Phytotoxicity of Dredged Sediment from Urban Canal As Land Application

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Phytotoxicity of dredged sediment from urban canal as land application

Y.X. Chena,*, G.W. Zhua, G.M. Tiana, G.D. Zhoub, Y.M. Luoc, S.C. Wuc aDepartment of Environmental Engineering, Zhejiang University, Hangzhou 310029, People’s Republic of China bEnvironmental Protection Institute of Hangzhou, Hangzhou 310005, People’s Republic of China cInstitute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, People’s Republic of China

Received 29 March 2001; accepted 20 August 2001

‘‘Capsule’’: Pakchoi (Brassica chinensis L.) was used as an indicator of phytotoxicity of dredged sediment.

Abstract Phytotoxicity of dredged sediment from Hangzhou section of the Grand Canal as land application was evaluated by pakchoi (Brassica chinensis L.) germination tests and pot experiments. Germination rates of pakchoi in the dredged sediment and in sediment-applied soils were both significantly higher than that in the soil controls, while the germination rate between the sediment- applied soils was no significant difference. In pot experiments, plant height and biomass were increased by the dredged sediment application rate in the rate of lower than 540 t ha1, but decreased when the application rate was over this rate. Concentra- tions of Zn and Cu in pakchoi were linearly increased with the increasing of the application rate of the dredged sediment. Both plant height and biomass of pakchoi in sediment-treated red soil were higher than that in sediment-treated paddy soil, regardless the application rate. The results suggest that plant biomass of pakchoi may be used as an indicator of the phytotoxicity of the dredged sediment. It also showed that red soil is more suitable to accept the dredged sediment than paddy soil, and 270 t ha1 is a safe application rate both in red soil and paddy soil. # 2002 Elsevier Science Ltd. All rights reserved. Keywords: Sediment; Land disposal; Heavy metal; Biological accumulation coefficients; Risk assessment

1. Introduction Woodard, 1999). Thus, two thirds of the dredged sediment from the canal was planning to land application Large amount of sediment was dredged each year for near the canal. However, as the land applied dredged the need of ecological restoration of degenerative water sediment is subjected to drying and oxidation, transfor- bodies and maintenance of ports and waterways (For- mations in the chemical forms of heavy metals may stner and Calmano, 1998), but the disposal of dredged aﬀect their mobility and bioavailability (Gambrell, sediment may also cause environmental problems (Tack 1994), and phytotoxicity may be occurred by the et al., 1998). The Grand Canal of China, which is more dredged sediment land application. Therefore, it is than 1700 km long from Beijing to Hangzhou, has been necessary to assess the environmental risk of the seriously polluted by industrial wastewater and sewage, dredged sediment before its land application. especially in the urban section. In the Hangzhou sec- Various single and sequential chemical extraction tion, 4,000,000 m3 sediment is dredging for the ecologi- procedures are the common methods for evaluation of cal restoration. Zinc, copper, cadmium and lead are the the bioavailability of metals in sediments (Pickering, major pollutants in the sediment (Weng and Chen, 1981; Rauret, 1998), but these methods do not success- 2000; Zhu et al., 2001). In view of resource recycling, fully predict the long-term phytotoxicity of metals in land application is a sustainable and economical outlet various soil types (Salomons, 1995; Muller and Pluquet, of the dredged sediment (Muller and Pluquet, 1998; 1998). Moreover, apart from heavy metals, salinity and + NH4 ion in sediments may also be hazardous to plants * Corresponding author. Tel.: +86-571-86971159; fax: +86-571- (Tiquia and Tam, 1998). So the bio-indicator is more 86971411. accurate to assess the phytotoxicity of dredged sediment E-mail address: [email protected] (Y.X. Chen). than chemical extraction methods, and may provide

