Research on the construction ventilation scheme of concealed subway station

With the development of underground transportation, in order to reduce the impact on the surrounding environment and traffic, Hejiaying subway island station adopts the concealed excavation method. During the construction process, considering the construction method, tunnel layout, ventilation requirements, and the construction working face as a multi-conductor cave, more stringent requirements are put forward for the construction ventilation of the tunnel. Through the combination of theoretical calculation and numerical simulation, a ventilation method suitable for the actual construction conditions at the site was developed. After applying the scheme to practice, the feasibility of the scheme was verified through the determination of field data, and the improvement of the construction environment for tunnel personnel was achieved, which has certain reference value for similar projects.

A measurement and model study on ozone characteristics in marine air at a remote island station and its interaction with urban ozone air quality in Shanghai, China

To understand the characteristics and changes of baseline ozone (O3) in oceanic air in East China, a six-year measurement of O3 concentration was conducted from 1 January 2012 to 15 September 2017 at a remote offshore station located on the Sheshan Island (SSI) near the megacity of Shanghai. The observed monthly mean O3 concentrations at SSI ranged from 33.4 to 61.4 ppbv during the study period, which were about 80 % and 12 % higher, respectively than those measured at downtown and rural sites in Shanghai. Compared to the remarkable O3 increases observed at urban and rural sites in Shanghai, observed O3 concentrations at SSI exhibited statistically insignificant increasing changes (1.12 ppbv yr−1, α > 0.10) during the observation period, suggesting less impacts of anthropogenic emissions on O3 levels in oceanic air. In addition, an insignificant decreasing change (−0.72 ppbv yr−1, α > 0.10) was detected in O3 concentrations at SSI in September and October when the influence of regional transport was minimum throughout the year, providing a good proxy to study the baseline oxidation capacity of the oceanic atmosphere. City plumes from Shanghai usually carried higher levels of NOx, resulting in decreased O3 concentrations at SSI during southwesterly and westerly winds. However, In MAM (March–May) and JJA (June–August), due to the enhanced oxidation of oxygenated volatile organic compounds, O3 could be continuously produced during daytime in aged city plumes, resulting in elevated O3 concentrations transported to SSI. The impacts of the offshore O3 on O3 levels in Shanghai are quantified during an easterly wind dominant episode (September 1–30, 2014) using the WRF-Chem model. Sensitivity results suggest that O3 in the oceanic air inflows can lead to 20–30 % increases in urban O3 concentrations, which should be crucially considered in dealing with urban O3 pollution in large coastal cities like Shanghai.

Relationship of Distribution Seagrass Species with Dugong (Dugong dugon) Sighting at Liki Island-Papua

Dugong dugon is a herbivorous marine mammal. One of Dugong's favorite foods is seagrass. This study examines the distribution of seagrass species to dugong sighting in Liki Island. The study was conducted in November 2018. Observation of seagrass conditions was carried out using a line transect method and a 50x50 cm transect with a distance interval between 10 m plots. Interviews were also conducted with the community to find out the location of Dugong presence in Liki Island. There are seven species of seagrass found in Liki Island :Enhalus acoroides, Cymodocea rotundata, Thalassia hemprichii, Halophila ovalis, Halodule uninervis, Halodule pnifolia and Syringodium isoetifolium spread over four observation stations. The results showed that Dugong in Liki Island is often found during the eastern season, they often appear in seagrass ecosystem area to do eating activities. Dugong is often found in the eastern part of Liki Island (Station 4) and sometimes also found in the western part of Liki Island (Station 3).Keywords:biodiversity,Dugong dugon, liki, papua, seagrass

Komposisi Makroalga Yang Berasosiasi Di Ekosistem Padang Lamun Pulau Tumpul Lunik, Pulau Rimau Balak Dan Pulau Kandang Balak Selatan, Perairan Lampung Selatan

