VNU Journal of Science: Earth and Environmental Sciences

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Tóm tắt. Bài báo trình bày một số biểu hiện của biến đổi khí hậu ở Việt Nam trong các thập kỷ qua, xu thế biến đổi trong tương lai cũng như một số bằng chứng và khả năng tác động tiềm ẩn của nó. Việc nghiên cứu biến đổi khí hậu trong quá khứ được dựa trên các tập số liệu quan trắc từ hệ thống mạng lưới trạm khí tượng thuỷ văn của Việt Nam; việc đánh giá xu thế biến đổi trong tương lai được thực hiện thông qua các mô hình khí hậu khu vực nhằm chi tiết hoá các kịch bản biến đổi khí hậu toàn cầu. Bên cạnh các yếu tố như lượng mưa, nhiệt độ, tốc độ gió, v.v… bài báo cũng sẽ chỉ ra một số kết quả về sự biến đổi của các hiện tượng khí hậu cực đoan như mưa lớn, nắng nóng, rét đậm, rét hại, hạn hán, hoạt động của xoáy thuận nhiệt đới, v.v… Vấn đề hợp tác và hội nhập quốc tế trong lĩnh vực nghiên cứu biến đổi khí hậu và xây dựng các kịch bản biến đổi khí hậu cho Việt Nam, phục vụ chiến lược và kế hoạch ứng phó hiệu quả với biến đổi khí hậu, góp phần phát triển bền vững kinh tế - xã hội - môi trường cũng sẽ được đề cập.Từ khóa:  Biến đổi khí hậu, dự tính khí hậu, Việt Nam.

Abstract. Reusing domestic wastewater for irrigation is a common practice in peri-urban areas in Vietnam. This study investigates the characteristic of domestic wastewater in Hanoi City in terms of nutritive value and potential risk in using for agriculture. The wastewater samples were collected in four main drainage rivers of the City including Lu, Set, Kim Nguu, and To Lich River during March to May 2010. We found that the wastewater of Hanoi City is seriously polluted by organic matters. The nutrient parameters were really high and which is suitable for agricultural irrigation. The wastewater might supply enough nutrients for plant growing. However, municipal wastewater contains a variety of inorganic substances from domestic and industrial sources, including a number of potentially toxic elements such as 1.09-2.14 µg Cd L-1, 0.16-0.33 mg Cu L-1, 2.75-4.02 µg Pb L-1, 0.20-0.34 mg Zn L-1 and 0.22-0.44 mg Mn L-1. These were also a significant quantities of heavy metals being higher than natural river water, and possible threat to soil biota and hence on microbial and faunal activity, and then human health.Keywords:  heavy metals, irrigation, trace metals, treatment, wastewater.

Abstract. Bird watching ecotourism is highly-responsible and educative kind of nature tourism which helps conserve natural environment and culture values of the local area, develop community and bring about remarkable economic benefits. Birds are seen everywhere but especially found with many species in nature reserves and national parks. There are 30 National Parks, 67 Nature Reserves, more than 50 Bird Sanctuaries in Vietnam, and more 16 Marine Protected Area are planned to be established until 2015, which has great potentials to develop bird watching ecotourism. In order to develop this tourism model in nature reserve, it is necessary to improve personnel’s capability and to set up database for identifying wild birds in each area. Conserving precious and specific bird species, characteristic communities for habitats plays an important role in attracting tourists toVietnam for bird watching. Some database in analyzing bioacoustics in some specific wind season tropical forests inVietnam are presented in this paper such as Orange-bellied leafbird, Silver-eared mesia and Indian cuckoo.Keywords: ecotourism, bird watching, nature reserve, bioacoustics.

