低温引起苹果品质及有机物的变化

以霜冻前后林芝金冠苹果为实验材料 ,研究了冻害对林芝金冠苹果组织中维生素C、苹果酸、谷胱甘肽等有机物的影响 ,实验结果表明 :苹果酸、维生素C、水分是影响金冠品质的限制性因子 ,为进一步研究林芝金冠苹果的贮藏、保鲜技术 ,提供了理论依据。

红麻鲜茎加菌脱胶过程中有机物动态变化规律

利用红麻专用脱胶菌T1163 分别在振荡和静置条件下 ,对红麻鲜茎进行了脱胶试验 ,测定了发酵液中的活菌量、pH值、挥发酸、COD、还原糖、胞外可溶蛋白及脱落物和总残渣量等指标。结果表明 ,在振荡条件下 ,84小时完成红麻鲜茎脱胶 ;pH值为 6 .80～ 7.45 ;挥发酸和可溶蛋白含量较低 ,其峰值分别为 1 48mg/l和 5 3mg/l。在静置条件下 ,72小时完成红麻鲜茎脱胶 ;pH值为 6 .2 0～ 6 .80 ;挥发酸随脱胶的进程而不断增加 ,脱胶完成时下降 ,峰值 6 35mg/l;胞外可溶蛋白变化趋势呈“M”型。两种发酵体系中 ,脱落物和总残渣量均随脱胶时间延长而呈不断增加趋势 ,脱胶完成时 ,其去除率均达 1 1 %左右 ;微生物均在 2— 6小时迅速旺盛繁殖 ;COD和还原糖均呈“M”型趋势。

Dynamic Analysis on Organic Matter and Nitrogen Pollution of Dongchang Lake

The aim was to explore dynamic changes of organic matter and nitrogen pol ution in Dongchang Lake. [Method] Monitoring data, including BOD5, CODCr, NH3-N and TN, of Dongchang Lake were chosen for analysis during 2002-2011. [Result] Water quality of the six lake districts showed deteriorating in monitor-ing period, and TN was the dominant pol ution factor; BOD5/CODCr ratio was low, suggesting biodegradability of organic pol utant in the lake was lower. NH3/TN ratio was higher, indicating NH3-N was a major factor causing nitrogen exceeding in 2010. In addition, correlations between BOD5 and CODCr and between NH3-N and TN in the lake districts maintained at a significant level. [Conclusion] The research provides references for improving water in Dongchang Lake.

Changes of Labile Organic Carbon Fractions in Soils Under Different Rotation Systems

Soil labile (biologically active) organic carbon fractions under different crop rotation systems in Jiangsu Province, China, were investigated after 10 years of rotation. The rotation systems, including green manurerice-rice (GmRR), wheat-rice-rice (WRR), wheat-rice (WR) and wheat/corn intercrop-rice (WCR) rotations,were established on paddy soils using a randomized complete block design with three replicates. The total organic carbon (TOC), total nitrogen (TN) and water-soluble organic carbon (WSOC) in the soils under different systems were greater in the GmRR and WRR than in the WR and WCR rotation systems because the soils under triple cropping often received more crop residues than the soils under double cropping. Both the WSOC and the microbial biomass carbon (MBC) contents in the soils of the GmRR rotation system were significantly greater than those in the other crop rotation systems, which was due to the return of green manure to the fields of the GmRR rotation system. The results of a 13C nuclear magnetic resonance (13C-NMR) analysis indicated that the structural characteristics of soil WSOC were similar under the four crop rotation systems with carbohydrates and long-chain aliphatics being the major components. Correlation analysis showed that the content of the WSOC was positively correlated with that of the MBC (P ＜0.01),and all had significantly positive correlations with TOC and TN. The coefficients of variation (CVs) for WSOC and WSOC/TOC were greater than the other indices (e.g, MBC, TOC and TN), suggesting that WSOC in the soils was more sensitive to these rotation systems. The results above indicated that the soil amended with green manure could not only increase the usable C source for soil microorganisms, but could also enhance soil organic matter content; hence, rotation with green manure would be a good strategy for sustainable agriculture.

