Lª THÞ LÀI¹, JOERN KASBOHM², §µO HUY QUý³;
TRÇN TRäNG HUÖ ¹, MARIA-THERESIA SCHAFMEISTER²

Nam §Þnh is one of the most densely populated provinces in the Red River delta region (about 3000 - 4000 people per sq km in the craft oriented settlements). It is an economical and political important territory for the North of ViÖt Nam generally (economical index, degree of employment etc.). Family manufacturing and other small companies are the typical craft trading producers in the settlements of this administrative province.

The small family production without any treatment system has however created various environmental effects such as sediment, water, and soil pollution. It also causes serious community health problems.

The average life expectancy for ViÖt Nam is about 65 years of age, but for the settlements involved with the metal working trade, the average life expectancy is less than 55 years of age and is accompanied by a high degree of cancerous, neurotic, and pulmonic diseases.

The heavy metals like Pb, Cr, Cu, Zn or Cd resulting from production processes in the settlements accumulated in water, sediment and soil and may be potential risks for human health and ecosystems in the region. Lead, for example, is poisonous and may lead to many toxic effects [7]. Even Zn and Cu are less toxic heavy metals, they may lead to diarrhea, nausea etc. by significant quantities [4].

In order to provide fundamental information on the anthropogenic impacts on environment as a basis for the development of an in-situ treatment system to cut off the contribution of pollutant in the environment it is necessary to characterize the relevant pollutant’s pathway: Production-pollutant-environment-human.

Nam §Þnh is a region with a long tradition of craft manufacturing. It is a part of the Red River delta with its characteristic alluvial landforms. It is situated ca. 100 km SE of Hà Néi, on the right bank of the Red River. The study area is bound by the S«ng §µo in the West, by the S«ng Ninh C¬ in the East (both branches of the Red River) and by the Red River in the North (Fig. 1).

The climate of the region is a humid tropical type. Usually 70-80 % of the total annual rainfall occurs during July, August and September. The intensity and the duration of the rainy season affect strongly on the mobilization of the pollutant in this region.

In the province, there are 71 traditional craft villages with different production branches. Most of workshops are located right at the living areas, yards or garden. The statistical data concerning raw material used in nine villages with metal production (mechanic, casting, plating etc.) per year are as follow [5]: iron, steel, copper, aluminium: 98,100 tons; coal: 104,960 tons; petrol oil: 1,510 tons; chemicals: 1,100 tons.

Sediment and soil samples were collected in April 2000 and September 2001 for analyses of heavy metals. Water and sediment samples were taken from the drainage networks and ponds of the settlements. The sediment samples were collected manually with the help of a plastic scraper and a plastic spatula from the uppermost 5-30 cm of the sediments of the river channels. They were dried at ambient room temperature and stored in the dark.

Surface water samples were collected at different locations along the water streams V©n Chàng, where uncontrolled wastewaters are discharge direct in. The samples were filtered and then split into acidified (using a 15% nitric acid) for heavy metals analysis and non-acidified samples for pH measurement in situ. In Xu©n TiÕn and Tèng X¸ only, wastewater from production sites are collected and analyzed.

Soils samples were taken from areas adjacent to the settlement drains, from the river channel and from family gardens in order to find out the contaminant pathway ´production-soil`. Additionally, soil samples were collected from some agricultural areas in which the flooding of wastewater may occur during heavy rainfall and in which farmers utilize wastewater for irrigation. Soil samples were collected with the help of a hand-boring machine. The depth of drilling was 1 meter. In each location 4 soil samples were taken: 0-25 cm (sample a), 25-50 cm (sample b), 50-75 cm (sample c), and 75 - 100 cm (sample d). Sampling tools were washed and cleaned with water before the next sample was collected.

For analyzing the dust producing from different manufacturing processes, masks were given to the workers for protection the respiration. After 8 hours using, the masks were taken off for SEM investigation.

Plant samples were collected and analyzed in order to find out the influence of the pollutants on the ecosystem. The plant samples are mixtures of different types of plants that grow on the riverbanks and drainage banks. They are used by the farmers as vegetables or as fodder. The plants were taken out with the root, washed with clean water, and dried immediately at ambient room temperature.

To identify the impact of metal pollutants on the inhabitants in the settlements with metal working trade, human hair was collected and analyzed. Hair from inhabitants of Hà Néi was used as control sample.

Table 1. Accuracy of the analytical data with reference to certified values of the international Standard Reference sample pacs- 1 (SD standard deviation, RSD relative standard deviation)

The determination of pH values in soil and sediment was done after [10]. The suspension is prepared by addition from 12 g of material and 25 ml 0.01M CaCl₂-solution. After intensive stir, the solution is already for pH- measurement. The moisture and the humus were estimated after Lewandovski et al., 1997 [10].