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more directly useful information about the phytotoxi- Table 1 city of dredged sediment. Furthermore, bio-indicator is Basic properties of the soils and dredged sediments in the experiments also relatively inexpensive and easy to record (Vasseur Property Dredged Red Paddy et al., 1998). materials soil soil Pakchoi (Brassica chinensis L.), a kind of Chinese Brassica chinensis pH (H2O 1:5) 6.95 4.84 5.92 cabbage ( ), is one of the most popular ECECa, mmol kg1 111 91.4 140 vegetables in China. It has relatively high uptake coeﬃ- Saturated water content, % 62.09 62.84 83.46 cient for heavy metals (Lee et al., 1998; Li et al., 1998), Organic matter, g kg1 32.5 14.8 35.6 and it grows quickly (averagely harvest in 40 days from Total N, mg kg1 2301 320 450 1 sowing). It was also popular to be used in studying the Total P, mg kg 1136 349 758 Total K, g kg1 7.3 8.9 18.6 environmental risk of soil contamination by heavy Total Ca, g kg1 37.9 0.8 6.7 metals (Hirsch, 1998; Chen et al., 2000). Therefore, it Total Mg, g kg1 10.6 2.3 8.2 may be a good plant material for phytotoxicity evalu- Olsen P, mg kg1 89.1 10.9 58.7 ation of the dredged sediment from the canal. Total Cd, mg kg1 3.50 1.40 1.51 1 The objectives of this study are: (1) evaluate the fea- Total Cu, mg kg 196 19.3 28.0 Total Pb, mg kg1 133 53.5 23.3 sibility to use pakchoi indicating the phytotoxicity of Total Zn, mg kg1 1257 54.23 81.45 dredged sediment from urban canal as land application; Total Hg, mg kg1 0.65 0.14 0.20 and (2) make sure that which kind of soil type in Total Cr, mg kg1 103.2 51.6 55.1 the local area is more suitable for the application of the Total As, mg kg1 23.42 8.86 7.22 b 1 dredged sediment and determine the opportune appli- DTPA extracted Cd, mg kg 0.22 0.07 0.12 DTPA extracted Cu, mg kg1 16.66 1.31 6.54 cation rate. DTPA extracted Pb, mg kg1 7.66 14.08 6.68 DTPA extracted Zn, mg kg1 57.95 1.77 3.64

2. Materials and methods a ECEC, effective cation exchange capacity. b DTPA, diethylenetriamine pentaacetic acid. 2.1. Sediment and soils sampling treatment had six replicates, thus resulted in 72 pots for Dredged sediment, red soil and paddy soil were sam- six red soil treatment and six paddy soil treatments. pled in 12–16 March 1999. The top layer sediment (0–50 Soils, mixtures and sediment in pots were saturated at cm) was sampled from the urban section of the Grand water content of 70% with distilled water 5 days before Canal (industrial district of Hangzhou), which is pol- sown for the ion equilibrium in soil solution. Solutions luted by long-term industrial wastewater and sewage of K2HPO4,P2O5 and CO(NH2)2 were applied to the drainage (Weng et al., 1997). Surface red soil (an acidic pots in the rate of 1.2 g N, 0.4 g P, 0.8 g K per pot to Oxisol), which is the prevalent soil type in Hangzhou diminish the effect on the growth resulting from the dif- area, was sampled from an orchard near the canal. ference of nutrition between the soil and the sediment. Paddy soil, another popular soil type in Hangzhou area, Two seeds of pakchoi were sown in each pot to ensure was sampled from a rice field 200 m away from the to get the sprout, and one of them was discarded after canal. Basic properties of the dredged sediment, red soil germination. During the experiment, plants were water and paddy soil were presented in Table 1. Before used, every day with 50 ml distilled water. Ten days after dredged sediment, red soil and paddy soil were air- germination, every pot was put on a bigger pot that filled dried, crushed, mixed thoroughly and passed through a with sands, watered the sand every day to keep enough 2 mm sieve, respectively. moisture for pakchoi growth. Tested plants in three pots of each treatment were harvested in 20 days after sow- 2.2. Experimental design ing, and another three pots of plant in each treatment were harvested in 40 days after sowing. The plant height The pot experiment of pakchoi was carried out in the of pakchoi was measured before harvest, and the fresh greenhouse, cylindrical polyvinyl chloride pots with 15 weight of the plant was also recorded immediately after cm in diameter and 15 cm in depth were used. For each harvest. Then the plant was dried at 70 C for 48 h for kind of soil, six kinds of treatments were carried out, dry mass determination and tissue analysis. Plant shoots which were soils (CK), 4:1 mixture of soil and sediment were ground, digested and analyzed for Cd, Cu, Pb and (T-A), 3:2 mixture of soil and sediment (T-B), 2:3 mix- Zn. After pot experiment, the DTPA extractable Cd, ture of soil and sediment (T-C), 1:4 mixture of soil and Cu, Pb and Zn in potted soils, soil–sediment mixtures, sediment (T-D), and sediment (DS). The soil–sediment and sediment were analyzed. mixtures were prepared with air-dried soils and sedi- Germination test was carried out in petri dishes (diam- ment, and were thoroughly mixed. Each pot contained 2 eter 10 cm and depth 1.5 cm). For each treatment, 75 g kg soils, soil–sediment mixtures, or sediment, and each soil was put in petri dish and moisten with deionized 中国科技论文在线 http://www.paper.edu.cn

