Field-Controlled Hydrological Experiments in Red Soil-Covered Areas (South China): A Review

Investigation of runoff generation processes and response to changes in catchment characteristics (e.g. land use, soil type, slope, etc.), tillage practice and climate pattern (e.g. rainfall intensity and rainfall duration) is important for understanding of the hydrological cycle and developing land management practices for water and soil conservation. Field and indoor artificial hydrological experiments provide an efficient way for the study of the above processes. This study gave a summary of artificial hydrological experiments using rainfall simulator in China, especially in the red soil-covered region of Jiangxi province. Experiment setting for field and indoor artificial hydrological experiments were introduced; the water balance, runoff components (i.e. surface runoff, subsurface runoff at different depths), runoff amount and relationship to rainfall events were studied and assessment of land coverage and tillage practices on soil and water conservation were conducted. Based on the literature review, it implies that hydrological process at field slope requires more investigation in the following aspects: (1) improvement of monitoring strategies and methodology and isotopic method may be used to improve understanding of hydrological regimes, (2) developing long-term in situ experimental study to analyse soil water movement at different temporal and spatial scales and (3) developing and improving modelling of soil water movement

Hydrologische Gewässergütemodellierung in genesteten mesoskaligen Einzugsgebieten

In this study, the HYPE model was tested for simulation ofdischarge and stream water inorganic nitrogen (IN) concentration in two different mesoscale catchments of the German lower mountain range, the Selke (463 km2) and Weida catchments(99 km2). Results showed that IN concentration and daily IN load had a proportional relationship with discharge, indicating that IN leaching ismainly controlled by runoff in managed catchments. The HYPE model was proved to be capable of capturing dynamics and balances of water and IN load with a Nash-Sutcliffe coefficient above 0.83. PEST (Model-Independent Parameter Estimation & Uncertainty Analysis) and DREAM(ZS) (DiffeRential Evolution Adaptive Metropolis algorithm)were combined with the HYPE model to implement parameter calibration and uncertainty analysis. Results showed that multi-site calibration improved model performances at internal sites and decreased parameter posterior uncertainty ranges and prediction uncertainty, indicating the importance of observations from internal sites for spatially distributed prediction. Compared with the parameter calibration against biweekly nitrate-N concentration measurements, nitrogen-process parameters calibrated using daily averages of nitrate-N concentration observations produced better and more robust model performance on simulations of IN concentration and IN load, narrower posterior parameter uncertainty ranges and IN concentration prediction uncertainty. This is attributed to the fact that different hydrological conditions are covered under a temporal high resolution monitoring program. Both PEST and DREAM(ZS) are found to be efficient for hydrological water quality parameter calibration. However, DREAM(ZS)is more sound and appropriate than PEST because of its capability to evolve parameter posterior probability density functions and estimate prediction uncertainty objectively based on Bayesian inference.In dieser Studie wurde das HYPE Model zur Simulation von Abfluss und Konzentration von inorganischem Stickstoff (IN) für zwei Einzugsgebiete der unteren Mittelgebirgslagen, der Selke (463 km2) und der Weida (99 km2), getestet. Die Ergebnisse zeigten, dass sich die IN-Konzentration und die tägliche IN-Fracht proportional zum Abfluss verhalten. Dies deutet darauf hin, dass der Abbau von IN in anthropogen genutzen Einzugsgebieten vom Abfluss abhaengig ist. Das HYPE Model konnte die Dynamiken von Abfluss und IN-Konzentrationen gut abbilden (Nash-Sutcliffe Koeffizient >0.83). Zur Parameterkalibrierung und Unsicherheitsanalyse wurde das HYPE Modell mit den Tools PEST(Model-Independent Parameter Estimation and Uncertainty Analysis) und DREAM(ZS) (DiffeRential Evolution Adaptive Metropolis Algorithm) kombiniert. Durch eine Multi-site calibration konnten die Modellgenauigkeit fuer gebietsinterne Messstellen erhoeht sowie die Vorhersageunsicherheiten vermindert werden. Dies belegt die Bedeutung der Beobachtungen von gebietsinternen Messstellen für die räumlich verteilte Vorhersage. Dies kann damit erklaert werden, dass räumliche Heterogenitäten der Einzugsgebietscharakteristika bei einer Multi-site calibration besser berücksichtigt werden. Die Kalibrierung von Stickstofftransport- und -umsatzprozessen mittels Nitrattageswerten führt im Vergleich zur Verwendung von 2-wöchentlichen Werten zu einer höheren Modellgenauigkeit. Zudem werden Parameterunsicherheiten verringert. Dies ist darauf zurueckzufuehren, dass die Variabilitaet hydrologischer Bedingungen durch zeitlich hoch aufgelöste Messdaten besser erfasst werden. Sowohl PEST als auch DREAM(ZS) erwiesen sich als geeignet zur Kalibrierung der Modellparameter. Allerdings weist DREAM(ZS) Vorteile gegenueber PEST auf, da es ueber einen globalen Suchalgorithmus verfügt und Vorhersageunsicherheiten anhand Bayesischer Inferenz objektiv berechnet werden

