Distinct Aeolian-fluvial Interbedded Landscapes in Three Watersheds of the Northern China

Due to the complex dynamic of aeolian and fluvial interacted processes behind the landform development,most of previous works started from classifying the types of landscape characterized by various aeolian and fluvial features.Such classifications are usually generalized based on large geomorphic data set abstracted from satellite images without field verification and dynamic field data.In this study,we identified river banks in deserts as a unique geographical unit dominated by aeolian-fluvial processes.Three distinct locations have been identified as representative study cases,which are in the Keriya River Basin in the west,the Mu Bulag River Basin in the middle and the Xar Moron River Basin in the east of the northern China.The aeolian-fluvial interaction types were quantified based on site observation and measurement,topographic mapping and remote-sensing image analysis.Dimensional morphological relationship between river channel and adjacent sand dunes areas were explored.We concluded that different channels are often associated with different distributions of riparian dunes.The quantitative data enabled us to distinguish statistically four different types of landscape in aeolian-fluvial dominant environment,namely riverside dunes-straight channel,symmetrical interleaving dunes-meandering channel,river-island dunes-braiding channel,and grid-like dunes-anastomosing channel,aiming to provide compensational information to current aeolian-fluvial interaction studies.The angle of interaction between aeolian and fluvial systems,the windward and leeward sites of the bank,vegetation coverage and underlying landform determines the distribution,morphology,scale and direction of extension of the riparian dunes.The results of the work study can provide a reference for study of aeolian-fluvial interactions at different spatial scales in arid region.

A Study of the Yesilirmak River Catchment in Northern Turkey: Spatial Patterns and Temporal Trends in Water Quality

This paper presents a comprehensive study of spatial and temporal patterns of water chemistry (1995-2008) in the Yesilirmak River catchment in Northern Turkey. Biological oxygen demand (BOD), dissolved oxygen (DO) and nutrient concentrations (nitrogen and phosphorus) are variable across the catchment because the upland areas are relatively undisturbed, and the lower catchment is dominated by urban, industrial and agricultural inputs. Seasonally, high nutrient concentrations occur in winter possibly due to flushing from the soil zone. Low summer flow and reduced dilution lead to high orthophosphate concentrations. However, denitrification seems to be more significant than dilution processes and this generates low nitrate concentrations in summer. Nutrient levels since 1995 do not show a significant upward trend. The current water quality status indicates that the river system is in poor condition. The majority of sites fall in the Turkish water classification class II-III and more than half fail the EU standards because of high nutrient concentrations. In order to improve the status of water quality to achieve good chemical and ecological status, there is clearly a need to improve pollution control within the river system by installing waste water treatment plants, while keeping the agricultural pollution to a minimum in the system.

Spatial pattern analysis of forest trees based on the vectorial mark

Analysis of spatial patterns to describe the spatial correlation between a tree location and marks(i.e.,structural variables),can reveal stand history,population dynamics,competition and symbiosis.However,most studies of spatial patterns have concentrated on tree location and tree sizes rather than on crown asymmetry especially with direct analysis among marks characterizing facilitation and competition among of trees,and thus cannot reveal the cause of the distributions of tree locations and quantitative marks.To explore the spatial correlation among quantitative and vectorial marks and their implication on population dynamics,we extracted vertical and horizontal marks(tree height and crown projection area)characterizing tree size,and a vectorial mark(crown displacement vector characterizing the crown asymmetry)using an airborne laser scanning point cloud obtained from two forest stands in Oxfordshire,UK.Quantitatively and vectorially marked spatial patterns were developed,with corresponding null models established for a significance test.We analyzed eight types of univariate and bivariate spatial patterns,after first proposing four types.The accuracy of the pattern analysis based on an algorithm-segmented point cloud was compared with that of a truly segmented point cloud.The algorithm-segmented point cloud managed to detect 70–86%of patterns correctly.The eight types of spatial patterns analyzed the spatial distribution of trees,the spatial correlation between tree size and facilitated or competitive interactions of sycamore and other species.These four types of univariate patterns jointly showed that,at smaller scales,the trees tend to be clustered,and taller,with larger crowns due to the detected facilitations among trees in the study area.The four types of bivariate patterns found that at smaller scales there are taller trees and more facilitation among sycamore and other species,while crown size is mostly homogeneous across scales.These results indicate that interspecific facilitation and competition mainly affect tree height in the study area.This work further confirms the connection of tree size with individual facilitation and competition,revealing the potential spatial structure that previously was hard to detect.

Analyzing the Relation between Greek Paper and Paperboard Imports and Exports with Macroeconomic Variables

This paper describes the relation between Greek imports and exports of paper and paperboard and a number of major macroeconomic variables, such as population, gross domestic product, the industrial production index and domestic round wood production. The Pearson correlation coefficient and multiple regression analysis were employed in the analysis of the data. The study shows that there is no significant relation between paper and paperboard imports as a dependent variable and population, gross domestic product and domestic round wood production as independent variables. Despite this, an acceptable model is constructed using only gross domestic product as an independent variable. The study also shows that there is a significant relation between the export of paper and paperboard and gross domestic product, the industrial production index and round wood production. The results indicate that gross domestic product as an independent variable has the greatest effect on wood imports and exports in Greece during the period studied. Using these models is confirmed that the use of socioeconomic variables and the construction of future scenarios for the Greek forest sector is very efficient considering the special characteristics of the Greek economy. These models could help the establishment of economic growth, the reduction of the financial and ecological deficit, the implementation of economic reforms and to increase new investments.

