A combined study of whole-rock major and trace elements, Sr–Nd isotopes, zircon U–Pb dating, and in situ zircon Hf–O isotopes has been carried out for late Mesozoic magmatic rocks in the Lower ...Yangtze River Belt. The results provide insights into the origin of mantle sources of magma above a subduction zone, and thus into the petrogenesis of high-K calc-alkaline rocks, shoshonites, and A-type granites on continental margins, and the associated tectonic transformation from a continental arc to a back-arc extensional setting. The late Mesozoic magmatism can be subdivided into three stages: high-K calc-alkaline intrusions (148–133Ma), shoshonitic rocks (133–127Ma), and A-type granitoids (127–123Ma). All the rocks have consistent arc-like trace element characteristics with positive anomalies of Rb, Th, U, Pb, and LREE, negative anomalies of Nb, Ta, and Ti, and enriched Sr–Nd–Hf isotopic signatures. The first-stage intrusions in the Tongling area usually host dark enclaves of diorite, have high Sr/Y ratios, and low Y contents, and contain zircons with relatively low εHf(t) values (−38.6 to −6.6) and high δ18O values (5.7‰ to 10.1‰). A few inherited zircons with Neoarchean to Paleoproterozoic ages and highly enriched Hf isotopic compositions were detected in both the host intrusive rocks and the enclaves. The second-stage Ningwu volcanics contain zircons with moderate εHf(t) values (−13.3 to −3.8) and elevated δ18O values (5.4‰ to 7.6‰). The third-stage intrusions can be divided into A1- and A2-type granitoids, and their zircons have relatively high δ18O values of 6.7‰ to 10.3‰ and high εHf(t) values of 0 to −7.9. Based on these geochemical data we drew the following conclusions. Before 148Ma, following metasomatism by slab-derived fluid/melts, partial melting of the lithospheric mantle produced basaltic magma in the context of a subducting paleo-Pacific plate. This basaltic magma mixed with magma derived from the Archean lower crust, and the underplated and thickened juvenile lower crust. From 148 to 133Ma, continuous production of these mixed magma resulted in their intrusions as basic rocks at shallow levels. Meanwhile, partial melting of the thickened juvenile crust formed the intermediate-acid rocks of the first stage. As subduction continued, and the dip angle of the subducting plate increased, the continental arc tectonic setting was transformed to one of back-arc extensions. Metasomatism and decompression induced intensive partial melting of the lithospheric mantle, and these magmas, together with a limited amount of assimilated crustal materials, formed the second-stage volcanics. Roll-back of the subducted slab resulted in extension, causing disassembling of the lower lithosphere and lithospheric thinning, and the upwelling of hot asthenosphere. The A2-type granites were the result of the reworking of the Mesoproterozoic juvenile crust in this tectonic setting of extension. On the other hand, the A1-type granitoids were formed from magmas that were derived both from the matasomatized mantle and from the A2-type granitic material that had its origins in the Mesoproterozoic juvenile crust. We suggest that an integrated and comparative study of the multiple stages of development of these magmatic rocks is the key to understanding the tectonic evolution and associated magmatic activities in this continental intraplate setting.
•Three stages of Late Mesozoic magmatisms in the LRYB were studied.•Three stages of magmatisms are characterized by different zircon Hf–O isotopes.•Petrogenesis of the three stage magmatisms reveals progressive deep processes.•These magmatisms were genetically related to Paleo-pacific plate subduction.•Tectonic setting transformed from continental arc to back arc at ca. 130±3Ma.
Degradation of chlorpyrifos at different concentrations in soil and its impact on soil microbial functional diversity were investigated under laboratory condition. The degradation half-live of ...chlorpyrifos at levels of 4, 8, and 12 mg/kg in soil were calculated to be 14.3, 16.7, and 18.0 d, respectively. The Biolog study showed that the average well color development （AWCD） in soils was significantly （P 〈 0.05） inhibited by chlorpyrifos within the first two weeks and thereafter recovered to a similar level as the control. A similar variation in the diversity indices （Simpson index lID and McIntosh index U） was observed, but no significant difference among the values of the Shannon-Wiener index H＇ was found in chlorpyrifos-treated soils. With an increasing chlorpyrifos concentration, the half-life of chlorpyrifos was significantly （P ≤ 0.05） extended and its inhibitory effect on soil microorganisms was aggravated. It is concluded that chlorpyrifos residues in soil had a temporary or short-term inhibitory effect on soil microbial functional diversity.