Abstract

Cỏ Vetiver đã được nghiên cứu rộng rãi như một giải pháp tiềm năng cho phytoremediation, đặc biệt là trong việc xử lý đất bị ô nhiễm kim loại nặng. Nghiên cứu này tập trung vào việc đánh giá khả năng của cỏ Vetiver trong việc hấp thụ cadmium (Cd) và chì (Pb) từ các loại đất khác nhau bị ô nhiễm. Cỏ Vetiver được trồng trong điều kiện kiểm soát với mức độ ô nhiễm kim loại cao, và các thông số sinh trưởng của cây cũng như nồng độ kim loại được đo lường định kỳ. Kết quả cho thấy cỏ Vetiver có khả năng hấp thu tiết diện lớn các kim loại nặng, đặc biệt là từ đất sét và đất phù sa. Đồng thời, các chỉ số tăng trưởng của cỏ vẫn được duy trì, chứng minh rằng cây có thể phát triển tự nhiên mà không bị ảnh hưởng tiêu cực. Nghiên cứu này khẳng định phương pháp phytoremediation bằng cỏ Vetiver không chỉ hiệu quả mà còn mang tính bền vững, hứa hẹn góp phần cải thiện môi trường đất nhiễm kim loại nặng trong tương lai.

Abstract: Application of fertilizers and pesticides or using waste water for irrigation can result in an accumulation of heavy metals (HM) in cultivation areas. Under flooding condition of the paddy soils, HM can be leached and result in a potential risk for groundwater. In this study, Hydrus – 1D was applied to simulate the infiltration of Cu, Pb and Zn in paddy soils (in Huu Hoa, Dai Ang and Ta Thanh Oai communes, Thanh Tri district, Hanoi) in the time span from 1 to 720 days. Simulations were based on input data of the soils: texture, bulk density, Freundlich constants (Kf and β), head pressure as 20 cm ± 10 cm and assummed concentrations of the HM in irrigated water as 0.5 mmol Cu cm-3, 0.1 mmol Pb cm-3 and 0.75 mmol Zn cm-3.Leaching rates of the HM were observed to decrease in the order: Zn > Cu > Pb. Under constant flooded conditions at a water table of 20 cm, Cu, Pb and Zn were estimated to reach 1 m deep in the soil domain within 193, 312 and 450 days, respectively. At water layers of 10 and 30 cm, the leaching rate of HM increase or decrease 17%, respectively. Speciation experiments revealed that Zn transport might be affected by the presence of Fe-, Al-oxides, while the factor prohibiting the leaching rate of Cu was soil organic matter. Pb showed a strong dependence on both Fe-, Al-oxides and organic matter. These results reinforce the necessity of using transport models to improve predictions of HM transport and more efficient remediation of contaminated aquifers. Uncertainties in modeling arise as several parameters in the simulation can be determined only with significant errors. However, Hydrus-1D is a suitable tool for simulation of the transport of HM in paddy soil.Keywords: Hydrus-1D, simulation, transport, heavy metal, paddy soil.

In Bangladesh, clay bricks are extensively used as building construction material. Rapid urbanization in the country has spurred the brick production of 8.6 billion each year. The larger part of brick fields has been set up illicitly, near human homes, schools, colleges, medicinal services offices, disregarding the current laws in this regard. Top soil of agricultural land is collected for producing bricks. As a result, our country is losing hectares of precious topsoil each year. In Bangladesh, around 12,000 brick kilns are in operation. A kiln produces averagely 8,500 bricks using 1,000 cubic feet of topsoil. Tons of forest wood is burned to produce bricks every year. Brick kilns emissions consist of carbon-dioxide (CO2), particulate matter (PM) including black carbon (BC), sulfur-dioxide (SO2), oxides of nitrogen (NOx), and carbon monoxide (CO), thereby causing air pollution. Brick kilns around Dhaka are responsible for up to 58 percent of all the fine-particulate air pollution in the capital. The qualitative research approach was followed in order to explore the scope of Alternative Bricks (ABs) and also the role of law to control brick manufacturing and kiln establishment in Bangladesh. This study indicates that the law enforcement mechanism is not functioning properly as well as there are lots of loopholes in the existing laws to prevent the production of harmful clay bricks and promote Alternative Bricks (ABs). Keywords Alternative bricks, brick kiln, clay bricks, law. References [1] S. Khan, Topsoil grabbing by brick kilns, The Financial Express, Dhaka, 2018.[2] D. Biswas, E. S. Gurley, S. Rutherford and S. P. Luby, The Drivers and Impacts of Selling Soil for Brick Making in Bangladesh, Environmental Management, vol. 62, no. 4, pp. 792-802, 2018.[3] "Pollution the killer," The Daily Star, Dhaka, 2018.[4] A. 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