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1.
The ecological dose (ED50) of Cd on alkaline and acid phosphatase activity and the ATP content of three contrasting forest soils was measured with or without Cu and Zn to assess the additive toxic effects of these two metals. Soils polluted with Cu and/or Zn were treated with increasing Cd concentrations to give the following metal combinations: Cd, Cd+Cu, Cd+Zn and Cd+Cu+Zn. Alkaline and acid phosphatase activities and ATP content of the three soils were analysed 4 h, 7 and 28 days after the metal additions. The ED50 values were obtained by interpolating the enzyme activities or ATP data with a kinetic model and the goodness of fit was satisfactory.Generally, the ED50 values of both acid and alkaline phosphatase activities for Cd were lower (higher toxicity) with than without Cu and Zn and the effect of Cu and Zn was particularly adverse when these two metals were both added to soils. The alkaline phosphatase was more sensitive in the acid and neutral soil whereas the acid phosphatase was more sensitive in the alkaline soil. Both phosphatase activities and the ATP content were more sensitive in the sandy than in the finer textured soils. The ATP content was less sensitive to the additive effects. Increasing toxicity was observed during the incubation.Analysis of 1 M NH4NO3-extractable Cd, Cu and Zn revealed that Cd competed with Zn for the adsorption sites but not with Cu. However, the lower ED50 values for Cd of the two phosphatase activities and of the ATP content in the presence of heavy metal combinations could be not explained by the heavy metal solubility data. It is concluded that the ED50 may be a sensitive tool for assessing additve toxic effects to soil biochemical parameters.  相似文献   

2.
The aim of this study was to provide data to assess the additive effects of soil salinity on the toxicity of Cd to soil alkaline phosphatase (EC 3.1.3.1). Two soils (Langroud acid soil and Shervedan calcareous soil) were artificially salinized with NaCl. The natural and salinized soils were treated with CdSO4 solutions to give a Cd concentration in the range 3–5000 mg kg?1. Soil alkaline phosphatase activity was measured after 3 days of incubation. Salinity enhanced the extractable Cd concentration in both Langroud and Shervedan soils. The percentage of soil alkaline phosphatase activity inhibited by Cd was significantly increased from 27.8 to 45 in the Langroud acid soil as salinity increased from natural levels to 28 dS m?1. An increase in the inhibition percentage was not observed in the Shervedan soil. Lower values for the ecological dose causing 50% inhibition (ED50) under saline conditions in the Shervedan soil supported the hypothesis that Cd may be more toxic to soil alkaline phosphatase when the soil is more saline. We conclude that Cd toxicity to soil alkaline phosphatase is salinity dependent and that higher Cd concentrations under saline conditions are probably responsible for the enhanced Cd toxicity to soil alkaline phosphatase.  相似文献   

3.
《Soil biology & biochemistry》2001,33(4-5):483-489
Two soils of contrasting texture, organic matter content and pH were treated with CdSO4 solutions to give a Cd concentration range of 0–4000 mg kg−1 soil. The content of ATP and dehydrogenase and urease activities of soils were assayed after 3 h, and 7 and 28 days of Cd contamination. The relative ED50 values were calculated by two kinetic models (model 1 and model 2) used by Speir et al. (1995) and by the sigmoidal dose–response model (model 3) employed by Haanstra et al. (1985). Model 1 was the most successful in calculating the ED50 values for the ATP content, urease and dehydrogenase activities when both soils were contaminated by Cd. Similar ED50 values were predicted by model 1 (describing the full inhibition) and model 3 only when the correlation coefficients r2 were higher than 0.9. The ED50 values of ATP calculated by model 1 were markedly higher than those calculated by model 2 (describing partial inhibition) when both models gave correlation coefficients higher than 0.9. This behavior was due to the high asymptote values obtained using model 2. According to model 2, some of the enzyme activities responsible for the ATP synthesis were probably not inhibited at the highest Cd concentrations. The inhibitory effect of Cd on the ATP content and both enzymatic activities was lower in the Castelporziano soil, which had the highest total organic carbon content.  相似文献   