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water to 70% of saturated water content. Then 50 seeds 3. Results were sowed in surface soil (depth within 2 mm) in each petri dish and incubated 5 days at 20 C. Each treat- 3.1. Pollution of the sediment ment was triplicate. After incubated for 5 days, the number of germinated seeds was counted, and the ger- Compared with red soil and paddy soil, the sediment mination rate was calculated as: from the Grand Canal is fertile. Contents of total N, total P and Olsen-P in the sediment were much higher Germination rateðÞ % than that in red soil and paddy soil (Table 1). Thus the ¼ ðÞnumber of germinated seeds = application of the sediment may increase the fertility of number of sowed seeds 100 the soil, and be beneficial to the growth of the crops. Table 1 showed that, according to the EPA’s standard (Wallace and Wallace, 1994), concentrations of heavy metals in the dredged sediment were lower than the 2.3. Analytical methods ‘‘clean’’ concentration in sludge (limitation is 41 for As, 39 for Cd, 1200 for Cr, 1500 for Cu, 300 for Pb, 17 for The pH of dredged sediment and soil was determined Hg, 2800 for Zn, all in mg kg1), which means that by a glass combination electrode (soil:water ratio, 1:5 the dredged sediment may be applied to land beyond the v:v), organic matter by Walkley and Black method EPA’s standard. Compared with the Environmental (Nelson and Sommers, 1982), and soil electrical con- Quality Standard for Soils (Chinese EPB, 1995), only ductivity was determined in 1:1 water soil ratio (Carter, Zn was overtopped the standard (500 mg kg 1), which 1993). means that the dredged sediment were ‘‘clean soil’’, The ‘total’ trace metal concentrations were deter- instead of ‘‘solid wastes’’, if Zn had not over 500 mg 1 mined after digestion with HF–HNO3–HClO4 proce- kg . And according the Limitation of Pollutants in dures (John, 1972) by Perkin-Elmer analyzer-100 atomic Solid Wastes for Agricultural Use of China (Chinese absorption spectroscopy (AAS) with deuterium lamp EPB, 1984), all the heavy metals concentrations were background correction. Percolate water samples were lower than the standard. Therefore, it is undoubted that first filtered through a 0.45-mm filter before the deter- the dredged sediment from the Hangzhou section of the mination of dissolved metal concentrations. The stand- Grand Canal could be used in land. ard calibration was performed with standard metal Cd, Cu, Pb, and Zn in the dredged sediment were solution (provided by Perkin-Elmer company) in 1% mainly existed in residual fraction (Fig. 1), indicating HNO3, the background absorption was accounted with that a large part of these metals will not be uptake by the blank of digestion reagent. The bio-available heavy the plant and soil organisms. However, fractions of metals were evaluated by diethylenetriamine pentaacetic heavy metals in the sediment may be changed as land acid (DTPA) extraction procedure (Lindsay and Nor- application with the decomposition of the organic mat- vell, 1978), fractions of heavy metals in soils and sedi- ter. Moreover, because the total content of Cd, Cu, Pb ment was sequential extracted following the method and Zn in the sediment is by far higher than that in red of Tessier et al. (1979). And the particle size analysis of soil and paddy soil, the absolute value of the salt dis- soils and dredged sediment were carried out by pipette placeable metals in sediment was higher than that in red method (Carter, 1993). soil and paddy soil. The content of salt displaceable Cd, For heavy metal analysis in plant, plants were first Cu, Pb and Zn in sediment was 0.15, 3.20, 2.50 and rinsed with tap water and then with distilled water, 3.40 mg kg1, however, in red soil, it was only 0.04, dried at 70 C for 48 h, and then ground with an agate 2.49, 0.32, 1.91, respectively. The amount of DTPA- mortar. The concentrations of Cd, Cu, Pb, and Zn were extractable Cu and Zn in sediment was also higher than also measured by AAS after HNO3–HClO4 digestion those in red soil and paddy soil (Table 1). Thus, the (Environmental Protection Agency of China, 1999). potential environmental risk of the dredged sediment must be considered. Cadmium in red soil and paddy 2.4. Statistical analysis soil, however, was mainly existed in salt-displaceable fraction and reducible fraction. The percentages of Germination rate was compared between treatments reducible fractions of heavy metals in two kinds of soils against the control using Chi-square analysis. Biomass were also higher than that in the sediment. was compared between treatments and between soils Moreover, direct application of the sediment without using two-way analysis of variance (ANOVA) with composting may cause the increasing of soil salinity. repeated measures. And the difference between the ger- Table 2 showed the electrical conductivity (EC) of the mination rate of pakchoi in red soil and paddy soil were soils, soils–sediment mixtures, and the sediment before used paired t-test. All the statistical analyses were per- pot experiment. It showed that application of the sedi- formed by SPSS for Windows. ment increased soil EC of both red soil and paddy soil. 中国科技论文在线 http://www.paper.edu.cn

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Fig. 1. Relative partitioning of Cd, Cu, Pb and Zn forms in the dredged sediment, red soil and paddy soil. Cd —— Cu –.–.–Pb––––Zn......

