The Potential Use of Indigenous Nickel Hyperaccumulators for Small-scale Mining in the Philippines

Uptake of nickel and three other heavy metals (copper, cobalt, and chromium) was examined in 33 species of the common and rare native vascular plants growing in an ultramafic area currently subjected to mining in Zambales Province, Luzon, Philippines. Leaf tissue samples were initially screened in the field using filter paper impregnated with dimethylglyoxime (1% solution in 70% ethyl alcohol) and later analyzed by atomic absorption spectroscopy. One species was found to be a hypernickelophore (>10,000 µg/g), eight species were nickel hyperaccumulators (>1,000 µg/g), nineteen species were hemi-accumulators (>100-1,000 µg/g), and five species were non-accumulators (<100 µg/g). This paper significantly adds to the list of hyperaccumulator species first reported for the Philippines in 1992. The findings will be discussed in context of using indigenous species for post mining ecological restoration and nickel phytoextraction in small-scale mining in the Philippine

Intermittent maser flare around the high mass young stellar object G353.273+0.641 I: data & overview

We have performed VLBI and single-dish monitoring of 22 GHz H$_{2}$O maser emission from the high mass young stellar object G353.273+0.641 with VERA (VLBI Exploration of Radio Astrometry) and Tomakamai 11-m radio telescope. Two maser flares have been detected, separated almost two years. Frequent VLBI monitoring has revealed that these flare activities have been accompanied by structural change of the prominent shock front traced by H2O maser alignments. We have detected only blue-shifted emissions and all maser features have been distributed within very small area of 200 $\times$ 200 au$^{2}$ in spite of wide velocity range (> 100 km s$^{-1}$). The light curve shows notably intermittent variation and suggests that the H$_{2}$O masers in G353.273+0.641 are excited by episodic radio jet. The time-scale of \sim2 yr and characteristic velocity of \sim500 km s$^{-1}$ also support this interpretation. Two isolated velocity components of C50 (-53 \pm 7 km s$^{-1}$) and C70 (-73 \pm 7 km s$^{-1}$) have shown synchronised linear acceleration of the flux weighted V_{\rmn{LSR}} values (\sim-5 km s$^{-1}$ yr$^{-1}$) during the flare phase. This can be converted to the lower-limit momentum rate of 1.1 \times 10$^{-3}$ M_{\sun} km s$^{-1}$ yr$^{-1}$. Maser properties are quite similar to that of IRAS 20126+4104 especially. This corroborates the previous suggestion that G353.273+0.641 is a candidate of high mass protostellar object. The possible pole-on geometry of disc-jet system can be suitable for direct imaging of the accretion disc in this case.Comment: 13 pages, 5 figures accepted for publication in MNRA

Energetic radiation and the sulfur chemistry of protostellar envelopes: Submillimeter interferometry of AFGL 2591

CONTEXT: The chemistry in the inner few thousand AU of accreting envelopes around young stellar objects is predicted to vary greatly with far-UV and X-ray irradiation by the central star. Aim We search for molecular tracers of high-energy irradiation by the protostar in the hot inner envelope. METHODS: The Submillimeter Array (SMA) has observed the high-mass star forming region AFGL 2591 in lines of CS, SO, HCN, HCN(v2=1), and HC15N with 0.6" resolution at 350 GHz probing radial scales of 600-3500 AU for an assumed distance of 1 kpc. The SMA observations are compared with the predictions of a chemical model fitted to previous single-dish observations. RESULTS: The CS and SO main peaks are extended in space at the FWHM level, as predicted in the model assuming protostellar X-rays. However, the main peak sizes are found smaller than modeled by nearly a factor of 2. On the other hand, the lines of CS, HCN, and HC15N, but not SO and HCN(v2=1), show pedestal emissions at radii of about 3500 AU that are not predicted. All lines except SO show a secondary peak within the approaching outflow cone. A dip or null in the visibilities caused by a sharp decrease in abundance with increasing radius is not observed in CS and only tentatively in SO. CONCLUSIONS: The emission of protostellar X-rays is supported by the good fit of the modeled SO and CS amplitude visibilities including an extended main peak in CS. The broad pedestals can be interpreted by far-UV irradiation in a spherically non-symmetric geometry, possibly comprising outflow walls on scales of 3500 -- 7000 AU. The extended CS and SO main peaks suggest sulfur evaporation near the 100 K temperature radius.Comment: Astronomy and Astrophysics, in pres