4.
Summary The aim of this study was to provide manageable data to help establish permissible limits for the pollution of soil by heavy metals. Therefore the short-and long-term effects of heavy metal pollution on phosphatase activity was studied in five different soil types. The results are presented graphically as logistic dose-response curves. It was possible to construct a curve for sand and silty loam soil but it was more difficult to establish a curve for sandy loam and clay soil and nearly impossible (except for Cu) for peat. The toxicity of the various metals can be compared on the basis of mmol values. In clay soils, for Cd, Cr, Cu, and Zn, the 50% effective ecological dose (ED50) values were comparable (approximately 45 mmol kg–1), but the ED10 values were very different, at 7.4, 41.4, 15.1, and 0.55, respectively. At the ED50 value, toxicity did not decrease with time and, in sandy soils, was approximately 2.6 mmol kg –1 dry soil for Cd, Cu, and Zn. In four out of five soils, the Cd toxicity was higher 1.5 years after the addition of heavy metal salts than after 6 weeks. Toxicity was least in the sandy loam, silty loam, and clay soil, and varied in general between 12 and 88 mmol kg–1. In setting limits, the criteria selected (no-effect level, ED10 or ED50) determine the concentration and also the toxicity of the sequence. It is suggested that the data presented here could be very useful in helping to set permissible limits for heavy metal soil pollution.  相似文献   

5.
The effects of adding a crushed cotton gin compost (CCGC) and poultry manure (PM) on the biological properties of a Typic Xerofluvent soil contaminated with Ni were studied in the laboratory. Urease, BBA-protease, alkaline phosphatase, β-glucosidase and arylsulfatase activities were measured in soils containing seven concentrations (100, 250, 500, 1000, 2500, 5000 and 8000 mg kg−1 soil) of Ni after four incubation times (1 day, 7 days, 15 days and 45 days). The resulting inhibition was compared with that of the enzymatic activities in the same soil containing similar concentrations of the Ni but amended with crushed cotton gin compost and poultry manure. The 50% ecological dose (ED50) values were calculated by the two kinetic models used by Speir et al. [T.W. Speir, H.A. Kettles, A. Parshotam, P.L. Searle, L.N.C. Vlaar, A simple kinetic approach to derive the ecological dose value, ED50, for the assessment of Cr(VI) toxicity to soil biological properties, Soil Biol. Biochem. 27 (1995) 801–810] and by the sigmoidal dose–response model used by Haanstra et al. [L. Haanstra, P. Doelman, J.H. Oude Voshaar, The use of sigmoidal dose response curves in soil ecotoxicological research, Plant Soil 84 (1985) 293–297]. The urease, BBA-protease, β-glucosidase, alkaline phosphatase and arylsulfatase activities were higher in the organic amended soils (76%, >99.7%, >95.7%, >27.6% and >87.2%, respectively) than in the control soil. Also, the enzymatic activities were higher in CCGC-amended soils than in the PM-amended soils (51%, 20%, 11.2%, and 11.3% increase for urease, BBA-protease, β-glucosidase and alkaline phosphatase, respectively). For all soil enzymatic activities and at the end of the period of incubation, the ED50 values were lowest in control soil, followed by PM and CGCC-amended soils. This may have been due to the adsorption capacity of Ni being higher in the humic acid (CGCC) than in the fulvic acid-amended soil (PM).  相似文献   

6.
Effects of different soil properties on the microbial toxicity of lead and cadmium Effects of different soil properties on the microbial toxicity of lead and cadmium were investigated in laboratory experiments on ten arable and nine preserve area soils. Microbial activity was measured by means of the dehydrogenase and the arginine-ammonification tests. The latter was not suitable to show the microbial toxicity of both metals. Effects of lead on dehydrogenase activity were mainly influenced by its concentration in soil solution (r = 0,79). Thus, all soil properties which determined the adsorption of lead correlated significantly with the relative dehydrogenase activities of the contaminated soils. The most important abiotic factors influencing the toxicity of lead were the soil pH and the CEC. Cd solubility and Cd toxicity were influenced by soil pH in a contrary way. Low Cd concentrations caused greater inhibitions of dehydrogenase activity at neutral and slightly alkaline soil reaction than under acidic conditions. Therefore, correlations between Cd concentrations of soil solutions or clay content and dehydrogenase activity were only significant if partial correlation analysis (constant pH) was used.  相似文献   

