CHẤT LƯỢNG MÔI TRƯỜNG NƯỚC VÙNG CỬA SÔNG BA LẠT

Ba Lat estuary is the large mouth of the Red river; every year, the Ba Lat estuary receives million cubic meters of water before the water is dissolved in the sea. Therefore, polluted materials in the water from the continent are also transported to the sea through the estuary. However, the volume of the water pouring into the sea varies with the season. In this paper, the water quality at Ba Lat estuary (Red river) was surveyed in July 2017 representing the Southwest wind season (rainy season) and in October 2017 representing the Northeast wind season (dry season). The research results show that the values of chemical parameters of water at Ba Lat estuary changed according to the season: the average temperature of water in the rainy season was 2.5oC higher than in the dry season; average pH in the rainy season (7.45 ± 0.36) was higher than that in the dry season (7.01 ± 0.17). Parameters such as conductivity, salinity, NO3-N, NH3-N, PO4-P, total grease, Fe and Zn in the dry season were 1.22–2.92 times higher than in the rainy season. Concentration of some nutrition (including NO3-N; NH3-N; PO4-P and SiO3-Si), heavy metals (Fe, Zn), and total grease in the water were high, in which NO3-N ranged from 0.565 mg/l to 1.129 mg/l; NH3-N ranged from 0.139 mg/l to 6.16 mg/l, 1.53 to 4.47 times higher than the standard of Vietnam. PO4-P ranged from 0.16 mg/l to 0.82 mg/l, which was 2 to 3.14 times higher than the standard. SiO3-Si ranged from 3.49 mg/l to 5.31 mg/l. Iron concentration in the water was 2.2 to 9.7 times higher than the standard and not different between the two seasons. Zn ranged from 0.64 mg/l to 2.56 mg/l, 1.28 to 5.12 times higher than the standard. Total grease ranged from 2.8 mg/l to 7.0 mg/l, 5.6 to 14 times higher than the standard. Other parameters such as DO, BOD5, Fe, SiO3-Si in the Northeast wind season were 1.01 to 1.35 times lower than in the Southwest wind season. In particular, DO ranged from 3.75 mg/l to 4.99 mg/l, lower than the QCVN 10-MT: 2015 standard and the DO was not suitable for the growth and development of aquatic life. Iron concentration ranged from 2.172 mg/l to 2.209 mg/l, 4.3 to 4.4 times higher than the standard. Water quality also varies with the space, most notably in electrical conductivity, salinity and grease. In particular, the salinity and conductivity tend to increase gradually from the river to the sea, the total oil and grease reached the highest point at BL7 in both phases, and NO3-N in phase 2 reached the highest value at BL6 to BL11.

Assessing the Possibility of Appearing RIP Current at Quy Nhon Beach, Binh Dinh Province

RIP current is a strong, popular water flow at beaches in Vietnam as well as in the world, with the direction of flow from the shore to the sea. This is a dangerous flow, each year there are unfortunate accidents for swimmers. This study used the measured data source implemented by the Center for Environmental Fluid Dynamics in 2018 to build the model MIKE 21 Coupled for simulating the hydrodynamic field and the rip current at Quy Nhon beach area. Through calculation scenarios under different conditions show that, the area near the amusement park (An Duong Vuong road) and the southern-most area of Quy Nhon beach are likely to appear rip current in the northeast wind season. In the southwest monsoon season, the intensity of the rip current is strong, appearing near the Victory Monument area. These areas are often crowded by swimmers with local people and tourists, so pay attention to avoid accidents that may happen.

Rip current simulation on some beaches in coastal Quang Nam province

This paper presents modelling results of rip currents on the main beaches along coastal Quang Nam province including Ha My, Binh Minh, Tam Thanh and Rang beaches during two typical wind seasons: Northeast monsoon (Northeast wind direction, wind levels: 4, 5, 6) and Southwest monsoon (Southeast wind direction, wind levels: 4, 5) using Mike 21 model. Calculation results show that during the Northeast monsoon, the rip current formed in all beaches. In the scenario of level 4 of wind speed, average rip speed was about 40–50 cm/s. In particular, at Tam Thanh beach area, the rip was a typical one with the components such as feeder current, rip neck and rip head. With the level 5 of wind field, the formation of the rip was clearer, the speed of the rip was stronger, average value was about 50–60 cm/s. Meanwhile, with the level 6 of wind field, the typical rip structure was broken, creating local eddies or longshore currents at some positions, but strengthened at other positions. During the Southwest monsoon, the rip current did not form at the beaches and the longshore currents were dominant.

