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An exploratory study on the use of enzyme activities as sediment tracers:biochemical fingerprints?

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International Journal of Sediment Research 2011年第2期26卷 136-151页

作者： Kazem NOSRATI Gerard GOVERS Hassan AHMADI Forood SHARIFI Mohammad Ali AMOOZEGAR Roel MERCKX Matthias VANMAERCKE Department of Physical geography Faculty of Earth SciencesShahid Beheshti University division of geography Department of Earth and Environmental Sciences 3. Faculty ofNatural ResourcesUniversity of Tehran 4. ForestRange and Watershed Management Organization 5. Faculty of BiologyCollege of SciencesUniversity of Tehran 6. Division of Soil and Water ManagementDepartment of Earth and Environmental Sciences 7. Division of GeographyDepartment of Eaeth and Environmental Sciences

Little information exists on the potential of soil enzyme activities,which are sensitive to soil properties and management,for the characterization of sediment sources at the catchment *** objective of this study is to explore and evaluate enzyme activity as tracer for sediment fingerprinting in the Hiv catchment(55 km~2),***,four enzymes were measured from 42 different sampling sites,covering three sediment source areas(rangeland/surface erosion,orchard/surface erosion,and streambank erosion),as well as from 12 sediment samples from reservoir check dams (sediment sinks).The results indicate that,based upon backward mode discriminant analysis,βglucosidase and dehydrogenase,allowed more than 95%of the samples to be correctly assigned to their source *** enzymes were selected as input data for a mixing-model to determine the relative contribution of the sampled sediment *** mean contributions from rangeland, orchard and streambank sources in the study area were estimated as 11.3%,15.1%and 73.7%, *** geochemical tracers,the mean contribution from rangeland,orchard and streambank sources was estimated as 14.1%,9.5%and 74.8%,*** biochemical and geochemical tracers,similar values were obtained(18.7%,10.7%and 70.7%,respectively).Our results indicate that soil enzyme activity allows for a good characterization of sediment sources,and can provide a complementary tool to currently existing sediment fingerprinting ***, the method should be also tested in other regions.

关键词： Sediment source Enzyme activity Biochemical fingerprints Mixing model Hiv catchment

Shifting cultivation in Mizoram, India: An empirical study of its economic implications

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Journal of Mountain Science 2019年第9期16卷 2136-2149页

作者： Vishwambhar Prasad SATI Department of geography and Resources Management School of Earth Sciences Mizoram University

Shifting cultivation is the major occupation and the main source of income of the marginal farmers(Jhumias) in Mizoram. At present, net area sown in Mizoram State is only 5.5%, of which, 16.9% area is devoted to shifting cultivation. Meanwhile, about 54% people, living in the rural areas, are engaged in practicing it. This paper examines economic implications of shifting cultivation in Mizoram, the eastern extension of the Himalaya. A total of 16 villages from eight districts(two villages from each district), were selected for case study, based on their location and distance from the district’s headquarter. Household level survey was conducted and a purposive random sampling method was employed to select households with 34.2% sampling size. The case study reveals that production and yield of the principal crops grown under shifting cultivation has decreased during the last 17 years(2000-2017), whereas, there is a slight increase in area sown. It further shows that although, a large group of Jhumias are practicing shifting cultivation and growing subsistence cereals, yet, their economic viability is significantly less than cash crops. As a result, a large section of people in rural areas are living below poverty line. The study suggests that for sustainable livelihood, cash crops can replace subsistence crops and shifting cultivation can be converted into permanent cultivation through terracing the Jhum plots.

关键词： Shifting cultivation Jhumias Jhumlands Economic implication Empirical study Mizoram

Contribution of biophysical and climate variables to the spatial distribution of wildfires in Iran

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Journal of Forestry Research 2023年第6期34卷 1763-1775页

作者： Kobra Shojaeizadeh Mahmoud Ahmadi Abbasali Dadashi-Roudbari Department of Physical geography Faculty of Earth SciencesShahid Beheshti UniversityTehranIran Department of geography Ferdowsi University of MashhadMashhadIran

This study investigated the relationship between climate and biophysical variables in burned areas in *** fire burned area(FBA)product(Fire CCI 5.1.1),land surface temperature(MOD11C3C),vegetation index(MOD13A1),and climate variables such as temperature,wind speed,relative humidity,and volumetric soil moisture from the ERA5 reanalysis dataset were *** correlation coefficient was used to determine the relationship between biophysical and climate variables and fire *** results show that FBA increased by 1.7 hectares/decade from 2001 to *** high FBA in 2010(the black summer of Iran)was due to high temperatures and significant heatwaves that led to extensive *** anthropogenic activities are considered a significant cause of wildfires,several variables,including increased temperatures,less precipitation,relative humidity,and wind speed and direction,contribute to the extent and occurrence of *** country’s FBA hotspot is in the Arasbaran region during the summer *** and relative humidity are the most significant variables influencing the occurrence of *** results show the vulnerability of Iran s forests and their high potential for *** the frequency of fire occurrences in Iran and the limited equipment,fire prevention plans should be carried out by applying proper management in high-risk regions.