7.
Solution cadmium (Cd) concentrations and sorption and desorption of native and added Cd were studied in a range of New Zealand soils. The concentration of Cd in solution and the concentrations and patterns of native soil Cd desorbed and added Cd sorbed and desorbed varied greatly between the 29 soils studied. Correlation analysis revealed that pH was the most dominant soil variable affecting solution Cd concentration and sorption and desorption of native and added Cd in these soils. However, organic matter, cation exchange capacity (CEC) and total soil Cd were also found to be important. Multiple regression analysis showed that the log concentration of Cd in solution was strongly related to soil pH, organic matter and total Cd, which in combination explained 76% of the variation between soils. When data from the present study were combined into a single multiple regression with soil data from a previously published study, the equation generated could explain 81% of the variation in log Cd solution concentration. This reinforces the importance of pH, organic matter and total Cd in controlling solution Cd concentrations. Simple linear regression analysis could at best explain 53% of the total variation in Cd sorption or desorption for the soils studied. Multiple regression analysis showed that native Cd desorption was related to pH, organic matter and total Cd, which in combination explained 85% of the variation between soils. For sorption of Cd (from 2 μg Cd g–1 soil added), pH and organic matter in combination explained 75% of the variation between soils. However, for added Cd desorption (%), pH and CEC explained 77%. It is clear that the combined effects of a range of soil properties control the concentration of Cd in solution, and of sorption and desorption of Cd in soils. The fraction of potentially desorbable added Cd in soils could also be predicted from a soil’s Kd value. This could have value for assessing both the mobility of Cd in soil and its likely availability to plants.  相似文献   

8.
Recent studies indicate that aerobic rice can suffer injury from ammonia toxicity when urea is applied at seeding. Urea application rate and soil properties influence the accumulation of ammonia in the vicinity of recently sown seeds and hence influence the risk of ammonia toxicity. The objectives of this study were to (i) evaluate the effects of urea rate on ammonia volatilization and subsequent seed germination for a range of soils, (ii) establish a critical level for ammonia toxicity in germinating rice seeds and (iii) assess how variation in soil properties influences ammonia accumulation. Volatilized ammonia and seed germination were measured in two micro‐diffusion incubations using 15 soils to which urea was applied at five rates (0, 0.25, 0.5, 0.75 and 1.0 g N kg?1 soil). Progressively larger urea rates increased volatilization, decreased germination and indicated a critical level for ammonia toxicity of approximately 7 mg N kg?1. Stepwise regression of the first three principal components indicated that the initial pH and soil texture components influenced ammonia volatilization when no N was added. At the intermediate N rate all three components (initial pH, soil texture and pH buffering) affected ammonia volatilization. At the largest N rate, ammonia volatilization was driven by soil texture and pH buffering while the role of initial pH was insignificant. For soils with an initial pH > 6.0 the risk of excessive volatilization increased dramatically when clay content was <150 mg kg?1, cation exchange capacity (CEC) was <10 cmolc kg?1 and the buffer capacity (BC) was <2.5 cmolc kg?1 pH?1. These findings suggest that initial pH, CEC, soil texture and BC should all be used to assess the site‐specific risks of urea‐induced ammonia toxicity in aerobic rice.  相似文献   

9.
Traditionally, three threshold levels have been accepted for heavy metal concentrations in agricultural soils, depending on soil pH. The aim of this work was to ascertain how the three threshold values proposed for Cd (3, 6.5, and 12.5 mg kg?1) and Zn (300, 650, and 1300 mg kg?1) really affect soil microbial activity. Two soils, a scrubland soil and a forest soil, differing widely in their organic C content, were used in this study. Despite the different soil characteristics, the fractions of Cd and Zn extracted with a solution of diethylenetriaminepentaacetic acid (DTPA) showed little difference between soils. Parameters, such as microbial biomass C (Cmic), soil basal respiration (BR), adenosine triphosphate (ATP) content, dehydrogenase activity (DHA), urease activity (UA), alkaline phosphatase activity (APA), and β-glucosidase (β-GA), were less affected by heavy metals in the forest soil than in the scrubland soil. In general, the simultaneous addition of both metals had a synergistic effect on microbial activity, and this treatment produced a significant decrease of microbial activity of both soils with respect to control. The highest level (L3) of Cd, Zn and Cd + Zn treatments produced significant decrease of microbial and biochemical parameters in both soils.  相似文献   