Water-soluble UV curable urethane methyl acrylate coating：preparation and properties

Two kinds of water-soluble and ultraviolet (UV) curable oligomers were synthesized and characterized. The oligomers were evaluated as resins for water-based UV curable coating. The rheology of the two oligomers' aqueous so-lutions was investigated in terms of solid fraction, pH dependence, and temperature dependence. The solutions were found to be Newtonian fluid showing rather low viscosity even at high solid fraction of 0.55. The drying process of the coatings and the properties of the cured coatings were studied by comparing them with water-dispersed UV-curable polyurethane methyl acrylate. It was evident that the water-soluble coating dried more slowly; and that the overall properties were inferior to those of the water-dispersed coating.

Soil nutrients in relation to vertical roots distribution in the riparian zone of Three Gorges Reservoir,China

Since the impoundment of the Three Gorges Reservoir(TGR), the riparian zone has been subjected to numerous environmental changes. This study was conducted to recognize the distribution of grass roots and its impacts on soil nutrients in the water level fluctuation zone of TGR. Roots of four predominant herbaceous plants in the study area, specifically, Cynodon dactylon, Hemarthria altissima, Hemarthria compressa, and Paspalum paspaloides, and their corresponding relation with soil nutrient contents were investigated. Root surface area density was determined with Win RHIZO, and the relationships of root distribution with soil depths and soil nutrient contents were studied. The results indicates that most roots are distributed in the top soil layer of 0-10 cm. Estimated root surface area density for the selected grass species ranges from 0.16 to 13.44 cm^2/cm^3, and decreases exponentially with an increase in soil depth. Soil organic matter and total nitrogen contents are significantly lower on bare control area than the corresponding values on the grasslands. Total nutrient contents on grasslands of C. dactylon and H. compressa are higher than those of other grass areas. Root length density and root surface area density are significantly correlated with soil organic matter and total nitrogen content for the four grasslands. The present results suggests that plant roots have significant effects on the distribution of soil nutrients in soil profiles in the riparian zone along the TGR. Nevertheless, additional investigations are needed to reveal the specific interactions between plant roots distribution, soil nutrients and water level fluctuations.

Significance of Transients in Soil Temperature Series

The primary objective of this study was to investigate the impact of observation scale on the estimation of soil thermal properties.Transients are usually filtered out and ignored when classical Fourier approaches are used to deconstruct and model temperature time series.It was hypothesized that examination of such transients may be more important in identifying and quantifying short-term perturbations in internal soil heat transfer induced by agronomic disturbances. Data-logged temperatures were collected at 10-minute intervals from thermistor probes installed at 10 and 25 cm depths in isolated areas of two grassed plots.One plot(6T)had been treated twice with 6 Mg ha^(-1)composted turkey litter as received.The other plot(NPK)was fertilized at the same time with NPK fertilizer.Various methods were used to analyze the series to obtain apparent soil thermal diffusivity(D-value)at various time scales.Results supported the hypothesis that short-term differences in internal soil heat transfer between the 6T and NPK plots were more manifest and effectively captured by estimated D-values calculated from the monthly and daily partial series.The 6T plot had higher soil organic matter content than the NPK plot and had lower apparent soil thermal diffusivity.Diurnal soil temperature amplitudes, required to calculate the mean D-values from partial series,were more effectively obtained using a temperature change rate method.The more commonly used Fourier analysis tended to be effective for this purpose when the partial series reasonably presented well-defined diurnal patterns of increasing and decreasing temperatures.