Carbendazim, a systemic benzimidazole fungicide, is applied repeatedly to control plant diseases including soilborne diseases, over a growing season. Studies were carried out under laboratory ...conditions to assess the effects of repeated carbendazim applications on its persistence and microbial community in soil. The results indicate that dissipation of carbendazim in soil was accelerated with its application frequency. The degradation rate constant of carbendazim was increased significantly from 0.074 d-1 to 0.79 d-1. The corresponding half-life was shorten markedly from 9.3 d to 0.9 d after four repeated applications. No significant inhibitory effect of carbendazim on soil microbial utilization of the carbon sources was observed after first treatment, but a slight increase in average well color development （AWCD） was shown after second, third, and fourth applications. It suggested that soil microorganisms become adapted to carbendazim after repeated application. Simpson and Shannon indexes of soil microbial community from carbendazim treated soil were also similar to those from the control soil, indicating that the richness and dominant character of soil microorganisms remain unchangeable after repeated application. However, after first, second, and third addition of carbendazim, McIntosh indexes on day 21 were significantly higher compared with the control, suggesting that balance of soil microorganisms was altered due to the enrichment of the specific carbendazim-adapting strains in soil
In practice, pesticides are usually applied simultaneously or one after another for crop protection, and this type of pesticide application often leads to a combined contamination of pesticide ...residues in the soil environment. A laboratory study was conducted to investigate the influence of chlorothalonil on chlorpyrifos degradation and its effects on soil bacterial, fungal, and actinomycete populations. Under the experimental conditions here, the half-lives of chlorpyrifos alone, and in combination with chlorothalonil, at the recommended and double dosages, were measured to be 3.24, 2.77, and 2.63 d, respectively. Chlorpyrifos degradation was not significantly altered by its combination with chlorothalonil. However, the inhibitory effect of chlorpyrifos on soil microorganisms was increased by its combination with chlorothalonil, and the increase was related to the levels of chlorothalonil added. Compared to those in the controls, the populations of bacteria, fungi, and actinomycetes were significantly reduced by 44.1%, 61.1%, and 72.8%, respectively, on the first day after treatment （DAT） by chlorpyrifos alone. With the addition of chlorothalonil, the inhibition was increased to 55.2%, 79.3%, and 85,8% at the recommended dosage, and 86.0%, 94.1%, and 90.8% at the double dosage, at one DAT, respectively. The results suggested that combined effects should be taken into account to assess the actual impacts of pesticide applications.
The effect of repeated carbendazim applications on functional diversity of culturable microorganisms and bacterial community composition was studied under field conditions. The functional diversity ...of soil culturable microbial community (Shannon index,
H′) reduced significantly (
P<0.05) after the first introduction of carbendazim at levels of 0.94, 1.88 and 4.70
kg active ingredient (a.i.)
ha
−1 and then recovered to that in the control with subsequent applications. An evident (
P<0.01) difference in the bacterial community composition was observed after the second carbendazim application by Temperature Gradient Gel Electrophoresis (TGGE) analysis of 16
S rRNA genes amplified from treated and control soils, which remained after the third and fourth treatments. Our results indicated that repeated carbendazim applications have a transient harmful effect on functional diversity of soil culturable microbial community and result in an alteration in bacterial community composition largely due to one species within the γ-
proteobacterium.
► Effect of repeated carbendazim applications on microbial functional diversity. ► Effect of repeated carbendazim applications on bacterial community composition. ► A transient harmful effect on culturable microbial functional diversity occurs. ► Repeated applications induce an alteration in bacterial community composition. ► Structural alteration is largely due to one species within the
γ
-
proteobacterium.
This study was conducted to find an appropriate approach for the assessment of bioavailability of DDTs in soil to both earthworm and vegetables. Four chemical approaches—Soxhlet extraction with ...n-hexane, n-butanol agitation extraction, water agitation extraction, and matrix solid-phase microextraction (matrix-SPME)—were used to assess the relationships between the extractability of 1,1-dichloro-2,2-bis(p-chlorophenyl) ethylene (p,p′-DDE), 1,1,1-trichloro-2-(p-chlorophenyl)-2-(o-chlorophenyl) ethane (o,p′-DDT), 1,1-dichloro-2,2-bis(p-chlorophenyl) ethane (p,p′-DDD), and 1,1,1-trichloro-2,2-bis(p-chlorophenyl) ethane (p,p′-DDT) in soil and their amounts uptaken by the earthworm (Eisenia foetida), Chinese cabbage (Brassica campestris L. spp.), and cole (Brassica napus L.). These results indicated that the extractability and bioavailability of DDTs in soil decreased with time of aging. Correlation analysis showed that n-butanol extraction or 12-h matrix-SPME could be used to assess the bioavailability of DDTs to the earthworm, and Soxhlet extraction, n-butanol extraction, or 12-h matrix-SPME could be used to predict the bioavailability of DDTs to both Chinese cabbage and cole. As a solventless, time-efficient, and negligible-depletion technique, it could be concluded that matrix-SPME is a better approach to predict the bioavailability of DDTs to both the earthworm and vegetables, compared with Soxhlet extraction, n-butanol extraction, and water extraction.
The density functional theory was used to investigate the adsorption of CH4 and H2O on different rank coal surfaces.The coal rank is the dominant factor in affecting the adsorption capacity of ...coal.In order to better understand gas and water interaction with coal of different maturity,we developed fourteen coal models to represent the different rank coal.The interactions of CH4 and H2O with coal surfaces were studied and characterized by their adsorption energies,Mulliken charges and electrostatic potential surfaces.The results revealed that the interaction between coal and CH4 was weak physical adsorption,and that the interaction between coal and H2 O consisted of physical and chemical adsorption.Adsorption energy of coal–H2O system was larger than that of coal–CH4 on all rank coals,suggesting that the adsorption priority in the coal models is H2 O > CH4.Consequently,the injection of H2 O into the different rank coal could effectively enhance the coal bed methane（CBM） recovery.
Taking Environment and Plant Protection Institute in Chinese Academy of Tropical Agricultural Sciences as an example,it summarized major experience and practice in management of scientific research ...projects from strengthening project database,enhancing project planning,reinforcing scientific research management team construction,bringing into play functions of academies and institutes,and improving management system. It analyzed existing problems and came up with recommendations from strengthening project process management,improving management team quality,and improving incentive mechanism,in the hope of providing reference for scientific research project management in agricultural scientific research institutes.
This paper firstly analyzed current situation of agricultural technological innovation system in China and obstacles restricting agricultural enterprises to become technological innovation entities. ...It discussed exploration and practice of Chinese Academy of Tropical Agricultural Sciences in supporting and serving technological innovation entities. Finally,it came up with ideas and approaches for supporting and serving technological innovation entities in the new trend,to provide a new idea and practice for agricultural scientific research institute supporting and serving technological innovation entities.
