[Effects of straw returning on maize yield and root system spatial distribution under water stress]. / æ°´åˆ†èƒè¿«ä¸‹ç§¸ç§†è¿˜ç”°å¯¹çŽ‰ç±³äº§é‡å’Œæ ¹ç³»ç©ºé—´åˆ†å¸ƒçš„å½±å“.

To investigate the effects of straw amendments on the yield and root spatial distribution of maize under water stress, an experiment with rainproof shelter was conducted in the field experimental station of Shenyang Agricultural University in 2016 and 2017. The drip irrigation facilities were used to perform water stress treatments. Straw burying (T1) and straw incorporation (T2) as two approaches of straw amendments were conducted combined with three depths of 15 cm (D1), 30 cm (D2), and 45 cm (D3) for straw returning, ploughing tillage at above three depths without straw presence as control in this study. During seedling and silking stages of maize, drought and water logging stresses were introduced respectively to the plants. Our results showed that the yield of maize under S1T1D2 treatment in 2016 was significantly increased by 5.7%-7.1%. Compared with all the rest treatments, the dry weights of lateral roots and deep roots under S1T1D2 treatment were increased by 67.3%-149.9% and 17.9%-116.4%, respectively. The dry matter accumulation in shoot of maize observed from S1T1D2 treatment was significantly lower than those under other treatments, with 2.1%-35.8% reduction. Our results indicated that S1T1D2 could significantly promote the growth and spatial distribution of maize root, accounting to release water stress and keep yield stabilization or promotion. Therefore, 30 cm of straw burying could be used as a suitable approach of straw returning for maize production in northeastern China, where the climate is with a pattern of drought first and waterlogging in later stage.

Occurrence, distribution, and attenuation of pharmaceuticals and personal care products in the riverside groundwater of the Beiyun River of Beijing, China.

This study investigated the occurrence, seasonal-spatial distribution characteristics, and attenuation process of 15 pharmaceuticals and personal care products (PPCPs) in riverside sections of Beiyun River of Beijing. The overall PPCP levels both in surface water and riverside groundwater were moderate on the global scale, and showed higher concentrations in the dry season mainly caused by water temperature variation. Caffeine (CF), carbamazepine (CBZ), metoprolol (MTP), N,N-diethyl-meta-toluamide (DEET), diclofenac (DF), bezafibrate (BF), and gemfibrozil (GF) were seven representative PPCPs, because the rest eight studied compounds occurred in low concentrations and less than 15% of the total concentration of PPCPs. Caffeine and bezafibrate, respectively, was the most abundant compound in surface water and riverside groundwater, with median concentrations of 3020.0 and 125.0 ng L-1. Total concentrations of PPCPs in surface water were much higher than those in the riverside groundwater spatially. Attenuation of PPCPs during riverbank filtration was largely depending on the sources, site hydrogeological conditions, and physical-chemical properties of PPCPs, also was influenced by dissolved organic matter and environmental physicochemical parameters. CF, MTP, DEET, and CBZ were potential groundwater attenuation contaminants; DF, BF, and GF were groundwater-enriched contaminants based on their removal rates. Predominant removal mechanism of PPCPs like CF was biodegradation. Attenuation simulation showed that the one-way supply between Beiyun River and riverside groundwater, and further confirmed Beiyun River, was the main source of pharmaceutical compounds in the riverside groundwater.

[Forming mechanism of humic acid-kaolin complexes and the adsorption of trichloroethylene].

The interaction between soil organic components and mineral components was explored in this study. Humic acid and kaolin were used for the preparation of organic-mineral complexes with different contents of organic matter, for experimental study of the adsorption of trichloroethylene. The results showed that the adsorption of trichlorethylene fitted the Freundlich isotherm model. The existence of interaction between humic acid and kaolin was indicated by the significant difference between the actual value and the theoretically overlaid value of the adsorption capacity. With various characterizations, such as FTIR and surface area & pore analysis, the mechanism of interaction between humic acid and kaolin was suggested as follows. When their contents were low, humic acid molecules firstly loaded on the surface binding sites of kaolin. Then with the content increased, as O/M( organic-mineral mass ratio) was 0.02-0.04, some surface pores of kaolin were filled by part of the molecules. After reaching a relatively stable stage, as O/M was 0.04-0.08, humic molecules continued to load on the surface of kaolin and formed the first humic molecule-layer. With humic acid content continued increasing, as O/M was 0.08-0.10, more humic molecules attached to kaolin surface through the interaction with the first layer of molecules and then formed the second layer. O/M was 0.10-0.16 as the whole second layer stage, meanwhile the first layer was compressed. Then when O/M was 0.16-0.4, there were still some humic loadings onto the second layer as the third layer, and further compressed the inner humic acid layers. Besides, some humic acid molecules or aggregates might go on attaching to form as further outer layer.

[Distribution Characteristics of Fluoroquinolones Antibiotics in Surface Water and Groundwater from Typical Areas in A City].

In order to investigate the characteristics of 5 typical kinds of fluoroquinolones (FQs) pollution in waters from a city, surface water and groundwater samples from main drainage rivers and typical areas were collected, respectively. The conventional test and FQs concentrations analysis of the water samples were conducted. The results showed the concentration and composition of FQs in groundwater differed substantially from those in surface water. The average concentration of FQs in surface water was 789.1 ng x L(-1) with the main components of ofloxacin (OFL) and lomefloxacin (LOM). This value was higher than the average concentration of FQs in groundwater: 342.7 ng x L(-1) with the main components of norfloxacin (NOR) and lomefloxacin (LOM). The enrofloxacin (ENR) exhibited relatively lower levels in both surface water and groundwater as compared to others. The highest FQs concentrations in surface water were found in trenches, followed by tributaries and the main stream. For groundwater, FQs concentrations were relatively higher in the sewage riverside. A decreasing trend of FQs concentration was monitored with the increasing distance of sampling points to the drainage rivers and all components mentioned above showed similar changing trends. The results of this study preliminarily indicated that FQs in groundwater along the riverside probably came from the surface water.

[Contamination characteristics of fluoroquinolones in different kinds of soil profiles in Southeast suburb of Beijing].

Eighty-six soil samples were collected using Geoprobe soil sampler from 11 borehole profiles of Beijing Southeast suburb. The sampling sites could be divided into 8 kinds of landuse. Physical and chemical properties of samples were analyzed. The concentrations of 5 fluoroquinolones (FQs) were analyzed by the high-performance liquid chromatography. Results show that the average value of total concentrations of 5 FQs is 46.1 µg x kg(-1). Ofloxacin (OFL) is the predominant among them, and then is norfloxacin (NOR). Last comes to enrofloxacin (ENR), ciprofloxacin (CIP) and lomefloxacin (LOM). There are significant differences in FQs concentrations and kinds among the 8 land use types of soil profiles. The average value of total concentrations of 5 FQs decrease with an increasing of soil depth. The average concentration of OFL, NOR, LOM and ENR decrease with an increasing of soil depth. But CIP has the opposite result. Based on FQs concentrations from 42 soil samples with a depth among 0 to 3 meters, contamination characteristics of FQs were analyzed by fuzzy hierarchial clustering. Sampling sites of vegetable greenhouse, woods, sewage irrigation zone, groundwater irrigation zone, livestock and poultry farm, sediments from sewage river have similar components and contents of FQs, with less kinds and low concentration. In contrast, sampling sites of pharmaceutical enterprises and refuse landfill have more kinds and medium concentration of FQs.