Phytoplankton biomass, taxonomy, primary productivity, and photosynthetically available radiation (PAR) were studied as part of baseline data collection for prospective nodule mining in the Central Indian Basin during the ORV Sagar Kanya cruise SK-120 in January 1997. The phytoplankton cell counts and chlorophyll a estimates showed low biomass level, suggesting low rates of primary productivity in the region studied. The average chlorophyll a value was 0.775 mg m?3 at surface and 17.75 mg m?2 in the water column. Similarly, average primary productivity at surface was 3.72 mg C m?3 d?1 and was 51.23 mg C m?2 d?1 in column. The chlorophyll a maxima at 50 to 80 m was the characteristic feature of the euphotic zones of the area. Average phytoplankton counts at the surface were low (3960 cells/l), compared to those at 25 m (6421 cells/l) and 75 m (5187 cells/l). At most of the stations mesozooplankton biomass was maximum in the top 50 m water column, indicating the importance of grazing in the euphotic zone. Appreciable quantities of mesozooplankton were observed below the euphotic zone, where settlement of chlorophyll a occurs. The low iron concentration in the water and its relationship with the water column productivity were correlated. The results show that waters in the CIB have low productivity in the surface as well as subsurface layers. This is expected to change in this case of a mining discharge in to these layers, possibly locally affecting the existing marine ecosystems. The final impact of such mining activity may remain negligible in the deep sea environment. 相似文献
We present optical UBVRI photometric and spectroscopic data of the Type Ibn supernova SN 2006jc, until the onset of the dust-forming phase. The optical spectrum shows a blue continuum and is dominated by the presence of moderately narrow (velocity ∼2500 km s−1) He i emission lines superimposed over a relatively weak supernova spectrum. The helium lines are produced in a pre-existing He-rich circumstellar shell. The observed helium line fluxes indicate the circumstellar shell is dense, with a density of ∼109–1010 cm−3 . The helium mass in this shell is estimated to be ≲0.07 M⊙ . The optical light curves show a clear signature of dust formation, indicated by a sharp decrease in the magnitudes around day 50, accompanied by a reddening of the colours. The evolution of the optical light curves during the early phase and that of the uvoir bolometric light curve at all phases is reasonably similar to normal Ib/c supernovae. 相似文献
The chemical industry is one of the most important industry sectors in terms of energy consumption and CO2 emissions in China. However, few studies have undertaken accounting of the CO2 emissions in the chemical industry. In addition, there are some shortcomings in the traditional accounting method as a result of poor data availability, such as the incomplete consideration of emission sources and overestimation of actual emissions. Based on the traditional accounting method and the actual situation of the chemical industry, this study proposes a method called the Emission Accounting Model in the Chemical Industry, which covers fossil energy-related emission, indirect emission generated by electricity and heat, carbonate-related process emission and the reuse of CO2. In particular, fossil energy used as feedstock is included. By applying the Emission Accounting Model in the Chemical Industry in China, the calculated CO2 emissions would be 19–30% less than the result from the traditional method. In addition, it is found that the indirect CO2 emissions generated by electricity and heat account for 67% of the total amount, the fossil energy-related emissions account for approximately 37%, the process-related emissions accounted for 2%, and reuse of CO2 accounts for ??6% in 2016. The production of ammonia, ethylene and calcium carbide generated approximately half of the total CO2 emissions in 2016. In addition, in view of emission sources and carbon source flow, two other bottom-up accounting methods are proposed that can take effect when the chemical plant-level data are available.
Precambrian granitic basement rocks obtained from well BH-36 of Bombay High Field, western offshore of India has been studied
both by Rb-Sr and K-Ar dating methods. Seven basement samples chosen from two cores have yielded whole rock Rb-Sr isochron
age of 1446 ± 67 Ma with an initial87Sr/86Sr ratio of 0.7062 ± 0.0012. This age has been interpreted as the formation/emplacement time of the granite. Two biotite fractions
of different grain size separated from a sample CC6B2T have yielded Rb-Sr mineral isochron age of 1385 ± 21 Ma. However, these
fractions when studied by K-Ar dating method have yielded slightly higher but mutually consistent ages of 1458 ± 43 Ma and
1465 ± 43 Ma, respectively.
