This study is supported by the National Key Research and Development Program of China (2016YFC0401401) and the National Natural Science Foundation of China (51609256, 51609122, 51522907, 51739011, and 51569026). Partial support is also from the Young Elite Scientists Sponsorship Program by the China Association for Science and Technology (2017QNRC001