MODERN BIOGEOCHEMISTRY: SECOND EDITION Phần 9

356 CHAPTER 17 Figure 19. Critical loads of sulfur at terrestrial ecosystems of South Korea (Park and Bashkin, 2001). the Pusan-Ulsan industrial agglomeration takes place and minimum in the north-eastern part. Accordingly, a significant part of Korean ecosystems was subjected n intensive input of S acid-forming compounds. The values of exceedances of sulfur deposition over sulfur critical loads (ExS) are shown in Figure 20. During 1994–1997 the Sdep values were higher than CLmaxS values at about one third of terrestrial Korean ecosystems (38%). Among them, the ExS values were in the range 176–500 eq/ha/yr for 16.1% of total number of ecosystems, in the range of 500–1,000 eq/ha/yr were for 7.9%, in the range of 1,000–2,000 eq/ha/yr were 10.7% and the values even higher than 2,000 eq/ha/yr were found for 3.5% of Korean ecosystems. The other part of Korean territory (61.8%), where the sulfur depositions were relatively less but critical load values are relatively higher (see Figure 18), was not subjected to excessive input of sulfur-induced acidity. This area can be considered as sustainable to sulfur input. Aswehavementionedabove,duringthe1990supto30–35%ofsulfurdeposition was due to emission of SO2 by transboundary sources, occurred mainly in China. TRANSBOUNDARY N AND S AIR POLLUTION 357 Figure 20. Exceedances of critical loads of sulfur over South Korea (Park and Bashkin, 2001). Thus, the emission abatement strategy in South Korea has to be developed taking into account both local and transboundary emission reduction in the whole East Asian domain. The values of CL and their mapping can present a good possibility for the creation of ecological optimization models. At present, these CL values and corresponding mappings have been carried out by national research teams in almost all the East Asian countries, such as China, Japan, South Korea, Asian part of Russia and Taiwan (Bashkin and Park, 1998). Accordingly, this national-based mapping can be considered as a scientific basis for decreasing local and regional air pollution in the East Asian domain. 3.6. Acid Deposition Influence on the Biogeochemical Migration of Heavy Metals in Food Webs Aninterestingstudyofacidraineffectsonthebiogeochemicalaccumulationofheavy metals (Cd, Cu, Pb, and Zn) in crops has been presented by Chen et al., 1998. The authors have compared the ratios of relative concentration of four heavy metals in the brown rice and leaves of vegetables sampled from acid rain affected areas and 358 CHAPTER 17 Table 5. The ratios of relative concentration of heavy metals in brown rice and the leaves of vegetable species growing in Lung-tang area (affected by acidic rains) and Lung–luan–tang area (non-affected by acidic rains) from 1996 to 1997 in Taiwan (Chen et al., 1998). acid rain/non-acid Ratio in acid rain/non-acid rain affected area rain area Rice and vegetable species (sampling number) Cd Cu Pb Zn Rice Rice, (Oryza sativa Linn.) Sweet potato, (Ipomoea bataus) Welsh onion, (Allium fistulosum) 24/15 Vegetables 14/9 10/12 1.25 1.05 1.09 1.03 1.00 1.45 1.07 1.11 0.89 1.48 3.08 2.03 Pickled cabbage, (Brassica chineniss) Chinese chives, (Allium tuberosum) Mustard, (Brassica juncea) Lettuce, (Lactuce sativa) Chickweed, (Alsine media) Garlic, (Allium sativum) Kohlrabi, (Brassica campestris) Cabbage, (Brassica oleracea) Tassel flower, (Amaranthus caudatus) Celery, (Apium graveolens) Spinach, (Spinacia oleracea) Coriander, (Coriandrum stivum) Basil, (Ocimum basilicum) Radish, (Raphanus sativus) Pepper, (Capsicum frutescens) Kidney bean, (Phaseolus vulgaris) Water convolvulus, (Ipomoea aquatica) 3/10 5.03 1.23 7/5 4.97 0.70 2/4 — 1.59 6/8 3.73 1.87 3/1 — 2.40 6/7 0.85 2.44 1/1 2.00 2.00 2/1 — 1.99 6/2 0.97 2.23 2/1 — — 2/1 — 0.75 1/4 8.02 5.01 1/3 — 8.05 4/2 — 2.76 3/4 1.97 2.04 3/10 2.07 1.78 6/3 0.28 1.97 —# 1.33 0.08 1.56 — 2.19 1.00 1.97 — 0.36 — 4.64 — 5.50 — 3.06 — 1.47 — 1.55 0.80 0.42 — 1.80 — 0.36 — 1.08 3.92 0.88 1.09 1.44 3.50 0.66 # The ratios of relative concentration can not be calculated because the heavy metal contents of rice or vegetables growing in an acidic rain area or in a non-acidic rain area is lower than the method detection limit (MDL) of heavy