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1.Progress of Research on Aeolian Sediment Transport Influenced by Tide

Author:He Yanyu;Liu Jianhui;Cai Feng;Li Bailiang;Wang Lihui;Ning Qingqian

Source:Journal of Desert Research,2018,Vol.38

Abstract:Alternate wetting and drying beachface induced by tide is one of the most important process influencing beach aeolian sediment transport.From the aspects of temporal and spatial variabilities of surface moisture content and cyclical variation of wind fetch length,as well as their own effect on beach aeolian sediment transport in the environment of alternate wetting and drying induced by tide,this paper summarizes the main progress and achievements of beach aeolian sediment transport influenced by tide.The main conclusions of this review are shown as:(1)The relationship between surface moisture variabilities and tidal oscillation is nonlinear,which is separated by a double hysteresis effect induced by watertable and capillary fringe;(2)A positive correlation between aeolian sediment transport threshold and surface moisture has been found in the case of surface moisture less than critical moisture threshold and the beach aeolian transport system will nearly shut down once surface moisture greater than critical moisture threshold;(3)The correlation between aeolian mass flux and fetch length can be divided into three stages according to the equilibrium state of sediment transport:positive before equilibrium state,negative after equilibrium state and irrelevant during equilibrium state.Finally,some necessary future research directions in China are put forward,according to the present research situation of beach aeolian sediment transport influenced by tide.

2.A new perspective on landscape impact in bee populations:Considering the bee gut microbiome

Author:Tang Min;Zou Yi;Su Qinzhi;Zhou Xin

Source:Biodiversity Science,2019,Vol.27

Abstract:Pollinator bees are providers of an important ecosystem service,and their survival relies completely on the landscape.Now with the landscape dominated by agriculture,bee diversity has been significantly reduced.Studies suggest that bee populations decline as agricultural land-use increases due to increased exposure to detrimental pesticides.Further,the protein content of pollen is highly important for the growth and development of a bee,and different landscapes provide distinct sources of nutrition.Although many studies have demonstrated the apparent impacts of landscape change on the population dynamics and individual survival of the bees,the underpinning mechanisms remain largely unknown.On the other hand,an increasing body of literature has shown that bee gut symbionts are of great importance to the health of the host bees in absorbing nutrients and resisting pathogens.When foraging,pollinator bees are exposed to particular microbes from pollen and nectar which have been suggested to be a source of some bee gut symbionts and could be either probiotics or pathogens.Together with landscape-related nutrition and pesticides,environmental microbes have been reported to affect bee microbiomes significantly.A number of pilot studies suggest that landscape change could affect bee microbiota,thereby influencing host health.An important linkage,however,is missing between environmental microbiota,especially those associated with the flowers,and that of the bee gut in a changing habitat.It is worth exploring how gut microbiomes respond to landscape changes.This will hopefully help us identify landscape types that are friendly to bees,so proper land-use can be implemented to protect the bees.

3.Regulating effect of agricultural landscape pattern on ecological pest control by natural enemies

Author:Jiang Ting;Fu Daomeng;Zhang Wanna;Zou Yi;Xiao Haijun

Source:Chinese Journal of Applied Ecology,2019,Vol.30

Abstract:It,s well known that regional agricultural landscape pattern can significantly regulate the relationship between plants,herbivorous insects and natural enemies. The improvement of the ecosystem services of regional agricultural landscape pattern has profound impacts on pest control, which has received much interests in current landscape ecology and pest control studies. This review systematically summarized the impacts of agricultural landscape pattern,as well as its succession on the diversity and ecological pests control of important natural enemies. From the perspective of different natural enemies,the impacts of agricultural landscape pattern on natural predators,parasitoids, beneficial microorganisms and its ecological pests control functions were all recapped. We outlined crop spatial distribution and vegetation habitat management strategies. This review could provide useful insights in improving the ecosystem services of natural enemies in agricultural landscape based on the vegetation habitat management, and offer theoretical support for regional ecological agriculture in response to the strategy of chemical pesticide reduction application'.

