Landscape patterns in a watershed potentially have significant influence on the occurrence, migration, and transformation of pollutants, such as nitrogen (N) and phosphorus (P) in rivers. Human ...activities can accelerate the pollution and complicate the problem especially in a peri-urban watershed with different types of land use. To characterize the heterogeneous correlations between landscape patterns and seasonal variations of N and P in a peri-urban watershed located upstream of Tianjin metropolis, China, observations of total nitrogen (TN) and total phosphorus (TP) at 33 locations were performed in the wet and dry seasons from 2013 to 2016. The data from individual locations were averaged for the wet and dry seasons and analyzed with geographical detector to identify influential landscape indices on seasonal water quality variations. The geographically weighted regression method, capable of analyzing heterogeneous correlations, was used to evaluate the integrated effects from different landscape indices. The results demonstrated that the location-weighted landscape contrast index (LWLI), the ratio of urban areas, and the ratio of forest areas were major influential indicators that affected TN and TP in river water. These indices also had integrated effects on variations of TN and TP together with other indices such as Shannon diversity index, landscape shape index, largest patch index, and contagion index. The integrated effects were different in the wet and dry seasons because of different effects of flushing and dilution by rainwater and the heterogeneity in landscape patterns. The LWLI had a positive relationship to water quality in the areas with high ratio of urban areas, indicating that domestic wastewater can be a major source of N and P pollution. The approaches and findings of this study may provide a reference for characterizing the major factors and integrated effects that control nonpoint source pollution in a watershed.
The purpose of this work was to identify the features of the gut microbiome in cases of ankylosing spondylitis (AS) testing positive for human leukocyte antigen- (HLA-) B27 and healthy controls (HCs) ...as well as to determine how bacterial populations were correlated with C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). Fecal DNA extracted from fecal samples from 10 AS cases and 12 HCs was subjected to 16S rRNA gene sequencing. The two research groups did not differ significantly regarding alpha diversity. By comparison to HCs, AS cases displayed a lower relative level of Bacteroidetes (P<0.05), but a higher level of Firmicutes and Verrucomicrobia (P<0.05). Furthermore, the correlation between the specific gut bacteria and ESR or CRP was investigated. At the phylum level, Firmicutes and Verrucomicrobia had a positive association with ESR and CRP, while Bacteroidetes exhibited an inverse correlation with ESR and CRP. Meanwhile, in terms of genus, Bacteroides had a positive association with ESR and CRP, whereas Ruminococcus and Parasutterella had an inverse correlation with ESR and CRP, and Helicobacter also displayed an inverse correlation with CRP. Such findings indicated dissimilarities between AS cases and HCs regarding the gut microbiome, as well as the existence of correlations between bacterial populations and both ESR and CRP.
•Graph neural networks (GNN) model is established to simulate spring discharge.•The model is applied to Niangziguan Springs, the max karst spring in North China.•Three types of graph structures of ...GNN are constructed, and we find the best one.•After comparing ChebNet and graph convolutional network, we find ChebNet is better.
Over past decades, extensive groundwater development in karst aquifers has led to significant declines in groundwater levels and spring discharges. While the recent implementation of sustainable karst aquifer development policies appears to have lessened the declining trend of spring discharge, many aspects of karst aquifers remain to be explored. This paper applied two spectral-based graph neural networks (GNN) models of ChebNet and graph convolutional networks (GCN) for karst hydrological processes by considering the correlations among precipitation, spring discharge, and human impacts. This approach captures the spatial dependence of precipitation infiltration, groundwater propagation in heterogeneous karst aquifer and spring discharge from bared karst aquifer. This study proposed three graph structures (complete graph, information flow graph, and association graph of groundwater flow field) to depict relations between precipitation and spring discharge in the GNN models in Niangziguan Springs, China. The results show that the association graph of groundwater flow field is the optimal graph structure of GNN models. Based on the optimal structure, we investigated precipitation-driven-discharge models using ChebNet and GCN to predict the discharge. The results show that the high-order ChebNet is more adaptable to simulate the karst hydrological processes with nonlinear and nonstationary behaviors than that GCN. Moreover, the study confirms that the groundwater sustainable development policy has achieved a prominent contribution 2 m3/s in water conservancy in Niangziguan Springs catchment.
Objective
There is growing evidence that ultraviolet B (UVB) irradiation can change the expression profile of microRNAs (miRNAs) in immortalized human epidermal melanocytes (Pig-1). We aimed to ...investigate the effect of miR-340 on regulating UVB-induced pigmentation.
Methods
Real-time quantitative PCR (qRT-PCR) was used to evaluate the expression of miR-340 in Pig-1 cells. Immunoblotting analysis, qRT-PCR, and luciferase reporter assays were used to detect the potential target of miR-340. The sodium hydroxide dissolution assay was used to assess the effect of miR-340 on changes in melanin content.
Results
Expression of miR-340 was reduced in human Pig-1 cells after UVB irradiation. We found a negative correlation between miR-340 and melanocyte inducing transcription factor (MITF) in Pig-1 cells after UVB irradiation. Knockdown and overexpression of MITF in Pig-1 cells down- and upregulated melanogenesis, respectively. Overexpression of miR-340 inhibited MITF expression, reduced the amount of melanin, and suppressed expression of multiple key molecules involved in the pigment synthesis pathway, whereas knockdown of miR-340 showed the opposite results.