Table 2 Table 3 Soil electrical conductivity (S.D.)a of 1:1 water soil ratio extract before Germination rate of pakchoi per treatment pot experiments Treatment Germination rate (%) Treatment Soil electrical conductivity (dS m1) Red soil Paddy soil Red soil Paddy soil Control 63.3 57.3 Control 0.36 (0.01) 1.01 (0.01) T-A 82.0 72.7 T-A 1.41 (0.01) 2.21 (0.04) T-B 88.7 72.0 T-B 2.05 (0.19) 2.87 (0.12) T-C 82.7 62.7 T-C 2.72 (0.08) 3.13 (0.12) T-D 88.0 77.3 T-D 3.02 (0.10) 3.07 (0.21) DSa 78.7 78.7 DSb 3.11 (0.35) 3.11 (0.35) a DS, dredged sediment control. a S.D., standard deviation. b DS, dredged sediment control. ( 2=1.29, d.f.=4, P=0.86). Furthermore, between the red soil control and all the sediment-applied treatment, According to Bernstein (1975), there were almost negli- the difference was significant ( 2=6.62, d.f.=1, gible effects on yield of crop when soil EC of the P<0.005).For paddy soil, germination rate did not dif- saturation extract was in the range of 0–2 dS m1, the fered significantly between treatments ( 2=7.59, yields restrict of very sensitive crops in the range 0–2 ds d.f.=5, P=0.19). But the difference of the germination of 2–4 dS m1, and, yields restrict of most crops over 4 rate between paddy soil control and all the sediment- dS m1. In this study, soil EC was extract in soil: water applied treatment was also significant ( 2 =4.20, ratio of 1:1, so the EC is probably lower than that d.f.=1, P=0.04). This result suggests that the sediment- extract by saturation condition. Thus, excessive appli- applied soils were more suitable for the germination of cation of sediment on the red sol and paddy soil may pakchoi. affect the growth of corps. In general, germination rate of pakchoi in red soil treatment was significantly higher than that in paddy 3.2. Germination rate of pakchoi soil treatment (F=8.77, d.f.=1, P=0.03). But the germination rate between red soil control and paddy soil The results showed that the application of dredged control was no significant difference ( 2=0.05, d.f.=1, sediment on both red soil and paddy soil significantly P=0.85). increased the germination rate of pakchoi (Table 3). For red soil, germination rate differed significantly between 3.3. Growth of pakchoi treatments ( 2=11.29, d.f.=P<0.05), and the lowest germination rate was in the red soil control treatment. If The results in pot experiments were quite different this treatment was removed from the analyses, there was from that in germination test. The growth of pakchoi no significant difference between the rest treatments was best in the 20 or 40% sediment-applied treatment 中国科技论文在线 http://www.paper.edu.cn

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Table 4 Means (S.D.) of plant heights and biomass of pakchoi per treatment

TreatmentHeight 20 days (cm)Fresh weight 20 days (g)Dry weight 20 days (g)Height 40 days (cm)Fresh weight 40 days (g)Dry weight 40 days (g)

Red soil Control 9.2 (2.7) ab 10.0 (2.1) cde 0.83 (0.18) def 21.0 (2.3) de 50.6 (3.9) g 3.19 (0.26) cd 20% DSa 7.2 (4.0) ab 15.8 (3.4) b 1.28 (0.26) b 28.2 (2.9) a 84.2 (4.7) a 4.35 (0.38) a 40% DS 11.2 (3.2) a 22.4 (4.0) a 1.84 (0.35) a 26.4 (1.4) ab 69.0 (3.1) b 3.58 (0.24) bc 60% DS 9.4 (2.9) ab 13.6 (2.5) bc 1.11 (0.23) bcd 26.1 (3.1) ab 62.5 (5.2) cd 3.61 (0.41) bc 80% DS 9.1 (2.4) ab 10.6 (1.7) cd 0.94 (0.14) bcde 23.8 (1.9) bcd 58.0 (2.4) cdef 3.03 (0.18) d DS 6.4 (2.0) ab 6.4 (1.5) de 0.65 (0.11) ef 18.2 (1.4) e 35.8 (2.2) h 2.11 (0.17) e

Paddy soil Control 5.8 (3.1) b 5.4 (1.9) e 0.50 (0.13) f 24.8 (1.2) abcd 57.0 (3.5) def 3.39 (0.24) ab 20% DS 8.1 (2.4) ab 7.1 (2.2) de 0.57 (0.16) ef 25.4 (3.2) abc 63.3 (3.3) c 4.02 (0.27) cd 40% DS 8.9 (2.9) ab 17.5 (3.1) b 1.26 (0.27) bc 25.3 (1.8) abc 60.0 (2.6) cde 3.63 (0.20) bc 60% DS 8.5 (2.6) ab 14.2 (2.8) bc 1.10 (0.22) bcd 23.1 (1.2) bcd 55.7 (2.5) efg 3.23 (0.20) cd 80% DS 8.1 (2.0) ab 10.8 (3.0) cd 0.87 (0.25) cdef 22.1 (1.6) cd 53.0 (2.8) fg 3.19 (0.23) cd DS 6.4 (2.0) ab 6.4 (1.5) de 0.65 (0.11) ef 18.2 (1.4) e 35.8 (2.2) h 2.11 (0.19) e

a DS, dredged sediment control.