4.Several characteristics of beach aeolian sand transport influenced by tide: A case study in the Yuandangao Beach,Pingtan Island,Fujian Province

Author:He Yanyu;Liu Jianhui;Cai Feng;Li Bailiang;Wang Lihui;Zhou Changmao

Source:Acta Oceanologica Sinica,2018,Vol.40

Abstract:Coastal aeolian is a typical product of sea,land and air interaction. Based on a comprehensive observation of beach aeolian sand in the Yuandangao beach of Pingtan Island,Fujian Province,this paper aims to explore and summarize the vertical distribution,entrainment and transport characteristics of beach aeolian sand influenced by tide. The main conclusions are as follows: (1) The vertical distribution of wind-sand flow in intertidal zone is almost entirely(98.9%%) in the range of 0 -30 cm,and the specific distribution function varies with different particle size; (2) The threshold velocity of beach aeolian sand is significantly higher than that of inland desert,and the changing process of it in the tidal circulation mainly reflects the interaction between average surface moisture and fetch length; (3) The wind-blown sand flux of intertidal zone involves the interaction of average surface moisture,fetch length and wind speed,and the dominant factors of its changing process vary in different stages of ebb and flow; (4) Entrainment of sand from a dry source and transport across a moist surface is one of the typical beach aeolian sand transport mode,with a short delivered distance at a time,and a highly relayed way of overall transport.

5.Effect of Beach Nourishment on the Coastal Aeolian Sand Accumulation: a case study in Pingtan,Fujian,China

Author:Liu Jianhui;Cai Feng;Li Bailiang;Lei Gang;Qi Hongshuai;Zhang Zhenwei;Li Bing

Source:Journal of Desert Research,2016,Vol.36

Abstract:After the implementation of the beach nourishment project,some environmental issues come up accompanying with the function of mitigating beach erosion and protecting the coast.Especially in the coast with strong wind,nourishment alters the environmental factors of beachface,which significantly impact the characteristics of aeolian sand transport and wind-blown sand flux.To study the aeolian sand transport and sediment accumulation after beach nourishment,Longfengtou beach in Pingtan Island,Fujian province,has beach taken as a typical study area.It is indicated that the beach characters such as dry beach width,surface sediment grain size,surface moisture and beach elevation,have significant impacts on beach aeolian sand transport and deposition process.The main conclusions of this study are showed as:(1)the increase of dry beach elevation enhance the wind speed of beach surface,which improves beach surface aeolian sand transport rate and wind-blown sand flux;(2)the elongation of dry beach width of nourished beach increases the fetch and provides sufficient sediment resource for aeolian sediment transport,and also elongates the duration of sediment transport;(3)after nourishment,the lower sediment moisture of beach surface decreases beach sediment transport threshold velocity and reinforces beach surface aeolian transport.

6.Effects of Boron Treatment on Arsenic Uptake and Efflux in Rice Seedlings

Author:Zhu Yi;Sun Guoxin;Chen Zheng;Hu Ying;Zheng Ruilun

Source:Environmental Science,2018,Vol.39

Abstract:The impacts of boron ( B) root application and foliar spray on arsenic ( As) uptake,translocation,and efflux by /in rice seedlings ( Oryza sativa L. ) were investigated in three hydroponic experiments. The addition of B to culture medium did not alter concentrations of arsenite ( As[Ⅲ]) ,arsenate ( As[Ⅴ]) ,and total As,nor did it alter transfer coefficients or uptake efficiency of As in rice seedlings under either As( Ⅲ) or As( Ⅴ) exposure. Foliar B supply increased shoot B concentrations 15. 8-fold,and decreased root As concentrations and As uptake efficiency by 20. 9%% and 18. 0%% under As( Ⅴ) treatment,and by 12. 6%% and 13. 8%% under As( Ⅲ) treatment,respectively,yet did not significantly decrease shoot As concentrations ( P > 0. 05) . Interestingly,foliar B supply reduced root B concentrations by up to 47. 1%% under exposure to As( Ⅴ) but not As( Ⅲ) ,and corresponding root B concentrations were 85. 3%% higher in As( Ⅴ) treatment than in As( Ⅲ) treatment on average ( P < 0. 05) . Both total As and As( Ⅴ) concentrations were positively related to B concentration in rice roots under As( Ⅴ) treatment following foliar B supply ( P < 0. 05) . Rice seedlings extruded 105. 2%% more As after As( Ⅲ) -pretreatment than after As( Ⅴ) -pretreatment. Foliar B supply increased the amount of As excreted by As( Ⅲ) -pretreated rice root by 14. 0%%-16. 9%% ( P > 0. 05) ,and had no effect on the As efflux of As( Ⅴ) -pretreatment seedlings. A range of 45. 9%%-70. 7%% of root As was excreted to solution during one week. These results indicate that the root application of B at four times the concentration of As can slightly decrease As accumulation by rice,whereas foliar B supply is conducive to a decline in As acquisition by rice roots. It is likely that the B channel is at least not the main pathway for As( Ⅲ) entering into rice roots,and the As( Ⅴ) distribution mechanism in rice plants may be shared with that of B.

