餐厨垃圾水解酸化性能的研究

采用批式进料方式,研究了不同进料负荷和不同接种量时餐厨垃圾水解酸化的效果,探索了酸化阶段发酵液中的pH、VFA含量和产物中主要成分的变化规律.结果发现,不同有机负荷进料时水解酸化过程在前4d基本完成,反应后期有机负荷不同,发酵类型也有所不同.40 g（TS）/L负荷进料时水解酸化效果比较好,水解酸化产物中主要成分为乙醇和乙酸,乙醇和VFA含量高.餐厨垃圾在接种率为30％时,反应能够获得目标酸化产物乙醇和乙酸,比不接种和接种率为50％时效果明显要好.     

三峡库区紫色土坡地土壤粗骨沙化和酸化特征

土壤侵蚀是三峡库区紫色土坡地土壤退化的主因,并由此造成土壤粗骨沙化和酸化。利用土地特性系列比较法,通过野外调查和室内分析相结合,研究了三峡库区紫色土坡地土壤退化特征,结果表明:(1)与未退化样地相比,不同利用方式和不同坡度段土壤粗化现象明显,表明它们存在不同程度的侵蚀退化。各土地利用类型pH值均有所减少,表征该研究区紫色土向酸性方向发展,特别是园地和菜地。(2)不同利用方式下土壤沙化程度由高到低的顺序是:荒地>建设用地>耕地>草地>林地>菜地>园地。(3)不同坡度段紫色土坡地土壤沙化程度基本随坡度的增加而增大,但>30°坡度段土壤沙化最轻。(4)不同利用方式和不同坡度段土壤粘粒、有机质、全N、碱解氮、全P、速效P、全K、速效K、阳离子交换量、pH值及微量元素之间存在着明显的相关性。     

Combining conservation tillage with nitrogen fertilization promotes maize straw decomposition by regulating soil microbial community and enzyme activities

Straw return can effectively improve farmland soil microenvironment and fertility. However, excessive straw in the topsoil adversely affects seed germination and crop growth. At present, the characteristics and key driving factors of straw decomposition in dry farmlands are unclear. Based on the interactions between tillage practices including zero tillage (ZT), chisel tillage (CT), and plow tillage (PT) and nitrogen (N) fertilization, i.e., low N (N1, 180 kg ha^-1), normal N (N2, 240 kg ha^-1), and high N (N3, 300 kg ha^-1), quantitative polymerase chain reaction technology and an enzymatic detection kit were used to investigate the effects of key straw C-degrading enzyme activities and microbial abundance in soil on maize straw decomposition during the growth period of winter wheat in the winter wheat/summer maize double cropping system in a dry farmland of the Loess Plateau, China. Between 2018 and 2020, ZT and CT significantly increased winter wheat yield (by 10.94% and 12.79%, respectively) and straw decomposition velocity (by 20% and 26.67%, respectively), compared with PT. Compared to N1 and N3, N2 significantly increased wheat yield (by 4.65% and 5.31%, respectively) and straw decomposition velocity (by 26.33% and 13.21%, respectively). The partial least squares pathway modelling showed significant positive direct effects of soil moisture, NO-₃, NH⁺₄, total N, bacteria, and cellulase, laccase, and xylanase activities on straw decomposition, while soil pH, fungi, and Actinomycetes had significant negative direct effects. Overall, conservation tillage (ZT and CT) combined with N2 was beneficial for straw decomposition in the drylands of the Loess Plateau and improved straw resource utilization and basic soil fertility. The results of the study clarified the key drivers of straw decomposition in dry farmlands and provided new ideas for developing updated soil management practices and adaptive N application strategies to promote the resource utilization of straw and achieve the goals of carbon peaking and carbon neutrality.     

Changes of cation pools of the topsoil in south Swedish beech forests between 1979 and 1989

Repeated analyses of exchangeable K, Ca, Mg and Zn revealed that the pools have decreased significantly in the topsoil (0–5 cm) of south Swedish beech forest during the 1980s. The largest decreases of K, Ca and Mg were found in the originally least acid soils, indicating that the limit for further losses from the topsoil is being approached in the most acid soils at today's deposition climate. The decrease of Zn was, on the other hand, largest in the most acid soils. Manganese had increased in especially the least acid soils, probably due to a conversion from non‐exchangeable pools as a result of the acidity change. The base saturation of the studied beech stands ranged 7.7–58.5% (mean 20.3%). The decrease rate of the exchangeable pools of K, Ca and Mg, estimated from two different time series has been relatively constant since 1949. The Zn pool has, however, decreased faster during the last decade, partly due to a lowered deposition of this element. Extrapolation of the data indicates that, as an average, only 20% of the pools of 1950 will remain in the topsoil in the year 2050.     

Long-term physico-chemical and faunal changes in a small,rural South African estuary

The Palmiet Estuary is a small, rural estuary in the Western Cape that only closes briefly during dry summers. The system was previously surveyed during 1979 to 1980 and we repeated the survey in April 2015 (mouth closed) and September 2015 (mouth open). Salinity, temperature, pH and oxygen saturation were measured, and invertebrate and fish faunas surveyed. Physico-chemical characteristics have undergone little directional change, apart from an apparent increase in pH, possibly as a result of changes in land use and application of fertilisers and pesticides in the catchment. Invertebrate species richness increased from 31 to 40 species, despite lower sampling effort in 2015. Most changes were among rare species, or were readily explained by changes in mouth condition and water chemistry. We also confirmed a substantial range extension of the tropical crab, Varuna litterata, rediscovered the locally endemic amphipod, Quadrivisio aviceps, and reported several new distribution records. Gastropods had virtually disappeared from the system, whereas the previously unreported bivalve, Brachidontes virgilae, had become abundant. Overall, fish diversity dropped from 19 to 11 species, but this can largely be ascribed to differ- ences in sampling frequency, season and mouth state. Comparisons of samples from like months showed the fish assemblage to have remained fairly stable, despite changes in inflowing water chemistry and infection of fish by the pathogenic water mould, Aphanomyces invadans. Bird abundance and diversity increased substantially. No alien invertebrate or fish species were recorded. Accordingly, in marked contrast to other smaller estuaries in the region, the Palmiet Estuary has remains in relatively good condition.     

假色槭叶色变化对土壤施FeSO_4酸化处理的响应

采用质量分数为2%和4%的硫酸亚铁溶液分别对假色槭进行单因素土壤酸化处理,结合蒙塞尔色彩系统对假色槭的叶色表达及叶片花青素含量等进行了研究。结果表明,土壤酸化处理对假色槭叶色变化具有显著的影响,其中以质量分数为4%的硫酸亚铁溶液处理效果最为显著,使假色槭的叶色主色调变化阶段的数量增至7个,并且使其发生阶段有所提前;同时,土壤酸化处理的假色槭叶色饱和度、明度在特定时期均高于对照,叶色较浓重;土壤酸化处理可以影响假色槭叶片中花青素的合成,从而引起其叶色饱和度和明度的响应,促进了叶片呈色,提高了假色槭的观赏价值。适当的酸化栽培处理,可以增加假色槭的叶色主色调变化阶段的数量,并且可以在一定程度上使叶色主色调发生阶段提前,从而起到提早假色槭最佳红叶观赏期的作用。     

Naturally acidic waterways: conceptual food webs for better management and understanding of ecological functioning

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Sporophytic photosynthesis and gametophytic growth of the kelp Ecklonia stolonifera affected by ocean acidification and warming

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