Stefania Romano, Silvia Giuliani, Luca Giorgio Bellucci, Mauro Frignani

Transcription

1 Proceedings of the workshop Environmental Quality in the Province of Bac Giang and the Cau River Basin. Perspectives for the improvement of monitoring activities and methods. Hanoi, August 27 th, Paper No. 3 Promotion of Environmental Quality in the Districts of Viet Yen, Yen Dung and Hiep Hoa in the Bac Giang Province, Vietnam: sediment and soil samples for environmental quality assessment Stefania Romano, Silvia Giuliani, Luca Giorgio Bellucci, Mauro Frignani CNR-Institute of Marine Sciences, Via Gobetti 101, 40129, Bologna, Italy stefania.romano@bo.ismar.cnr.it; silvia.giuliani@bo.ismar.cnr.it; luca.bellucci@bo.ismar.cnr.it; mauro.frignani@bo.ismar.cnr.it Tóm tắt Để có được thông tin về chất lượng tổng thể của môi trường ở phía tây nam tỉnh Bắc Giang (miền Bắc Việt Nam) một loạt các mẫu được thu thập từ các con sông (sông Cầu, Ngũ huyện Khê), cánh đồng lúa, ao, vũng nước và giếng gia đình. Mẫu được phân loại theo kích thước hạt và các chất hữu cơ (carbon hữu cơ, nitơ tổng số, δ 13 C) trong thành phần trước khi phân tích các chất gây ô nhiễm chính. Abstract To obtain information on the overall quality of the environment in the southwestern Bac Giang Province (northern Vietnam) a series of samples was collected from rivers (Cau, Ngu Huyen Khe), rice fields, ponds, puddles and family wells. Samples were characterized by their grain size, and organic matter (organic carbon, total nitrogen, δ 13 C) content. Samples were then analysed for major contaminants. Keywords: Soils and sediments, grain size, organic matter, 137 Cs, Bac Giang Province, Vietnam. 1. Introduction Contaminants enter the river system through various pathways. Hydrological conditions determine the contribution of the various sources and whether contaminated sediments remain in the riverbed or become more widely distributed over floodplains and wetlands. Contaminants in sediment may impact the ecological or chemical water quality status. 33

2 A common distinction is between point and diffuse sources of contamination; which reflects their behavior under changing meteorological conditions (Vink and Berendt, 2001). However, both of them contribute to the total contaminant load of rivers. Riverine material is characterized by a continuum of sizes from coarser grain to purely dissolved forms. Dissolved compounds are transferred across aquatic systems together with the water, while the particulate compounds are transferred differently: they may settle and be remobilized, according to flow velocity, particle size and shape, river bed morphology, etc. The fine and medium-sized particles, i.e. below 63 microns, are the most important. The properties of these fine particles (e.g. large specific surface areas, high ion exchange capacities) enable them to act as efficient scavengers of contaminants discharged into the river system. Moreover, when total suspended solids concentrations (TSS) exceed 100 mg/l, more than 90% of the most toxic metals, and major Persistent Organic Pollutants (POPs), are present in river, adherent to particulates (SedNet Strategy paper, 2004). The main goal of this study is to present the physico-chemical characteristics of samples collected for the study of environmental quality in the southwestern Bac Giang Province through their location and basic characteristics, such as grain size composition and organic matter content. Also the concentration of the radionuclide 137 Cs was measured. 2. Study area The Bac Giang Province (first formalized in 1997) is located in Northern Vietnam and lies in the Red River Delta Region (Fig. 1). The weather regime has the dominant characteristics of the tropical, temperate climate zone of the Northern Plain. Temperature, humidity and rainfall vary over months and seasons. Since the province is located away from Vietnam's eastern coast and the South China Sea (East Sea), the incidence of hurricanes and storms is rare, with only localized phenomenon in few mountainous districts. 34

3 (a) (b) Figure 1: Location of the Bac Giang Province (a) and its Administrative Map (b). 35

4 The Province borders Quảng Ninh to the east, Lạng Sơn to the north, Thái Nguyên and the urban district of Sóc Sơn in the capital Hanoi to the west, and Bắc Ninh and Hải Dương to the south (Fig. 1). It comprises three land forms, namely: the lowland or delta land, the midland and the mountainous region (Statoids, 2010). The Province economy is primarily dedicated to agriculture (31% of total land use). In particular, the Province is known as a producer of rice, vegetables, fruit crops and bulb trees. 27.7% of Bac Giang's area is devoted to forestry that produces wood and trees of bamboo and neohouzeaua. Different villages in the area are dedicated to wood handcrafts. The rest of the Province land is residential and urban. Moreover, the Bac Giang territory hosts mineral activity that involves the mining extraction of 15 types of minerals such as coal, metal, industrial minerals, building materials registered on the territory (Bac Giang Industrial Zones Authority, 2010). During the period , the province has launched several industrial projects in all its districts. As a result, several economic farming models were introduced, which resulted in "Rural Economic Development" amd social consumer retail sales. Services got a boost, the poverty rate (2005 level) reduced to 17.78%, and textiles and garment exports reached 76% of the province's export turnover (Bac Giang Department of Industry and Trade 2010). Infrastructures such as the National Highway, and rural roads were expanded. Key industries like fertilizer, high technology, engineering, building materials, assembling automobiles, agricultural processing, forestry products, textiles and electric power generation are planned with the objective of achieving a GDP growth rate of 11-12% by 2020 (Population and Employment: General Statistics Office of the Government of Vietnam, 2010). Navigation was part of its beneficial uses as a transport route for shipment of rice and salt from Hai Phong to Thái Nguyên. The scheme, as built, has a concrete across the Cau River, the mainstream of the Thai Binh River system (Bac Giang Department of Agriculture and Rural Development, 2010). 36

