Optimization of extraction method for quantitative analysis of Si/Al in soil phytoliths

Elemental information carried by phytoliths plays a crucial indicative role in geochemical research.For instance,it serves as an indicator of the carbon pool effect in phytoliths and aids in the elucidation of silicon sources.However,early extraction methods for soil phytoliths primarily focused on obtaining their morphological and quantitative information,lacking efficient techniques for quantitative elemental analysis.In this study,we aimed to extract Si/Al information from soil phytoliths.Considering the need for complete extraction of phytolith,six extraction methods were developed and further by alkaline dissolution to determine Si/Al.Six methods were compared in terms of enrichment capacity,the weight of extracted phytoliths,and Si/Al differences.The results indicated that the addition of Ammonia-Catechol in the commonly used heavy liquid flotation method effectively improved phytolith extraction capability and the accuracy of Si/Al results.Additionally,the inclusion of an acetic acid step before alkaline dissolution further removed surface-adsorbed impurities and enhanced the analytical quality of Si/Al in phytolith.The comparison of the data in this study with other published data shows that our method is relatively robust.The improved method proposed in this study can provide a new idea for the quantitative analysis of other elements in soil phytoliths.

Pilot study on binding of bovine salivary proteins to grit silicates and plant phytoliths

Mostly fed with grass in fresh or conserved form,cattle and other livestock have to cope with silicate defence bodies from plants(phytoliths)and environmental silicates(grit),which abrade tooth enamel and could additionally interact with various salivary proteins.To detect potential candidates for silicate-binding proteins,bovine whole saliva was incubated with grass-derived phytoliths and silicates.Interactions of salivary proteins with pulverized bovine dental enamel and dentine were additionally analysed.After intense washing,the powder fractions were loaded onto 1D-polyacrylamide gels,most prominent adhesive protein bands were cut out and proteins were identified by mass spectrometry within three independent replicates.All materials were mainly bound by bovine odorant-binding protein,bovine salivary protein 30×10^(3) and carbonic anhydrase VI.The phytolith/silicate fraction showed additional stronger interaction with haemoglobinβand lactoperoxidase.Conceivably,the binding of these proteins to the surfaces may contribute to biological processes occurring on them.

Contribution of phytoliths to total biogenic silica volumes in the tropical rivers of Malaysia and associated implications for the marine biogeochemical cycle

The contribution of phytoliths to total biogenic silica(BSi) volumes in rivers worldwide,and the associated implications for the biogeochemical cycle,require in-depth study.Based on samples from rivers in Peninsular Malaysia,this project investigated the source and characteristics of B Si found in Asian tropical rivers,as well as the process of reverse weathering taking place in these fluvial systems.Results indicated that BSi samples collected in sediments consisted of phytolith,diatom and sponge spicules.Phytoliths,predominantly of the elongate form,comprised 92.8%-98.3% of BSi in the Pahang River.Diatom BSi in this river consisted mainly of pennatae diatoms,but represented a relatively small proportion of the total BSi volume.However,diatom BSi(predominantly of the Centricae form) was more prevalent in the Pontian and Endau Rivers with shares of 68.8% and 79.3% of the total BSi volumes,respectively,than Pahang River.Carbon contents of the BSi particulates ranged from 1.85% to 10.8% with an average of 4.79%.These values are higher than those recorded in other studies to date,and indicate that BSi plays a major role in controlling permanent carbon burial.This study suggests that phytoliths from terrestrial plants are the primary constituents of BSi in the rivers of Peninsular Malaysia,and therefore represent a significant proportion of the coastal silica budget.

