Yuyuan Li

Adsorption of Cu and Zn onto Mn/Fe oxides and organic materials in the extractable fractions of river surficial sediments.

The roles of the extractable components (Mn oxides, Fe oxides, and organic materials) of surficial sediments in controlling metals adsorption were investigated. Cu and Zn adsorptions were conducted before and after the surficial sediments extracted with hydroxylamine hydrochloride, an oxalate solution, and H 2 O 2 , respectively. The extraction removed target components with extraction efficiencies from 63 to 98%. Nonlinear regression analyses of Cu and Zn adsorptions based on the assumption of additive Langmuir adsorption isotherm were employed to estimate the relative contributions of sediment components to Cu and Zn adsorptions. The results indicate that the greatest contribution to total Cu and Zn adsorption to the surficial sediments on a molar basis was from Mn oxides in the extractable fractions. Both Cu and Zn adsorption capacities of Mn oxides exceeded those of Fe oxides by approximately one order of magnitude, fewer roles were attributed to the adsorption of organic material (OM), and the estimated contribution of the residual fraction to total Cu and Zn adsorption was insignificant. These information implied that the roles of metal oxides (Fe and Mn oxides) in the extractable form of the surficial sediments, especially Mn oxides, was the most important component in controlling heavy metal transportation in aquatic environments.

Selective extraction and separation of Fe, Mn oxides and organic materials in river surficial sediments

In order to investigate the adsorption mechanism of trace metals to surficial sediments (SSs), a selective extraction procedure was improved in the present work. The selective extraction procedure has been proved to selectively remove and separate Fe, Mn oxides and organic materials (OMs) in the non-residual fraction from the SSs collected in Songhua River, China. After screening different kinds of conventional extractants of Fe and Mn oxides and OMs used for separation of heavy metals in the soils and sediments, NH2OH x HC1 (0.1 mol/L) + HNO3 (0.1 mol/L), (NH4)2C204 (0.2 mol/L) + H2C2O4 (pH 3.0), and 30% of H2O2 were respectively applied to selectively extract Mn oxides, Fe/Mn oxides and OMs. After the extraction treatments, the target components were removed with extraction efficiencies between 86.09% -93.36% for the hydroxylamine hydrochloride treatment, 80.63% -101.09% for the oxalate solution extraction, and 94.76%-102.83% for the hydrogen peroxide digestion, respectively. The results indicate that this selective extraction technology was effective for the extraction and separation of Fe, Mn oxides and OMs in the SSs, and important for further mechanism study of trace metal adsorption onto SSs.

A GIS-based fertilizer decision support system for farmers in Northeast China: a case study at Tong-le village

Application of computer technology such as Geographical Information Systems (GIS) to help farmers optimize fertilization, improve soil fertility and protect soil from erosion is currently of considerable interest as a topic of research. The objective of this study was to develop a GIS-based software package that can be used to help farmers select fertilizer application rates and manage soil nutrients. The ease of integration and programming in current digital spatial technology made it feasible to combine a fertilization model with a GIS platform to develop a GIS-based Fertilizer Decision Support System (FDSS) that enables farmers to determine precise fertilizer recommendations through an interactive computer interface. This paper outlines the development and test application of a GIS-based FDSS at Tong-le Village of Baiquan county, Heilongjiang province of Northeast China. The FDSS uses a farm field as the base mapping unit and incorporates data from field samples, farmer surveys and remote sensing, as well as expert knowledge in agriculture, soil science and computer science to develop a spatial database and soil/crop management system. The FDSS is a crop fertilization and management software developed on the SuperMap platform, and will help farmers and managers of agricultural production units to increase their fertilizer utilization efficiency, and thus their net profit.

Seasonality distribution of the abundance and activity of nitrification and denitrification microorganisms in sediments of surface flow constructed wetlands planted with Myriophyllum elatinoides during swine wastewater treatment

Surface flow constructed wetlands (SFCWs) planted with Myriophyllum elatinoides for treatment of swine wastewater were examined to evaluate the effect of season, segment (site S1, S2, and S3), and treatment (100mgL-1 TN, T1; 300mgL-1 TN, T2; 500mgL-1 TN, T3) on the activity, and abundances of nitrifying and, denitrifying microorganisms, and on the abundance of sediment bacteria. The activity and abundances of nitrifiers, denitrifiers, and the abundance of bacteria were the highest in T3 samples, especially in S1 (P<0.05). The potential nitrification rate (PNR) was highest in the summer and potential denitrification rate (PDR) showed an increasing trend over seasons. The abundance of ammonia-oxidizing bacteria (AOB) was strongly correlated with PNR, while abundance of denitrifying gene (nirK) was strongly correlated with PDR. These results indicate that M. elatinoides SFCWs for swine wastewater treatment stimulate the growth of nitrifiers, denitrifiers and bacteria in sediments.