Land Use Effects on Soil Organic Carbon, Microbial Biomass and Microbial Activity in Changbai Mountains of Northeast China

Land use changes are known to alter soil organic carbon （SOC） and microbial properties, however, information about how conversion of natural forest to agricultural land use as well as plantations affects SOC and microbial properties in the Changbai Moun- tains of Northeast China is meager. Soil carbon content, microbial biomass carbon （MBC）, basal respiration and soil carbon mineraliza- tion were studied in five selected types of land use： natural old-growth broad-leaved Korean pine mixed forest （NF）; spruce plantation （SP） established following clear-cutting of NF; cropland （CL）; ginseng farmland （GF） previously under NF; and a five-year Mongolian oak young forest （YF） reforested on an abandoned GF, in the Changbai Mountains of Northeast China in 2011. Results showed that SOC content was significantly lower in SP, CL, GF, and YF than in NF. MBC ranged from 304.4 mg/kg in CL to 1350.3 mg/kg in NF, which was significantly higher in the soil of NF than any soil of the other four land use types. The SOC and MBC contents were higher in SP soil than in CL, GF, and YF soils, yielding a significant difference between SP and CL. The value of basal respiration was also higher in NF than in SP, CL, GF, and YF. Simultaneously, higher values of the metabolic quotient were detected in CL, GF, and YF soils, indicat- ing low substrate utilization of the soil microbial community compared with that in NF and SP soil. The values of cumulative mineral- ized carbon and potentially mineralized carbon （Co） in NF were significantly higher than those in CL and GF, while no significant dif- ference was observed between NF and SP. In addition, YF had higher values of Co and C mineralization rate compared with GF. The results indicate that conversion from NF into agricultural land （CL and GF） uses and plantation may lead to a reduction in soil nutrients （SOC and MBC） and substrate utilization efficiency of the microbial community. By contrast, soils below SP were more conducive to the preservation of soil organic matter, which was reflected in the comparison of microbial indicators among CL, GF, and YF land uses. This study can provide data for evaluating soils nutrients under different land use types, and serve as references for the rational land use of natural forest in the study area.

Study on Aerobic Composting of Mixed Municipal Sludge, Kitchen Waste and Water Hyacinth

In this study, a in vessel aerobic composting method is adopted to investigate the variation rules of various evaluation parameters （temperature, moisture content, pH, organic matter, water soluble ammonia nitrogen, water soluble nitrate nitrogen and germination index） in cocomposting of municipal sludge, kitchen waste and water hyacinth at different proportions. The results show that, in composting, the parameters of moisture content, pH, water soluble ammonia nitrogen and water soluble nitrate nitrogen demonstrate marked dynamic change rules during composting process; the temperature of three groups of compost materials rapidly rise to above 55 ~C within 96h, and last for 3 - 7d, meeting the harmless requirements, and their organic matter degradation rate excess 30%, the GI index is higher than 83%, in line with the requirements on maturity, which proves that the co-composting of municipal sludge, kitchen waste and water hyacinth can realize harmlessness and resource reutilization after composting.

Impacts of global biogenic isoprene emissions on surface ozone during 2000-2019

Biogenic isoprene is an important precursor of tropospheric ozone(O_(3)).Here,a coupled chemistry-vegetation model was used to quantify the contributions of isoprene emissions to surface O_(3)pollution on the global scale during 2000-2019.The biogenic isoprene emissions showed high values in mid-low latitudes and seasonal peaks in the summer hemispheres.They promote global surface O_(3)concentrations by 1.75 ppbv annually with regional hotspots of 4.39 ppbv(8.8%)in China and 5.36 ppbv(11.1%)in the U.S.in boreal summer.In the past two decades,isoprene emissions increased by 1.32 TgC yr^(−1)(0.67%yr^(−1))in the Northern Hemisphere but decreased by 0.71 TgC yr^(−1)(0.44%yr^(−1))in the Southern Hemisphere.Such changes of isoprene made opposite contributions to the surface O_(3)trend,with 0.26 ppbv yr^(−1)in eastern China but−0.32 ppbv yr^(−1)in the southeastern U.S.due to the changes in the background regime of chemical reactions.The impact of anthropogenic changes on the O_(3)trend is consistent with that of biogenic isoprene,but two to four times stronger in magnitude.This study revealed that the effective control of anthropogenic NO_(x)emissions could mitigate regional O_(3)pollution even with the increased isoprene emissions under global warming.