The Need of Time:Phytoliths for Earth Science

Phytoliths take the shape and size of the cells from which they are formed.They are microscopic and composed of opal silica—SiO2 and other traces of Al, Fe,Mn,P,Cu,N and organic carbon.Phytoliths are present in the roots,leaves,stem and the rest parts of the plant body including inflorescences.The shapes of phytolith can be used to determine the taxonomy of the plants,which may be dumbbell,squares,rectangular,

Climate indexes of phytoliths from Homo erectus' cave deposits in Nanjing

A study on phytoliths and their climate indexes is carried out from Homo erectus?cave deposits in HuluCave, Nanjing. Evidence shows that phytolith assemblages of the cave deposits are dominated by the cold resistant types with a lower warm index, reflecting an overall cold inclined climate. This possibly connects the cave deposits with glacial climate to a great extent, which is in accordance with thenorthern fauna revealed by fossil mammals and temperateclimate indicated by pollen assemblages. According to the distributional state of the phytoliths and their climate in-dexes on 4 profiles in the cave, it is revealed that profiles Ⅰand Ⅱ display certain cold/warm, and dry/wet fluctuations; profile Ⅲ shows a humid and cold condition with the high-est humility in the cave deposits; while profile Ⅳ indicates a possible quick accumulating process because of its stableclimate indexes except for its bottom and top.

Analysis of carbon isotope in phytoliths from C3 and C4 plants and modern soils

The analysis of carbon isotope in phytoliths from modern plants and surface soils in China shows that the values of carbon isotope are consistent with those from C3 and C4 plants, and the processes of photosynthesis of the original plants can be clearly identified by carbon isotope in phytoliths. The value of carbon isotope varied from -23.8‰ to -28‰, with the maximum distributed in the latitude zone from 34°N to 40°N in North China and East China areas, and the minimum in the Northeast China and South China regions. The values of carbon of phytoliths tend to increase from low to high and then reduce to low value again as the latitude increases. In the same latitude zone, the carbon isotope in phytoliths from grassland soil under the trees is obviously lower than that from grassland soil without any trees with the difference of 1‰ - 2‰.

Discovery of rice phytoliths in the neolithic site at Jiahu of Henan Province and its significance

The neolithic ruins of rice cultivation play an important role in the study on origin,evolution and propagation of cultivated rice. There are more than one hundred neolithicsites in China. where the ruins of rice have been found. and 80 percent of them and allthe earlier ones (Hemudu and LuoJiajiao. about 7 ka B.P.: Pengtoushan. about 7.5—9 kaB. P.) are distributed over the areas of the Yangtze River. Are there the earlier. cultivatedrice in the areas of the Yellow River and Huaihe River? This problem has received

Characteristics of phytoliths in Leymus chinensis from different habitats on the Songnen Plain in Northeast China and their environmental implications

The characteristics of phytoliths in Leymus chinensis leaves from five different pH-value habitats from Songnen Plain in China were analyzed to reveal their environmental implications and possible use for quantitative reconstruction of the paleoenvironment. The phytoliths in leaves of L. chinensis from the five habitats showed a non-linear correlation with soil pH. The main types of phytoliths from the different habitats were exactly the same, including silicified stomata, hat-shaped, lanceolate, elongated, multilateral-plate, and tooth-shaped. However, there were significant differences in the contents of each shape of phytoliths among the five habitats. The amount and the volume of weakly tooth-shaped, lanceolate phytoliths and silicified stomata increased with increased pH, while the total amount of phytoliths was reduced. In addition, there were different types of phytoliths in the L. chinensis leaves from the five habitats of different pH, suggesting that the types of phytoliths were controlled, at least in part, by soil pH. The changes of size and percentage of phytoliths were most remarkable at pH 10.15–10.18, indicating that this is the highest pH value that L. chinensis can tolerate.

Evaluation of the occluded carbon within husk phytoliths of 35 rice cultivars

Rice is a well-known silicon accumulator. During its periods of growth, a great number of phytoliths are formed by taking up silica via the plant roots. Concurrently, carbon in those phytoliths is sequestrated by a mechanism of long-term biogeochemical processes within the plant. Phytolith occluded C （PhytOC） is very stable and can be retained in soil for longer than a millennium. In this study, we evaluated the carbon bio- sequestration within the phytoliths produced in rice seed husks of 35 rice cultivars, with the goal of finding rice cultivars with relatively higher phytolith carbon sequestra- tion efficiencies. The results showed that the phytolith contents ranged from 71.6 mg. g^-1 to 150.1 mg. g^-1, and the PhytOC contents ranged from 6.4 mg.g^-1 to 38.4 mg.g^-1, suggesting that there was no direct correlation between the PhytOC content and the content of rice seed husk phytoliths （R = 0.092, p 〉 0.05）. Of all rice cultivars, six showed a higher carbon sequestration efficiency in phytolith seed husks. Additionally, the carbon bio- sequestration within the rice seed husk phytoliths was approximately 0.45-3.46 kg-e-CO2-ha^-1. yr^-1. These rates indicate that rice cultivars are a potential source of carbon biosequestration which could contribute to the global carbon cycle and climate change.

