Optimization of Glycosaminoglycan Extraction on Patinopecten Yessoensis Waste

AbstractOn the basis of single factor experiment, the pH of enzymatic hydrolysis, enzymolysis temperature, enzymolysis time and solid-liquid ratio as independent variable, extraction rate as response value, extraction technology of glycosaminoglycan from Patinopecten yessoensis waste were optimized using response surface methodology. The order affecting glycosaminoglycan extraction rate was determined: the enzymatic pH > solid-liquid ratio > enzymatic time > enzymatic temperature. The optimal conditions of extraction were: the pH of enzymatic hydrolysis was 8.0, enzymolysis temperature was 40°C, enzymolysis time was 3.5h and solid-liquid ratio was 1:2. Click here and insert your abstract text

Enrichment of Phosphate on Ferrous Iron Phases during Bio-Reduction of Ferrihydrite *

The reduction of less stable ferric hydroxides and formation of ferrous phases is critical for the fate of phosphorus in anaerobic soils and sediments. The interaction between ferrous iron and phosphate was investigated experimentally during the reduction of synthetic ferrihydrite with natural organic materials as carbon source. Ferrihydrite was readily reduced by dissimilatory iron reducing bacteria (DIRB) with between 52 % and 73 % Fe(III) converted to Fe(II) after 31 days, higher than without DIRB. Formation of ferrous phases was linearly coupled to almost complete removal of both aqueous and exchangeable phosphate. Simple model calculations based on the incubation data suggested ferrous phases bound phosphate with a molar ratio of Fe(II):P between 1.14- 2.25 or a capacity of 246- 485 mg·P·g −1 Fe(II). XRD analysis indicated that the ratio of Fe(II): P was responsible for the precipitation of vivianite (Fe3(PO4)2·8H2O), a dominant Fe(II) phosphate mineral in incubation systems. When the ratio of Fe(II):P was more than 1.5, the precipitation of Fe(II) phosphate was soundly crystallized to vivianite. Thus, reduction of ferric iron provides a mechanism for the further removal of available phosphate via the production of ferrous phases, with anaerobic soils and sediments potentially exhibiting a higher capacity to bind phosphate than some aerobic systems

Different forms of nitrogen contents and their vertical variations of transformation modes of the sediments of Lake Yuehu, Wuhan

Vertical distributions of nitrogen contents, net nitrification rates, net N-mineralization rates and nitrate reductase activities in sediments of Lake Yuehu in June, 2005, were described on basis of four samples from the lake. The results showed that there was a critical layer in which exchangeable nitrate contents were the highest. Exchangeable ammonium and available nitrogen contents were the lowest in the Subsurface sediment (5-10cm). Available nitrogen was stored mainly in the form of exchangeable ammonium in both surface (0-5cm deep) and deeper layers (>10cm deep) where their contents were higher. The pattern of this distribution can be explained by anaerobic conditions. The surface sediment not only showed higher contents of total nitrogen and organic nitrogen, rates of net nitrification, N-mineralization and nitrate reductase activities, but also displayed the highest ammonium and the lowest nitrate concentrations in interstitial water. Therefore, based on a nitrogen cycling mode, we proposed that organic nitrogen was re-mineralized to ammonium and nitrate with processes of the former being nitrified into the later, resulting in anaerobic conditions that contributed to ammonium accumulation by the production of its own and nitrate reduction in interstitial water of surface sediment. In general, the surface sediment in eutrophic lakes, enriched by organic nitrogen, is the most active dimension for the biogeochemical cycling of nitrogen with ammonium being the major and most effective forms

Numerical investigations of urban pollutant dispersion and building intake fraction with various 3D building configurations and tree plantings

