scholarly journals Effects of subsurface barriers on seawater intrusion and nitrate accumulation in coastal aquifers

2021 ◽  
Author(s):  
Qiguo Sun ◽  
Tianyuan Zheng ◽  
Xilai Zheng ◽  
Marc Walther
Keyword(s):  
Barrier Height ◽  
Seawater Intrusion ◽  
The Other ◽  
Stagnation Zone ◽  
Coastal Regions ◽  
Nitrate Accumulation ◽  
Subsurface Barrier ◽  
Engineering Measures ◽  
Doc Concentration ◽  
Subsurface Dam

The subsurface barrier is one of various engineering measures used to prevent seawater intrusion in coastal regions which has been widely applied. However, its two common types, the cut-off wall and the subsurface dam, are both found to cause nitrate (NO3-) accumulation in landward aquifers. In this study, numerical simulations were conducted to investigate the mechanism of NO3- accumulation caused by the two types of subsurface barriers, as well as the influence of several key parameters, i.e. the infiltration NO3- concentration, the inflow DOC concentration, the barrier height and the barrier location on the performance of the subsurface barriers. The results showed that the cut-off wall generally requires a large height to ensure a satisfactory seawater prevention effectiveness, and it is more likely to cause NO3- accumulation compared to a subsurface dam. On the other hand, despite the subsurface dam may not result in the significant increase of NO3- concentration in groundwater upstream, it cannot be applied to the areas where SI has occurred due to the residual seawater problem. Moreover, the construction of a cut-off wall results in a stagnation zone appeared at the upper corner of the barrier, where accumulated NO3- significantly. With the increase of the barrier height, the stagnation zone expanded, leading to further increase of mean NO3- concentration in the landward aquifer. Since the construction of a subsurface dam will not generate such a zone, the subsurface dam generally has little impact on NO3- accumulation.

Structure Analysis of In-Grown Stacking Faults and Investigation of the Cause for High Reverse Current of 4H-SiC Schottky Barrier Diode

2008 ◽  
Vol 600-603 ◽  
pp. 963-966 ◽  
Author(s):  
Shin Harada ◽  
Yasuo Namikawa ◽  
Ryuichi Sugie
Keyword(s):  
Schottky Barrier ◽  
Barrier Height ◽  
Structure Analysis ◽  
Stacking Faults ◽  
Reverse Current ◽  
Schottky Barrier Diode ◽  
The Other ◽  
Poly Type

Two types of structures related to in-grown SF having a different influence on reverse currents of 4H-SiC SBDs were investigated. One type contained only a single SF formed by 1c of 8H poly-type and showed low reverse currents. The other type was accompanied with short SFs which consisted of 3C poly-type in addition to two SFs formed by 1c of 8H poly-type and showed high reverse currents. SF formed by 1c of 8H poly-type was not the cause of the high reverse current, and we speculate that the barrier height lowering at the short SF attributed to the high reverse currents of SBDs.

Research on the Feasibility of Water Diversion Project

2014 ◽  
Vol 580-583 ◽  
pp. 1874-1877
Author(s):  
Li Hua Zhang ◽  
Guang Hui Wang ◽  
Xiao Hui Hao
Keyword(s):  
Water Resources ◽  
Optimal Allocation ◽  
Water Shortage ◽  
The Other ◽  
Water Diversion ◽  
Actual Condition ◽  
Other Hand ◽  
Water Diversion Project ◽  
Engineering Measures ◽  
The One

The research on the feasibility of Feicheng Water Diversion from Dawen River Project is based on a thorough investigation in the actual condition of water resources in Feicheng city. It is found that on the one hand this city has been suffering from water shortage, while on the other hand it has allowed most of the water flowing away in vain from Dawen River, which runs through this area. To resolve this contradiction, this research demonstrates the feasibility of networking of Dawen River and Shangzhuanglu Reservoir through engineering measures to realize the optimal allocation of water resources

Classification of the degradability of 30 pharmaceuticals in water with ozone, UV and H2O2

2008 ◽  
Vol 57 (2) ◽  
pp. 195-200 ◽  
Author(s):  
I. H. Kim ◽  
H. Tanaka ◽  
T. Iwasaki ◽  
T. Takubo ◽  
T. Morioka ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Batch Reactor ◽  
The Other ◽  
Oh Radicals ◽  
Intermediate Products ◽  
Other Hand ◽  
Doc Concentration ◽  
Process Combination ◽  
Environmental Relevance

Experiments were conducted to assess the degradability of 30 PPCPs, selected on the basis of consumption and environmental relevance, by O3 process, UV process and AOPs consisting of UV/ H2O2, O3/UV and O3/H2O2. A batch reactor with volume of 22L of water including the PPCPs was used. For UV process, combination of UV and H2O2 or O3 that can generate OH radicals was capable of degrading the PPCPs faster than UV radiation alone. On the other hand, O3 process and O3-based/UV-based AOPs could remove a variety of the PPCPs effectively, while some PPCPs such as 2-QCA, DEET and cyclophosphamide showed a relatively low degradability compared with the other PPCPs. However, further evaluation on formation of intermediate products resulting from the degradation of the parent PPCPs will be needed because DOC concentration was not decreased with lowered concentrations of the PPCPs.

