Vertical distribution analysis and total mass estimation of nitrogen and phosphorus in large shallow lakes.

Analysing the vertical distribution of nutrient salts and estimating the total mass of lake nutrients is helpful for the management of lake nutrient status and the formulation of drainage standards in basins. However, studies on nitrogen (N) and phosphorus (P) in lakes have focused on obtaining measures of N and P concentrations, but no understanding exists on the vertical distribution of N and P in the entire water column. The present study proposes algorithms for estimating the total masses of N/P per unit water column (ALGO-TNmass/ALGO-TPmass) for shallow eutrophic lakes. Using Lake Taihu as an example, the total masses of nutrients in Lake Taihu in the historical period were obtained, and the algorithm performance was discussed. The results showed that the vertical distribution of nutrients decreased with increasing depth and exhibited a quadratic distribution. Surface nutrients and chlorophyll-a concentrations play important roles in the vertical distribution of nutrients. Based on conventional surface water quality indicators, algorithms for the vertical nutrient concentration in Lake Taihu were proposed. Both algorithms had good accuracy (ALGO-TNmass R2 > 0.75, RMSE <0.57; ALGO-TPmass R2 > 0.80, RMSE ≤0.50), the ALGO-TPmass had better applicability than the ALGO-TNmass, and had good accuracy in other shallow lakes. Therefore, deducing the TPmass using conventional water quality indicators in surface water, which not only simplifies the sampling process but also provides an opportunity for remote sensing technology to monitor the total masses of nutrients, is feasible. The long-term average total mass of N was 11,727 t, showing a gradual downward trend before 2010, after which it stabilised. The maximum and minimum intra-annual total N masses were observed in May and November, respectively. The long-term average total mass of P was 512 t, showing a gradual downward trend before 2010, and a slow upward trend thereafter. The maximum and minimum intra-annual total masses of P occurred in August and February or May, respectively. The correlation between the total mass of N and meteorological conditions was not obvious, whereas some influence on the total mass of P was evident, particularly water level and wind speed.

Development of remote sensing algorithm for total phosphorus concentration in eutrophic lakes: Conventional or machine learning?

Phosphorus is a limiting nutrient in freshwater ecosystems. Therefore, the estimation of total phosphorus (TP) concentration in eutrophic water using remote sensing technology is of great significance for lake environmental management. However, there is no TP remote sensing model for lake groups, and thus far, specific models have been used for specific lakes. To address this issue, this study proposes a framework for TP estimation. First, three algorithm development frameworks were compared and applied to the development of an algorithm for Lake Taihu, which has complex water environment characteristics and is a representative of eutrophic lakes. An Extremely Gradient Boosting (BST) machine learning framework was proposed for developing the Taihu TP algorithm. The machine learning algorithm could mine the relationship between FAI and TP in Lake Taihu, where the optical properties of the water body are dominated by phytoplankton. The algorithm exhibited robust performance with an R2 value of 0.6 (RMSE = 0.07 mg/L, MRE = 43.33%). Then, a general TP algorithm (R2 = 0.64, RMSE = 0.06 mg/L, MRE = 34.13%) was developed using the proposed framework and tested in seven other lakes using synchronous image data. The algorithm accuracy was found to be affected by aquatic vegetation and enclosure aquaculture. Third, compared with field investigations in other studies on Lake Taihu, the Taihu TP algorithm showed good performance for long-term TP estimation. Therefore, the machine learning framework developed in this study has application potential in large-scale spatio-temporal TP estimation in eutrophic lakes.

Hyperbaric-Oxygen Therapy Improves Survival and Functional Outcome of Acute Severe Intracerebral Hemorrhage.

BACKGROUND: Prognosis of spontaneous intracerebral hemorrhage (ICH) remains poor worldwide. AIMS OF THE STUDY: To investigate the effect and optimal protocol for hyperbaric-oxygen therapy (HBOT), and reduce incidence of upper gastrointestinal bleeding (UGIB) in ICH. METHODS: This prospective, randomized, controlled trial included 565 patients with acute severe ICH. Participants were randomly assigned to a sham-control group (Group A) and four intervention groups: Groups B and C with 2.0 atmospheres absolute (ATA) pressure and HBOT exposure for 60 or 90 sessions, respectively; and Groups D and E with 1.5 ATA for 60 or 90 sessions, respectively. All patients received emergency craniotomy with hematoma evacuation. Outcome measures were modified Barthel Index (MBI) and modified Rankin Scale (mRS) scores, mortality rates at follow-up six months. UGIB rates were assessed as potential side effect. RESULTS: In four intervention groups, MBI and mRS scores were all significantly improved, and mortality rates were all significantly decreased compared with Group A (all p < 0.005). UGIB rates were 39.25, 60.00, 64.49, 36.79, and 34.26% in Groups A, B, C, D, and E, respectively. UGIB rates in Groups B and C were significantly increased compared with Groups A, D and E (all p < 0.005). None of UGIB were clinically significant. CONCLUSIONS: HBOT significantly improves survival and functional outcomes of ICH. HBOT at 1.5 and 2.0 ATA had the same beneficial effect. A pressure of 1.5 ATA and 60 HBOT exposures represents an optimal protocol for HBOT. Further studies are needed to optimize the protocol per specific patient.