The water, soil and sediment samples were analyzed by ICP-AES and AAS after digestion by the Koernigswasser method. To control the accuracy of the analysis, one International Standard Sample pacs - 1 was prepared and analyzed using the same procedure (see Tab.1).

The element behaviour in water of V©n Chàng water stream, which is used as dischage stream for waste water as well as irrigation stream for rice field or vegetables, is very variable and strongly depended from the production branches. Along the water stream there are three sites of pollution´s input with remarkable changing of stream parameter and three different kinds of element behaviour: (i) high content of Cd, Ni, Zn and Cu in an alkalic condition; (ii) high content of Fe, Al, Cr in an acidic condition; and (iii) high content of Pb and CN, which loadings are going out of the settlement. Comparision the result with the permitable values B (TCVN B 1995) is it recognizes, that the concentration of most analyzed elements is higher than the norm value. The higher concentration of Ni and Cr or Zn in some locations is result of the discharge of waste water from plating sites. The element distribution in surface water is showed in the Fig. 2.

All sediment samples have a high percentage of C-organic matter (from 30.5 to 50%) with a mean pH value of 7.87 (ranges from 6.45 to 8.21). The moisture estimating is between 5.78% to 6.45%.

 The mean concentrations of Cd, Co, Cr, Cu, Mn, Ni, Pb, and Zn in sediment are given in Tab. 2. As expected the heavy metals concentration in sediment is very high. In the exposed areas by local production, all measured heavy metals are with critical values, except Co. The maximum values in stream sediment are determined for Zn of 15000 mg/kg, for Ni: 12000 mg/kg, for Cr: 10200 mg/kg, for Pb: 681 mg/kg, and for Cd: 6.6 mg/kg. It is recognized, that the element distribution in stream sediment is the result from resedimentation processes caused by temporary irrigation. The ponds sediment in the exposed area shows extremely high concentrations (maximum values) of Cr: 15440 mg/kg and Zn: 17 210 mg/kg.

Table 3. Mean concentration and enrichment factor of heavy metals in soil of the study area (mg/kg)

The element distribution in soil is very variable and ` hot pot ` like. In non-exposed sites, no critical values for measured elements are determined. However, a slight increasing of Zn, Pb, Mn, Cr and Cu in the samples inside in comparison with the samples outside is recognized. In the exposed sites (living/production sites) critical values for Zn, Pb, Cd and Cu are determined. Soil in the farmer garden contains the highest values of Cd, Cu, Mn, Pb and Zn: Cu (up to 490 mg/kg), Pb (up to 580 mg/kg), and Zn (up to 7 200 mg/kg). Outside of the settlements the heavy metals, contents in the soil surface (0-25 cm) are lightly enriched, while inside of the settlement an enrichment of element concentration in the deeper horizons (25-50 cm) can be observed. In the living and production area, at some sites a high accumulation of elements in the horizon 25-75 cm can be detected too. These tendency, however of element distribution in soil cannot clearly be seen at all investigated sites.

The elements Co and Ni do not increase in comparison to the local geological background. The concentrations of heavy metals in the soils of Dong Coi only lightly increase in comparison with the local background. The elements Co, Ni, and Cr do not increase. It is observed, that the concentrations of elements increase in the fine soil fraction due to the heavy metals tend to concentrate both within, and on the surface of soil particles. Hence, the fine fraction with expandable layers has larger contact surface area, which leads to the increase of metal sorption intensity [12]. The variability of concentration of Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn in soil are given in Tab. 3.

Analyzing the masks using by workers it is observed, that dust resulting from different production processes content a lot of small metal particles, Al-, iron particles etc. (SEM-photos), which are caused by flying ash. Iron bearing ash spheres have a remarkable amount of a diameter <2µm. The detected Al-grains show sharp edges under the scanning electron microscope, which could enhance inner injuries and inflammations.

Figure 4. Percentages of anthropogenic contribution to the total concentration of various heavy metals in relation to the local geological background in the soil exposed area (V©n Chàng, Xu©n TiÕn and Tèng X¸)

In the non-exposed area, the soil shows nearly no anthropogenic input of heavy metals, only by the elements Cd, Cu and Mn a very low percentage of input is recognized. Figure 5 shows the percentages of the anthropogenic input to the sediments of watercourse in exposed area in relation to the local geological background values. These inputs are as follows: high for elements Cr, Ni, Zn and Cu (95 - 97%); for elements Mn, Pb and Cd between 90 and 88%. For Co element, there is no input to be recognized.

