Effects of Arbuscular Mycorrhizal Fungi on Root Growth and Architecture of Tulip Gesneriana

Arbuscular mycorrhizal fungi(AMF) can promote the absorption of soil water and mineral nutrients, improve photosynthesis, and make host attain higher quality finally by establishing symbiotic relationship between AMF and host root. To improve Tulip gesneriana quality have practical meaning under no bad affect to cultivation soil, in the light of its economical and ecological values. However, some AMF may be diverse from others, the concrete function of AMF on commercial tulip varieties need to explore. Therefore, three different sets of  arbuscular mycorrhizal fungi were inoculated into tulip rhizosphere soil, which were set as 4(Diversispora versiformis), 7(Diversispora spurca) and 1 + 3 + 4 (Rhizophagus intraradias + Funneliformis mosseae + Diversispora versiformis), respectively. The results showed that the activity of most of the measured indices increased, the average root diameter and sucrose content decreased in those three mycorrhizal treatments. Our research provide some theoretical basis for the application of AMF on T.gesneriana ecological cultivation in future

Geochemistry of the dissolved loads during high-flow season of rivers in the southeastern coastal region of China: anthropogenic impact on chemical weathering and carbon sequestration

The southeastern coastal region is one of the most developed and populated areas in China. Meanwhile, it has been severely impacted by acid rain over many years. The chemical compositions and carbon isotope compositions of dissolved inorganic carbon (delta C-13(DIC)/in river water in the high-flow season were investigated to estimate the chemical weathering and associated atmospheric CO2 consumption rates as well as the acid-deposition disturbance. Mass balance calculations indicated that the dissolved loads of major rivers in the Southeast Coastal River Basin (SECRB) were contributed to by atmospheric (14.3 %, 6.6 %-23.4 %), anthropogenic (15.7 %, 0 %-41.1 %), silicate weathering (39.5 %, 17.8 %-74.0 %) and carbonate weathering inputs (30.6 %, 3.9 %-62.0 %). The silicate and carbonate chemical weathering rates for these river watersheds were 14.2-35.8 and 1.8-52.1 t km(-2) a(-1), respectively. The associated mean CO2 consumption rate by silicate weathering for the whole SECRB was 191 x 10(3) mol km(-2) a(-1). The chemical and delta C-13(DIC) evidence indicated that sulfuric and nitric acid (mainly from acid deposition) were significantly involved in the chemical weathering of rocks. There was an overestimation of CO2 consumption at 0.19 x 10(12) g Ca-1 if sulfuric and nitric acid were ignored, which accounted for about 33.6% of the total CO2 consumption by silicate weathering in the SECRB. This study quantitatively highlights the role of acid deposition in chemical weathering, suggesting that the anthropogenic impact should be seriously considered in estimations of chemical weathering and associated CO2 consumption

The influence of carbonate precipitation on riverine magnesium isotope signals: New constrains from Jinsha River Basin, Southeast Tibetan Plateau

Magnesium isotope behavior in dissolution and precipitation reactions during chemical weathering have been well documented. However, mechanisms of mineral dissolution and precipitation impact on the riverine Mg isotope composition under different climatic and geology background are not well constrained, which limits Mg isotope application in weathering research. Mg isotopic compositions for solute and suspended sediments in Jinsha River Basin, located in Tibetan Plateau, China, were examined to address this issue. The delta Mg-26 values for dissolved loads range from -1.67 parts per thousand to -0.5 parts per thousand, and the suspended loads show systematically heavier Mg isotope compositions (-1.15 parts per thousand to -0.06 parts per thousand). Conservative mixing between different rock weathering end-members fails to fully explain Mg isotopic composition variation of Jinsha River waters based on mass balance and mixing model with the river geochemistry data. Mg in rivers draining dominantly carbonate and evaporite is isotopically heavier compared with the value of catchment bedrocks, and water pH and delta Mg-26 values are negatively correlated in carbonate (calcite and dolomite) oversaturated river waters, which suggests the precipitation of secondary carbonate as an important mechanism driving the delta Mg-26 of dissolved loads heavier. For carbonate unsaturated waters, Mg concentrations and delta Mg-26 values are intermediate between those of silicate dominated basins and carbonate oversaturated waters. The results suggest two possible different mechanisms controlling river solute delta Mg-26 values: fractionation during carbonate precipitation incorporating of Mg; and conservative mixing between a solute end-member formed from carbonate precipitation and end-members from rock weathering. This study provides new evidence and insights in carbonate precipitation processes regulating river Mg isotope signature and its potential influence on Mg cycling. (C) 2019 Elsevier Ltd. All rights reserved