Conclusions
Our results showed that miR-340 inhibited melanogenesis by regulating the downstream molecules of MITF and its signaling pathways, suggested that miRNA-340 may be a new target for the clinical treatment of UVB-induced pigmentation.
•Large scale climate phenomena are linked with spring discharge.•Use spring discharge as proxy to reflect regional groundwater system.•Identify effects of human activity on spring discharge using ...piecewise analysis.•Human activity did not alter the periods of the monsoons-driven spring discharge.•Human activity enhanced the magnitudes of the monsoons-driven spring discharge.
Karst hydrological process has largely been altered by climate change and human activity. In many places throughout the world, human activity (e.g. groundwater pumping and dewatering from mining) has intensified and surpassed climate change, where human activity becomes the primary factor that affects groundwater system. But it is still largely unclear how the human activity affects spring discharge in magnitude and periodicity. This study investigates the effects of anthropogenic activity on spring discharge, using the Xin'an Springs of China as an example. The Xin'an Spring discharge were divided into two time periods: the pre-development period from 1956 to 1971 and the post-development period from 1972 to 2013. We confirm the dividing time (i.e. 1971) of these two periods using the Wilcoxon rank-sum test. Then the wavelet transform and wavelet coherence were used to analyze the karst hydrological processes for the two periods respectively. We analyze the correlations of precipitation and the Xin’an spring discharge with the monsoons including the Indian Summer Monsoon (ISM) and the West North Pacific Monsoon (WNPM) and the climate teleconnections including El Niño Southern Oscillation (ENSO) and Pacific Decadal Oscillation (PDO), respectively. The results indicated that the spring discharge was attenuated about 19.63% under the influence of human activity in the Xin’an Springs basin. However, human activity did not alter the size of the resonance frequencies between the spring discharge and the monsoons. In contrast, it reinforced the periodicities of the monsoons-driven spring discharge. It suggested that human has adapted to the major climate periodicities, and human activity had the same rhyme with the primary climate periodicity. In return, human activity enhances the correlation between the monsoons and the spring discharge.
•Investigate how rainfall and evaporation drive depth to water table (DWT).•Fit multiscale rainfall and evaporation via multi-modes truncated Fourier series.•Develop a field equipment isolating ...lateral flow to observe DWT vertically.•Develop and calibrate a first-cut mathematical tool to predict the DWT.
Depth to water table (DWT) in shallow groundwater affects land salinization, ecological system, irrigation scheduling, and agriculture output. Few researches have, however, focused on the impact of the complex transient dynamics of precipitation and evapotranspiration on the behavior of DWT in shallow groundwater. This study proposes a one-dimensional DWT model driven by complex multi-periodic precipitation and evapotranspiration, coupling the Boussinesq equation with the Averianov formula. The model is calibrated using multi-modes truncated Fourier series against 1-D data from the field experiment in Guanzhong Basin, Shaanxi Province, China. The experiment shields lateral groundwater flow effectively to ensure an accurate measurement of the effect of precipitation and evapotranspiration on DWT in the vertical direction. Results of the study show that fluctuations of DWT are driven by multi-periodic evapotranspiration and precipitation primarily in the long-wave components because the high-frequency precipitation and evapotranspiration are essentially filtered out when they propagate through unsaturated zones. This result beneficial for future studies on DWT via the Fourier series. In particular, the calibrated model can quickly determine the DWT of Guanzhong Basin site, predict DWT in the short term, and simulate the dynamic change of groundwater level, the vegetation in the study area. Besides, although the calibrated parameters cannot be directly applied to other sites, they may be useful to the prediction of the DWT fluctuations in the sites.
Hydraulic tomography (HT) has emerged as a potentially viable method for mapping fractures in geologic media as demonstrated by recent studies. However, most of the studies adopted equivalent porous ...media (EPM) models to generate and invert hydraulic interference test data for HT. While these models assign significant different hydraulic properties to fractures and matrix, they may not fully capture the discrete nature of the fractures in the rocks. As a result, HT performance may have been overrated. To explore this issue, this study employed a discrete fracture network (DFN) model to simulate hydraulic interference tests. HT with the EPM model was then applied to estimate the distributions of hydraulic conductivity (K) and specific storage (Ss) of the DFN. Afterward, the estimated fields were used to predict the observed heads from DFN models, not used in the HT analysis (i.e., validation). Additionally, this study defined the spatial representative elementary volume (REV) of the fracture connectivity probability for the entire DFN dominant. The study showed that if this spatial REV exists, the DFN is deemed equivalent to EPM and vice versa. The hydraulic properties estimated by HT with an EPM model can then predict head fields satisfactorily over the entire DFN domain with limited monitoring wells. For a sparse DFN without this spatial REV, a dense observation network is needed. Nevertheless, HT is able to capture the dominant fractures.
