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The controlling processes of excessive ammonium in surface water and groundwater in the central Yangtze River Basin remain unclear. In this study, monitoring of water levels and temporal-spatial distributions of major N compounds were implemented at the large Jiangshan plain and at the local site scale in the central Yangtze River Basin. The results indicate that the recharge, movement and transformation of ammonium were controlled by hydrogeological conditions. Manure and sewage from anthropogenic activities were identified as the main source of nitrogen compounds. The nitrogen loading into aquifers were governed by water table and groundwater flow. After entering subsurface soils, nitrification and dissimilatory nitrate reduction to ammonium (DNRA) were proposed as the ammonium consumption and production mechanisms, respectively, by combining the concentrations of ammonium‑nitrogen and nitrate‑nitrogen with the corresponding isotopic compositions. These microbially mediated processes controlling transport and transformation of nitrogen compounds were influenced by the seasonally varying groundwater flow regime that changed the redox conditions in the aquifers. In the subsurface environments, ammonium was converted to nitrate when sufficient oxygen supply was available, and this process was reversed under anoxic conditions along the groundwater flow path. A conceptual model for the reactive transport of nitrogen compounds jointly controlled by the vertical groundwater flows and biogeochemical processes was proposed, which provides new insights into the genesis of high ammonium groundwater.

Although phenolic compounds linked to proteins or polysaccharides in the cell wall from herbal plant through β -glycoside bonds are difficult to extract in aqueous solution, microorganisms that produce some key enzymes may be useful for enhancing the release of phenolic compounds. Solid-state fermentation with a combination of different microorganisms was used to promote the bioactivities of the polyphenol component in GL. The results showed that co-fermentation of GL with Monascus anka GIM 3.592 and Saccharomyces cerevisiae GIM 2.139 led to a significant increase in contents of quercetin and total polyphenols. Including gallic acid, chlorogenic acid, rutin, isoquercitrin, avicularin, quercitrin, kaempferol, and quercetin, all polyphenols extracted from fermented guava leaves (FGL) were quantitatively identified by high-performance liquid chromatography time-of-flight electrospray ionization mass spectrometry (HPLC-TOF-ESI/MS). Quercetin, which presented the highest bioactivity, was significantly increased after microbial conversion. Total polyphenols extracted from FGL showed higher bioactivities in scavenging 1,1-Diphenyl-2-picrylhydrazyl (DPPH) and 2,2-Azino-bis 3-ethylbenzothiazoline-6-sulfonic acid diammonium salt (ABTS) caption radicals, anti-bacterial activity, and α-glucosidase inhibitory activity than those from GL. The activities of total polyphenols extracted from FGL by methanol were determined by calculating the IC 50 , with the highest values found to be 30.57 μg/mL, 24.53 μg/mL, and 0.09 mg/mL for the scavenging of DPPH and ABTS + radicals and inhibition of α-glucosidase, respectively. Methanol was more effective for extracting components with high α-glucosidase inhibitory activities than acetone. The methanol extract (0.20 mg/mL) efficiently inhibited 92.05% of α-glucosidase activity, which was significantly higher than that obtained using acarbose solution at an equal concentration. This microbial co-fermentation method can be used to upgrade the nutritional or medicinal values of herb leaves efficiently.

Guava leaves are used in traditional herbal teas as antidiabetic therapies. Flavonoids are the main active of Guava leaves and have many physiological functions. However, the flavonoid compositions and activities of Guava leaves could change due to microbial fermentation. A high-performance liquid chromatography time-of-flight electrospray ionization mass spectrometry method was applied to identify the varieties of the flavonoids in Guava leaves before and after fermentation. High-performance liquid chromatography, hierarchical cluster analysis and principal component analysis were used to quantitatively determine the changes in flavonoid compositions and evaluate the consistency and quality of Guava leaves. Monascus anka Saccharomyces cerevisiae fermented Guava leaves contained 2.32- and 4.06-fold more total flavonoids and quercetin, respectively, than natural Guava leaves. The flavonoid compounds of the natural Guava leaves had similarities ranging from 0.837 to 0.927. The flavonoid compounds from the Monascus anka S. cerevisiae fermented Guava leaves had similarities higher than 0.993. This indicated that the quality consistency of the fermented Guava leaves was better than that of the natural Guava leaves. High-performance liquid chromatography fingerprinting and chemometric analysis are promising methods for evaluating the degree of fermentation of Guava leaves based on quality consistency, which could be used in assessing flavonoid compounds for the production of fermented Guava leaves.

Understanding factors influencing groundwater quality is critical to the development of best management practices at the large watershed scale. In this study, the shallow groundwater (10&ndash, 20 m depth) in the Su-Xi-Chang region, eastern China, was investigated as part of a monitoring program from 2007 to 2008 to analyze the regional groundwater quality as well as the hydrogeochemical processes and their controlling factors. Conventional physicochemical water parameters (pH, turbidity, electrical conductivity, dissolved oxygen, total phosphorus), major cations (Na+, Ca2+, Mg2+ and NH4+) and anions (Cl&minus, NO3&minus, and SO42&minus, ) were measured. Hydrochemical methods and multivariate statistical methods were applied to analyze the hydrogeochemical signatures, origins, the similarities among the variables and to identify the main pollution sources in the groundwater. The results showed that (1) the concentrations of TDS (224.89&ndash, 1086.70 mg/L) and turbidity (0.1&ndash, 18.60 NTU) were higher than the class II groundwater quality standards in China and the WHO drinking water standards, (2) there were extremely high concentrations of ammonia (0.01&ndash, 32.90 mg/L), with a mean value of 0.72 mg/L and (3) the nitrate concentrations (average value of 22.07 mg/L) exceeded the class III groundwater quality standards. The study also provided evidence that weathering, dissolution of carbonate, halite and silicate and cation exchange were the possible primary hydrogeochemical control mechanisms in the groundwater. The sources of ammonia, total phosphorus, sulfates and nitrates included rock&ndash, water interactions and anthropogenic activities. The groundwater administration of pollution sinks and sources, long-term legal frameworks and economic incentives should be improved to optimize watershed scale management in the context of rapid development in China.

