The Geographical Features of China

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Combining bioactive compounds and antioxidant activity profiling provide insights into assessment of geographical features of Chinese jujube

As the largest jujube cultivating areas of the world,the market price and quality of Chinese jujube are obviously affected by its producing regions in China.Therefore,traceability of Chinese jujube has become an important issue.To search the suitable geographical labels of Chinese jujube,26 major cultivars from five geographical regions of China were investigated by evaluating their bioactive compounds and antioxidant activity profiling.Multivariate statistical techniques(e,g.,PCA,PLS,VIP value)applied to the above-obtained data were further used to identify geographical origin in different areas of Chinese jujube.The results indicated that the highest median contents of total phenols(TP)and flavonoids(TF)of Chinese jujube were originated from Ningxia and Henan provinces,both of which also exhibited the stronger bioactivity.p-Hydroxybenzoic acid and rutin exhibited the highest contents among the all detected individual phenolic compounds.The highest median contents of cyclic adenosine monophosphate(cAMP),cyclic guanosine monophosphate(cGMP)and polysaccharides were all found in Chinese jujube samples of Xinjiang province.In particular,p-hydroxybenzoic acid,rutin,cAMP,cGMP and polysaccharides can be regarded as the potential biomarkers in distinguishing the geographical origin of Chinese jujube.Additionally,the high altitude and latitude might be benefit for the accumulation of cAMP,cGMP and polysaccharides(primary metabolites),and high longitude and annual precipitation maybe improve the contents of TP and TF(secondary metabolites).These information could provide an effective methods in distinguishing the geographical features of Chinese jujube,and also be benefit for the products development.

Modeling potential wetland distributions in China based on geographic big data and machine learning algorithms

Climate change and human activities have reduced the area and degraded the functions and services of wetlands in China.To protect and restore wetlands,it is urgent to predict the spatial distribution of potential wetlands.In this study,the distribution of potential wetlands in China was simulated by integrating the advantages of Google Earth Engine with geographic big data and machine learning algorithms.Based on a potential wetland database with 46,000 samples and an indicator system of 30 hydrologic,soil,vegetation,and topographic factors,a simulation model was constructed by machine learning algorithms.The accuracy of the random forest model for simulating the distribution of potential wetlands in China was good,with an area under the receiver operating characteristic curve value of 0.851.The area of potential wetlands was 332,702 km^(2),with 39.0%of potential wetlands in Northeast China.Geographic features were notable,and potential wetlands were mainly concentrated in areas with 400-600 mm precipitation,semi-hydric and hydric soils,meadow and marsh vegetation,altitude less than 700 m,and slope less than 3°.The results provide an important reference for wetland remote sensing mapping and a scientific basis for wetland management in China.

Geographic variability of Twitter usage characteristics during disaster events

Twitter is a well-known microblogging platform for rapid diffusion of views,ideas,and information.During disasters,it has widely been used to communicate evacuation plans,distribute calls for help,and assist in damage assessment.The reliability of such information is very important for decision-making in a crisis situation,but also difficult to assess.There is little research so far on the transferability of quality assessment methods from one geographic region to another.The main contribution of this research is to study Twitter usage characteristics of users based in different geographic locations during disasters.We examine tweeting activity during two earthquakes in Italy and Myanmar.We compare the granularity of geographic references used,user profile characteristics that are related to credibility,and the performance of Naive Bayes models for classifying Tweets when used on data from a different region than the one used to train the model.Our results show similar geographic granularity for Myanmar and Italy earthquake events,but the Myanmar earthquake event has less information from locations nearby when compared to Italy.Additionally,there are significant and complex differences in user and usage characteristics,but a high performance for the Naive Bayes classifier even when applied to data from a different geographic region.This research provides a basis for further research in credibility assessment of users reporting about disasters.

Scrutinise the variations of glaciers and their climatic attributions in the Sanjiangyuan National Park during 1969-2018

Since 2020,the first national park of China,the Sanjiangyuan National Park(Park)has been put into operation in China.This Park is one of the most vulnerable regions to the rapid climate change in the Tibetan Plateau.There have not been any investigations into the current status of the glacier resources in the Park so far.This study reported the first summary of the glaciers in the Park at present and their variations since the 1960s.The data used here come from the two Chinese Glacier Inventories finished during 1969-1970 and 2006-2010,respectively,and the remote-sensing images during 1985-1990,1995-2000 and 2018.The total glacier area in the Park is 772 km^(2)to our best estimate,much less than 2342 km^(2)reported in the first Chinese Glacier Inventory published in 2009.The shrinkage rate of the glaciers in the Yangtze River Park(a sub-park)had slowed from-0.37%per year during the 1970s to-0.09%per year during 2002-2012 in area,while that in the Lancang River Park had sped up from-0.34%per year during 1968-2000 to-0.67%per year during 2000-2018.There are no glaciers in the Yellow River Park(a sub-park).The change in the glaciers was related to the regional relatively rapidly warming and insufficient mass supply from precipitation.The geographic features of the glaciers in the Yangtze and Lancang Parks also lead to their different change extents,most of which happened at 5500 m a.s.l.and below.