Review of the Research Progress on Static Earth Gravity Field and Vertical Datum in China during 2019—2023

The contribution presents the representative research progress on global static gravity field modeling,regional geoid/quasigeoid determination,vertical datum study,as well as the theory,algorithm and software for gravity field study in China from 2019 to 2023,which are the highlights of the chapter 6“Progress in Earth Gravity Model and Vertical Datum”in the“2019—2023 China National Report on Geodesy”that submitted to the International Association of Geodesy(IAG).In addition,suggestions are proposed to promote the research in the fields of earth gravity field,geoid/quasigeoid and vertical datumin China according to trends of international geodesy and related disciplines.

Vertical deformation analysis based on combined adjustment for GNSS and leveling data

A method is proposed to fuse the velocity data of the global navigation satellite system(GNSS) and leveling height via combined adjustment with constraints. First, stable GNSS-leveling points are uniformly selected, and the constraints of the geodetic height change velocity and normal height change velocity are given. Then, the GNSS vertical velocities and leveling height difference are used as observations of combined adjustment, and robust least-squares estimation are used to estimate the velocities of the unknown points. Finally, a vertical movement model is established with the GNSS vertical velocities and leveling vertical velocities obtained via combined adjustment. Data from the second-order leveling network and GNSS control points in Shandong Province are taken as test data, and eight calculation schemes are used for discussion. One of the schemes, the bifactor robust combined adjustment method based on variance component estimation with two kinds of vertical velocity constraints achieves the optimal results. The method applied in the scheme can be recommended for data fusion of GNSS and leveling, further improving the reliability of vertical crustal movement in Shandong Province.

Divergent allocations of nonstructural carbohydrates shape growth response to rainfall reduction in two subtropical plantations

Nonstructural carbohydrates(NSC)are indicators of tree carbon balance and play an important role in regulating plant growth and survival.However,our understanding of the mechanism underlying drought-induced response of NSC reserves remains limited.Here,we conducted a long-term throughfall exclusion(TFE)experiment to investigate the seasonal responses of NSC reserves to manipulative drought in two contrasting tree species(a broadleaved tree Castanopsis hystrix Miq.and a coniferous tree Pinus massoniana Lamb.)of the subtropical China.We found that in the dry season,the two tree species differed in their responses of NSC reserves to TFE at either the whole-tree level or by organs,with significantly depleted total NSC reserves in roots in both species.Under the TFE treatment,there were significant increases in the NSC pools of leaves and branches in C.hystrix,which were accompanied by significant decreases in fine root biomass and radial growth without significant changes in canopy photosynthesis;while P.massoniana exhibited significant increase in fine root biomass without significant changes in radial growth.Our results suggested that under prolonged water limitation,NSC usage for growth in C.hystrix is somewhat impaired,such that the TFE treatment resulted in NSC accumulation in aboveground organs(leaf and branch);whereas P.massoniana is capable of efficiently utilizing NSC reserves to maintain its growth under drought conditions.Our findings revealed divergent NSC allocations under experimental drought between the two contrasting tree species,which are important for better understanding the differential impacts of climate change on varying forest trees and plantation types in subtropical China.

Study on the interaction between inherent minerals of coal with refuse derived fuel(RDF)during co-firing

In this paper,refuse derived fuel(RDF)and bituminous coal were co-fired to investigate the particulate matter(PM)yields and the interaction between the inherit minerals in a lab-scale drop tube furnace(DTF).The PM1-10 yields during the co-firing of coal and RDF dramatically decreased by 16.29%~28.5%of the combustion of coal alone.In addition,methane auxiliary combustion inhibited the PM_(1) yields by 7.95%at air atmosphere.The Si-rich minerals in coal interreacted with the organic alkali(earth)metals in RDF,massively generating sticky particles with high liquid amount of K-Al-Si and Ca-Al-Si,promoting the transformation of fine grains into coarser mode.Moreover,it was proved that both methane auxiliary combustion and co-firing can reduce the emission of fine particles.The additional heat accelerated the burn of the char at the early stage of combustion,providing adequate time for the interaction between the inorganic species.Through thermodynamic equilibrium calculations of 1500~3000 fly ash grains,it was found that co-firing increased the formation of sticky particles by 64.8%~70.3%,resulting in a significant enhancement in capturing fine particles and Na,K vapor.Therefore,the co-firing of coal with RDF offers a promising approach to realize the harmless and resourceful treatment of municipal solid waste(MSW),and inhibit land resource losses caused by landfill.

A chromosome-level genome assembly for Dracaena cochinchinensis reveals the molecular basis of its longevity and formation of dragon’s blood

Dracaena,a remarkably long-lived and slowly maturing species of plant,is world famous for its ability to produce dragon’s blood,a precious traditional medicine used by different cultures since ancient times.However,there is no detailed and high-quality genome available for this species at present;thus,the molecular mechanisms that underlie its important traits are largely unknown.These factors seriously limit the protection and regeneration of this rare and endangered plant resource.Here,we sequenced and assembled the genome of Dracaena cochinchinensis at the chromosome level.The D.cochinchinensis genome covers 1.21 Gb with a scaffold N50 of 50.06 Mb and encodes 31619 predicted protein-coding genes.Analysis showed that D.cochinchinensis has undergone two whole-genome duplications and two bursts of long terminal repeat insertions.The expansion of two gene classes,cis-zeatin O-glucosyltransferase and small auxin upregulated RNA,were found to account for its longevity and slow growth.Two transcription factors(bHLH and MYB)were found to be core regulators of the flavonoid biosynthesis pathway,and reactive oxygen species were identified as the specific signaling molecules responsible for the injuryinduced formation of dragon’s blood.Our study provides high-quality genomic information relating to D.cochinchinensis and significant insight into the molecular mechanisms responsible for its longevity and formation of dragon’s blood.These findings will facilitate resource protection and sustainable utilization of Dracaena.