[Identifying the Sources of Groudwater NO3--N in Agricultural Region of Qingdao].

To increase crops yields, applying large amounts of fertilizers has become increasingly common in agricultural regions, resulting in NO3--N groundwater pollution. Agricultural non-point pollution is the main source of groundwater NO3--N pollution. To ensure drinking water safety and quality, it is crucial to clarify the sources of NO3--N pollution in agricultural regions. In this study, 35 sampling sites were randomly selected in the Qingdao agricultural area in 2009 and 2019. The spatial distribution of NO3--N concentration was analyzed by the inverse distance weighting method (IDW). The nitrogen and oxygen isotopes were used as a tool to trace sources of NO3--N and the SIAR model was used to quantify contribution proportion of pollution sources. The results showed that the concentration of NO3--N (average) in groundwater in Qingdao has been reduced from 38.49 mg·L-1 in 2009 to 22.37 mg·L-1 in 2019, but it is still higher than the maximum allowable concentration of NO3--N in drinking water set by the World Health Organization (WHO). The NO3--N concentration gradually increased from south to north both in 2009 and 2019. The cross diagram of δ15N-NO3- and δ18O-NO3- show that the main sources of NO3--N in groundwater in Qingdao are chemical fertilizers, soil nitrogen, and manure and sewage. Water isotopes indicate that precipitation was the main source of groundwater in Qingdao. The SIAR model results indicated that the contribution of each source ranked as follows:manure and sewage (47.42%) > soil nitrogen (27.80%) > chemical fertilizer (14.32%) > atmospheric nitrogen depositions (10.43%). From 2009 to 2019, the quality of groundwater in Qingdao has been improved, but NO3--N pollution still cannot be ignored. According to the results, prevention and control should be made to ensure the safety of drinking water and the sustainable development of agriculture.

[Seasonal variation of phytoplankton community and its relationship with environment in subtropical reservoirs: A comparison between two methods of functional groups classification]. / äºšçƒ­å¸¦æ°´åº“æµ®æ¸¸æ¤ç‰©ç¾¤è½çš„å­£èŠ‚å˜åŒ–åŠå ¶ä¸ŽçŽ¯å¢ƒçš„å ³ç³»: 两种功能群分类法的比较.

Phytoplankton is the most important biological component in the reservoir ecosystem, which could indicate the status of aquatic ecosystem due to its sensitive to environmental variation. To understand the application and difference between two methods of phytoplankton functional group classification, functional groups (FG) and morphology-based functional groups (MBFG), in indicating the changes of reservoir environment, we investigated water quality and phytoplankton in Qingshitan Reservoir monthly from March 2016 to February 2017. Two phytoplankton functional groups classifications (FG and MBFG) were used to analyze phytoplankton community composition, seasonal succession, and its driving factors. We compared the application and differences of two methods of functional group classifications in indicating environmental changes. The results showed that there were 109 species belonged to seven phylum, which could be classified into 17 FG or 5 MBFG functional groups. Results from both methods indicated that the reservoir was meso-eutrophic. The phytoplankton seasonal succession under 8 or 9 steps with FG or 8 steps with MBFG. Results from the redundancy analysis showed that the response of phytoplankton community reflected with FG to environmental variation was more sensitive than that with MBFG, especially in the response to the changes of pH and nitrate concentration. In conclusion, FG was more appropriate in describing community succession and exploring the relationship between phytoplankton and environment.

[Effects of elevated CO2 concentration on production and water use efficiency of spring wheat in semi-arid area.] / CO2æµ“åº¦å¢žåŠ å¯¹åŠå¹²æ—±åŒºæ˜¥å°éº¦ç”Ÿäº§å’Œæ°´åˆ†åˆ©ç”¨æ•ˆçŽ‡çš„å½±å“.