5 We also need to mention Da Hoi in Bac Ninh Province. This is a village with iron steel industries located south of Cau River and east of Hanoi, and is part of Chau Khe quarter, Tu Son district. Originally, Da Hoi was a metallic mechanical engineering professional village manufacturing household appliances. In recent time, it played also the role of recycling steel village. Its source of raw materials is mainly iron in loose bits collected from other provinces in the country. Industrial waste consists mainly of discarded scrap, iron rust, scrap iron, soil and sand, and a great amount of coal ash that results from the manufacturing process. 3. Methods 3.1. Sampling Sampling campaigns were realized in 2011 and 2012 and some stations of the 2011 survey were sampled again in 2012 in order to perform some additional analyzes. Soil and sediment samples were taken at rivers, rice fields, sewages, pounds, puddles and family wells (Fig. 2) in the Province of Bac Giang (Vietnam). Samples were taken by grab sampling or via manual collection (Fig. 3). Sediment and soil samples were kept frozen until the arrival in the laboratory and then freeze-dried and homogenised before the analysis Grain size Grain size analyses were carried out by wet mechanical sieving, using a sieve with 63 μm openings to separate sand and mud fraction, after a pretreatment with H 2 O 2. Then the two fractions were dried and weighed to calculate the relative percent content Organic matter Organic Carbon (C org ), Total Carbon (TC) and Organic Nitrogen (ON) contents were determined using a Fisons Elemental Analyser NA2000. Prior to the analysis of the organic carbon fraction, inorganic carbonates were eliminated by pre-treatment with 1.5 M HCl. 37

6 Figure 2: Location of samples collected in 2011 (1-18) and 2012 (19-30). Sites 27 and 28 belong to the Bac Ninh Province. 38

7 d) c) b) a) Figure 3: Pictures of sampling areas or operations. a) well (Tu Mai), sample 17; b) Quang Chau (Dong Tien), sample 19; c) Canal collector (industrial area of Song Khe,) sample 26; d) Quang Chau (Dong Tien), sample

8 Cs Activities of gamma emitting radionuclides were obtained through gamma counting of dry samples in standard geometries with a detector coupled with an analyzer. Detection limits were set in a range between 1 and 3 Bq Kg Results and Discussion The purpose of the project was to evaluate the quality of the environment in the southwestern sector of the Bac Giang Province (Romanelli, this volume). Then the sampling strategy had to take into account the potential pressures and impact on the different zones and situations. Therefore the sampling campaign carried out in 2011 was focused on the definition of contaminant levels in areas not influenced by direct sources, in order to obtain a general overview on the presence of metals, As, and selected POPs in the study areas. On the contrary, the second sampling in 2012 was focused on those areas where main industrial activities are present. Figure 4: Sand and fines percentage content for samples collected in 2011 and As for grain size composition, samples show a general high content of fines (fraction that best interact with contaminants) and only for seven of them fines content was below 50% (Table 1 and Fig. 4). 40

9 Table 1: Samples collected in 2011 and 2012, their location and characteristic: grain size content (as % of mud and sand content), organic carbon (OC %), organic nitrogen (ON %), C/N ratio, δ 13 C and 137 Cs (Bq kg -1 ) activity. 41