关键词： Wildfire Burned areas Vegetation index(Ⅵ) Air temperature Iran

Sand dunes as potential sources of dust in northern China

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Science China earth sciences 2016年第4期59卷 760-769页

作者： Mark R SWEENEY LU HuaYu CUI MengChun Joseph A MASON FENG Han XU ZhiWei Department of earth sciences University of South Dakota Laboratory of earth Surface Process and Environment School of Geographic and Oceanographic Sciences Nanjing University Department of geography University of Wisconsin-Madison

While saltation bombardment of sand grains on a fine substrate can produce considerable dust, the well-sorted nature of sand dunes tends to preclude them from consideration as major dust sources. Recent research, however, has revealed that sand dunes can, in some cases, be large sources of dust. We used the PI-SWERL(Portable In-Situ Wind Erosion Laboratory) to measure in the field the potential of sand dunes and other desert landforms to emit particulate matter <10 μm(PM-10) dust in the Tengger, Ulan Buh, and Mu Us deserts of northern China. Combined with high resolution particle size measurements of the dune sand, an assessment of sand dunes as a dust source can be made. Large active transverse dunes tend to contain little to no stored PM-10, yet they produce a low dust flux. Coppice dunes stabilized by vegetation contain appreciable PM-10 and have very high dust emission potential. There is a positive correlation between the amount of PM-10 stored in a dune and its potential dust flux. Saltation liberates loose fines stored in dunes, making them very efficient dust emitters compared to landforms such as dry lake beds and washes where dust particles are unavailable for aeolian transport due to protective crusts or sediment cohesion. In cases where large dunes do not store PM-10 yet emit dust when active, two hypotheses can be considered:(1) iron-oxide grain coatings are removed during saltation, creating dust, and(2) sand grains collide during saltation, abrading grains to create dust. Observations reveal that iron oxide coatings are present on some dune sands. PI-SWERL data suggests that low dust fluxes from dunes containing no stored dust may represent an estimate for the amount of PM-10 dust produced by removal of iron oxide coatings. These results are similar to results from dunes in the United States. In addition, PI-SWERL results suggest that dust-bearing coppice dunes, which cover vast areas of China's sandy deserts, may become major sources of dust in the f

关键词： Coppice dunes Transverse dunes Dust PI-SWERL Desert

Lake variations in response to climate change in the Tibetan Plateau in the past 40 years

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International Journal of Digital earth 2013年第6期6卷 534-549页

作者： Jingjuan Liao Guozhuang Shen Yingkui Li Center for earth Observation and Digital earth Chinese Academy of SciencesBeijingChina Department of geography University of TennesseeKnoxvilleUSA

The Qinghai-Tibetan Plateau plays an important role in global climate and environmental change and holds the largest lake area in China,with a total surface area of 36,900 km^(2).The expansion and shrinkage of these lakes are critical to the water cycle and ecological and environmental systems across the *** this paper,surface areas of major lakes within the plateau were extracted based on a topographic map from 1970,and Landsat MSS,TM and ETM+satellite images from the 1970s to ***,a multivariate correlation analysis was conducted to examine the relationship between the changes in lake surface areas and the changes in climatic variables including temperature,precipitation,evaporation,and sunshine *** results suggest that the variations in lake surface areas within the plateau are closely related to the warming,humidified climate transition in recent years such as the rise of air temperature and the increase in *** particular,the rising temperature accelerates melting of glaciers and perennial snow cover and triggers permafrost degradation,and leads to the expansion of most lakes across the *** addition,different distributions and types of permafrost may cause different lake variations in the southern Tibetan Plateau.

关键词： lake variation climate change Qinghai-Tibetan Plateau

Food security status in rural areas of Mizoram,Northeast India

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Journal of Mountain Science 2017年第4期14卷 795-805页

作者： Vishwambhar Prasad SATT Lalrinpuia VANGCHHIA Department of geography and Resources Management School of Earth SciencesMizoram UniversityAizawl 796004India

Rural areas practice subsistence of the Mizoram state, India agriculture where shifting cultivation dominates the farming systems. As a result, output from crops is very low and thus, the rural areas suffer from food insecurity. This paper analyses food security status in the rural areas of Mizoram and suggests the measures to attain food security. A case study of 16 villages, lying in all the eight districts of Mizoram, was conducted in 2014 and 1527 households （76%） out of total 2010 households were surveyed through purposive random sampling method. Structured questionnaire was constructed and questions on three food security components and 13 indicators were asked. We used Z score technique to calculate data and finally got a composite score of all the components of food security. Our result shows that food availability in the study villages is very less as composite score stands for ***3 whereas food accessibility is comparatively higher, mainly due to availability of fair price shops （mean value is one）, high agricultural working population （40.1%） and high literacy rate （70.6%）. Therefore, its composite score is 0.236. Food stability scores only -0.062 and finally overall food security stands for 0.178, which is inadequate. We have suggested that‘system rice intensification＇, which is already in practice, should be given priority. Adequate irrigation facilities, proper public distribution system, cultivation of fruits and vegetables, value addition in farm products and access to market may achieve food security.