(T-A and T-B), and the worst in dredged sediment con- Table 5 trol (DS), red soil control, or paddy soil control (CK). Two-way ANOVA with repeated measures on plant height and bio- In 20 days, treatment of soils in 40% dredged sediment mass applied had the highest plant height and biomass Sources d.f. MS F values F critical P (Table 4), treatments of over this application rate had decreasing trend with the increase of application rate of Between treatments Plant height the sediment. In 40 days, trends of height and biomass 20 days 5 9.81 1.30 2.62 0.295 of pakchoi along with dredged sediment application 40 days 5 55.63 12.91 2.62 <0.0001 rate was similar to that in 20 days, but the peak value was transferred from 40% DS treatment to 20% DS Biomass treatment (Table 4). 20 days 5 141.66 21.11 2.62 <0.0001 40 days 5 963.74 86.71 2.62 <0.0001 Table 5 showed that the results of statistical analysis between treatments and between soils. It showed that, Between soils the height of pakchoi was no significant difference at Plant height 20 days among treatments, while in 40 days it was 20 days 1 11.22 1.49 4.26 0.234 significant difference (P<0.0001); plant biomass of 40 days 1 5.76 1.34 4.26 0.259 pakchoi was significantly different among treatments Biomass both in 20 days and in 40 days. In general, plant height 20 days 1 75.69 11.28 4.26 0.0026 of pakchoi in red soil treatment was higher than that 40 days 1 311.52 28.03 4.26 <0.0001 in comparable paddy soil treatment, but the difference was not significant (P>0.05); biomass between them, however, was significant different both in 20 days and in 40 days. between the two soil types, too (Fig. 2). Concentrations The results suggest that the sediment application of Zn in pakchoi, which was the key heavy metal in the caused both beneficial and harmful effects on pakchoi dredged sediment, increased significantly with the depending on the application rate. Beneficial effects, increasing of dredged sediment application rate in both such as increasing the nutritious elements and improv- soil types. Copper, the second serious polluting heavy ing soil physicochemical properties, were the major metal next to Zn, had the similar trend with Zn. With effects when the application rate was lower than 40% the increasing of application rate of the sediment, cad- (Table 4). However, when the application rate was mium, however, decreased at first and followed by higher than this value, harmful effects, such as toxicity increasing as the application rate over 80% for red soil of heavy metals, maybe overrun the beneficial effects. and 40% for paddy soil. Pakchoi in DS had the highest Cd concentration in all the treatments. In red soil 3.4. Heavy metals contents in pakchoi treatments, lead approximately increased with increasing of dredged sediment application rate. But in paddy Concentrations of Cd, Cu, Pb and Zn in pakchoi were soil, it was disordered with high standard deviation. also varied drastically in different treatments, and This can be likely ascribed to the difference of growth 中国科技论文在线 http://www.paper.edu.cn

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Fig. 2. Concentrations of Cd, Cu, Pb, Zn in pakchoi grown on red soil (^) and paddy soil (*) with diﬀerent dredged sediment treatments (1, control; 2, 20% dredged sediment; 3, 40% dredged sediment; 4, 60% dredged sediment; 5, 80% dredged sediment; 6, dredged sediment).