严寒地区垃圾焚烧发电厂发酵菌群温度响应特性

针对严寒地区冬季生活垃圾发酵过程中细菌群落演替设计实验,探究发酵过程中不同温度下(0,10,15,20,30,40℃)的有机物含量变化及细菌温度响应特性。研究表明:在0~40℃内发酵前3 d渗滤液中有机物含量变化均呈先下降再上升的变化趋势,温度越高,渗滤液中有机物在第3天的COD值也越高,且3~6 d下降幅度增大,而后6~10 d内的回升幅度也增大。通过微生物测序发现,最优势菌门为厚壁菌门(Firmicutes),其相对丰度为64.41%~99.74%,最优势菌属为乳杆菌属(Lactobacillus),其相对丰度为13.18%~96.95%。在0℃发酵温度下,乳杆菌属(Lactobacillus)相对丰度占比下降迅速,魏斯氏菌属(Weissella)成为最优势菌属;在其他温度下,乳杆菌属(Lactobacillus)相对丰度占比均超过68.92%。结果表明:垃圾样品中细菌种类及数量受发酵温度影响显著,在15℃以上的发酵温度下,乳杆菌属(Lactobacillus)的数量均出现上升趋势,30℃发酵温度下增长幅度最大。乳杆菌属数量的增加对有机物的降解作用也增强,并对其他菌属有明显的抑制作用。从利于垃圾入炉焚烧的角度考虑,结合垃圾解冻能耗问题,建议将垃圾储存池温度设置为15~20℃。

Seasonal Variability of Soil Organic Carbon Fractions Under Arable Land

Carbon fractions in soils apparently vary not only in space, but also over time. A lack of knowledge on the seasonal variability of labile carbon fractions under arable land hampers the reliability and comparability of soil organic carbon(SOC) surveys from different studies. Therefore, we studied the seasonal variability of two SOC fractions, particulate organic matter(POM) and dissolved organic carbon(DOC), under maize cropping: POM was determined as the SOC content in particle-size fractions, and DOC was measured as the water-extractable SOC(WESOC) of air-dried soil. Ammonium, nitrate, and water-extractable nitrogen were measured as potential regulating factors of WESOC formation because carbon and nitrogen cycles in soils are strongly connected. There was a significant annual variation of WESOC(coefficient of variation(CV) = 30%). Temporal variations of SOC in particle-size fractions were smaller than those of WESOC. The stocks of SOC in particle-size fractions decreased with decreasing particle sizes, exhibiting a CV of 20%for the coarse sand-size fraction(250–2 000 μm), of 9% for the fine sand-size fraction(50–250 μm), and of 5% for the silt-size fraction(20–50 μm). The WESOC and SOC in particle-size fractions both peaked in March and reached the minimum in May/June and August, respectively. These results indicate the importance of the time of soil sampling during the course of a year, especially when investigating WESOC.

Recognition on the forming-vanishing process and underlying mechanisms of the hypoxia off the Yangtze River estuary