The phytoliths in Core C_1 from the Okinawa Trough

THE application of phytolith study in geology in the world has experienced a history of over 30 years. The earliest application of phytolith study to marine geology was made by Smithson when he made a study on the submarine sediments in Leigwy Bay. Later, he made the analysis of phytoliths in the neritic sediments in Ariake Bay in Kyushu, Japan. Dumitrica analysed the phytoliths in the cores drilled in the Mediterranean Sea. Phytoliths in the deepsea

Morphological characteristics of homozygous wild rice phytoliths and their significance in the study of rice origins

The analysis of wild rice cell structures,tissues,organs,and other morphological characteristics and the development of identification markers for wild rice are the basis for identifying the origins and evolution of prehistorical rice agriculture.However,contemporary wild rice strains are often subject to gene introgression from domesticated rice cultivated by humans during the evolutionary process,which may affect the accuracy of wild rice identification markers.This means that how to eliminate the effects of gene introgression from domesticated rice and other plants on the identification of origin markers,and the purification of the morphological characteristics of wild rice have become critical in research to identify the origin of rice.In this study,we compared and analysed the phytolith morphologies of three common wild rice species(Oryza rufipogon Griff.)from various habitats and one species of ectopically preserved homozygous common wild rice after six consecutive generations of self-crossing.We found that the morphology of the bulliform phytolith in the homozygous wild rice with reduced domestication gene introgression had three significant differences compared with native wild rice:(1)an overall reduction in size(body length decreased from 41.9μm in VLnativeto 38.6μm in VLhomozygous);(2)an increase in the proportion of the long-stalked phenotype,with the ratio of B/A decreasing from 1.22±0.47 in B/Anativeto 0.92±0.30 in B/Ahomozygous;and(3)a decrease in the number of fish-scale decorations,with the proportion of bulliform phytoliths with≥9 fish-scale decorations reduced from 53.4%in native wild rice to 37.2%in homozygous wild rice.Thus,this study provides a reliable reference for the identification of rice origins using rice phytolith morphology.

“植硅体”含义和禾本科植硅体的分类

针对国内文献中对英文“Phytolith”等词语的中文译名呈多样化现象 ,建议统一用“植硅体”来涵盖之 ,其含义包括“Opal phytolith”和“Silica bodies”等 ,代表一门新兴学科 ,即植硅体学。已有的禾本科植硅体分类中 ,不同学者采用了各自不同的分类规则和术语。本文通过分析、对比现有禾本科植硅体不同的分类方案 ,以期对其分类系统的研究现状和所存在问题提出看法 ,有利于今后深入研究。

对phytolith汉译名的商榷

基于对ｐｈｙｔｏｌｉｔｈ一词内涵和使用沿革的回顾，笔者主张将其译为植结石，可以与动结石（ｚｏｏｌｉｔｈ）匹对，不主张将其译为“植物硅酸体”、“植物硅石”、“植物硅体细胞”和“植物石”。同样，一门新兴的边缘学科──ｐｈｙｔｏｌｉｔｈｉｃｓ可译为植结石学。

