Effect of extracellular polymeric substances on Dolichospermum aggregation during temperature rise

Dolichospermum,a typical model filamentous of cyanobacteria,has the potential to cause severely bloom.Extracellular polymeric substances(EPSs)are considered to influence the aggregation of the algae,and temperature is a significant factor affecting EPSs secretion.However,the mechanism of how EPSs affects the aggregation of Dolichospermum is still unclear because the structure and composition of EPSs are complex.In this study,the effects of EPSs on the aggregation of Dolichospermum during the rise of temperature(7-37℃)were determined.The results showed that the concentration of extracellular polysaccharides and proteins changed significantly with increasing temperature(P<0.01).Firstly,during the increasing temperature,the polysaccharide content of EPSs increased from 20.34 to 54.64 mg/L,and the polysaccharides in the soluble EPS(S-EPS)layer changed significantly.The protein content reached maximum value at 21℃(14.52 mg/L)and varied significantly in S-EPS and loosely bound EPS(LB-EPS).In the EPSs matrix,humus substances and protein were main components of S-EPS and LB-EPS,and protein was the main component of tightly bound EPS(TB-EPS).Secondly,the cell density of Dolichospermum increased during the temperature rise while the aggregation ratio decreased.Moreover,zeta potential and surface thermodynamic analysis of Dolichospermum revealed that the interfacial free energy and electrostatic repulsion increased gradually with increasing temperature,which further reduced the aggregation of Dolichospermum.Finally,principal component analysis(PCA)analysis showed the aggregation of Dolichospermum was directly related to the changes of protein in EPSs(especially S-EPS and LB-EPS)and zeta potential,and polysaccharides in EPSs inhibited the aggregation of Dolichospermum.Based on these results,it was illustrated that the composition and concentration of EPSs affected the cell surface properties of Dolichospermum with the change of temperature and thus affected the aggregation of Dolichospermum.

气象水文集合预报的多源不确定性影响评估研究

评估复杂水文预报的来源不确定性对于深刻理解和改进水文预报精度至关重要,以往研究较少关注多源不确定性对气象水文预报复杂过程的影响。本研究提出了一种通用的基于贝叶斯模型平均(BMA)的集合框架,用于评估多源不确定性对气象水文预报全过程的影响。采用TIGGE中心的八种数值天气预报产品,四种完全不同结构的水文模型和1000组参数分别考虑来自输入、结构和参数的不确定性。在中国金溪池潭流域的实际应用表明:气象水文预报中数值预报输入的不确定性比水文模型的不确定性更大,水文模型结构的不确定性则明显大于模型参数的不确定性。洪峰流量预报的精度与数值天气预报的精度紧密相关,水文模型结构和参数及其交互作用则是枯水期流量预报的主要不确定性来源。当同时考虑三种不确定性来源时,径流过程预报精度更高。通过考虑复杂预报过程的主要不确定性源,基于BMA集合预报的预测精度更高,并可降低其他因素带来的不确定性。本文提出的多源不确定性评估框架可以较好地提升对气象水文预报过程的理解,在提高复杂水文预报精度方面具有广阔的应用前景。

Supportive Technologies and Roadmap for China’s Carbon Neutrality

The vision of carbon neutrality is a climate ambition of milestone significance for China and a key step for China’s transition from industrial civilization to ecological civilization.The realization of carbon neutrality requires profound changes in China’s technological and socioeconomic systems involving zero-carbon electric power,lowcarbon and zero-carbon end-use energy consumption,and negative emission technologies.Achievement of carbon neutrality is subject to the choice of pathways for various sectors,especially the electric power,industrial,transportation and construction sectors with significant carbon emissions and decarbonization difficulties.The goal of carbon neutrality will influence China’s economic and industry systems,resource and industrial layout,technological innovation and ecological environment in profound ways.Hence,China’s future policymaking on carbon neutrality needs to consider environmental,technological,economic and social impacts,establish a correlation between carbon peak and carbon neutrality,identify climate-friendly clean technology innovations in real earnest,and put carbon neutrality into the overall plan for ecological civilization.

Microplastic pollution in Yellow River,China:Current status and research progress of biotoxicological effects

This study aims to comprehensively assess the environmental risks of microplastics in the Yellow River,achieving the following results through comprehensive research.The average microplastic abundances in the river waters and sediments are 5358-654000 n/m3 and 43.57-615 items/kg,respectively,and there are fewer microplastics in water samples than in sediments.Microplastics in the study area can be divided into five types according to their occurrence morphologies,namely fragments,foams,films,fibers,and particles.The most widely distributed pollution types in sediments include debris,fibers,and particles.In contrast,fibers are the dominant type in water samples,accounting for 68.18%‒98.93%.The chemical components of the microplastics include polyethylene,polypropylene,polystyrene,polyethylene terephthalate,and polyvinyl chloride.The microplastics are in four colors,with white accounting for a higher proportion.The grain size of the microplastics in tributaries or lakes of the Yellow River is less than 2 mm,which makes them liable to enter organisms for enrichment.Furthermore,the sources of the microplastics are closely related to agricultural and industrial production and biological activities in habitats and exhibit seasonal and hydrological characteristics.The microplastics in the study area show the adsorption of metals and nonmetals to different degrees,which increases the pollution risks of heavy metals combined with microplastics.In addition,microplastics can accumulate in organisms in the Yellow River and cause physical,biochemical,and other damage to aquatic organisms,thus further posing carcinogenic risks to human beings.Therefore,it is necessary to study,monitor,and control the pollution and effects of microplastics in the Yellow River,in order to provide theoretical references for the control of pollution and ecological risk of microplastics in the river.

