Effects of meteorological factors on different grades of winter wheat growth in the Huang-Huai-Hai Plain, China

The sown area of winter wheat in the Huang-Huai-Hai（HHH） Plain accounts for over 65% of the total sown area of winter wheat in China. Thus, it is important to monitor the winter wheat growth condition and reveal the main factors that influence its dynamics. This study assessed the winter wheat growth condition based on remote sensing data, and investigated the correlations between different grades of winter wheat growth and major meteorological factors corresponding. First, winter wheat growth condition from sowing until maturity stage during 2011–2012 were assessed based on moderate-resolution imaging spectroradiometer（MODIS） normalized difference vegetation index（NDVI） time-series dataset. Next, correlation analysis and geographical information system（GIS） spatial analysis methods were used to analyze the lag correlations between different grades of winter wheat growth in each phenophase and the meteorological factors that corresponded to the phenophases. The results showed that the winter wheat growth conditions varied over time and space in the study area. Irrespective of the grades of winter wheat growth, the correlation coefficients between the winter wheat growth condition and the cumulative precipitation were higher than zero lag（synchronous precipitation） and one lag（pre-phenophase precipitation） based on the average values of seven phenophases. This showed that the cumulative precipitation during the entire growing season had a greater effect on winter wheat growth than the synchronous precipitation and the pre-phenophase precipitation. The effects of temperature on winter wheat growth varied according to different grades of winter wheat growth based on the average values of seven phenophases. Winter wheat with a better-than-average growth condition had a stronger correlation with synchronous temperature, winter wheat with a normal growth condition had a stronger correlation with the cumulative temperature, and winter wheat with a worse-than-average growth condition had a stronger correlation with the pre-phenophase temperature. This study may facilitate a better understanding of the quantitative correlations between different grades of crop growth and meteorological factors, and the adjustment of field management measures to ensure a high crop yield.

Dynamic influence of Holocene characteristics on vadose water in typical region of central North China Plain

In the typical region of central North China Plain, vadose sediments are Holocene sediment strata. With samples from field drillings, the study analyzes the sedimentary characteristics of vadose zone. The study takes the content of silty sand as the basis for sedimentary environment analysis, and the content of clay and sand as the sensitive indicator for sedimentary characteristics. Combining palynology analysis, the study divides vadose zone from top to bottom into diluvia oxbow lacustrine sediments, lacustrine sediments, lacustrine and swamp sediments, weak palaeohydrodynamic lacustrine sediments and alluvial sediments. Based on the sedimentary characteristics of Holocene strata, it analyzes the changes across depth of vadose zone water potential and matrix potential, obtaining the influence of vadose zone sedimentary characteristics on the migration of water in typical region of central North China Plain.

Spatial Heterogeneity Analysis of PM2.5 Concentration in Central Plains Economic Region

The research of the spatial heterogeneity of PM2.5 concentration in an area, is of great significance for understanding its regional spatial distribution structure, exploring the transmission relationship between regions, in order to formulate joint prevention and control measures within the entire area. Based on the daily monitoring data of PM2.5 concentration in the Central Plains Economic Region in 2019, this paper utilizes cluster analysis to divide the regional PM2.5 concentration into 5 classes, builds their spatial semi-variogram model, and then utilizes interpolation analysis method to study the regional overall distribution characteristics and transmission law. The results show that the PM2.5 concentration in the Central Plains Economic Region has a medium or higher spatial autocorrelation. The critical value of the overall PM2.5 concentration in the area is 150 μg/m3, as the overall PM2.5 concentration less than the value, the PM2.5 in a region mainly comes from local emissions, as the overall PM2.5 concentration higher than the value, the influence of spatial structure on the distribution of PM2.5 concentration is gradually obvious. PM2.5 has a certain degree of spatial transmission, which mainly includes two routes as Puyang-Xingtai and Puyang-Zhengzhou, and the transmission intensity of the former is greater than the latter.