The upper reaches of the Heihe River have been regarded as a hotspot for phytoecology, climate change, water resources and hydrology studies. Due to the cold-arid climate, high elevation, remote location and poor traffic conditions, few studies focused on heavy metal contamination of soils have been conducted or reported in this region. In the present study, an investigation was performed to provide information regarding the concentration levels, sources, spatial distributions, and environmental risks of heavy metals in this area for the first time. Fifty-six surface soil samples collected from the study area were analyzed for Cr, Mn, Ni, Cu, Zn, As, Cd and Pb concentrations, as well as TOC levels. Basic statistics, concentration comparisons, correlation coefficient analysis and multivariate analyses coupled with spatial distributions were utilized to delineate the features and the sources of different heavy metals. Risk assessments, including geoaccumulation index, enrichment factor and potential ecological risk index, were also performed. The results indicate that the concentrations of heavy metals have been increasing since the 1990 s. The mean values of each metal are all above the average background values in the Qinghai Province, Tibet, China and the world, except for that of Cr. Of special note is the concentration of Cd, which is extremely elevated compared with all background values. The distinguished ore-forming conditions and well-preserved, widely distributed limestones likely contribute to the high Cd concentration. Heavy metals in surface soils in the study area are primarily inherited from parent materials. Nonetheless, anthropogenic activities may have accelerated the process of weathering. Cd presents a high background concentration level and poses a severe environmental risk throughout the whole region. Soils in Yinda, Reshui daban, Kekeli and Zamasheng in particular pose threats to the health of the local population, as well as that of livestock and wildlife.

Understanding the heavy metal (HM) contamination in alpine mountain headwaters regions is important to maintaining the ecosystem stability of the basin. A total of 119 water samples and 104 sediment samples were collected along tributaries and the main course of Heihe River. The concentrations of eight heavy metals (As, Cd, Cr, Cu, Mn, Ni, Pb, and Zn) in water and sediment were measured to describe their spatial variability and to assess water quality. To identify the origins and pathways of HMs, anions, cations, and trace elements, as well as &delta, D/&delta, 18O stable isotopes in water samples were also measured. The results of water quality assessment suggested that tributaries were affected by local mining activity. Factor analysis in sediments showed that all HMs in sediments were inherited from the parent bedrock. Both natural weathering and mining contribute HMs. Cr and Ni were homologous with a source from the weathering of basic gabbro and serpentine at Yushigou. Mn appeared to be influenced more by artificial activities such as agriculture and grazing. Depending on the mining technique involved, two pathways for the release of HMs were distinguished in this area. For open-pit mining, mining promoted the release of HMs primarily via enhanced weathering. For underground mining, HMs might have contributed to greater acid mine discharge at high elevations due to the weak weathering processes. As the elevation decreases, precipitation increases, and a series of complex hydrological factor significantly affect leaching and runoff. The study results can be applied to improve water management efficiency.

It is important that the magnetohydrodynamic (MHD) flow velocity in the cross section of the junction region of a manifold pipe be related to materials compatibility, heat transfer, and MHD pressure drop. Experimental results are given of the velocity distribution across the circular pipe on the center plane in the region of the junction of a manifold pipe and the MHD pressure drop due to the junction MHD effects. The results show that both the boundary layer and core velocity distribution on the center plane of the cross section of the junction region of the manifold pipe increase with an increase of the Hartmann number M and that the velocity at the boundary is jet flow and in the core is flat flow. However, the approach theory expects the core velocity distribution to decrease with an increase of M and never in jet flow at the boundary layer. For the downstream case, the velocity distribution is strongly affected by the junction of the manifold pipe only in a half area of the cross section and for the upstream case in the whole cross-section area. The factor for MHD pressure drops due to the junction MHD effects is also carried out,more » which explains the experimental data.« less

It is important that magnetohydrodynamic (MHD) flow velocity distribution in the cross section ofa duct be related to materials compatibility, heat transfer, and MHD pressure drop. The first experimental results are given of the velocity distribution across the rectangular duct on the center plane and of the two-dimensional (2-D) MHD pressure drop effect due to the 2-D velocity distribution. The results show that both the boundary and core velocity distributions on the center plane of the duct increase with an increase of the Hartmann number M. However, the approach theory expected the core velocity distribution to decrease with an increase of M. The 2-D effect factor for the MHD pressure drop due to the 2-D velocity distribution was also carried out. This explains why the numerical results of the MHD pressure drop gradient are lower than in the experiments. Theoretical analysis of the 2-D and three-dimensional effects on the velocity distribution and MHD pressure drop is also included.