The origin of the [C II] emission in the S140 PDRs - new insights from HIFI

Using Herschel's HIFI instrument we have observed [C II] along a cut through S140 and high-J transitions of CO and HCO+ at two positions on the cut, corresponding to the externally irradiated ionization front and the embedded massive star forming core IRS1. The HIFI data were combined with available ground-based observations and modeled using the KOSMA-tau model for photon dominated regions. Here we derive the physical conditions in S140 and in particular the origin of [C II] emission around IRS1. We identify three distinct regions of [C II] emission from the cut, one close to the embedded source IRS1, one associated with the ionization front and one further into the cloud. The line emission can be understood in terms of a clumpy model of photon-dominated regions. At the position of IRS1, we identify at least two distinct components contributing to the [C II] emission, one of them a small, hot component, which can possibly be identified with the irradiated outflow walls. This is consistent with the fact that the [C II] peak at IRS1 coincides with shocked H2 emission at the edges of the outflow cavity. We note that previously available observations of IRS1 can be well reproduced by a single-component KOSMA-tau model. Thus it is HIFI's unprecedented spatial and spectral resolution, as well as its sensitivity which has allowed us to uncover an additional hot gas component in the S140 region.Comment: accepted for publication in Astronomy and Astrophysics (HIFI special issue

Influence of UV radiation from a massive YSO on the chemistry of its envelope

We have studied the influence of far ultraviolet (UV) radiation from a massive young stellar object (YSO) on the chemistry of its own envelope by extending the models of Doty et al. (2002) to include a central source of UV radiation. The models are applied to the massive star-forming region AFGL 2591 for different inner UV field strengths. Depth-dependent abundance profiles for several molecules are presented and discussed. We predict enhanced column densities for more than 30 species, especially radicals and ions. Comparison between observations and models is improved with a moderate UV field incident on the inner envelope, corresponding to an enhancement factor G0~10-100 at 200 AU from the star with an optical depth tau~15-17. Subtle differences are found compared with traditional models of Photon Dominated Regions (PDRs) because of the higher temperatures and higher gas-phase H2O abundance caused by evaporation of ices in the inner region. In particular, the CN/HCN ratio is not a sensitive tracer of the inner UV field, in contrast with the situation for normal PDRs: for low UV fields, the extra CN reacts with H2 in the inner dense and warm region and produces more HCN. It is found that the CH+ abundance is strongly enhanced and grows steadily with increasing UV field. High-J lines of molecules like CN and HCN are most sensitive to the inner dense region where UV radiation plays a role. Thus, even though the total column density affected by UV photons is small, comparison of high-J and low-J lines can selectively trace and distinguish the inner UV field from the outer one. In addition, future Herschel-HIFI observations of hydrides can sensitively probe the inner UV field.Comment: Accepted for publication in A&A. 13 pages, 10 figure

The Influence of Emissions from Maritime Transport on Air Quality in the Strait of Gibraltar (Spain)

Gaseous and particulate emissions from oceangoing ships have a significant effect on the quality of air in cities. This study estimates mainly the influence of NOx, SOx, and particulate matter (PM2.5) on air quality in the Strait of Gibraltar (Spain) using the authors' own Ship's Energy and Emissions Model (SENEM) and the California Puff air quality model (CALPUFF) in 2017. The Algeciras Bay Industrial Zone recorded the highest levels of pollutants, and the Palmones area was identified as a major hotspot, with mean daily ship-sourced SOx concentrations >215 mu g/m(3), while the highest concentrations of PM10 reached 8.5 mu g/m(3) inside the Strait, and the mean yearly contribution of PM2.5 reached 0.86 mu g/m(3) in the city of Algeciras. The incidence of maritime traffic emissions on the levels of particle emissions, CO, HC, NMVOC, and CO2 reached values of up to 20-25% in all the receivers defined in the study