Key Points
Spatial REV of fracture connectivity probability defines the equivalence of a discrete fracture network (DFN) and porous media
For a highly dense DFN with spatial REV, hydraulic properties derived from hydraulic tomography predict independent flow fields well
For a sparse DFN without a spatial REV, hydraulic tomography with an Equivalent Porous Media model captures large‐scale dominant fractures
In this paper, the authors propose a new approach to solving the groundwater flow equation in the Toth basin of arbitrary top and bottom topographies using deep learning. Instead of using traditional ...numerical solvers, they use a DeepONet to produce the boundary-to-solution mapping. This mapping takes the geometry of the physical domain along with the boundary conditions as inputs to output the steady state solution of the groundwater flow equation. To implement the DeepONet, the authors approximate the top and bottom boundaries using truncated Fourier series or piecewise linear representations. They present two different implementations of the DeepONet: one where the Toth basin is embedded in a rectangular computational domain, and another where the Toth basin with arbitrary top and bottom boundaries is mapped into a rectangular computational domain via a nonlinear transformation. They implement the DeepONet with respect to the Dirichlet and Robin boundary condition at the top and the Neumann boundary condition at the impervious bottom boundary, respectively. Using this deep-learning enabled tool, the authors investigate the impact of surface topography on the flow pattern by both the top surface and the bottom impervious boundary with arbitrary geometries. They discover that the average slope of the top surface promotes long-distance transport, while the local curvature controls localized circulations. Additionally, they find that the slope of the bottom impervious boundary can seriously impact the long-distance transport of groundwater flows. Overall, this paper presents a new and innovative approach to solving the groundwater flow equation using deep learning, which allows for the investigation of the impact of surface topography on groundwater flow patterns.
•DeepONet is used to represent boundary-to-solution maps for solving groundwater flow equations.•It maps domain geometries and boundary conditions to solutions of the groundwater flow equation.•Maps with Dirichlet and Robin conditions at the top and Neumann conditions at the bottom are implemented.•Two implementations of DeepONets are presented: domain embedding and nonlinear transformation.•Using boundary-to-solution maps, the impact of surface topography on flow patterns is studied.
Backward erosion piping (BEP) is one of the major causes of seepage failures in levees. Seepage fields dictate the BEP behaviors and are influenced by the heterogeneity of soil properties. To ...investigate the effects of the heterogeneity on the seepage failures, we develop a numerical algorithm and conduct simulations to study BEP progressions in geologic media with spatially stochastic parameters. Specifically, the void ratio e, the hydraulic conductivity k, and the ratio of the particle contents r of the media are represented as the stochastic variables. They are characterized by means and variances, the spatial correlation structures, and the cross correlation between variables. Results of the simulations reveal that the heterogeneity accelerates the development of preferential flow paths, which profoundly increase the likelihood of seepage failures. To account for unknown heterogeneity, we define the probability of the seepage instability (PI) to evaluate the failure potential of a given site. Using Monte‐Carlo simulation (MCS), we demonstrate that the PI value is significantly influenced by the mean and the variance of ln k and its spatial correlation scales. But the other parameters, such as means and variances of e and r, and their cross correlation, have minor impacts. Based on PI analyses, we introduce a risk rating system to classify the field into different regions according to risk levels. This rating system is useful for seepage failures prevention and assists decision making when BEP occurs.
Key Points
Proposing a numerical approach that involves the heterogeneity of soils in simulating of back erosion piping
Interpreting the influences of the uncertainty and the spatial variability of soil properties
Introducing the risk rating system to classify the field into regions according to different risk levels
•Quasi-analytical solutions of depth to water table (DWT) in unconfined aquifer.•Amplitude of DWT correlates with that of precipitation linearly and positively.•Amplitude of DWT correlates with that ...of evapotranspiration (ET) parabolically.•The phase of ET is in advance of DWT lags in arid area.•The ET and precipitation affect the phase of DWT in synchrony in humid area.
Depth to water table (DWT) for an unconfined aquifer affects a wide range of hydrological, ecological, and agricultural problems such as soil salinization, plant type, and crop output. In a world without human impacts, DWT in shallow groundwater zones is mainly driven by evapotranspiration and precipitation. In the real-world however, human impacts on groundwater hydrological processes are ubiquitous, which hinders one to fully understand the natural groundwater hydrological rule. The purpose of this study is to derive an analytical solution of precipitation-evapotranspiration driven DWT irrespective of the human impacts. Through pretreatment of practical data to eliminate human impacts, we show that the proposed method is efficient in dealing with the real-world problems. Specifically, we establish a mathematical model describing impacts of periodic evapotranspiration and precipitation on DWT. An innovative quasi-analytical solution using the Fourier series is developed and analyzed in detail based on the model. This study indicates that the amplitude of DWT is correlated linearly with the amplitude of precipitation and quadratically with the amplitude of potential evapotranspiration. The phase position of DWT is subject to the phase lag between the precipitation and potential evapotranspiration. In arid regions, the evapotranspiration has a greater influence on the phase of DWT than the precipitation. This quasi-analytical solution is limited for a shallow groundwater situation in which DWT is less than the extinction depth of groundwater evapotranspiration.
PDF
