VNU Journal of Science: Earth and Environmental Sciences

Việc tiếp xúc với khí thải động cơ có thể là một vấn đề nghề nghiệp nghiêm trọng đối với các cảnh sát điều khiển hoạt động giao thông. Mục tiêu của nghiên cứu này là lấy mẫu khí tại điểm tiếp xúc và đánh giá liều lượng phơi nhiễm của cảnh sát điều khiển giao thông bởi bụi tổng số TSP và NO2 vào giờ cao điểm tại Hà Nội. Nghiên cứu được tiến hành quan trắc và đánh giá mức phơi nhiễm bởi TSP và NO2 của cảnh sát giao thông trong giờ cao điểm (07h - 09h) tại nút giao Nguyễn Trãi - Khuất Duy Tiến, Thanh Xuân, Hà Nội. Nồng độ phơi nhiễm của bụi TSP là 96 ± 71 mg/m3, và NO2 là 109 ± 141 mg/m3. Tương tự, liều lượng phơi nhiễm hít thở của cảnh sát giao thông tại khu vực này đối với TSP xấp xỉ 1,04 mg/ngày, và NO2 vào khoảng 1,2 mg/ngày.

The Red-shanked Douc (Pygathrix nemaeus) is the only douc species recorded in all three countries of Indochina. It is classified as Endangered by IUCN, and is believed to have experienced a major drop of more than 50% of its population over the last 40 years. The known distribution of main P. nemaeus populations in Vietnam ranges from Pu Mat National Park, Nghe An Province in the North to the Kon Ha Nung, Gia Lai Province in the South. In this study, we used Maxent, a species distribution modeling approach that is shown to a have high predictive power even with low number of occurrence records, to predict the current distribution of the Red-shanked Douc in Vietnam based on published records. The results show that P. nemaeus inhabits a region from Nghe An to Kon Tum Province, with areas from Ha Tinh, Quang Binh, Quang Tri, Thua Thien – Hue, Da Nang – Quang Nam Provinces exhibiting the highest potential. With all model parameters already listed here, studies in the future may incorporate more occurrence records to develop better models, or other environmental variables to assess the influence of different factors on the species distribution. The results also suggest that species distribution modeling, coupled with a carefully checked and filtered occurrence dataset, as well as species-specific model fine-tuning and evaluating, can help address many conservation issues in Vietnam.      

Abstract: The expansion of perennial crops area plays an important role for supporting the human livelihood in the Central Highlands, so have negative impacts on deforestation and sustainable development. Remote sensing and GIS were used to analyze the trajectories of perennial crops cover change in relationship with deforestation. The Logistic regression models were used to analyze proximate reasons and spatial changing determinants of main land cover changes for the period 2004-2016 of Bảo Lâm district. The result show that the perennial crops changes are indicator for deforestation in Bảo Lâm district with high deforestation rate 0,8% per year caused by the expansion of annual crops, blind area and the expansion of perennial crops. The facile accessed forest and suitable forest area for perennial crops have more destroyed. The trajectories of perennial crops and forest cover changes are important scientific towards sustainable development.  

Reservoirs system in upstream of Ba River has been affecting to the hydrology and sediment regime at the downstream. Sediment imbalance causes consequences such as erosion at river bank, lack of sediment supply to downstream areas and deposition/erosion in estuaries. This study focused on a quantitative assessment of the impact of Ba Ha reservoir and Song Hinh reservoir on sediment regime at the Cung Son hydrological station (12 km downstream of Ba Ha reservoir and 45 km from the mouth of the Da Dien river). Research used analytical and statistical methods with flow and suspended sediment data measured at the Cung Son hydrological station from 1977 to 2016. The results show that the system of these two reservoirs has a huge impact to the sedimentation regime, especially after the operation of Ba Ha reservoir. The average amount of sediment in the period before and after 2008 significantly reduced from about 2.5 million to about 1 million tons per year.

Abstract: This study used the Denitrification-Decomposition (DNDC) model to calculate greenhouse gas emissions from a paddy rice cultivation in ​​Nam Dinh province. The results show that the total CH4 emission from paddy rice field in Nam Dinh province ranges from 404 to 1146kg/ha/year. Total N2O emissions range from 0.8 to 4.2 kg/ha/year; The total amount of CO2e varies between 10,000 and 30,000 kg CO2e / ha / year. CH4 emissions on typical salinealluvial soils, light mechanics are the highest and lowest on alkaline soils. Alluvium, alkaline soils have the highest N2O emissions and the lowest is the typical saline soils. The study has also mapped CH4, N2O and CO2e emissions for Nam Dinh province. Keywords: DNDC, Green house gas, agricultural sector, Nam Dinh,  GIS. References: [1] Bộ Tài nguyên và Môi trường, Báo cáo kỹ thuật kiểm kê quốc gia KNK của Việt Nam năm 2014, NXB Tài Nguyên Môi trường và Bản đồ Việt Nam, Hà Nội, 2018.[2] D.L. Giltrap, C.Li, S. Saggar, DNDC: A process-based model of greenhouse gas fluxes from agricultural soils, Agriculture, Ecosystems & Environment 136 (2010) 292–300. https://doi:10. 1016/j.agee.2009.06.014.[3] Viện Thổ nhưỡng Nông hóa, Báo cáo kết quả đề tài: “Nghiên cứu, đánh giá tài nguyên đất sản xuất nông nghiệp phục vụ chuyển đổi cơ cấu cây trồng chính có hiệu quả tại tỉnh Nam Định”, 2017.[4] Trung tâm Khí tượng thủy văn quốc gia – Bộ TN&MT, Số liệu thống kê khí tượng thủy văn các trạm khí tượng Văn Lý, Nam Định, Ninh Bình, Thái Bình năm 2014, 2015.[5] Niên giám thống kê tỉnh Nam Định, 2015.[6] T. Weaver, P. Ramachandran, L. Adriano, Policies for High Quality, Safe, and Sustainable Food Supply in the Greater Mekong Subregion. B.T.P. Loan, N.H. Son, M.V. Trinh, N.T. Thuy, D.T.P. Lan, Chapter 7, ADB, Manila, Philippines, 2019, pp. 178-204.[7] Mai Văn Trịnh, Sổ tay hướng dẫn đo phát thải khí nhà kính trong canh tác lúa. NXB Nông nghiệp, Hà Nội, 2016.