In the present study, the response of spring wheat production and water use efficiency (WUE) to the elevated CO2 concentrations was investigated based on the open-top chamber (OTC) experiment platform in Dingxi, a typical semi-arid area. Three different CO2 concentrations (390 µmol·mol-1, 480 µmol·mol-1 and 570 µmol·mol-1) were involved. The results showed that the air temperature above plant canopy increased and the soil temperature at depth of 10 cm decreased by elevated CO2. The increased CO2 concentration substantially enhanced the total and each component biomass. The aboveground dry mass under the increased CO2 concentrations (480 and 570 µmol·mol-1) was increased by 20.6% and 41.5%, respectively, and the total dry mass was increased by 19.3% and 39.6%, respectively. The biomass enhacement was mainly due to the increases of dry mass of stems and leaves, which was strongly related to the material production capacity during the middle growth stage. The root/shoot ratio under the increased CO2 concentrations (480 and 570 µmol·mol-1) was decreased by 7.3% and 11.8%, respectively, indicating that the elevated CO2 affected the dry matter accumulation of aboveground more than that of belowground. The yields of spring wheat under the increased CO2 concentrations (480 and 570 µmol·mol-1) were higher than that of the control by 8.9% and 19.9%, respectively, mainly due to the increase of grains per spike. The long-term effect of elevated CO2 concentration on the photosynthesis of spring wheat was not obvious. The photosynthetic rate significantly increased, the transpiration rate decreased and the evapotranspiration reduced with the increases of CO2 concentration. WUE at the leaf, population, and yield levels increased under elevated CO2 concentration, with the increase range of WUE being the largest at the population level and the lowest at the yield level.

[Effects of organic and inorganic fertilizers on emission and sources of N2O in vegetable soils.] / æœ‰æœºè‚¥å’Œæ— æœºè‚¥å¯¹èœåœ°åœŸå£¤N2OæŽ’æ”¾åŠå ¶æ¥æºçš„å½±å“.

To clarify the microbial pathway of the N2O production and consumption under different fertilizers and provide theoretical basis for the reduction of N2O emission and rational management of fertilization in vegetable soils, we examined dynamics of N2O flux and isotope signatures under different fertilizer treatments in the vegetable soils of Beijing, by setting up four treatments (organic-acetylene, organic-nonacetylene, inorganic-acetylene, inorganic-nonacetylene) and using the stable isotope technique of natural N2O abundance. The results showed that the cumulative N2O emission from organic-acetylene group, organic-nonacetylene group, inorganic-acetylene group and inorganic-nonacetylene group was (374±37), (283±34), (458±36), (355±41) g·m-2 in cabbage growing season, respectively. N2O fluxes were significantly lower in treatments with organic fertilizer than those with inorganic fertilizer and significantly higher in acetylene group than nonacetylene group. The degree of N2O reduction were similar in both fertilizer treatments, and higher nitrification was found in inorganic fertilizer than organic fertilizer treatments. Acetylene only inhibited partial nitrification and partial N2O reduction at the peak of N2O emission. When the emission was reduced, N2O reduction could be completely suppressed. Therefore, the inorganic fertilizer might trigger nitrification and promote higher N2O emission. The high concentration of N2O could withstand that acetylene to inhibite N2O reduction. Hence, using organic fertilizers instead of some inorganic ones could effectively reduce N2O emission in vegetable soils of Beijing. The N2O concentration threshold should be considered when we identify N2O source by acetylene inhibition method.

[Effects of soil water condition on N2O emission and its sources in vegetable farmland of North China Plain]. / 不同灌溉量对华北平原菜地N2OæŽ’æ”¾åŠå ¶æ¥æºçš„å½±å“.