metals. non-affected areas. The data indicated that the ratios of relative concentration of Cd, Cu, Zn in brown rice and 19 vegetable species growing in an acid rain area (Lung– tang) and growing in an acid rain non-affected area (Lung–luan–tang) sampled from 1996to1997arealmosthigherthan1,orhigherthan3,exceptforPb(Table5).These TRANSBOUNDARY N AND S AIR POLLUTION 359 results suggested that biogeochemical accumulation of heavy metals in brown rice seems not affected by long-term acid rains but on the contrary for vegetables species in northern Taiwan. Therefore, these accumulations are dangerous for humans eating the vegetables produced in acid rain affected area. Table5alsorevealsthatthemeanconcentrationofPbinbrownriceandleavesof19 vegetable species from acid rain affected areas and non-affected areas are almost the same.Ontheotherhand,theratioiscloseto1.Thisresultindicatedthatacidraindoes notinfluencethebiologicalaccumulationofPbinbrownriceandleavesofvegetables species sampled in Taiwan. Some studies have indicated that concentration of Pb in the crops was only affected when the concentration of Pb in the soils is higher than 500 mg/kg (Kabata–Pendias and Pendias, 1992). Sloan et al. (1997) also indicated that the relative bioavailability of biosolids-applied heavy metals in agricultural soils was Cd ÀZn >Ni >Cu ÀCr >Pb, for the soils 15 years after biosolids application. It is quite consistent with the results achieved by research of Chen et al. (1998). Thus, the phyto-availability of heavy metals caused by acid deposition followed the trend: Cd >Zn >Cu À Pb. Finally, this determines the exposure pathways and environmental risk values to human beings. CHAPTER 18 TRANS-BOUNDARY HM AIR POLLUTION Pollutionoftheenvironmentbyheavymetalsisthesubjectofconcernofanumberof national and international bodies. In 1998 a number of Parties to the Convention on Long-Range Trans-boundary Air Pollution (hereinafter the Convention) signed the Protocol on Heavy Metals (Protocol). The aim of the Protocol was to control atmo-spheric emissions of toxic metals (lead, cadmium and mercury). In accordance with theProtocoltheCo-operativeProgramforMonitoringandEvaluationofLong-Range Transmission of Air Pollutants in Europe (EMEP) provides assessments of pollution levels of heavy metals in the European region. Measurements of heavy metal concen-trations in the air and precipitation are carried out at the EMEP monitoring network. Along with that the Meteorological Synthesizing Centre-East (MSC-E) performs model assessments of depositions and air concentrations of heavy metals throughout the European region as well as trans-boundary fluxes between the European coun-tries (http://www.msceast.org/reps). In 2003 the Protocol on Heavy Metals came into force,andatpresentthesecondprioritymetals(As,Ni,Cr,Zn,Cu)areunderpollution assessment. In order to correlate the existing pollution levels with the environment risk to human and ecosystem health, they are compared with scientifically sound crit-ical loads, developed by the Working Group on Effects (WGE). The environmental risk of heavy metals is related to various sources, and the trans-boundary pollution plays a very important role for the European region. 1. MONITORING OF HEAVY METALS IN EUROPE 1.1. Emissions of Heavy Metals in Europe The resulting maps of the spatial distribution of lead, cadmium and mercury anthro-pogenic emissions in Europe in 2002 are presented in Figures 1–3 respectively (Ilyin et al., 2004). According to the available data the most significant sources of lead emissions are located in Central Europe (Poland, Germany), Southern Europe (Italy, Croatia, Serbia and Montenegro, Romania, Greece) and Eastern Europe (Russia). In contrast, emissions of cadmium are distributed more or less uniformly over Western, Central and Southern Europe except Poland, where emission levels are significantly higher. Low emissions are in Northern Europe and in some countries of Eastern Eu-rope (Belarus, Ukraine). The most significant emissions of mercury are also located in Western, Central and Southern Europe. The total emission of lead, cadmium and mercury in Europe in 2002 amounts to 8,003 t/yr, 257 t/yr and 180 t/yr respectively. 361 ... - tailieumienphi.vn