Further, two biotites separated from additional samples CC5B9T and CC6B3B have yielded K-Ar ages of 1452 ± 42 Ma and 1425
± 40 Ma with an overall mean age of 1438 ± 19 Ma. This mean K-Ar age is indistinguishable from whole rock Rb-Sr isochron as
well as mineral isochron age within experimental error. The similarity in the whole rock and biotite ages obtained by different
isotopic methods suggests that no thermal disturbance has occurred in these rocks after their emplacement/formation around
1450 Ma ago. The present study provides the evidence for the existence of an important Middle Proterozoic magmatic event around
1400-1450 Ma on the western offshore of India which, hitherto, was thought to be mainly confined to the eastern Ghats, Satpura
and Delhi fold belt of India. This finding may have an important bearing on the reconstruction of Proterozoic crustal evolution
of western Indian shield. 相似文献
Tower platforms, with instrumentation at six levels above the surface to a height of 30 m, were used to record various atmospheric
parameters in the surface layer. Sensors for measuring both mean and fluctuating quantities were used, with the majority of
them indigenously built. Soil temperature sensors up to a depth of 30 cm from the surface were among the variables connected
to the mean data logger. A PC-based data acquisition system built at the Centre for Atmospheric Sciences, IISc, was used to
acquire the data from fast response sensors. This paper reports the various components of a typical MONTBLEX tower observatory
and describes the actual experiments carried out in the surface layer at four sites over the monsoon trough region as a part
of the MONTBLEX programme. It also describes and discusses several checks made on randomly selected tower data sets acquired
during the experiment. Checks made include visual inspection of time traces from various sensors, comparative plots of sensors
measuring the same variable, wind and temperature profile plots, calculation of roughness lengths, statistical and stability
parameters, diurnal variation of stability parameters, and plots of probability density and energy spectrum for the different
sensors. Results from these checks are found to be very encouraging and reveal the potential for further detailed analysis
to understand more about surface layer characteristics. 相似文献
We demonstrate that a large-scale longitudinally symmetric global phenomenon in the Southern Hemisphere sub-polar region can transmit its influence over a remote local region of the Northern Hemisphere traveling more than 100° of latitudes (from ~70°S to ~40°N). This is illustrated by examining the relationship between the Southern Annular Mode (SAM) and the Korean Monsoon Rainfall (KMR) based on the data period 1983-2013. Results reveal that the May-June SAM (MJSAM) has a significant in-phase relationship with the subsequent KMR. A positive MJSAM is favorable for the summer monsoon rainfall over the Korean peninsula. The impact is relayed through the central Pacific Ocean. When a negative phase of MJSAM occurs, it gives rise to an anomalous meridional circulation in a longitudinally locked air-sea coupled system over the central Pacific that propagates from sub-polar to equatorial latitudes and is associated with the central Pacific warming. The ascending motion over the central Pacific descends over the Korean peninsula during peak-boreal summer resulting in weakening of monsoon rainfall. The opposite features prevail during a positive phase of SAM. Thus, the extreme modes of MJSAM could possibly serve as a predictor for ensuing Korean summer monsoon rainfall. 相似文献
Hydrographic data collected on board ORV Sagar Kanya in the southern Bay of Bengal during the BOBMEX-Pilot programme (October–November
1998) have been used to describe the thermohaline structure and circulation in the upper 200 m water column of the study region.
The presence of seasonal Inter-Tropical Convergence Zone (ITCZ) over the study area, typically characterized with enhanced
cloudiness and flanked by the respective east/northeast winds on its northern part and west/southwest winds on its southern
part, has led to net surface heat loss of about 55 W/m2. The sea surface dynamic topography relative to 500 db shows that the upper layer circulation is characterised by a cyclonic
gyre encompassing the study area. The eastward flowing Indian Monsoon Current (IMC) between 5‡N and 7‡N in the south and its
northward branching along 87‡E up to 13‡N appear to feed the cyclonic gyre. The Vessel-Mounted Acoustic Doppler Current Profiler
(VM-ADCP) measured currents confirm the presence of the cyclonic gyre in the southern Bay of Bengal during the withdrawing
phase of the southwest monsoon from the northern/central parts of the Bay of Bengal. 相似文献
Optical spectroscopic data on the recurrent nova RS Ophiuchi obtained between 32 and 108 days after its last outburst on 1985
January 27 are presented. RS Oph was in the coronal-line phase at that time. The widths of the permitted as well as coronal-lines
decreased continuously. Assuming that the ejected envelope decelerated due to its interaction with circum stellar matter,
its size is deduced as a function of time. Observed fluxes in permitted lines would then imply that the electron density decreased
from 3 × 109 cm#x2212;3 on day 32 to 1.8 × 108 cm-3 on day 108, for an assumed filling factor of 0.01. The helium abundance in the ejecta is estimated to be n(He)/n(H) ∼ 0.16.
The mass of the unshocked ejecta was 3 × 10-6 (Φ/0.01)1/2 M⊙, (at this stage, where f is the filling factor. Observed fluxes in coronal-lines imply that the temperature of coronal-line
region decreased from 1.5 × 106 K on day 32 to 1.1 × 106 K on day 108. Most of the coronal line emission, as well as He n emission arises in shocked and cooling ejecta. This region
is not isothermal, but contains material at a wide range of temperatures. Mass of the shocked ejecta is estimated to be in
the range 10−7−10−6 M⊙ Based on the number of H- and He-ionizing photons, we estimate that the ionizing source evolved from a radius and temperature
of (2 × l012 cm, 3 × 104 K) on day 32 to (6 × l09 cm, 3.6 × 105K) on day 204.
We also present the spectra of RS Oph recorded in quiescent phase, 2 and 3 years after outburst, for comparison. The spectrum
is dominated by that of M2 giant secondary, with superposed emission lines of H and He I 相似文献