rate between treatments, which may lead to different BAC of heavy metals in red soil treatments was uptake of Pb. mainly lower than that in paddy soil (Table 6) except for In order to investigate the influence of heavy-metal Zn. This suggests that the soil pH of red soil did not concentration in soil-sediment mixtures on uptake by strongly affect the phytotoxicity of heavy metals in the plant, the biological absorption coefficients (BAC) was sediment. used (Table 6). BAC is the ratio of trace element concentrations in plant to those in soils (Brooks, 1983). The 3.5. DTPA extractable heavy metals in soils results showed that Cd had the highest BAC with the mean value of 3.15, followed by Zn, Pb, and Cu, The DTPA extractable cadmium, copper, and zinc with the mean value of 0.51, 0.35 and 0.13, respectively. were increased with the increasing of application rate of This result was similar to that obtained by Lee et al. the dredged sediment (Fig. 3), but DTPA extractable (1998), who found that Chinese cabbage had the highest lead in red soil treatments decreased. This trend was BAC among several crops and vegetables. BAC of Cd similar to that of concentrations of heavy metals in was extraordinary high in red soil and paddy soil con- plants, suggesting that the DTPA extractable fraction of trol (14.23 for red soil and 14.41 for paddy soil), owing heavy metals in sediment had a well relationship with to the low Cd concentrations and the relatively high the their availabilities. After pot experiment, the DTPA percentage of the salt-displaceable fraction in two soils extractable zinc, copper, and lead decreased, however (0.11 mg kg1 in red soil and 0.13 mg kg1 in paddy that of cadmium increased. This indicated that zinc, soil). copper, and lead maybe transfer to more stable frac- BAC of pakchoi for all the four heavy metals sig- tions through the cultivation, while cadmium maybe nificantly decreased with the increasing of dredged transfer to more mobile fraction. sediment application rate. This was similar with the result obtained by Chen et al. (2000). With the increasing of heavy metals in soil, pakchoi may adjust physio- 4. Discussion logical activities to decrease the absorption of heavy metals, including the decreasing of plant biomass and Germination is a complex physiological process of the growth rate (Xu and Yang, 1995). plant growth. The mainly environmental conditions 中国科技论文在线 http://www.paper.edu.cn

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Table 6 This study also showed that plant height and biomass Biological absorption coefficients of Cd, Cu, Pb, and Zn in pakchoi were more useful indicators for the assessment of phy- Treatment Red soil Paddy soil BACred:BAC paddya totoxicity of the dredged sediment in pot experiments. Vasseur et al. (1998) found a similar result when he used Cadmium the clover as the indicator of phytotoxicity of sewage Control 14.23 14.41 0.99 T-A 1.86 2.09 0.89 sludge. However, as leafy plant, plant height of pakchoi T-B 0.63 1.16 0.54 varies widely, it is also infeasible to indicate the phyto- T-C 0.50 0.77 0.65 toxicity of the sediment for the large deviation (Table 4). T-D 0.57 0.53 1.07 The plant biomass of pakchoi was, however, sig- b DS 0.54 0.57 0.95 nificantly different between treatments, which may effi- Zinc Control 2.07 1.30 1.59 ciently indicate the phytotoxicity of the sediment. Both T-A 0.44 0.39 1.06 in 20 days and in 40 days, biomass between treatments T-B 0.29 0.25 1.19 was significantly different (Table 4). Since the relatively T-C 0.20 0.22 0.91 short growth period and wide distribution in China, T-D 0.20 0.22 0.94 pakchoi is a feasible plant to assess the phytotoxicity of DS 0.31 0.27 1.15 Lead dredged sediment by measuring its biomass. Control 0.23 1.12 0.21 The other objective of this study was to make sure T-A 0.23 0.99 0.24 whether red soil or paddy soil was more suitable for the T-B 0.16 0.38 0.42 application of the dredged sediment. Red soil is more T-C 0.10 0.34 0.30 prevalent than paddy soil in Hangzhou area. Moreover, T-D 0.11 0.27 0.40 DS 0.14 0.17 0.79 red soil is a typical lean and coherent soil in local area; Copper quite a lot of them were deserted field for low prod- Control 0.39 0.31 1.26 uctivity. Hence dredged sediment application is ben- T-A 0.14 0.12 1.22 eficial to red soil for increasing the fertility and T-B 0.09 0.10 0.89 improving soil physicochemical properties. However, T-C 0.07 0.08 0.89 T-D 0.05 0.07 0.83 because the pH of red soil is lower than paddy soil, it is DS 0.08 0.09 0.89 argued to apply the heavy-metal polluted dredged sediment on red soil. According to the result of this study, it a BAC, biological absorption coefficients. was obvious that the dredged sediment presented lower b DS, dredged sediment control. phytotoxicity as applied on red soil than on paddy soil. Germination rate, plant height and biomass of pakchoi affected it are: water, temperature, oxygen, light, carbon in red soil treatment were higher than that in paddy soil dioxide, and chemical substances (Bewley and Black, treatment, the BAC of heavy metals was also consistent 1994). Generally, to evaluate the phytotoxicity of the with this (Tables 3 and 4). It was abnormal as the soil or solid wastes, the extracted solution was used in availability of heavy metals was generally increased germination test (Zucconi et al.,1981; Tiquia et al.,1996, with the decreasing of soil pH (Salam and Helmke, 1981; Tiquia and Tam, 1998), and the result of germi- 1998). The reason may partly due to the high content of nation test mainly reflects the chemical characteristics of clay in red soil (Fig. 4). Soil pH, CEC, clay content, and the tested materials. However, application of solid organic matter content are the major factors influent the wastes affects not only the chemical characteristics, but availability of heavy metals in soils (McBride et al., also the physical properties. Thus the assessment of the 1997). Red soil is a typical clayey soil, and may remark- phytotoxicity of the soil or solid wastes only by extrac- able increase the clay content of the dredged sediment. ted solution may be un-prefect. In this study, germina- Furthermore, the difference of soil pH between treat- tion test was taken directly by solid materials instead ments was not significant (Table 7). Thus it could be of the extracted solution. The result showed that, concluded that heavy metals in red soil treatment were although the concentrations of DTPA extracted heavy more stable than that in paddy soil treatment. metals in dredged sediment were higher than those in The last objective of this study was to give the rough red soil and paddy soil controls (Fig. 3), the application application rate of the dredged sediment. According to of dredged sediment increased the germination rate of the biomass of pakchoi, both in T-A and T-B treat- pakchoi. This may be due to the increasing of soil ments, biomass of pakchoi was higher than that in con- nutrients and the improving of soil physicochemical trol treatment. In treatment T-C and T-D, biomass of properties (e.g. porosity and component of soil solution) pakchoi sometimes was worse than that in control with the sediment addition. Unfortunately, due to the treatment. Therefore, it may be feasible to apply the high deviation of the data, the germination test failed to dredged sediment in 40% rate. However, since the long- distinguish the difference between different application term prediction of metal migration is uncertain (Tack et rates of the sediment. al., 1999), it is safer to apply in 20% rate. Calculated as 中国科技论文在线 http://www.paper.edu.cn