On the basis of compiled multidisciplinary historical data in 2006-2007 and incorporation of relevant simulation results and re- mote sensing data, we performed an in-depth study of the generation and dissipation process of the hypoxic zone and its distribu- tion morphology and structure off the Yangtze River estuary, Based on the hydrological circulation dynamics, reproduction of phytoplankton （leading to the decomposition of organic matter）, and other factors, we comprehensively and systematically inves- tigated the generation and dissipation of the hypoxic zone and underlying mechanisms for the seasonal variation in its position, explored the multi-factorial synergistic reactions during the generation and dissipation process of the hypoxic zone, and revealed the controlled mechanism for the morphology and structure of the hypoxic zone＇s distribution. Our studies indicate that in the winter and spring seasons, the hydrological environment off the Yangtze River estuary provides a water body with relatively low contents of dissolved oxygen （DO）, which is the background for the formation of a hypoxic zone. After entering into the summer season, the hypoxic zone gradually develops towards the north and becomes mature. Because of the impact of the terrain, local decomposition of organic matter, and upwelling of the Kuroshio subsurface water in July-August, the bypoxic zone off the Yang- tze River estuary exhibits the characteristics of discontinuous distribution in space and has a south and north ＂dual-core＂ structure in the inner continental shelf. In addition, there is a hypoxic core in the eastern outer continental shelf. The degrees of hypoxia vary for different areas; they are strongest overall in the north, next strongest in the south; they are weakest on the outer continen- tal shelf. In summer, the hypoxic zone in the north is related to the northward differentiation of the southern hypoxic zone and re- sults from local development and intensification. In August, the hypoxic zone in the north reaches its peak, and after September, it rapidly retreats southward and disappears because of weakening stratification. In the fall, there is hypoxic zone along the coast of Zhejiang in the south, and there is also a low-DO area to the southwest of Jeju Island, with both zones disappearing rapidly. In addition, the change of dynamic environment also causes the low-DO area of the outer continental shelf to move outward in the fall. The variation in the intensity of the stratification and its cumulative effects as a barrier of vertical DO transportation over long pe- riods of time have a significant impact on the degree of hypoxia in the hypoxic zone. In addition, the seasonal variations in the size of the stratified region, intensity of each current system/water mass, upwelling, front, and high-value area of phytoplankton biomass jointly restrict the extension of the hypoxic zone in the inner continental shelf and latitudinal （south-north direction） movement of its location off the Yangtze River estuary. The combined effect of dynamic factors, such as that of the Kuroshio subsurface water, causes a low-DO core in the outer continental shelI： The bottom cold water to the north of the East China Sea is the dynamic basis for the formation of the low-DO area to the southwest of Jeju Island during the fall season. The special seabed to- pography and mud area distribution off the Yangtze River estuary have a certain degree of influence on the development of the hypoxic zone. The generation and dissipation of the hypoxic zone and its distribution morphology off the Yangtze River estuary, and seasonal variation of its structure and position are a result of the synergistic effects of various factors.

Climate change and global cycling of persistent organic pollutants:A critical review

Climate warming, one of the main features of global change, has exerted indelible impacts on the environment, among which the impact on the transport and fate of pollutants has aroused widespread concern. Persistent organic pollutants(POPs) are a class of pollutants that are transported worldwide. Determining the impact of climate warming on the global cycling of POPs is important for understanding POP cycling processes and formulating relevant environmental policies. In this review, the main research findings in this field over the past ten years are summarized and the effects of climate warming on emissions, transport, storage, degradation and toxicity of POPs are reviewed. This review also summarizes the primary POP fate models and their application. Additionally, research gaps and future research directions are identified and suggested. Under the influence of climate change, global cycling of POPs mainly shows the following responses.(1) Global warming directly promotes the secondary emission of POPs; for example, temperature rise will cause POPs to be re-released from soils and oceans, and melting glaciers and permafrost can re-release POPs into freshwater ecosystems.(2) Global extreme weather events, such as droughts and floods, result in the redistribution of POPs through intense soil erosion.(3) The changes in atmospheric circulation and ocean currents have significantly influenced the global transport of POPs.(4) Climate warming has altered marine biological productivity, which has changed the POP storage capacity of the ocean.(5) Aquatic and terrestrial food-chain structures have undergone significant changes, which could lead to amplification of POP toxicity in ecosystems.(6) Overall, warming accelerates the POP volatilization process and increases the amount of POPs in the environment, although global warming facilitates their degradation at the same time.(7) Various models have predicted the future environmental behaviors of POPs. These models are used to assist governments in comprehensively considering the impact of global warming on the environmental fate of POPs and therefore controlling POPs effectively. Future studies should focus on the synergistic effects of global changes on the cycling of POPs. Additionally, the interactions among global carbon cycling, water cycling and POP cycling will be a new research direction for better understanding the adaptation of ecosystems to climate change.