Endovascular stent-graft placement and coil embolization for an anomalous splenic artery aneurysm

Aneurysms of the splenic artery originating anomalously from the superior mesenteric artery are extremely rare; however, they are clinically important because of the potential for fatal rupture and particular anatomical location. Most previous cases were managed by open surgical intervention. We present a case of an anomalous splenic artery aneurysm, which was successfully treated with endovascular stent graft placement and coil embolization. This appears to be a promising minimally invasive approach to manage this rare entity. Also, we review the literature of aneurysms of the splenic artery arising from the superior mesenteric artery

Spontaneous retroperitoneal hematoma associated with iliac vein rupture

ObjectiveSpontaneous retroperitoneal hematoma (SRH) associated with iliac vein rupture is a rare but life-threatening emergency with high operative mortality. This study summarizes our experience in providing diagnostic and therapeutic management for this rare clinical entity.MethodsBetween May 2002 and May 2009, nine patients were admitted to our hospital for SRH and acute deep venous thrombosis (DVT). Medical data for demographics, clinical presentation, auxiliary examinations, treatment modalities, outcomes, and follow-up were retrospectively analyzed.ResultsNine patients (8 women, 1 man) were enrolled in this study. All were aged >45 years (range, 46-70 years). The common clinical manifestations were sudden onset of left lower abdominal or lumbar pain, swelling of the left lower extremity, anemia, and hypotension. Most patients were diagnosed by duplex ultrasound imaging and computed tomography scan. Three patients were treated conservatively, and six underwent surgical or combined treatments, comprising 2 repairs of iliac vein, 1 iliac vein ligation and Palma-Dale bypass graft, 1 pelvic vein ligation, 1 removal of hematoma, and 1 repair of iliac vein, thrombectomy, and endovascular stent placement. The iliac vein ruptured in five patients. May-Thurner syndrome was found in three patients. One patient died after surgery (operative mortality, 16.7%). Postoperative morbidity was 50%. Mean volume of perioperative blood transfusion was 900 ± 640 mL (range, 0-2000 mL). Mean lengths of stay were 2.7 ± 1.4 days (range, 2-5 days) in the intensive care unit and 16.9 ± 2.4 days (range, 14-21 days) in the hospital. Eight patients were postoperatively treated with 6 months of warfarin. Mean follow-up was 30.5 ± 15.0 months (range, 6-50 months). The occurrence rate of chronic venous insufficiency was 87.5% during follow-up.ConclusionsSRH with concomitant DVT, especially in women aged >45, should be considered in patients with sudden lower abdominal or lumbar pain, leg swelling, anemia, and shock. Spontaneous iliac vein rupture and the presence of May-Thurner syndrome should be considered in these patients. Surgical interventions were associated with high mortality and morbidity. In our experience, conservative therapy was safer than open surgical procedures

Assessment of the spatial and temporal variations of water quality for agricultural lands with crop rotation in China by using a HYPE model

Many water quality models have been successfully used worldwide to predict nutrient losses from anthropogenically impacted catchments, but hydrological and nutrient simulations with little data are difficult considering the transfer of model parameters and complication of model calibration and validation. This study aims (i) to assess the performance capabilities of a new and relatively more advantageous model-hydrological predictions for the environment (HYPE) to simulate stream flow and nutrient load in ungauged agricultural areas by using a multi-site and multi-objective parameter calibration method and (ii) to investigate the temporal and spatial variations of total nitrogen (TN) and total phosphorous (TP) concentrations and loads with crop rotation using the model for the first time. A parameter estimation tool (PEST) was used to calibrate parameters, which shows that the parameters related to the effective soil porosity were most sensitive to hydrological modeling. N balance was largely controlled by soil denitrification processes, whereas P balance was influenced by the sedimentation rate and production/decay of P in rivers and lakes. The model reproduced the temporal and spatial variations of discharge and TN/TP relatively well in both calibration (2006–2008) and validation (2009–2010) periods. The lowest NSEs (Nash-Suttclife Efficiency) of discharge, daily TN load, and daily TP load were 0.74, 0.51, and 0.54, respectively. The seasonal variations of daily TN concentrations in the entire simulation period were insufficient, indicated that crop rotation changed the timing and amount of N output. Monthly TN and TP simulation yields revealed that nutrient outputs were abundant in summer in terms of the corresponding discharge. The area-weighted TN and TP load annual yields in five years showed that nutrient loads were extremely high along Hong and Ru rivers, especially in agricultural lands