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Fig. 3. Diethylenetriamine pentaacetic acid (DTPA) extractable fraction of Cd, Cu, Pb and Zn in treatments before and after pot experiment (R-B, red soil treatments, before pot experiments; R-A, red soil treatments, after pot experiments; P-B, paddy soil treatments, before pot experiments; P-A, paddy soil treatments, after pot experiments).

Table 7 Soil pH and organic matter content after pot experiment

Treatment Soil pH Organic matter content (%)

Red soil Paddy soil Red soil Paddy soil

Control 4.82 5.92 1.61 3.63 T-A 5.97 6.80 1.94 3.56 T-B 6.57 7.13 2.18 3.44 T-C 6.68 7.03 2.51 3.24 T-D 6.86 6.95 2.84 3.22 DSa 6.95 6.95 3.15 3.09

a DS, dredged sediment control.

between species, the exact application rate must be confirmed by field trial, and the long-term effect should Fig. 4. Particle size curve of red soil (^), paddy soil (&), and dredged be monitored. sediment (~) used.

the 15 cm depth of cultivated horizon, 20% of applica- References tion rate is equal to 270 t ha1 in the ﬁeld (bulk density of the dredged sediment is 0.9). Furthermore, as the Bernstein, L., 1975. Eﬀects of salinity and sodicity on plant growth. bioavailability of heavy metals varied drastically Annual Review of Phytopathology 13, 295–312. 中国科技论文在线 http://www.paper.edu.cn