Landscape Visual Environment Impact Analysis of Wind Power Project in Plain Region--Case in One Wind Power Farm Project of Zhanjiang

The construction of wind power project is conducive to saving energy,reducing emissions and regulating energy structure. But it inevitably causes some impacts on the environment in the construction process. Because that the height of wind power generator generally exceeds 100 m,and visual range in plain region is farther,it is necessary to scientifically and rationally evaluate and analyze landscape visual environment impact of wind power generator in plain region. One wind power farm project of Zhanjiang is located in typical plain region of Guangdong coast. Referring to traditional analytic method of landscape visual impact and comparing with actual situation for the same kind of project in the region,results show that it is ＂ extremely sensitive＂ area at 0- 2. 5 km from wind power generator, ＂ very sensitive＂ area at 2. 5- 5. 0 km, ＂ sensitive＂ area at 5- 10 km, ＂generally sensitive＂ area at 10- 20 km,and non-sensitive area outside 20 km.

Genesis and Quality of Groundwater in the Southeastern Region of Southern Vietnam

The origin and quality of groundwater in the Southeastern region （belongs to Southern Plain） were identified by using isotopic techniques and geochemical analysis. Groundwater samples were collected from 7 aquifers： the Holocene, upper Pleistocene, middle Pleistocene, lower Pleistocene, upper Pliocene, middle Pliocene and Miocene aquifers. The water isotopic compositions （82H and 8180） were determined to elucidate the origin and the interaction between surface water and groundwater studies. Transit time （age） of the groundwater samples was determined to explain the direction of groundwater flow. The dating techniques included 3H and ^14C isotopes measurement, followed by a correction for the initial ^14C-activity by the ^13C-composition （^13C） in TDIC （Total Dissolved Inorganic Carbon）. Geochemical parameters of the groundwater samples were measured either directly in the field or in the laboratory. The results showed that the groundwater from the Holocene and upper Pleistocene aquifers was most recharged from the local meteorological and hydrological systems, including local precipitation, fiver and reservoirs. Thus, it has short transit time and its stable isotopic composition is spread around the local meteoric waterline and lines for rivers or reservoirs water. The groundwater in the deeper aquifers： middle and lower Pleistocene, and Neogene aquifers has old age up to 22.5 ka BP. Its water seems to be recharged from the areas with an altitude from 600 to 700 m higher to the Neogene deposit layer altitude. The groundwater in the SE SP （South-Eastern Southern Plain） region has a high quality. The water type is Na-Ca-Mg-HCO3 with low content of chloride and TDS （Total Dissolved Solids）. Calcite/dolomite and gypsum dissolution, organic matter decomposition and sequence of red-ox reactions proceeding through different electron acceptors sediment were controlled the chemistry of the groundwater in the study region.

Historical experience in the elimination of visceral leishmaniasis in the plain region of Eastern and Central China

Visceral leishmaniasis(VL)(kala-azar)was most seriously prevalent in the plain regions of eight provinces/municipalities in the eastern and central parts of China.In the early 1950s,the number of counties/cities endemic for VL and the number of cases in the plain regions accounted for 60%and 80%,respectively,of the total numbers in the entire country.By implementing comprehensive control measures,including treatment of patients for eliminating the source of infection and spraying insecticide in endemic villages to kill sandflies,VL transmission has been brought under control in this region by the early 1960s,and no new infected cases have been found since 1983,achieving the goal of eliminating VL.

Assessment of the sources and transformations of nitrogen in a plain river network region using a stable isotope approach

The great spatial and temporal variability in hydrological conditions and nitrogen（N）processing introduces large uncertainties to the identification of N sources and quantifying N cycles in plain river network regions. By combining isotopic data with chemical and hydrologic measurements, we determined the relative importance of N sources and biogeochemical N processes in the Taige River in the East Plain Region of China. The river was polluted more seriously by anthropogenic inputs in winter than in summer. Manure and urban sewage effluent were the main nitrate（NO-3） sources, with the nitrification of N-containing organic materials serving as another important source of NO-3. In the downstream, with minor variations in hydrological conditions, nitrification played a more important role than assimilation for the decreasing ammonium（NH＋4-N） concentrations.The N isotopic enrichment factors（ε） during NH＋4utilization ranged from- 13.88‰ in March to- 29.00‰ in July. The ratio of the increase in δ^18O and δ^15N of river NO-3in the downstream was 1.04 in January and 0.92 in March. This ratio indicated that NO-3assimilation by phytoplankton was responsible for the increasing δ^15N and δ^18O values of NO-3in winter. The relationships between δ^15N of particulate organic nitrogen and isotopic compositions of dissolved inorganic nitrogen indicated that the phytoplankton in the Taige River probably utilized NH＋4preferentially and mainly in summer, while in winter, NO-3assimilation by phytoplankton was dominant.