To understand the mechanisms of agricultural N2O emission, we investigated the N2O emission dynamics, the N2O isotope signatures, and the site preference value under different soil water conditions in the vegetable farmland of North China, by using the stable isotope technique and the acetylene inhibition method. The results demonstrated that N2O emission was significantly affec-ted by the water condition, and N2O emissions from soil with water-filled pore space (WFPS) of 70% were significantly higher than that with 50% WFPS. N2O emission occurred mostly in the early stage of fertilization, and decreased rapidly in the later stage of fertilization. At 50% WFPS, nitrification was the major process generating N2O during the early fertilization stage, accounting for approximately 90% of the N2O emission. However, the contribution of nitrification decreased sharply, whereas denitrification became the dominant process, accounting for 80% of the N2O emission 7 days after the fertilization. On the other hand, at 70% WFPS, denitrification was the main process releasing N2O during the early fertilization stage, decreasing from 70% to 40% and then gradually increasing to 80% 10 days after the fertilization. Overall, N2O emission was mainly dominated by the denitrification. The effect of different water treatments on soil nitrification and denitrification took place mainly in the early stage of fertilization, and N2O emission was gradually dominated by the denitrification at the later stage. These results suggested we could reduce N2O emission by approp-riately reducing the amount of irrigation in the vegetable farmland of North China.

[A review on development of stable isotope technique in the studies of N2O formation mechanism]. / ç¨³å®šåŒä½ç´ æŠ€æœ¯åœ¨åœŸå£¤N2Oæº¯æºç ”ç©¶ä¸­çš„åº”ç”¨.

As one of three major greenhouse gases, nitrous oxide (N2O) has solicited substantial attention. Stable isotope has been widely used to explore the sources of N2O emissions. Here, we briefly introduced the microbial processes involved in N2O emissions, and the main influencing factors. We further summarized the development of N2O isotope signature of δ15N, δ18O and SP (site preference of 15N in different positions of N2O molecule) in exploring the N2O formation mechanism. The application of these techniques, especially the SP values, is still at the primary stage in China. Therefore, this paper focused on the development of the isotope ratios analysis in partitioning N2O sources from foreign countries, and put forward suggestions on the future research in China.

Structure elucidation of a bioactive polysaccharide from fruiting bodies of Hericium erinaceus in different maturation stages.

HPB-3, a heteropolysaccharide, with a mean molecular weight of 1.5×10(4)Da, was obtained from the maturating-stage IV, V and VI fruiting body of Hericium erinaceus, exhibited higher macrophages stimulation activities, was able to upregulate the functional events mediated by activated macrophages, such as production of nitric oxide (NO). Monosaccharide composition analysis showed that HPB-3 comprised l-fucose, d-galactose and d-glucose in the ratio of 5.2:23.9:1. Its chemical structure was characterized by sugar and methylation analysis, along with (1)H and (13)C NMR spectroscopy, including (1)H-(1)H COSY, TOCSY, NOESY, HMQC and HMBC experiments. The results indicated that HPB-3 contained a-(1/6)-linked galactopyranosyl backbone, partially with a side chain composed of α-l-fucopyranose at the O-2 position. The predicted primary structure of the polysaccharide was established as below.

Chemical Compositions and Macrophage Activation of Polysaccharides from Leon's Mane Culinary-Medicinal Mushroom Hericium erinaceus (Higher Basidiomycetes) in Different Maturation Stages.

We studied the effect of the maturation stage on the chemical compositions and macrophage activation activity of polysaccharides from the culinary-medicinal mushroom Hericium erinaceus. Results showed that total polysaccharides increased, whereas protein content decreased with the maturation stage development of fruiting body. Nine polysaccharide fractions, 3 from each of the maturity stages IV (small fungal spine stage), V (mid-fungal spine stage) and VI (mature), were prepared using the gradient ethanol precipitation method. The polysaccharide fraction HP4A isolated from the maturating-stage (stage IV) fruiting body had a significant difference from the fractions HP5A (stage V) and HP6A (stage VI) in the molecular weight distribution and monosaccharide compositions. Immunostimulating tests revealed that the polysaccharide fraction HP6 isolated from the mature stage (stage VI) fruiting body presented higher macrophage activation activity. Our findings provided important information for the harvest and use of H. erinaceus with higher qualities and functional benefits.