Using hyper-spectral indices to detect soil phosphorus concentration for various land use patterns.

The management of nonpoint source pollution requires accurate information regarding soil phosphorus concentrations for different land use patterns. The use of remotely sensed information provides an important opportunity for such studies, and the previous studies showed that soil phosphorus shows no clear spectral response feature, while the phosphorus concentrations can be indirectly detected from the normalised difference vegetation indices (NDVI). Therefore, this study uses an optimised index in the RED and near-infrared (NIR) wavelengths to estimate total phosphorus and Olsen-P concentrations. The prediction accuracy is not entirely satisfactory with respect to a mixed land use dataset in which the determination coefficient was maintained at approximately 0.6, with particularly poor performance obtained for forest land group. However, the prediction accuracy increases markedly with the separation of samples into broad land use categories, even the R(2) was exceeded 0.8 for tea plantation group. The soil phosphorus prediction effect showed obvious variance for different land use patterns, which was related to vegetation growth conditions and critical soil properties including soil organic matter and mechanical composition.

Analysis of Panax notoginseng metabolites in rat bile by liquid chromatography-quadrupole time-of-flight mass spectrometry with microdialysis sampling.

A dynamic microdialysis sampling method with liquid chromatography-quadrupole time-of-flight mass spectrometry (Q-TOF-MS) was developed for rapid and sensitive analysis of the metabolite profile of Panax notoginseng extract (PNE) in rat bile. In vivo studies in male Sprague-Dawley rats were performed with microdialysis probes implanted into the bile duct before bile samples were collected from 0 to 12h. Metabolites of PNE were identified using dynamic adjustment of the fragmentor voltage to produce structure-relevant fragment ions. The mass accuracy of precursor and fragment ions was typically within 5 ppm of the theoretical values. We identified 7 compounds: 4 parent compounds (notoginsenoside R1, ginsenosides Rg1, Rb1, and Rd) and 3 metabolites (ginsenosides Rg2, Rh2, and compound K). Data from this study suggest that this microdialysis technique could be used in notoginseng saponin metabolic animal studies.

In vivo microdialysis with LC-MS for analysis of spinosin and its interaction with cyclosporin A in rat brain, blood and bile.

Spinosin, a major bioactive herbal ingredient isolated from Semen Ziziphi Spinosae, plays an important role in sedation and hypnosis. However, the pharmacokinetic behavior of spinosin in special sites has not been reported. Microdialysis (MD) technique, as a continuous, realtime monitoring sampling technique, is very suitable for the evaluation of the disposition of diverse drugs. To obtain more useful information on spinosin, an in vivo microdialysis sampling technique with High Performance Liquid Chromatography-mass spectrograph (HPLC-MS) method was developed to investigate the pharmacokinetics of spinosin and its interaction with cyclosporin A (CsA) in the brain, blood and bile of rats. The method was validated in terms of selectivity, linearity and sensitivity, and showed advantages in monitoring the pharmacokinetic behavior of drugs. The results revealed that CsA has obvious effects on the pharmacokinetic process of spinosin. When co-administered, the area under the curve (AUC) of spinosin in blood, bile and brain increased from 205.70 to 673.51 mg min/L, 7.77 × 10(4) to 1.25 × 10(5) mg min/L, and 2.09 to 5.58 mg min/L, respectively. The t(1/2) values of spinosin in blood, bile and brain also changed from 48.07 to 95.04 min, from 97.20 to 152.21 and from 42.18 to 73.83 min, respectively. These results demonstrated that the CsA decreased the efflux of spinosin through the inhibition of P-glycoprotein (P-gp) efflux transporter and it might be used as a group of P-gp substrate. Other transporters or pathways may also be involved in the metabolism of spinosin.