Seasonal changes of organic matter origins and anammox activity in the Changjiang Estuary deduced from multi-biomarkers in suspended particulates

Human activity-induced eutrophication and harmful algal blooms are main causes of the expansion of the hypoxic zone in the Changjiang Estuary. Among the many changes in biogeochemical processes, anaerobic ammonium oxidation(anammox) is proposed to play an important role in the nitrogen cycle in hypoxic areas. Ladderane lipids have been used as biomarkers to indicate anammox activity in ecosystems, but the origins of anammox bacteria and ladderanes in suspended particulates are still unclear. In this study, we report the results of a suite of biomarker analyses of suspended particulates across a salinity gradient of the Changjiang Estuary in both the spring and summer to evaluate the origins of the ladderanes and their potential as proxies for anammox activity and hypoxia. The spatio-temporal variations in terrestrial biomarkers(n-alkanes and n-alkanols), marine biomarkers(brassicasterol and dinosterol), and the Terrestrial and Marine Biomarker Ratio and Branched and Isoprenoid Tetraether indices reveal that marine organic matter was dominant in the particulates in both the spring(55%) and summer(86%) seasons. Correlations with both marine and terrestrial biomarkers suggest that ladderanes were mainly produced in the water column, and therefore that ladderane concentrations in suspended particulates in the Changjiang Estuary mainly reflect anammox activity in the water column, although changes in anammox bacterial assemblages may also have played a role in ladderane concentrations. Overall, ladderane results suggest that anammox activity was widespread in the Changjiang Estuary; but higher ladderane concentrations in the summer(especially in the upwelling zone) were correlated with lower dissolved oxygen concentrations, which suggest that they are useful proxies for hypoxia.

Impact of Land-Use Change on Soil Microbial Community Composition and Organic Carbon Content in the Dry Tropics

Restoration of forests poses a major challenge globally, particularly in the tropics, as the forests in these regions are more vulnerable to land-use change. We studied land-use change from natural forest(NF) to degraded forest(DF), and subsequently to either Jatropha curcas plantation(JP) or agroecosystem(AG), in the dry tropics of Uttar Pradesh, India, with respect to its impacts on soil microbial community composition as indicated by phospholipid fatty acid(PLFA) biomarkers and soil organic carbon(SOC) content. The trend of bacterial PLFAs across all land-use types was in the order: NF > JP > DF> AG. In NF, there was dominance of gram-negative bacterial(G^-) PLFAs over the corresponding gram-positive bacterial(G^+) PLFAs. The levels of G^- PLFAs in AG and JP differed significantly from those in DF, whereas those of G^+ PLFAs were relatively similar in these three land-use types. Fungal PLFAs,however, followed a different trend: NF > JP > DF = AG. Total PLFAs, fungal/bacterial(F/B) PLFA ratio, and SOC content followed trends similar to that of bacterial PLFAs. Across all land-use types, there were strong positive relationships between SOC content and G-, bacterial, fungal, and total microbial PLFAs and F/B PLFA ratio. Compared with bacterial PLFAs, fungal PLFAs appeared to be more responsive to land-use change. The F/B PLFA ratio, fungal PLFAs, and bacterial PLFAs explained 91%, 94%,and 73% of the variability in SOC content, respectively. The higher F/B PLFA ratio in JP favored more soil C storage, leading to faster ecosystem recovery compared to either AG or DF. The F/B PLFA ratio could be used as an early indicator of ecosystem recovery in response to disturbance, particularly in relation to land-use change.