Seepage Characteristics Analysis of Geomembrane Earthrock Dams

2013 ◽  
Vol 739 ◽  
pp. 278-282 ◽  
Author(s):  
Yun Feng Peng ◽  
Dan Hao
Keyword(s):  
Quality Assurance ◽  
Influencing Factors ◽  
The Other ◽  
Embankment Dam ◽  
Control Material ◽  
Leakage Flux ◽  
Position Detection ◽  
Engineering Measures ◽  
Characteristics Analysis ◽  
Seepage Characteristics

As a new kind of seepage control material, the geomembrane has been widely used in embankment dam, yet the seepage characteristics and effect of the geomembrane have not been studied on theory. Based on seepage mechanism in geomembrane, this thesis classifies the seepage into two types: one is permeability of geomembrane itself; the other is defect leakage flux in geomembrane. After studies respectively the influencing factors of permeability and defect leakage flux in geomembrane, the corresponding engineering measures were summed up. The study shows that the reasonable design and careful construction are requisite condition for the success of geomembrane seepage prevention works. At last, the philosophy of leak-position detection with electricity and its function in construction quality assurance was described.

The Mosquitos of the funestus Series in East Africa

1937 ◽  
Vol 28 (4) ◽  
pp. 587-603 ◽  
Author(s):  
H. S. Leeson
Keyword(s):  
East Africa ◽  
Human Blood ◽  
Anopheles Funestus ◽  
The Other ◽  
Pistia Stratiotes ◽  
Wing Pattern ◽  
Coastal Regions ◽  
Type Form ◽  
The Many ◽  
Almost All

The paper deals with Anopheles funestus and its allies as they occur in East Africa. The species dealt with are A. funestus type form, A. rivulorum, A. rivulorum var. garnhamellus and A. leesoni.1. Differences between adults are so slight that they have until recently all been regarded as A. funestus. They may, however, be separated from one another by the points given in the Key (above). Differences between larvae of the species are much more pronounced.2. It is also shown that, in this part of Africa at least, A. funestus, though reared from identical larvae and pupae, has four main forms of wing pattern. One of the forms of A. funestus appears to be absent from Uganda, while another form is much more prevalent in coastal regions than inland. A. rivulorum occurs in Uganda, but only two specimens were taken in Tanganyika. A. rivulorum var. garnhamellus is widely distributed throughout E. Africa. A. leesoni was found only in Uganda.3. A. funestus, A. rivulorum and A. leesoni breed in similar situations, i.e., clear, shaded water with growing vegetation. The larvae are more frequently found among grass than among other types of vegetation. Such breeding-places occur in rivers, streams, pools and swamps. Light readings taken at breeding-places corrobate the many reports that these larvae prefer shaded situations and are absent from exposed waters. Larvae of A. rivulorum var. garnhamellus are found most frequently associated with Pistia stratiotes, though on at least two occasions they were found in water where this plant was absent.4. All the adults were taken inside buildings and none outside, in spite of continuous searching. Almost all were A. funestus, the remaining few were A. rivulorum and A. rivulorum var. garnhamellus; adults of A. leesoni were not taken at all. At several places, though adults of A. funestus were common in houses, very few or no larvae of this species were found; but larvae of the other forms were present. It is concluded that A. funestus is therefore an habitual house-frequenter and the others are not. Human blood was found in roughly half of the female A. funestus examined (239 out of 456); a very few contained ox blood and the remainder (204) were negative for ox and human blood. They were not tested for other bloods. Of 122 female A. funestus examined for malaria parasites 15 were found infected.

Optical–optical double resonance study of the and &([a-z]+);(3A2) states of thiophosgene

1994 ◽  
Vol 72 (3) ◽  
pp. 745-757 ◽  
Author(s):  
Benoit Simard ◽  
Valerie J. Mackenzie ◽  
Peter A. Hackett ◽  
Ronald P. Steer
Keyword(s):  
Barrier Height ◽  
Energy Levels ◽  
Double Resonance ◽  
The Other ◽  
Bending Angle ◽  
Optical Double Resonance ◽  
Out Of Plane ◽  
State Potential ◽  
Minimum Potential ◽  
Plane Bending