7.Ultrathin free-standing graphene oxide film based flexible touchless sensor

Author:Liu Lin;Wang Yingyi;Li Guanghui;Qin Sujie;Zhang Ting

Source:Journal of Semiconductors,2018,Vol.39

Abstract:Ultrathin free-standing graphene oxide (GO) films were fabricated by vacuum filtration method assisted with Ni(OH)2 nanosheets as the sacrifice layer. The surface of the obtained GO film is very clean as the Ni(OH)2 nanosheets can be thoroughly etched by HCl. The thickness of the GO films can be well-controlled by changing the volume of GO dispersion, and the thinnest GO film reached ~12 nm. As a novel and transparent dielectric material, the GO film has been applied as the dielectric layer for the flexible touchless capacitive sensor which can effectively distinguish the approaching of an insulator or a conductor.

8.Total phosphorus concentrations in surface water of typical agro- and forest ecosystems in China, 2004-2010

Author:Xie Juan;Zhang Xinyu;Xu Zhiwei;Yuan Guofu;Tang Xinzhai;Sun Xiaomin;Ballantine D J

Source:Frontiers of Environmental Science & Engineering,2014,Vol.8

Abstract:The concentrations of total phosphorus (TP) from 83 surface water sampling sites in 29 of the Chinese Ecosystem Research Network (CERN) monitored ecosystems, representing typical agro- and forest ecosystems, were assessed using monitoring data collected between 2004 and 2010 from still and flowing surface water. Results showed that, TP concentrations were significantly higher in agro-ecosystems than those in forest ecosystems both for still and flowing surface water. For agroecosystems, TP concentrations in the southern area were significantly higher than those in the northern and northwestern areas for both still and flowing surface water, however no distinct spatial pattern was observed for forest ecosystems. In general, the median values of TP within agro- and forest ecosystems did not exceed the Class V guideline for still (0.2 mg·L~(-1)) or flowing (0.4 mg·L~(-1)) surface water, however, surface water at some agroecosystem sampling sites was frequently polluted by TP. Elevated concentrations were mainly found in still surface water at the Changshu, Fukang, Linze and Naiman monitored ecosystems, where exceedance (>0.2 mg·L~(-1)) frequencies varied from 43%% to 78%%. For flowing water, elevated TP concentrations were found at the Hailun, Changshu and Shapotou monitored ecosystems, where exceedance (>0.4 mg·L~(-1)) frequencies varied from 29%% to 100%%. Irrational fertilization, frequent irrigation and livestock manure input might be the main contributors of high TP concentrations in these areas, and reduced fertilizer applications, improvements in irrigation practices and centralized treatment of animal waste are necessary to control P loss in these TP vulnerable zones.

9.Rapid evaluation of arsenic contamination in paddy soils using field portable X-ray fluorescence spectrometry

Author:Liang Jianhong;Liu Panpan;Chen Zheng;Sun Guoxin;Li Hong

Source:Journal of Environmental Sciences,2018,Vol.64

Abstract:Arsenic (As) in paddy fields is deteriorating food security and human health through rice ingestion. Rice is the dominant food source of arsenic exposure to half of the world's population. Therefore, an in situ effective method for As risk evaluation in paddy soil is strongly needed to avoid As exposure through rice ingestion. Herein, we developed a rapid analytical methodology for determination of As in plant tissues using field portable X-ray fluorescence spectrometry (FP-XRF). This method was applied to rice roots in order to evaluate the As contamination in paddy soils. The results showed that rice roots with iron plaques were superior to rhizosphere soils for generating FP-XRF signals, especially for field sites with As concentrations lower than the soil detection limit of FP-XRF (30.0 mg/kg). Moreover, the strong linear relationships of As concentrations between the rice roots and corresponding leaves and grains proved that the rice root, rather than the soil, is a better predictor of As concentrations in rice grains. The research provides an efficient As monitoring method for As contaminated paddy fields by using wetland plant roots with iron plaques and XRF-based analytical techniques.
Total 9 results found
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