Abstract

Abstract. Rapid socio-economic development leads to a great increase in water demand of manysectors and conflicts between water users. Moreover, studies have warned about serious degree ofinfluence of climate change (CC) on Vietnam, particularly on the water resources. Therefore,assess CC impacts on water balances are very necessary task. The Ministry of Natural Resourcesand Environment has com pleted the appropriate clim ate change scenarios in Vietnam [1]. In thisstudy, water balance results will be presented including three scenarios: high emissions scenario(A2), medium emission scenario (B2), and low emission scenario (B1). The water balanced inHong-Thai Binh river basin was calculated, which is one of the largest basins in Vietnam. Thebasin is very complicated: Under the influence of flow regime of international rivers [2], a systemof reservoừs and irrigation structures serving diverse purposes, such as of water supply, irrigation,flood control and hydropower [3-5]. MIKE BASIN model was applied to describe exploitation,utilization and to identify ứie water shortage areas according to the climate change scenarios.Keywfords: climate change, water resources, Hong-Thai Binh river.

Tóm tắt. Cho đến nay, mỗi nhân tố thành tạo địa hình đã trở thành một môn địa mạo riêng, như địa mạo kiến tạo, địa mạo dòng chảy sông (nước chảy trên mặt), địa mạo gió, địa mạo bờ biển (sóng), địa mạo karst (dòng chảy ngầm), địa mạo nhân sinh (con người), v.v.Tuy nhiên, vẫn chưa có địa mạo sinh vật. Gần đây, địa mạo sinh vật đang dần được hình thành. Địa mạo sinh vật được phát triển tại vị trí giao nhau giữa các hệ địa mạo và các hệ sinh thái. Địa mạo sinh vật có đối tượng, mục đích, nội dung, ý nghĩa khoa học và thực tiễn rõ ràng. Một trong những nội dung nổi bật của địa mạo sinh vật là nghiên cứu diễn thế địa mạo sinh vật. Địa mạo sinh vật ra đời góp phần hoàn thiện toàn bộ hệ thống khoa học địa mạo và hướng tới một hệ thống cao hơn-khoa học bề mặt trái đất. Bãi triều ven biển cửa sông Văn Úc và một số nơi khác đã được lựa chọn nghiên cứu minh họa cho quan điểm trên.Từ khóa: Địa mạo, địa mạo sinh vật, diễn thế địa mạo sinh vật.

The Gulf of Thailand is a semi-closed Gulf on the west and southwest side of the Indochina Penisula and experiences reversal monsoon.  The object of the present study is to investigate monthly and spatial distributions of the phytoplankton in the Gulf of Thailand during whole El Nino year 2002 by using remote-sensing measurements of chlorophyll-a (Chl-a) and surface wind vectors. Results show that monthly and spatial variations of the phytoplankton blooms are primarily associated with the monsoonal winds. In general, the average monthly Chl-a concentrations were quite low (<0.5 mg m-3) most area of the Gulf, with a belt of higher Chl-a concentrations along the coast during throughout year. Phytoplankton blooms extensively offshore in the near-coastal area of the Gulf in January and February, which is consistent with the winter northeast monsoon. In particular, one peak of Chl-a concentrations was observed in December. Areas with higher Chl-a concentrations along the coast were observed in both winter and summer monsoon months. Keywords: Phytoplankton blooms, Monsoon, Gulf of Thailand, El Nino.

The study was conducted to turn aquaculture sludge and agricultural by-products into organic fertilizer as part of the circular production. The main raw materials included sludge from catfish ponds after harvest and organic materials from agricultural by-products (25% from growing cordyceps, 25% from growing oyster mushrooms, 25% from peanut shells, and 25% from coconut fiber). The aquaculture sludge (AS) and agricultural by products (ABP) are mixed at five different ratios: 10% AS + 90% ABP; 30% AS + 70% ABP; 50% AS + 50% ABP; 70% AS + 30% ABP, and 90% AS + 10% ABP. The results showed that the experiment with the ratio of 30% AS + 70% ABP optimized the decomposition of organic compounds and produced organic fertilizer with higher nutrient content than the other four mixing ratios. Comparing the quality of organic fertilizer produced with the organic fertilizer quality standards of the Ministry of Agriculture and Rural Development, 15/18 biochemical indicators have met the regulations. The results of the study can provide a guideline for the local people to optimize organic fertilizer production utilizing aquaculture sludge and agricultural byproducts, save input costs for agricultural production, and contribute to reducing waste to the natural environment.