The &([a-z]+);(3A2) and [Formula: see text] states of jet-cooled thiophosgene (Cl2CS) have been studied by optical–optical double resonance (OODR) spectroscopy. Two OODR schemes have been used to probe the [Formula: see text] state. One scheme uses selected vibronic levels of the &([a-z]+);(1A2) state as the intermediate state, while the other uses the vibrationless and 2131 levels of the &([a-z]+);(3A2) state. All of the vibronic levels in the 33 980−35 600 cm−1 region can be rationalized with the following origin band and fundamentals: 0° = 34 277 cm−1, v1 = 505 cm−1, v2 = 470 cm−1, v3 = 213 cm−1, v6 = 249 cm−1, 42 = 341 cm−1, 44 = 627 cm−1. The discrepancies among the various studies of the [Formula: see text] state will be discussed and reconciled. It is conjectured that the [Formula: see text] state potential along the C—S coordinate exhibits an asymmetric double-minimum potential resulting from the interaction of the 1A1 states arising from the [Formula: see text] configurations. The minimum corresponding to the [Formula: see text] configuration lies higher in energy and the principal decay mechanism for molecules pumped to its first few vibronic levels is fluorescence. On the other hand, molecules pumped to the minimum corresponding to the nominal [Formula: see text] configuration decay nonradiatively. The barrier height to inversion and the out-of-plane bending angle along the out-of-plane bending coordinate, v4, have been determined to be 945 cm−1 and 25°, respectively, by fitting quartic-quadratic and quadratic-Gaussian double-minimum potentials to the observed energy levels. The &([a-z]+);(3A2) state has been studied by a novel OODR scheme which uses the fluorescent vibrationless level of the [Formula: see text] state to monitor [Formula: see text]transitions. A vibronic analysis has been carried out and the following origin band and fundamentals derived for the &([a-z]+);(3A2) state: 0° = 17 499 cm−1, v1 = 923 cm−1, v2 = 474 cm−1, v3 = 247 cm−1, 42 = 297 cm−1, 44 = 560 cm−1, 46 = 741 cm−1. With the exception of a few corrections and additions, the results confirm the findings of previous studies, notably regarding the bent geometry and barrier height to inversion. An overall comparison of the data suggests that the wavenumber of v6 in theÃ(1A2) state is 279 cm−1 instead of 189 cm−1.

scholarly journals The Challenges of Constructing the Connectivity between Indonesia and Malaysia in the Malacca Strait

2020 ◽  
Vol 10 (1) ◽  
pp. 1-15
Author(s):  
Awani Irewati
Keyword(s):  
Management System ◽  
The Other ◽  
Development Programs ◽  
Coastal Regions ◽  
Competitive Situation ◽  
Coastal Community ◽  
Two Cities ◽  
Community People ◽  
The Government ◽  
Malacca Strait

Today, people have lived in one integrated  space that make all their  needs and activities can be served quickly and they become interdependent . In line with that,  the implementation of connectivity concept within community, automatically, becomes inherent in their social and economic activities.Therefore, people need to construct connectivity in all activities. Even within the bigger community like ASEAN Community, people become more involved  in a cohesive and competitive situation in order to fulfill the desired goals. Referring to one of President Jokowi's maritime development programs, namely "Toll Laut", it is the Indonesia government's target to construct/ build up the potential regional zone as strategic hub that connects with its neighboring countries. The long-lived relationship between Indonesia and Malaysia in regards of the Malacca Strait has been articulated in numerous activities. This is in accordance with what the needs of coastal community of the two countries . In this case, Medan and Dumai of Sumatera Island in Indonesia are the two cities which have traditionally  established people to people connectivity with Penang  and Melaka cities of Malaysia. In the context of  ASEAN Community,  such a connectivity has been part of the ASEAN Community target. There are three elements inherent in the connectivity concept, namely infrastructures, institutions and people to people. The two Indonesia coastal regions in this regards need to construct the other two concepts of connectivity  in order to obtain the “normal” connectivity which is the prerequisite to connect Indonesia and Malaysia  in the Malacca Strait. This becomes a big challenge for the Indonesia to fulfill the target of competitive,cohesive and inclusive sub-regional connectivity development. This paper aims at scrutinizing the main quest, which focuses on the challenges faced by Indonesia in building up /constructing the maritime connectivity with Malaysia in the Malacca Strait. The paper  is in favor of the argument that the Indonesia’s maritime corridors [Dumai and Medan] seem to have problem. The maritime connectivity between the two countries has  not built adequately. In this regards, the government should streamline the management system linked to the internal connectivity issue.

Seasonal Incidence of Myxomatosis in New-South-Wales

1989 ◽  
Vol 16 (5) ◽  
pp. 563 ◽  
Author(s):  
I Parer ◽  
T Korn
Keyword(s):  
New South ◽  
New South Wales ◽  
Seasonal Trend ◽  
The Other ◽  
European Rabbit ◽  
Coastal Regions ◽  
Central Plains ◽  
Seasonal Incidence ◽  
South Wales

We analysed monthly records of the presence or absence of myxomatosis in the 59 Pasture Protection Board Districts of New South Wales for 1959-64 and 1980-86. These periods respectively precede and follow the introduction of the European rabbit flea, Spilopsyllus cuniculi (Dale), into New South Wales. Throughout New South Wales during the two periods, myxomatosis was reported more frequently in summer than in winter. The seasonal trend was more pronounced on the western and central plains than on the slopes, tablelands or coastal regions. The incidence of myxomatosis was positively related to rainfall on the western and central plains and slopes, but not on the tablelands and coast. After the introduction of the rabbit flea, the reported incidence of myxomatosis increased more on the tablelands than in the other regions.

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