Contribution of atmospheric nitrogen deposition to diffuse pollution in a typical hilly red soil catchment in southern China

Atmospheric nitrogen (N) deposition is currently high and meanwhile diffuse N pollution is also serious in China. The correlation between N deposition and riverine N export and the contribution of N deposition to riverine N export were investigated in a typical hilly red soil catchment in southern China over a two-year period. N deposition was as high as 26.1 to 55.8kgN/(ha·yr) across different land uses in the studied catchment, while the riverine N exports ranged from 7.2 to 9.6kgN/(ha·yr) in the forest sub-catchment and 27.4 to 30.3kgN/(ha·yr) in the agricultural sub-catchment. The correlations between both wet N deposition and riverine N export and precipitation were highly positive, and so were the correlations between NH4(+)-N or NO3(-)-N wet deposition and riverine NH4(+)-N or NO3(-)-N exports except for NH4(+)-N in the agricultural sub-catchment, indicating that N deposition contributed to riverine N export. The monthly export coefficients of atmospheric deposited N from land to river in the forest sub-catchment (with a mean of 14%) presented a significant positive correlation with precipitation, while the monthly contributions of atmospheric deposition to riverine N export (with a mean of 18.7% in the agricultural sub-catchment and a mean of 21.0% in the whole catchment) were significantly and negatively correlated with precipitation. The relatively high contribution of N deposition to diffuse N pollution in the catchment suggests that efforts should be done to control anthropogenic reactive N emissions to the atmosphere in hilly red soil regions in southern China.

AMI study of a novel crowned [60]fulleropyrrolidine

Abstract The computations of the electronic structures and properties of a novel crowned [60]fulleropyrrolidine (CFP) were performed by means of AM1 methods. It has been indicated that CFP has four isomers. The study of electronic structures showed that the energy levers of frontier orbitals are determined mainly by C60. C60 acted as an electronic acceptor, whereas crown ether acted as an electronic donor, which implies there exists intramolecular charge transfer effect in this molecule. The study of non-linear optical properties implied the hyperpolarizability of CFP can match that of p-nitroaniline.

White light emission from ultraviolet laser diode

A phosphor-conversion white light using an InGaN laser diode that emits 405 nm near-ultraviolet (n-UV) light and phosphors that emit in the red/green/blue region when excited by the n-UV light was fabricated. The relationship of the luminous flux and the luminous efficacy of the white light with injection current were discussed. Based on the evaluation method for luminous efficacy of light sources established by the Commission International de I’Eclairage (CIE) and the phosphor used in this experiment, a theoretical analysis of the experiment results and the maximum luminous efficacy of this white light fabrication method were also presented.

Preparation and characterization of three new charge transfer complexes of C60-tetracyanoethyleneoxide with tetrathiafulvalene derivatives

Abstract As shown by its electrochemical properties, the title fullerene derivative is better an acceptor than C60 itself. Therefore, it is able to easily form CTC with organic donors related to the tetrathiafulvalene series. Three CT complexes have been characterized by FT1R, VIS reflectance spectra and X-ray diffraction method.

Pedo-transfer functions for estimating the hydraulic properties of paddy soils in subtropical central China

ABSTRACT Pedo-transfer functions (PTFs) have been widely used to estimate soil hydraulic properties in the simulation of catchment eco-hydrological processes. However, the accuracy of existing PTFs is usually inadequate for use. To develop PTFs for local use, soil columns were collected from a double rice-cropped agricultural catchment in subtropical central China. The PTFs for saturated soil hydraulic conductivity (Ks) and parameters (θs, α, and n) of the van Genuchten model for the soil water retention curve (SWRC) were obtained based on soil’s basic properties, and compared with models developed by Li et al. in 2007 and Wösten et al. in 1999, respectively. Our results indicated that Ks in the range of 0.04–1087 cm d−1 and θs in the range of 0.34–0.51 cm3 cm−3 were both well estimated with the R2adj of 0.72 and 0.87, respectively, but α (0.04–0.65 cm−1) and n (1.05–1.21) were relatively poorly predicted with the respective R2adj of 0.38 and 0.55, despite the use of more input parameters. Our local derived PTFs outperformed the other two existing models. However, if the local PTFs for paddy soils are not available, the Wösten et al. 1999 model can be proposed as a useful alternative. Therefore, this study can improve our understanding of the development and application of PTFs for predicting paddy soil hydraulic properties in China.

Agro-farming systems determine phosphorus budget characteristics at the farm and catchment scales in subtropical China

Agricultural and economic activities may profoundly determine phosphorus (P) budget characteristics that affect environmental quality; therefore, P budget characteristics were investigated at the farm and catchment scales, and the total-phosphorus (TP) concentrations in stream water were observed to examine their relationships in eight Chinese subtropical catchments. The results showed that chemical fertilizer accounted for 67–76% of the total P input and cereal grain comprised of 60–62% of the output in the planting farms, while animal feed and animal product accounted for 62–95 and 48–71% in the planting–livestock farms and livestock farms, respectively, indicating that agro-farming systems determined the P budget characteristics at the farm scale. The P input, output, and surplus intensities linearly increased with agricultural incomes in the agro-farming systems, suggesting that economic activities greatly affected the P budget characteristics at the farm scale. The catchment P budget characteristics were largely shaped by the characteristics at the farm scale; the planting–livestock farm proportion was negatively correlated (R2 > 0.55) while the livestock farm proportion was positively correlated (R2 > 0.59) with catchment P budget items. These effects on catchment P budget characteristics greatly deteriorated stream water quality; both the TP concentrations and loadings in stream water were significantly correlated to catchment P input, output, and surplus intensities. Considering the higher economic benefits and lower P input and surplus intensities due to the closed P cycle loop between cropping and husbandry, planting–livestock system should be promoted at the farm scale to protect catchment water environmental quality in subtropical China.