Water and ammonia abundances in S140 with the Odin satellite

We have used the Odin satellite to obtain strip maps of the ground-state rotational transitions of ortho-water and ortho-ammonia, as well as CO(5-4) and 13CO(5-4) across the PDR, and H218O in the central position. A physi-chemical inhomogeneous PDR model was used to compute the temperature and abundance distributions for water, ammonia and CO. A multi-zone escape probability method then calculated the level populations and intensity distributions. These results are compared to a homogeneous model computed with an enhanced version of the RADEX code. H2O, NH3 and 13CO show emission from an extended PDR with a narrow line width of ~3 kms. Like CO, the water line profile is dominated by outflow emission, however, mainly in the red wing. The PDR model suggests that the water emission mainly arises from the surfaces of optically thick, high density clumps with n(H2)>10^6 cm^-3 and a clump water abundance, with respect to H2, of 5x10^-8. The mean water abundance in the PDR is 5x10^-9, and between ~2x10^-8 -- 2x10^-7 in the outflow derived from a simple two-level approximation. Ammonia is also observed in the extended clumpy PDR, likely from the same high density and warm clumps as water. The average ammonia abundance is about the same as for water: 4x10^-9 and 8x10^-9 given by the PDR model and RADEX, respectively. The similarity of water and ammonia PDR emission is also seen in the almost identical line profiles observed close to the bright rim. Around the central position, ammonia also shows some outflow emission although weaker than water in the red wing. Predictions of the H2O(110-101) and (111-000) antenna temperatures across the PDR are estimated with our PDR model for the forthcoming observations with the Herschel Space Observatory.Comment: 13 pages, 14 figures, 10 tables. Accepted for publication in Astronomy & Astrophysics 14 November 200

Calculating a Drop in Carbon Emissions in the Strait of Gibraltar (Spain) from Domestic Shipping Traffic Caused by the COVID-19 Crisis

As a consequence of the COVID-19 pandemic, the Spanish government declared a State of Emergency, and domestic passenger ship traffic was restricted in Spanish ports. This manuscript presents scenarios of emissions from domestic shipping traffic in the seas of the Strait of Gibraltar (Spain) over three months of the COVID-19 pandemic. Emissions were estimated for only 90 days of the pandemic, and two scenarios were studied: emissions while vessels were berthed at the Algeciras Port and emissions as a consequence of the interruption of passenger ship transportation in the Strait of Gibraltar. To this end, the authors' own model was used, which has near zero uncertainties. This model was used for the first time in this study and takes into account both meteorological and sea condition parameters, as well as the efficiency of the propulsion system. The manuscript concentrates on the emissions of greenhouse gases (GHGs), nitrogen oxides (NOx), sulphur oxides (SOx), carbon dioxide (CO2), and particulate matter (PM) from six Ro-Pax ships that ceased to operate. The main finding is that as a consequence of the pandemic, reductions of up to 12% were found in the Strait of Gibraltar in all the pollutants and GHGs when taking into account all international traffic, while the decrease in emissions from domestic traffic only reached 51%

Automation of the stone materials dosing process, controlled by variable frequency drives

The objective of this article is to determine to what extent the automation of the stone materials dosing process, controlled by sequential drive of frequency variators, contributes to improving the productivity of a company dedicated to the production of asphalt in Peru for which, initially, the characteristics of the procedure that will lead to achieving the automation will be described. The results will then be displayed with respect to the indicators used to compare productivity before and after automation. The automation will be done by means of the logo 230RE controller, which will be connected to three frequency inverters, the programming development will be through the logo soft comford V8 software, for the sequential actuation, timers with connection delay will be used. Applying the automation, it is possible to improve the annual efficiency by an average of 58.30%, this is reflected in the monthly decrease in production time by 13.92%, in turn increasing the amount of stone material produced by an average of 43.77%. Likewise, it is possible to significantly reduce the production loss capacity by an annual average of 93.99%