Y.X. Chen et al. / Environmental Pollution 117 (2002) 233–241 241

Bewley, J.D., Black, M., 1994. Seeds: Physiology of Development and Rauret, G., 1998. Extraction procedures for the determination of Germination, 2nd Edition. Plenum Press, New York. heavy metals in contaminated soil and sediment. Talanta 46 (3), Brooks, R.R., 1983. Biological Methods of Prospecting for Minerals. 449–455. Wiley Press, New York. Salam, A.K., Helmke, P.A., 1998. The pH dependence of free ionic Carter, M.R., 1993. Soil Sampling and Methods of Analysis. Lewis activities and total dissolved concentrations of copper and cadmium Publishers, London. in soil solution. Geoderma 83 (3–4), 281–291. Chen, H.M., Zheng, C.R., Tu, C., Shen, Z.G., 2000. Chemical meth- Salomons, W., 1995. Long-term strategies for handling contaminated ods and phytoremediation of soil contaminated with heavy metals. sites and large-scale areas. In: Salomons, W., Stigliani, W.M. (Eds.), Chemosphere 41 (1), 229–234. Biogeodynamics of Pollutants in Soils and Sediments: Risk Assess- Chinese EPB, 1984. Limitation of Pollutants in Solid Wastes for ment of Delayed and Non-linear Responses. Springer, Berlin, pp. 1–30. Agricultural Use of China (GB4284-84). Chinese State Standard. Tack, F.M.G., Singh, S.P., Verloo, M.G., 1998. Heavy metals con- Chinese EPB, 1995. Environmental quality standard for soils, centrations in consecutive saturation extracts of dredged sediment (GB15618-1995). Chinese State Standard. derived surface soils. Environmental Pollution 103 (1), 109–115. Environmental Protection Agency of China, 1999. Monitoring and Tack, F.M.G., Singh, S.P., Verloo, M.G., 1999. Leaching behaviour Analytical Methods of Environment. Chinese Environmental of Cd, Cu, Pb and Zn in surface soils derived from dredged sedi- Science Press, Beijing. (in Chinese). ments. Environmental Pollution 106 (1), 107–114. Forstner, U., Calmano, U., 1998. Characterisation of dredged materials. Tessier, A., Campbell, P.G.X., Bisson, M., 1979. Sequential extraction Water Science and Technology 38 (11), 149–157. procedure for the speciation of partionlate trace metals. Analytical Gambrell, R.P., 1994. Trace and toxic metals in wetlands—a review. Chemistry 51, 844–851. Journal of Environmental Quality 23, 883–891. Tiquia, S.M., Tam, N.F.Y., 1998. Elimination of phytotoxicity during Hirsch, M.P., 1998. Availability of sludge-borne silver to agricultural co-composting of spent pig-manure sawdust litter and pig sludge. crops. Environmental Toxicity and Chemistry 17 (4), 610–616. Bioresource Technology 65 (1), 43–49. John, M.K., 1972. Influence of soil properties and extractable zinc on Tiquia, S.M., Tam, N.F.Y., Hodgkiss, I.J., 1996. Effects of compost- zinc availability. Soil Science 113 (3), 222–227. ing on phytotoxicity of spent pig-manure sawdust litter. Environ- Lee, J.S., Chon, H.T., Kim, K.W., 1998. Migration and dispersion of mental Pollution 93 (3), 256–294. trace elements in the rock-soil-plant system in areas underlain by Vasseur, L., Fortin, M.J., Cyr, J., 1998. Clover and cress as indicator black shales and slates of the Okchon Zone, Korea. Journal of species of impacts from limed sewage sludge and landfill wastewater Geochemical Exploration 65 (1), 61–78. land application. The Science of the Total Environment 217, 231–239. Li, Q.X., Wong, J.W.C., Wong, M.H., 1998. Heavy metal accumula- Wallace, A., Wallace, G.A., 1994. A possible flaw in EPA’s 1993 new tion in Chinese cabbage (Brassica chinensis) grown in soil amended sludge rule due to heavy metal interactions. Communications of Soil with sewage sludge compost. Journal of China Agricultural Uni- Science and Plant Analysis 25 (1–2), 129–135. versity 3 (1), 113–118. (in Chinese). Weng, H., Chen, X., 2000. Impact of polluted canal water on adjacent soil Lindsay, W.L., Norvell, W.A., 1978. Development of a DTPA soil test and groundwater systems. Environmental Geology 39 (8), 945–950. for zinc, iron, manganese, and copper. Soil Sci. Soc. Am. J. 42, Weng, H., Zhang, D., Xu, C.Y., 1997. Distribution of heavy-metals in 421–428. the Grand Canal (Hangzhou section) and its contributing factors. McBride, M.B., Sauve´, S., Hendershio, W., 1997. Solubility control of Journal of Environmental Sciences 9 (3), 265–277. Cu, Zn, Cd and Pb in contaminated soils. European Journal of Soil Woodard, H.J., 1999. Plant growth on soils mixed with dredged lake Science 48 (2), 337–346. sediment. Journal of Environmental Science and Health, Part A: Muller, I., Pluquet, E., 1998. Immobilization of heavy metals in sedi- Toxic Hazardous Substances and Environmental Engineering 34 ment dredged from a seaport by iron bearing materials. Water (6), 1229–1252. Science and Technology 37 (6–7), 379–386. Xu, J.L., Yang, J.R., 1995. Heavy Metals in Terrestrial Ecosystem. Nelson, D.V., Sommers, L.E., 1982. Total carbon, organic carbon and Chinese Environmental Science Press, Beijing. (in Chinese). organic matter. In: Page, A.L., Miller, R.M., Keenet, D.R. (Eds.), Zhu, G.W., Chen, Y.X., Zhou, G.D., Wang, F.P., Wu, J.B., 2001. Methods of Soil Analysis. Part 2, 2nd Edition. American Society of Distribution of heavy metals in the sediments from the Grand Canal Agronomy, Madison, WI, pp. 539–579. (Hangzhou Section). China Environmental Sciences 21 (1), 65–69. Pickering, W.F., 1981. Selective chemical extraction of soil compo- (in Chinese). nents and bound metal species. Critical Reviews in Analytical Zucconi, F., Forte, M., Monaco, A., De Bertoldi, M., 1981. Biological Chemistry 12, 233–266. evaluation of compost maturity. Biocycle 22 (1), 27–29.