The biogenic silica composition, behavior and budget in the Changjiang Estuary

Three comprehensive surveys were performed in the Changjiang（Yangtze River） Estuary（CJE） to understand the biogenic silica（BSi） composition, behavior and budget. It is indicated that the BSi is composed of phytoliths,phytoplankton and sponges; phytolith BSi has 16 forms and account for 23% to 83% of the bulk BSi in the maximum turbidity zone. The budget shows that the major exogenous BSi source in the water column of the CJE is the riverine input, accounting for 95% of the total BSi input. Dominant processes that maintain BSi levels in the water column are the primary production（55 Gmol/a） and the subsequent BSi sedimentation（46 Gmol/a）; and the BSi pool produced by the primary production represents two point three times the BSi loading of the Changjiang River and 63% of the BSi output, respectively. The net export（26 Gmol/a） of BSi from the CJE to the East China Sea and Yellow Sea roughly equals the riverine BSi loading. The observed total accumulation of BSi is one point seven times larger than the loading of total BSi output, with 53% to 88% of phytolith BSi and their assemblage, indicating that there has already been a ＂filter＂ of terrestrial BSi. The reverse weathering in sediments is an important process for the reactive silica removal in the CJE due to authigenic alterations. It is indicated that the phytolith fluxes in the suspended load represent a significant BSi source in the estuary, and the CJE would act as a net BSi sink.

Paleo-environmental evolution based on high-resolution phytolith since 26 ka B. P. in Huanghe River Delta

The Huanghe River Delta is one of the world＇s large rivers, the Huanghe River Delta paleoenvironmental evolution in the Huanghe River has been a hot issue since the Last Glacial. Based on the core time series established by combining AMS 14C dating of Core DYZK1 sediments in submerged of Huanghe River Delta and acoustic sequence on sub-bottom profile, phytolith analyses are carried out on 96 sediment samples. The grain size parameters, magnetic susceptibility are combined with the vertical changes of biostratum to reconstruct the paleo-sedimentary and climatic conditions in the Huanghe River Delta. The study results show that there is a significant vertical change law in the index parameters, and that sedimentary environment of Huanghe River Delta experienced an evolutionary process of fluvial facies-sealand transition facies-tidal flat facies-neritic facies- delta facies since 26.0 ka B. P.. The phytolith analyses results are as following. Firstly, The phytoliths are divided into lanceolate, smooth-elongated, spiny-elongated, rondel, long rectangular, bulliform and other types. In different sedimental environment, the phytolith content changes regularly, indicating that the phytolith assembles in the same sedimentary environment has a certain degree of stability. Secondly, The lanceolate, smooth-elongated and spiny-elongated categories of phytoliths have greater contents in the tidal flat facies and delta deposition, while have a smaller contents in the neritic facies and fluvial facies environment. Thirdly, Through comparative analysis of variation coefficient, the content of major phytolith categories in the sediment has a greater change amplitude in the sealand transition facies and fluvial facies deposition, while being more stable in the tidalflat facies and delta facies deposition.

The Phytolith and Pollen Record since 10 ka BP from the Lhasa Region, Tibet

This paper presents a description of the river terrace at Tangjia Village in Lhasa, Tibet. Selected types of phytolith and pollen were used as proxies to study the paleoclimate in the study area. Ancient climate and vegetation changes since 10 ka BP were examined. The results demonstrated that between 10.2 and 8.9 ka BP, the dominating phytolith was the cold type and the dominating vegetation type was grassland-forest. This indicated that the climate changed from cool-humid to cool-dry and later turned back into a cool-humid climate. Between 8.9 and 8.1 ka BP, the main types of phytoliths were tooth, dumbbell, and polyhedral. This suggests that the vegetation consisted of forest-grassland and the period＇s climate had become warmer. Between 8.1 and 6.7 ka BP, the warm index of phytolith assembelage gradually increased, whereas the spore and pollen assembelage revealed that the vegetation was forest with hardwood. This suggested that the paleoclimate was warmest in this period. The herbaceous vegetation increased gradually, indicating that the climate had become colder since 7.5 ka BP. Between 6.7 and 4.6 ka BP, cold type phytolith such as tooth and cap were found. Simultaneously, the pollen assembelage indicated that the vegetation shifted from grassland to forest and then turned back into grassland. This implies that the climate fluctuated from cold-dry to cool- humid. Between 4.6 and 1.9 ka BP, the dominate type of phytolith was cold type and its warm index was in the range 0.04-0.28, suggesting a herbaceous vegetation cover and indicating that the climate was cold. The phytolith warm index from 1.9 ka BP revealed that the climate was continuously decreasing, and most of the pollen assembelage consisted of Chenopodiaceae and Artemisia. This conclusion is in agreement with the phytolith result that indicates that the climate was becoming colder and colder.