 3. Impact assessment on the environment-inhabitant

In order to have a better understanding of the environment impact on human and ecosystem and to determine the pathway production-environment-inhabitant, plant, water snail and hair samples were collected and analyzed. The plant samples were digested at the Institute of Hygiene and Environmental Medicine by the temperature-pressure-digestion method using microwave model MDS-2000, and were estimated of heavy metals by ICP-AES and AAS at the Institute of Geological Sciences (Greifswald University). The snail shells were prepared and analyzed at the Institute of Chemistry and Biochemistry, University of Greifswald, Germany. The results are shown in Figs. 6 and 7 and Tab. 4

Table 4. Heavy metal concentration in plants in the study area (mg/kg d. m.).

Shells of water snail are known to accumulate relatively high heavy metals concentration [9]. In the case of Nam §Þnh this is particularly true for Cu and Zn, while Pb and Cd have a lower value. The total concentration ranges of 9.14 – 20.61 mg/kg d.m for Cu; 0.59 – 1.43 mg/kg d.m for Pb; 0.020 – 0.087 mg/kg for Cd and 9.72-26.18 mg/kg for Zn. The general trend of the mean concentration of trace elements in the snail shell materials is Zn>Cu>Pb>Cd. The element distribution is showed in Fig. 6.

 After an investigation of [8] the most part of trace elements is more enriched in the soft tissue than in the hard valve of the mussels they analyzed.

Plants are known as an intermediate reservoir for heavy metals, through which they move from soil to man and animals, it is necessary to determine the heavy metal contents in plants, which are used by the inhabitants as fodder or vegetables. The result shows (Tab.4) that plants growing in the wastewater discharge area contain high values of Cd and other heavy metals like Cu, Cr, Ni and Zn. These samples were collected on the bank of a lake situated NE of the V©n Chàng settlement and on the bank of the V©n Chàng River. Generally the metal content in plants has the primary source in the soil [12]. However a relation between the content of Cr in plants and the total Cr in soil cannot be observed in V©n Chàng. Consequently, high levels of metals in plants are potential sources of an input of toxicity to the food chain.

The digestion of hair samples was done at the Institute of Hygiene and Environmental Medicine and at the Institute of Chemistry and Biochemistry (Greifswald University). The estimation of heavy metals was done by ICP-AES and AAS at the Institute of Geological Sciences too (Greifswald University). Additionally, to recognize any external influence like dust on the analytical results, each hair sample was divided into three parts and was prepared by three different procedures before digestion: (1) without any further treatment; (2) washing with distillated water and (3) washing with triton X-100. No strong tendency in the difference of the analytical results was noticed.

It is to consider, hair is an elimination path and storage place for many metals in human body. That means, when a metal elimination in hair is realized, than a great amount of these metals is available in the body. High concentration of metals in hair are an indication that large amounts of these metals are in the body. This is the case of the inhabitants of V©n Chàng. In Fig. 7a the heavy metal concentration in the hair of inhabitants of V©n Chàng is compared to the heavy metal concentration of inhabitants of Hà Nội City. It is clear, that the concentration of metal in the hair of inhabitants of V©n Chàng is higher than that

Figure 7a,b. Heavy metal concentration in the hairs of V©n Chàng inhabitants in comparison to the heavy metal concentration in the hair of Hà Néi inhabitants.

in the hair of inhabitants of Hà Néi. Fig. 7b shows the concentration of metal in the hair of three groups of people in this metal working settlement: (1) Children of under 12 years of age, (2) workers between 30 and 50 years of age and (3) people of over 70 years of age. The exploration of the employed inhabitants (age group of 30-50 years) is reflected by the element distribution in their hairs (about a magnitude higher as for juniors and seniors). It is clear to recognize, that the people, whose have direct contact with metal manufacturing work are the ones most affected by heavy metals. The high content of heavy metals in hairs of inhabitants is a consequence of ingestion and inhalation of heavy metals enriched vegetables and atmospheric particulate materials.

Thus exposures to heavy metals, such as those observed in this study indicate the critical dimension of pollution’s feedback to the residents of the studied area. They are also likely to exert potentially serious human health effects in the region.

The present data document the intensive impact of the metal manufacturing on soil and sediment in the watercourses of three typical production sites of Nam §Þnh province. High percentage values of anthropogenic input and high enrichment factors of various heavy metals in sediment and soil indicate that the study area is highly polluted by heavy metals.

The high content of various heavy metals in the hair of inhabitants and in plants indicates the toxic pollution dimension on people and on vegetables of the study area.

The results of this study provide further information about the most common pollutant pathways in this region. They are also an important database, which would be useful for a design of a microbiological in-situ treatment system for the elimination of pollution.

The authors would like to thank BMBF, Germany and MOST, ViÖt Nam for financial support. The Department of Science, Technology and Environment from Province Nam §Þnh is greatly acknowledged for the helpful assistance by our work. The laboratory analyses were carried out at the Greifswald University, Germany by Dr. Juergen Eidam, Dr. Harald Below, Dr. H. Kahlert and Manfred Zander. They are greatly appreciated.

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