Assosiation between macroalga and seagrass ecosystem in South Lampung has been determined. There were 3 sampling locations, ie. Station 1 (Tumpul Lunik Island), Station 2 (Rimau Balak Island) and Station 3 (Kandang Balak Selatan Island). Observation of macroalga and seagrass were carried out using quadran transect method (0,5 x 0,5 m2) along 100 meter with 10 meter distance berween transect. It is done triplicates. The research showed that there were twelve species macroalgae belong to three families found in seagrass bed. Their distribution were varied. Highest density of macroalga was Halimeda makroloba in habitat of seagrass Enhalus acorides at around Pulau Tempul Lunik Island. The substrat was sand and rubble which support good growth of both species The presence of macroalgae in seagrass bed could be a competitor related to the space for live and nutrient utilization in the waters. Keywords: macroalga, Halimeda macroloba, Enhalus acoroides, seagrass ecosystem Pengamatan tentang asosiasi antara makroalga di ekosistem padang lamun perairan Lampung Selatan telah dilakukan. Lokasi pengamatan yang terbagi menjadi 3 stasiun, yaitu Stasiun 1 (Pulau Tumpul Lunik), Stasiun 2 (Pulau Rimau Balak) dan Stasiun 3 (Pulau Kandang Balak Selatan). Pengamatan makroalga dan lamun di masing-masing lokasi dilakukan dengan metoda transek kuadran (0,5 x 0,5 m) sepanjang 100 meter dengan jarak pengamatan setiap 10 meter untuk penghitungan dengan kuadran. Pengamatan dilakukan dengan ulangan sebanyak 3 kali garis transek di setiap stasiun pengamatan. Duabelas jenis makroalga dari 3 Famili telah ditemukan di ekosistem padang lamun dengan sebaran kepadatan makroalga yang beragam. Kepadatan tertinggi makroalga ditemukan pada jenis Halimeda makroloba yang banyak ditemukan tumbuh pada habitat lamun Enhalus acorides di sekitar Pulau Tempul Lunik. Kondisi perairan yang bersubstrat dasar pasir dan pecahan karang sangat mendukung untuk pertumbuhan ke dua jenis vegetasi tersebut. Kehadiran makroalga di ekosistem padang lamun dapat menjadi kompetitor bagi keberadaan dan kondisi penutupan lamun, terkait dengan persaingan dalam menempati ruang dan pemanfaatan nutrien di perairan. Kata kunci: makroalga, Halimeda macroloba, Enhalus acoroides, ekosistem padang lamun

Angel Island Immigration Station

The Angel Island Immigration Station (1910–1940), located in San Francisco Bay, was one of twenty-four ports of entry established by the U.S. government to process and detain immigrants entering and leaving the country. Although popularly called the “Ellis Island of the West,” the Angel Island station was in fact quite different from its counterpart in New York. Ellis Island was built in 1892 to welcome European immigrants and to enforce immigration laws that restricted but did not exclude European immigrants. In contrast, as the primary gateway for Chinese and other Asian immigrants, the Angel Island station was built in 1910 to better enforce discriminatory immigration policies that targeted Asians for exclusion. Chinese immigrants, in particular, were subjected to longer physical exams, interrogations, and detentions than any other immigrant group. Out of frustration, anger, and despair, many of them wrote and carved Chinese poems into the barrack walls. In 1940, a fire destroyed the administration building, and the immigration station was moved back to San Francisco. In 1963, the abandoned site became part of the state park system, and the remaining buildings were slated for demolition. Thanks to the collective efforts of Asian American activists and descendents of former detainees, the U.S. Immigration Station at Angel Island was designated a National Historic Landmark in 1997, and the immigration site, including the Chinese poetry on the barrack walls, was preserved and transformed into a museum of Pacific immigration for visitors.

Multi-year investigations of aerosols from an island station, Port Blair, in the Bay of Bengal: climatology and source impacts

Long-term measurements of spectral aerosol optical depth (AOD) using multi-wavelength solar radiometer (MWR) for a period of seven years (from 2002 to 2008) from the island location, Port Blair (11.63° N, 92.7° E, PBR) in the Bay of Bengal (BoB), along with the concurrent measurements of the size distribution of near-surface aerosols, have been analyzed to delineate the climatological features of aerosols over eastern BoB. In order to identity the contribution of different aerosol types from distinct sources, concentration weighted trajectory (CWT) analysis has been employed. Climatologically, AODs increase from January to reach peak value of ~0.4 (at 500 nm) in March, followed by a weak decrease towards May. Over this general pattern, significant modulations of intra-seasonal time scales, caused by the changes in the relative strength of distinctively different sources, are noticed. The derivative (α') of the Angstrom wavelength exponent α in the wavelength domain, along with CWT analysis, are used to delineate the different important aerosol types that influence this remote island. Corresponding changes in the aerosol size distributions are inferred from the numerical inversion of the spectral AODs as well from (surface) measurements. The analyses revealed that advection plays a major role in modifying the aerosol properties over the remote island location, the potential sources contributing to the accumulation mode (coarse mode) aerosols over eastern BoB being the East Asia and South China regions (Indian mainland and the oceanic regions).