Effects of Changing Fertilization since the 1980s on Nitrogen Runoff and Leaching in Rice–Wheat Rotation Systems, Taihu Lake Basin

The nitrogen (N) loss associated with intensive agricultural activities is a significant cause of eutrophication and algal blooms in freshwater ecosystems. Taihu Lake has experienced serious surface water quality deterioration and eutrophication problems since the 1980s. The objective of this study is to examine the effect of fertilization changes since the 1980s on the N loss with runoff and leaching in the rice–wheat cropping rotation system. According to the results published in the literature since the 1980s, we set up four fertilization scenarios—N1980s: a fertilization rate of 350 kg N·ha−1·year−1 with 30% in manure fertilization to simulate fertilization in the 1980s; NA1990s: a fertilization rate of 500 kg N·ha−1·year−1 with 10% in manure fertilization to simulate fertilization in the early 1990s; NL1990s: fertilization rate of 600 kg N·ha−1·year−1 with 10% in manure fertilization to simulate fertilization in the late 1990s; and N2000s: fertilization rate of 550 kg N·ha−1·year−1 with all chemicals to simulate fertilization in the 2000s. Then, we calibrated and validated the DNDC (denitrification–decomposition) model through field experiments in two rice–wheat rotation seasons from November 2011 to October 2013 and simulated the N loss with runoff and leaching since the 1980s. The results show that N losses with leaching in the four periods (N 1980s, NA1990s, NL1990s, and N2000s) were 5.2 ± 2.1, 9.4 ± 3.2, 14.4 ± 4.6 and 13.5 ± 4.6 kg N·ha−1·year−1, respectively. N losses with surface runoff were 7.9 ± 3.9, 18.3 ± 7.2, 25.4 ± 10.2, and 26.5 ± 10.6 kg N·ha−1·year−1, respectively. The total N loss through runoff and leaching showed an increasing trend from 1980 to the late 1990s, when it reached its peak. The increase in N export to water due to fertilizer application occurs mainly during the rainy season from March to August, and especially from June to August, when rainfall events and intensive rice fertilization activities are frequent. After the 1990s, when the fertilizer rate was above 500 kg N·ha−1·year−1, the crop yields no longer increased significantly, which indicates that the optimized fertilization rate to balance crop yields and N loss to water is lower than 500 kg N·ha−1·year−1. The increase in fertilizer use has been unnecessary since the early 1990s, and at least about 30% of the N loss could have been prevented without reducing crop yields

Bacillus bombysepticus α-Toxin Binding to G Protein-Coupled Receptor Kinase 2 Regulates cAMP/PKA Signaling Pathway to Induce Host Death.

Bacterial pathogens and their toxins target host receptors, leading to aberrant behavior or host death by changing signaling events through subversion of host intracellular cAMP level. This is an efficient and widespread mechanism of microbial pathogenesis. Previous studies describe toxins that increase cAMP in host cells, resulting in death through G protein-coupled receptor (GPCR) signaling pathways by influencing adenylyl cyclase or G protein activity. G protein-coupled receptor kinase 2 (GRK2) has a central role in regulation of GPCR desensitization. However, little information is available about the pathogenic mechanisms of toxins associated with GRK2. Here, we reported a new bacterial toxin-Bacillus bombysepticus (Bb) α-toxin that was lethal to host. We showed that Bb α-toxin interacted with BmGRK2. The data demonstrated that Bb α-toxin directly bound to BmGRK2 to promote death by affecting GPCR signaling pathways. This mechanism involved stimulation of Gαs, increase level of cAMP and activation of protein kinase A (PKA). Activated cAMP/PKA signal transduction altered downstream effectors that affected homeostasis and fundamental biological processes, disturbing the structural and functional integrity of cells, resulting in death. Preventing cAMP/PKA signaling transduction by inhibitions (NF449 or H-89) substantially reduced the pathogenicity of Bb α-toxin. The discovery of a toxin-induced host death specifically linked to GRK2 mediated signaling pathway suggested a new model for bacterial toxin action. Characterization of host genes whose expression and function are regulated by Bb α-toxin and GRK2 will offer a deeper understanding of the pathogenesis of infectious diseases caused by pathogens that elevate cAMP