关键词： Food availability Food accessibility Food stability Food security Mizoram

Area and shape distortions in open-source discrete global grid systems

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Big earth Data 2022年第3期6卷 256-275页

作者： Alexander Kmoch Ivan Vasilyev Holger Virro Evelyn Uuemaa Department of geography Institute of Ecology and Earth SciencesUniversity of TartuTartuEstonia

A Discrete Global Grid System(DGGS)is a type of spatial reference system that tessellates the globe into many individual,evenly spaced,and well-aligned cells to encode location and,thus,can serve as a basis for data cube *** facilitates integration and aggregation of multi-resolution data from various sources to rapidly calculate spatial *** calculated normalized area and compactness for cell geometries from 5 open-source DGGS implementations-Uber H3,Google S2,RiskAware OpenEAGGR,rHEALPix by Landcare Research New Zealand,and DGGRID by Southern Oregon University-to evaluate their suitability for a global-level statistical data *** conclude that the rHEALPix and OpenEAGGR and DGGRID ISEA-based DGGS definitions are most suitable for global statistics because they have the strongest guarantee of equal area preservation-where each cell covers almost exactly the same area on the *** H3 has the smallest shape distortions,but Uber H3 and Google S2 have the largest variations in cell ***,they provide more mature software library *** provides excellent functionality to construct grids with desired geometric properties but as the only implementation does not provide functions for traversal and navigation within a grid after its construction.

关键词： Coordinate reference systems spatial indexing big spatial data analytics data cube DGGS

Analysis on variety and characteristics of maghemite

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Science China earth sciences 2010年第8期53卷 1153-1162页

作者： SHAW John BLOEMENDAL Jan HESSE Paul ROLPH Tim Department of earth sciences University of Liverpool Department of geography University of Liverpool Department of Environment and geography Macquarie University Department of Geology University of Newcastle

Maghemite (γ-Fe2O3) is a very common mineral at the earth’s surface and also an important material for making music and video tapes. Maghemite is usually synthesized from magnetite under oxidizing conditions after a few hours or a few days below a temperature of 300°C. The magnetic property of thermal instability and the chemical action after heating is an important character for maghemite. That is, it will become hematite in certain proportion after being heated above 250°C. Maghemite is therefore actually unable to have its Curie temperature measured. But late using synthetic sample, maghemite was further found partially thermal stable with a measurable Curie temperature ~645°C. During our thermally magnetic experiments for a set of synthetic magnetite, we found that extra fined grain size (pseudo single domain (PSD) and small multi-domain (MD), mainly 1-10 μm) magnetite was formed to a completely thermally stable maghemite. This maghemite can also be produced by heating the same powder up to 700°C in an oven and keeping this temperature for 10 min, then cooling it down. When the generated maghemite by these two ways is heated from room temperature to 700°C, it shows almost fully reversible, or thermally stable. We used X-ray powder diffraction and Mssbauer spectroscopy to confirm the identity of this maghemite and compared its magnetic hysteresis, high temperature magnetization, low temperature thermal demagnetization, and low temperature susceptibility with those of the original preheated magnetite. Such quickly oxidized maghemite by heating to high temperature implies some types of maghemite formed in certain natural condition can carry a thermal remnant magnetization (TRM). Four types of maghemite were characterized and discussed according to their thermal stability. Among them, partially stable and fully thermally stable maghemite after heating should possess capability of carrying TRM. There is possibly a compensation of synthetizing maghemite between heatin

关键词： maghemite paleomagnetism environmental magnetism magnetic mineral thermal stability TRM

Tourist management in national parks in the Czech-German borderland:Bohemian ’Switzerland’ and Saxon‘Switzerland’

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Journal of Mountain Science 2020年第12期17卷 2853-2879页

作者： Krzysztof KOLODZIEJCZYK Department of Regional geography and Tourism Institute of Geography and Regional DevelopmentFaculty of Earth Sciences and Environmental ManagementUniversity of WroclawWroclaw 50-137Poland

In the article tourist management in two national parks in the Czech-German borderland are being compared,namely Bohemian ’Switzerland’(also known as Czech ’Switzerland’) and Saxon’Switzerland’.Situated on either side of the state border,they feature the same type of geographical *** accessibility,transborder links and the hiking trail network are analyzed using methodology sourced from graph *** result of the analyses is a classification of tourist hubs and tourist centers,as well as an indication of the main directions of tourist *** German national park is decidedly more accessible but with a detrimental effect on the natural environment primarily due to its fragmentation by a dense network of tourist *** both parks trails enter the core zone(in theory a strict protection area) but this occurs on a larger scale on the German *** the Czech national park a greater number of positive examples of managing tourist movements can be ***,larger areas managed for dispersion,or from which tourists are generally excluded,are located there.

关键词： National parks Tourist management Tourist trails Bohemian’Switzerland’ Saxon’Switzerland’