The abundance of magnetic microspherules in a Triassic-Jurassic continuous sequence of alternating chert and shale beds in the Mino accretionary complex, central Japan, was measured systematically. Depending on time, the magnetic microspherules extracted from shale beds change in abundance considerably from the minimum 0.9 ppm/cm3 at latest Triassic (ca208Ma) and the maximum 75ppm/cm3 at late Early Jurassic (ca 187Ma); however, the abundance is always higher approximately 10-100 (average 70) times than those from adjacent chert bed at any stratigraphic horizon. Such systematic difference reveals the origin of radiolarian bedded chert as cyclic-rapid accumulation of biogenic SiO, under extremely slow accumulative environments of shale with probable aeolian dust in origin. The accumulation data for individual shale and chert beds were obtained based on the microspherule abundance and radiolarian biostratigraphy, i.e., ca 0.018 g/cm2 Ka for lower Jurassic shale beds and ca 1.9 g/cm2 Ka for adjacent chert beds.Duration time to make a chert-shale couplet corresponds to a dominantly 15-20 Ka interval (average 23 Ka) in Upper Triassic bedded cherts with a low paleolatitude, whereas a 40-45 Ka interval (average 42 Ka) in Lower Jurassic ones which may been formed in higher latitude than Triassics before the final accretion to the Asian continental margin. Depending on paleolatitude, the cyclicity of 23 and 42Ka may correspond to Milankovitch cycles which have been well documented in deep-sea sediments.
a b s t r a c tHigher relative humidity under elevated CO 2 conditions increases stomatal conductance and is expected to promote photosynthesis and growth of tomato. However, yield increase under higher relative humidity has been often reported to be unstable, depending on the growing conditions. Therefore, we investigated the effect of relative humidity and nutrient supply on growth and nutrient uptake under elevated CO 2 conditions in greenhouse tomato production. In two greenhouses, we grew tomato hydroponically at two electrical conductivity (EC) levels (low EC treatments: 0.8-1.2 dS m −1 , high EC treatments: 1.6-1.9 dS m −1 ). In one greenhouse, we installed a humidification system. The other was designated as a control. The dry weight (DW) per plant tended to increase with humidification though without significant differences. The leaf area per plant was not affected by humidification, but the high EC treatment increased the leaf area. The average water uptake in the low EC with mist decreased compared with that without mist. Our results suggested that water use efficiency was increased by higher humidity, whereas the nutrient content of leaves was suppressed by mist in the low EC. In both the treatments, supplying higher EC levels of nutrient solutions increased N, K and P contents but did not increased Ca or Mg contents as well as in low EC without mist. These results suggest that supplying high EC nutrient solutions cannot increase Ca and Mg contents sufficiently in leaves and stems. To stably increase yield of tomato by humidification under elevated CO 2 conditions, it is important to monitor the transpiration rate and carefully control relative humidity.
This paper proposes an innovative CO 2 enrichment system for crop production under a controlled greenhouse environment by means of tetra-n-butylammonium bromide (TBAB) + CO 2 semi-clathrate hydrate (SC). In this system, CO 2 is captured directly from exhaust gas from a combustion heater at night, which can be used for stimulating photosynthesis of crops in greenhouses during daytime. Although the gas capacity of TBAB + CO 2 SC is less than that of CO 2 gas hydrate, it is shown that TBAB + CO 2 SC can store CO 2 for CO 2 enrichment in crop production even under moderate pressure conditions (<1.0 MPa) at 283 K.
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