Phytolith Records in Vermicular Red Earth:Implications for Bioclimatic Variationsduring Pleistocene

Phytolith analysis is employed in bioclimatic research into vermicular red earth, especially into its form, assemblage and zonation. The phytolith assemblage is divided into 10 zones. The statistics and main factor analysis of phytolith show that the obtained main factor load curves could suggest a climate change. Combined with phytolith assemblage feature, the bioclimatic variation of vermicular red earth during its formation stage, consisting of 5 arid-cold stages, 4 warm-humid stages and 2 mild stages, is reconstructed in detail. The research results indicate that phytolith records are ideal paleoclimatic signals in vermicular red earth, and that abundant information on environmental evolution can be located.

Effects of Silicon Fertilization on Soil Chemical Properties and Phytolith Formation of Phyllostachys pubescens

Silicon is benefit to Gramineae plants in growth and resistance to various stresses.However,the effect of silicon fertilizer application on Phyllostachys pubescens is still not investigated yet.Phyllostachys pubescens Mazel ex J.Houz is one kind of Gramineae plants which distributes in a large area.In this study,a field experiment with five Si fertilizer application rates(0,125,250,375,and 500 kg ha-1)was setup in a Phyllostachys pubescens forest in China to examine the effects of Si fertilizer on bamboo Si and phytolith accumulation in fresh leaf and leaf litter.Results showed that Si application increased soil available Si content in deep layers.Si content of leaf-litter increased with the increasing level of Si fertilizer application rate,with the value ranging from 114.3 g kg^(−1)to 172.7 g kg^(−1),however,no significant difference was observed in fresh leaf,with the value ranging from 84.0 g kg^(−1)to 115.0 g kg^(−1).The phytolith contents of leaf-litter and fresh leaf were consistent with the Si contents,the phytolith content in leaf-litter of T4(500 kg ha^(−1))was 48.4%higher than the control,suggesting Phyllostachys pubescens exhibited an increasing carbon sink in phytolith when Si fertilizer applied,which is an effective way to increase long-term soil organic carbon storage in Phyllostachys pubescens forests with a suitable Si fertilization.

Rice use history in Southeast China:Phytolith evidence from the Nanshan site in Fujian Province

The southern spread of rice agriculture is of great academic interest.Although it already has a broad chronological framework,newly introduced rice use and its impact on local subsistence and ecological systems are still unclear.In this study,we explore these issues by analysing phytoliths recovered from continuous sediments of Cave No.4 at the Nanshan site in Fujian Province,together with evidence from surrounding sites.The results show that rice was introduced into southeast China at 7,500 cal.yr BP,but the dominance of the hunting-gathering system was not challenged until later,between 5,000 and 3,500 cal.yr BP,when cultivation of rice,together with foxtail and broomcorn millets,was widely practiced in the region.This suggests that mixed farming in Southeast China,likely originating around the middle Yangtze River,became widespread and gradually systematic during the previous two-millennium adoption.This rice-millet mixed agricultural system changed the former hunting-gathering subsistence system,promoting the agriculturalization process,cultural prosperity and population growth,thus providing a solid basis for rice expansion and cultural migration to Southeast Asia.

New methods and progress in research on the origins and evolution of prehistoric agriculture in China

China is one of the main global centers of origin of agriculture. Foxtail millet(Setaria italica), common millet(Panicum miliaceum), and rice(Oryza sativa) were the first crops to be domesticated in China. There remain many uncertainties and controversies in our current understanding of the chronology, locations, and plant types at the origins and the process of evolution of prehistoric millet and rice farming, and their relationships with climate change and human adaptation. This review summarizes the research progress made by Chinese scientists over the last decade on the origins and evolution of prehistoric agriculture. It highlights novel techniques and methods for identifying early crop remains, including plant macrofossils(carbonized seeds, spikelets), microfossils(phytoliths, calciphytoliths, starch, pollen), and biomarkers; new evidence on the origins, development, and spread of early agriculture; and research related to climate and environmental changes. Further, we pinpoint and discuss existing challenges and potential opportunities for further in-depth investigation of the origins and evolution of agriculture and the adaption of human activities to climate change.