Effect of cOVID-19 lockdown on the characterization and mixing state of carbonaceous particles in the urban atmosphere of Liaocheng, the North China Plain

To investigate the effect of covID-19 control measures on aerosol chemistry,the chemical compositions,mixing states,and formation mechanisms of carbonaceous particles in the urban atmosphere of Liao-cheng in the North China Plain(NCP)were compared before and during the pandemic using a single particle aerosol mass spectrometry(SPAMS).The results showed that the concentrations of five air pollutants including PM2.5,PM1o,SO2,NO2,and cO decreased by 41.2%-71.5%during the pandemic compared to those before the pandemic,whereas O3 increased by 1.3 times during the pandemic because of the depressed titration of O3 and more favorable meteorological conditions.The count and percentage contribution of carbonaceous particles in the total detected particles were lower during the pandemic than those before the pandemic.The carbonaceous particles were dominated by elemental and organic carbon(ECOC,35.9%),followed by elemental carbon-aged(EC-aged,19.6%)and organic carbon-fresh(OC-fresh,13.5%)before the pandemic,while EC-aged(25.3%),ECOC(17.9%),and secondary ions-rich(SEC,17.8%)became the predominant species during the pandemic.The carbonaceous particle sizes during the pandemic showed a broader distribution than that before the pandemic,due to the condensation and coagulation of carbonaceous particles in the aging processes.The relative aerosol acidity(Rra)was smaller before the pandemic than that during the pandemic,indicating the more acidic particle aerosol during the pandemic closely related to the secondary species and relative humidity(RH).More than 95.0%and 86.0%of carbonaceous particles in the whole period were internally mixed with nitrate and sulfate,implying that most of the carbonaceous particles were associated with secondary oxidation during their formation processes.The diurnal variations of oxalate particles and correlation analyses suggested that oxalate particles before the pandemic were derived from aqueous oxidation driven by RH and liquid water content(LwC),while oxalate particles during the pandemic were originated from O3-dominatedphotochemical oxidation.

Seasonal characteristics and provenance of organic aerosols in the urban atmosphere of Liaocheng in the North China Plain:Significant effect of biomass burning

To better understand the seasonal characteristics of urban organic aerosol(OA)in the North China Plain(NCP),PM2.5 samples in the urban atmosphere of Liaocheng were collected and analyzed.The molecular distribution of the organic markers in the urban atmosphere of Liaocheng reveals that n-alkanes(39.3%)was the most abundant species all year round,followed by saccharides(28.2%),phthalic acids(Ph,20.8%),biogenic secondary organic aerosol(BSOA)tracers(9.4%),and polycyclic aromatic hydrocarbon(PAHs,2.3%).PM2.5,organic carbon(OC),elemental carbon(EC),and primary organic markers exhibit the highest concentrations in winter,due largely to the increased biomass burning and coal combustion for house heating in local and surrounding regions.However,the concentration and relative abundance of BSOA are significantly higher in summer than other seasons,induced by the more favorable meteoro-logical conditions that would promote the emissions of biogenic volatile organic compounds(BVOCs)and the secondary production of BSOA.The ratios of OC/EC and 3-methyl-1,2,3-butanetricarboxylic acid to cis-pinic acid plus cis-pinonic acid(MBTCA/(PA+PNA)are higher in the warm seasons than those in the cold seasons,indicating that the oxidation of OA is sensitive to air temperature.Compared to 2017,the concentration level of PAHs during wintertime decreased by 40.8%,confirming that the stringent regulation of coal burning is effective.The highest concentration of high molecular weight(HMW)n-alkanes and three anhydrosugars in winter,and the close correlation of levoglucosan with HMW n-al-kanes suggests that the impact of biomass burning was more significant in winter.The same seasonal characteristic of the ratios of high-/low-NO_(x) products with NO_(x) and the strong correlation of high-/low-NO_(x) products with levoglucosan indicate that the formation of isoprene SOA(SOA1)tracers was signif-icantly influenced by anthropogenic emissions.The molecular compositions,the distributions of fire spots,backward trajectories of air masses,and correlation analysis suggest that air pollution events in spring were primarily resulted from biomass burning and secondary oxidation,while pollution events in winter were largely driven by the increased combustion sources,and promoted aqueous secondary formation.Our results suggest that the reduction of biomass and coal combustion should be taken into account to improve the urban air quality in the NCP.

G-WADI—the first decade

The G-WADI network by UNESCO promotes the global capacity for management of water resources in arid and semi-arid areas. The primary aim has been to build a comprehensive global network to promote regional and international cooperation so as to increase knowledge and improve management practices through the sharing of information. The G-WADI objectives and achievements of the past 10 years are reviewed. A number of key initiatives have been implemented--the formation of five regional networks, the creation of a central G-WADI web site, promotion of near-real-time rainfall distribution software enhanced by the inclusion of satellite based precipitation estimations, as well as workshop and web-based activities on chemical and isotopic tracers and on rain water harvesting. Two workshops on surface and on groundwater modeling, supported by publications have been held in India and China. The Asian G-WADI network remains very active, but activities in the other three regions are developing (Africa, Arab Region, Latin America and the Caribbean).

高温带来的健康风险 随着全球持续变暖,风险也在不断提升

破纪录的极端温度事件曾经很罕见,如今却越来越常见。相较于1986—2005年,2019年全球范围内额外增加了47.5亿例热暴露,这意味着每人都要遭受3天甚至更多的极热侵袭。有明确证据表明,极热的高强度和频发性正是与人类自身引起的全球变暖相关,而极热又增加了其他并发事件如热浪和干旱的耦合。