10 Table 2: Grain size content in replicate samples of the 2011 survey sample mud % sand % 1_r _r _r _r _r _r In detail these were: sample 5 (family well: 44 %), sample 13 (family well: 29 %), sample 16 (flooding field: 37 %).17 (family well: 0.98 %); 24 (Industrial area Song Khe-Noi Hoang: 32 %); samples 27 and 28 (from Bac Nihn Province, 40 % and 30 %, respectively). Replicate samples of the 2011 survey (Table 2) showed that, with the exception of sample 1 (Hoang Ninh, Table 1), there was an enrichment of fine fractions. The soil sample 12 was the sample with less evident changes. In general variations were significant, but not so important to change the samples characteristics. Only the family well of Thang Cuong (sample 13, Table 1) was really different: the first sediment was mainly sandy but the second sampling retrieved a mud (from 29 to 67 % of silt plus clay). This change is impossible to explain with available information. It is possible that, by chance, the sampled wells were not the same. Like grain size, also organic matter content can affect the capability to interact with particles and contaminants. OC concentrations showed high variability, spanning the interval from 0.08 to 8.1 % (Table 1). The maximum was found in sample 28 taken at Phong Ke. Its high organic matter content and its overall composition made impossible to perform reliable analysis of organic contaminants. As a consequence, they were not determined in this sample. As expected in terrestrial environment, C/N ratio values were above 10 and ranged between 10 and 15, with the only exception of site 7, where algae input seems relevant. Furthermore δ 13 C ranged between -20 e -27. Fig. 5 provides information on the sources of organic matter. In particular, δ 13 C 42

11 values indicates a mixed source between freshwater Dissolved Organic Carbon (DOC) and C3 plants (i.e. those organisms, including also rice, that fix CO 2 producing a molecule with three carbon atoms). Samples 16, 22, 24 and 30 showed higher influence from rice fields with a C/N value characterized by low nitrogen and high carbon levels. Figure 5: Distribution plot of C/N and δ 13 C Because the Fukishima (Japan) accident happened little before our first sampling survey, analysis of 137 Cs were performed on sediment and soil samples collected in 2011, to test the influence of radiation emission in the atmosphere on the Vietnamese territory. All samples presented activities of 137 Cs below detection limit (Table 1), thus indicating a poor influence of the Fukushima accident. Moreover, low 137 Cs values highlight the little influence of world nuclear experiment in the late fifties on the Vietnamese territory, as mentioned by Frignani et al. (2007), Giuliani et al. (2011) and Romano et al. (2012). 43

12 Acknowledgements Funds for the collection and analysis of samples from the Bac Giang Province and Cau River were provided by the Italian Ministry of Foreign Affairs, Direzione Generale Cooperazione Sviluppo (DGCS), under the GVC-UCODEP project Promotion of Environmental Quality in the Districts of Viet Yen, Yen Dung and Hiep Hoa in the Bac Giang Province, Vietnam.The authors are grateful to M. Romanelli and G. Santavicca for the management, and to Dario Cesarini, Nguyen Thi Xuyen, Trinh Thi Thuong, Chu Bich Hanh, Duong Thi Nga Duzng, Nguyen Van Diep for help. This is contribution No from ISMAR-CNR, Bologna. References Bac Giang Industrial Zones Authority Bắc Giang Province: Minerals. Retrieved 29 August Bac Giang Department of Industry and Trade Bắc Giang Department of Industry and Trade tasks and powers. Retrieved 29 August Bac Giang Department of Agriculture and Rural Development Irrigation Management Company of Bắc Giang: Water Rights and Water Allocation in Irrigation Scheme of Cầu River. Bắc Giang. Frignani M., Piazza R., Bellucci L.G.., Cu N.H., Zangrando R., Albertazzi S., Moret I., Romano S., Gambaro A., Polychlorinated biphenyls in sediments of the Tam Giang-Cau Hai Lagoon, Central Vietnam. Chemosphere, 67, Giuliani S., Romano S., Turetta C., Cu N.H., Bellucci L.G.., Capodaglio G.., Mugnai C., Nhon D.H., Frignani M., Soils and sediments of the Thua Thien-Hue Province (central Vietnam): recognizing trace element sources and the likely influence of natural events. Journal of Environmental Monitoring, 13, Population and Employment: General Statistics Office of the Government of Vietnam Number of cooperatives in 2008 by kind of activity and by province: Agriculture. Forestry and Fishery. 44

13 Population and Employment: General Statistics Office of the Government of Vietnam Agriculture. Forestry and Fishery: Output value of agriculture at constant 1994 prices. Romanelli M. Presentation of the Project Promotion of environmental protection in the Viet Yen, Yen Dung and Hiep Hoa districts in the Bac Giang Province, Vietnam : implementation, strategies and results. This volume. Romano S., Mugnai C., Giuliani S., Turetta C., Cu N.H., Bellucci L.G.., Nhon D.H., Capodaglio G.., Frignani M., Metals in Sediment Cores from Nine Coastal Lagoons in Central Vietnam. American Journal of Environmental Sciences, 8, SedNet strategy Paper, The opinion of SedNet on environmentally, socially and economically viable sediment management. European Sediment Network (SedNet), EC contract no. EVK1-CT , 13 pp, Statoids "Districts of Vietnam". Retrieved 20 June Vink R., Behrendt H., Part B: Present and future quality of sediments in the Rhine catchment area Heavy metals. In: Candrass J. Salomons W. (Eds.) Dredged material in the Port of Rotterdam - Interface between Rhine catchment area and North Sea. GKSS Geesthacht. Germany. 45

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