Rapid urbanisation and rising vehicular emissions aggravate urban air pollution. Outdoor pollutants could diffuse indoors through infiltration or ventilation, leading to residents’ exposure. This study performed CFD simulations with a standard k-ε model to investigate the impacts of building configurations and tree planting on airflows, pollutant (CO) dispersion, and personal exposure in 3D urban micro-environments (aspect ratio = H/W = 30 m, building packing density λp = λf = 0.25) under neutral atmospheric conditions. The numerical models are well validated by wind tunnel data. The impacts of open space, central high-rise building and tree planting (leaf area density LAD= 1 m2/m3) with four approaching wind directions (parallel 0° and non-parallel 15°, 30°, 45°) are explored. Building intake fraction is adopted for exposure assessment. The change rates of demonstrate the impacts of different urban layouts on the traffic exhaust exposure on residents. The results show that open space increases the spatially-averaged velocity ratio (VR) for the whole area by 0.40–2.27%. Central high-rise building (2H) can increase wind speed by 4.73–23.36% and decrease the CO concentration by 4.39–23.00%. Central open space and high-rise building decrease under all four wind directions, by 6.56–16.08% and 9.59–24.70%, respectively. Tree planting reduces wind speed in all cases, raising by 14.89–50.19%. This work could provide helpful scientific references for public health and sustainable urban planning

Analysis of Wholesale Industry efficiency in Liaoning Province -- Based on DEA model

Based on DEA model, the wholesale efficiency of 14 cities in Liaoning province was measured. From the perspective of input and output, the wholesale efficiency of each city in Liaoning Province was systematically studied to evaluate the development of the wholesale industry in Liaoning Province. The results show that the wholesale efficiency in Liaoning province is generally low, but the returns to scale are increasing. The efficiency level varies greatly among different cities, and the reasons for non-DEA effective wholesale investment in different cities are different

Dredging effects on P status and phytoplankton density and composition during winter and spring in Lake Taihu, China

Phytoplankton density and composition, together with phosphorus (P) concentrations and size-fractionated alkaline phosphatase activity (APA), were investigated in dredged and undredged zones in Lake Taihu from January to April 2004. P concentrations were also determined in the corresponding interstitial water. Enzyme Labeled Fluorescence (ELF) was used for localizing extracellular phosphatase on phytoplankton cell membranes in April. The increase in phytoplankton density was paralleled by a significant increase in soluble reactive P (SRP) concentrations in the water column and interstitial water at all sites from January to April, with chlorophyte gradually becoming dominant. In February, at the undredged site, more algae dominated by chlorophyte occurred in overlying water, rather than in the surface, coinciding with higher SRP concentrations in overlying and interstitial water. Therefore, P status in the bottom is important to phytoplankton development in terms of density and composition. Undredged sites had higher SRP concentrations in interstitial water than dredged sites. Furthermore, Higher APA was observed, accompanied by higher dissolved organic P (DOP) and lower total P at the undredged site in February. Enzymatic hydrolysis of DOP may have been an additional source of P for phytoplankton. In April, Schroederia sp. was ELF labeled in surface water at the dredged site, which showed markedly lower SRP concentration, but not at the undredged site with higher SRP concentration. Thus, the dredging might regulate algal density and composition in water column by reducing P bioavailability

Thin-layer fine-sand capping of polluted sediments decreases nutrients in overlying water of Wuhan Donghu Lake in China

International audienceCapping water body sediments with a thin layer of sand is an effective technique to decrease nutrient concentrations in the water column and accelerate ecological restoration of eutrophic water bodies. However, long-term effects of thin-layer sand capping in shallow lakes are reported less often. Using clean fine sand and geotextile mats as capping materials for sediments collected from Wuhan Donghu Lake in China, we designed a 290-day tank experiment with 3 cm of sand capping at four percentages of sediment coverage from 25 to 100% and a control (no capping). We monitored total nitrogen (TN), total phosphorus (TP), nitrate (NO3-), ammonia (NH4+), and soluble reactive phosphorus (SRP) in the overlying water every 7 days. Mean TN and NO3- concentrations were significantly the lowest (P < 0.05) at 50% coverage. Further increase in coverage kept them slightly fluctuating. NH4+ concentration was significantly lowest (P < 0.05) at 75% coverage. The relation between coverage and mean TP and SRP concentrations indicated that 75% coverage significantly decreased (P < 0.05) them, and increasing coverage to 100% decreased them even more. The fluxes of TN and TP estimated between sediments and overlying water showed that the thin fine-sand layer significantly increased the function of sediments as a sink of TN from overlying water and the potential of a sand layer to block release of TP from sediments (P < 0.05). Our results suggested that if thin-layer sand capping were applied to Wuhan Donghu Lake, more than 50% coverage is required to decrease nutrients in the lake's water