Effects of Main Climatic Factors on Plant Community Characteristics of a Meadow Steppe Under Different Grazing Intensities

This experiment studies the influence of main climatic factors on the structure of grassland plant community under different grazing intensities, determines the influence of climatic factors on the quantitative characteristics of meadow steppe community structure changes, and explores the response and adaptation of meadow steppe biodiversity and ecosystem functions to climate changes, so as to provide a reference and basis for rational utilization and management of natural grassland and prediction of development trend of meadow steppe under global climate changes. The results showed that the correlations between grassland community characteristic index and different climatic factors were significantly different under different grazing intensities. The average temperature and annual precipitation in the critical period were the main climatic factors affecting the changes in meadow steppe community characteristics, and the sensitivity of community indexes to the changes in average temperature of the critical period was greater than that to the changes in annual precipitation. The aboveground biomass of zero grazing and moderate grading was positively correlated with the average temperature and annual precipitation during the critical period, and the correlations between aboveground biomass and environmental factors were no significant under heavy grazing.

Microplastic contamination in lacustrine sediments in the Qinghai-Tibet Plateau:Current status and transfer mechanisms

This paper aims to investigate the present situation and transfer mechanisms of microplastics in lacustrine sediments in the Qinghai-Tibet Plateau.The study surveyed the average abundance of microplastics in sediments.The abundance of microplastics in sediments of lakes from the Qinghai-Tibet Plateau is 17.22-2643.65 items/kg DW and 0-60.63 items/kg DW based on the data of the Qinghai Lake and the Siying Co Basin.The microplastic abundance in sediments from small and medium lakes is very high compared to that in other areas in the world.Like microplastics in other lakes of the world,those in the lakes in the Qinghai-Tibet Plateau mainly include organic polymers PA,PET,PE,and PP and are primarily in the shape of fibers and fragments.The microplastic pollution of lacustrine sediments in the Qinghai-Tibet Plateau is affected by natural changes and by human activities,and the concentration of microplastics in lacustrine ecosystems gradually increases through food chains.Furthermore,the paper suggests the relevant administrative departments of the Qinghai-Tibet Plateau strengthen waste management while developing tourism and pay much attention to the impacts of microplastics in water environments.This study provides a reference for preventing and controlling microplastic contamination in the Qinghai-Tibet Plateau.

Nutrient enrichment driven by canopy rainfall redistribution:Mechanism,quantification,and pattern

Vegetation canopies intercept and redistribute rainfall into throughfall and stemflow,which transfer substantial amounts of elements into the soil,influencing soil microbial community,plant survival,and plant community succession.Despite advancements in ecohydrological research,the implication of nutrient enrichment resulting from this redistribution of rainfall by canopies remains largely unexplored.To address this gap,we conducted a systematic review of 1020 papers published between 2000 and 2022,gathering data on nutrient concentration and enrichment for critical ions(including K^(+),Na^(+),Ca^(2+),Mg^(2+),NH_(4)^(+),Cl^(-),NO_(3)^(-)and SO_(4)^(2-))from the Web of Science and Chinese Knowledge Infrastructure databases.We aimed to synthesize the mechanisms,quantify the enrichments,and identify global patterns of nutrient enrichment in stemflow and throughfall across climate zones,and vegetation types and ecosystems.The results of this study indicate that stemflow exhibits,on average,2.1times greater ion concentration(6.13 mg L^(-1))compared to throughfall.In particular,among the investigated ions,SO_(4)^(2-)(12.45and 6.32 mg L^(-1))for stemflow and throughfall,respectively,and Cl^(-)(9.21 and 4.81 mg L^(-1))exhibit the highest concentrations in both rainfall redistribution components,while K^(+)(13.7 and 5.8)and Mg^(2+)(5.6 and 2.8)have the highest enrichment factors.Across climate zones,throughfall and stemflow show the lowest ion concentrations but the highest enrichment factors in extremely humid regions.Along the temperature gradient,ion concentrations are the highest in cold climates with no clear patterns observed for enrichment factors with increasing temperature.In addition,shrubs,conifers,mixed forests,and artificial ecosystems demonstrate enrichment factors 1.1 to 3.0 times greater than those of trees,broad-leaved plants,pure forests,and natural ecosystems.These findings emphasize the need for increased attentions to artificial ecosystems,such as urban and agricultural ecosystems,which often received limited research focus,especially regarding shrubs and conifers exhibiting stronger nutrients enrichment capabilities.Future investigations should integrate soil moisture analysis to better understand the impact of rainfall redistribution on the nutrient enrichment processes,patterns,and nutrient balance in global terrestrial ecosystems.

Several key issues for CCUS development in China targeting carbon neutrality

Carbon capture,utilization,and storage(CCUS),as a technology with large-scale emission reduction potential,has been widely developed all over the world.In China,CCUS development achieved fruitful outcomes.CCUS gained further broad attention from the announcement of the carbon neutrality target by 2060,as CCUS is an indispensable important technology to realize carbon neutrality.It helps not only to build zero-emission and more resilient energy and industry systems but also provides negative emission potential.This paper discusses the new demand for carbon capture,utilization,and storage development brought by the carbon neutrality target analyzes the development status.As there remain various challenges of CCUS development,this paper focuses on several key issues for CCUS development in China targeting carbon neutrality:1)how to reposition the role of CCUS under the carbon neutral target?2)how shall we understand the technology development status and the costs?3)what role shall utilization and storage play in future?4)potential strategy applied to solve challenges of source-sink mismatch and resources constraints;and 5)new business model that suits large scale deployment of CCUS.This paper puts forward several policy suggestions that should be focused on now in China,especially to raise awareness under the vision of carbon neutrality that the role and contribution of CCUS are different,to accelerate the establishment of a comprehensive and systematic enabling environment for CCUS.