Characteristics of Wind Power Fluctuations

Wind power is also known as junk. This is because wind power fluctuations affect the security and stability operation. Wind power wind turbines created is mainly concerned with the speed of wind. Because of the wind direction uncertain, intermittent, and wake effects between each unit wind farm, wind turbines cannot make that kind of power according to the demand for energy as conventional generators. Due to the lack of experimental data, assess the volatility of wind power is still a lack of effective methods. This article studies the sample in a northeast wind farm power, and based on a sliding differential algorithm, distribution fitting and quantitative calculations describe the characteristics of wind power fluctuations. This article studies the sample in a northeast wind farm power, and based on a sliding difference algorithm, through the analysis showed that wind power fluctuations obey t location scale distribution. And it is affected by factors such as spatial and temporal distribution, there is a big difference between the output power fluctuation characteristics of wind farm output power and single wind turbine. This is due to the wind turbine suffered varying differences, and wake effects between field units, making the distribution of frequent power fluctuations; relative to a single unit, the fluctuation of the whole wind farm is more gentle, that is to say with the spatial distribution increased scale, wind power fluctuations presents certain "gentle effect."

Synoptic-Scale Environments Conducive to Orographic Impacts on Cold-Season Surface Wind Regimes at Montreal, Quebec

Orographic wind channeling, defined as dynamically and thermally induced processes that force wind to blow along the axis of a valley, is a common occurrence along the St. Lawrence River Valley (SLRV) in Quebec, Canada, and produces substantial observed weather impacts at stations along the valley, including Montreal (CYUL). Cold-season observed north-northeast (n = 55) and south-southeast (n = 16) surface wind events at CYUL are identified from 1979 to 2002. The authors partition the north-northeast wind events into four groups using manual synoptic typing. Types A and D (“inland cyclone” and “northwestern cyclone”) are associated with strong lower-tropospheric geostrophic warm-air advection and near-surface pressure-driven channeling of cold air from the north-northeast, along the axis of the SLRV. Type C (“anticyclone”) shows no evidence of a surface cyclone and thus is the least associated with inclement weather at CYUL, whereas type B (“coastal cyclone”) is associated with predominantly forced wind channeling along the SLRV. Type D of the north-northeast wind events and all south-southeast wind events exhibit similar sea level pressure patterns. The respective magnitudes of the pressure gradients in the Lake Champlain Valley south of CYUL and the SLRV play a large role in determining the favored wind direction. Soundings of the various event types illustrate substantial differences in temperature structure, with a large near-surface temperature inversion particularly prevalent in north-northeast events. The results of this study may provide guidance in forecasting winds, temperatures, and observed weather in and around the SLRV, given certain synoptic-scale regimes.

A HISTORICAL ATLAS OF OBJECTIVITY

The mythical scientist in early twentieth-century America cut a lone figure, “impersonal as the chill northeast wind” and “oblivious of everything save his experiment.” He toiled through the night in his laboratory, “a place unimpressive and unmagical save for the constant-temperature bath with its tricky thermometer and electric bulbs,” as if working in the lab were a prayer that promised illumination—“alone, absorbed, [and] contemptuous of academic success and of popular classes,” he knew all about material forces, but he was blind to the vital force that created all others. Accustomed to the “beautiful dullness of long labors,” he remained “illimitably ignorant” of literature, art, and music. He believed that unerring techniques in experimentation, impartial observations, and exquisitely minute calculations would bring progress—a steady march toward the truth. He chose the highest calling in the world because he was “intensely religious—so religious that he will not accept quarter-truths, because they are an insult to his faith.” He was “so devoted to Pure Science . . . that he would rather have people die by the right therapy than be cured by the wrong. Having built a shrine for humanity, he wanted to kick out of it all mere human beings.” This autocratic figure, brilliantly insane and tyrannically honest, embodied the cult of science and objectivity.