10.
Abstract

The adsorption of nutrient elements is one of the most important solid‐ and liquid‐phase interactions determining the retention and release of applied plant nutrients and the efficiency of fertilization. The study showed that the soils with high cation exchange capacity (CEC), CaCO3, organic matter contents, and heavy texture adsorbed more zinc (Zn). The alkaline soils from Pakistan adsorbed more Zn than English acidic soils. Langmuir and Freundlich isotherm fit was excellent, and r2 values for the Langmuir isotherm were highly significant (r2=0.84 to 0.99). The Langmuir b values, representing the adsorptive capacity of a soil, increased as the texture fineness increased in the soil, with increases in the concentration of adsorptive material (such as organic matter and CaCO3) and with increases in CEC and pH. The alkaline soils from Pakistan had higher bonding energy constant and higher log Kf values than the acidic English soils. Sequential extraction of Zn in these soils showed that most of the Zn was held in CaCO3 pool in the alkaline soils, whereas in acidic soils adsorbed Zn was in exchangeable form.  相似文献   

11.
Risk assessment of heavy metals in soil requires an estimate of the concentrations in the soil solution. In spite of the numerous studies on the distribution of Cd and Zn in soil, few measurements of the distribution coefficient in situ, Kd, have been reported. We determined the Kd of soils contaminated with Cd and Zn by measuring metal concentrations in the soil and in the soil solution and attempted to predict them from other soil variables by regression. Soil pH explained most of the variation in logKd (R2 = 0.55 for Cd and 0.70 for Zn). Introducing organic carbon content or cation exchange capacity (CEC) as second explanatory variable improved the prediction (R2 = 0.67 for Cd and 0.72 for Zn), but these regression models, however, left more than a factor of 10 of uncertainty in the predicted Kd. This large degree of uncertainty may partly be due to the variable degree of metal fixation in contaminated soils. The labile metal content was measured by isotopic dilution (E value). The E value ranged from 18 to 92% of the total metal content for Cd and from 5 to 68% for Zn. The prediction of Kd improved when metals in solution were assumed to be in equilibrium with the labile metal pool instead of the total metal pool. It seems necessary therefore to discriminate between ‘labile’ and ‘fixed’ pools to predict Kd for Cd and Zn in field contaminated soils accurately. Dilute salt extracts (e.g. 0.01 m CaCl2) can mimic soil solution and are unlikely to extract metals from the fixed pool. Concentrations of Cd and Zn in the soil solution were predicted from the concentrations of Cd and Zn in a 0.01 m CaCl2 extract. These predictions were better correlated with the observations for field contaminated soils than the predictions based on the regression equations relating logKd to soil properties (pH, CEC and organic C).  相似文献   

12.
Phytoextraction of soil Cd and Zn may require reduction in soil pH in order to achieve high metal uptake. Reducing the pH of high metal soil, however, could negatively affect soil ecosystem function and health. The objectives of this study were to characterize the quantitative causal relationship between pH and soil biological activities in two Zn and Cd contaminated soils and to investigate the relationship between metals and soil biological activities under low pH. Soils were adjusted to five or six different pH levels by sulfur addition, followed by salt leaching. Thlaspi caerulescens was grown for 6 months, and both the rhizosphere and non-rhizosphere soil biological activities were tested after harvest. Reducing pH significantly lowered soil alkaline phosphatase activity, arylsulphatase activity, nitrification potential, and respiration. However, acid phosphatase activity was increased with decreasing pH. The relationship between soil biological activities and pH was well characterized by linear or quadratic regression models with R2 values ranging from 0.57 to 0.99. In general, the three enzyme activities, nitrification potential, and the ratio of alkaline phosphatase to acid phosphatase activity were very sensitive indicators of soil pH status while soil respiration was not sensitive to pH change. The rhizosphere soil had higher biological activities than non-rhizosphere soil. The negative effects observed in the non-rhizosphere soil were alleviated by the rhizosphere influence. However, rhizosphere soil after 6 months phytoextraction showed lower nitrification potential than non-rhizosphere soil, probably due to substrate limitation in our study.  相似文献   

13.
Cadmium distribution coefficients, K d were determined at low Cd concentrations (solute: 0.2 to 3.0 μg Cd dm?3, soil: 0.044 to 1.1 mg Cd kg?1) for 63 Danish agricultural soils. The K d values ranged from 15 to 2450 L kg?1. About 40% of the soils had K d values below 200 L kg?1. The observed K d values correlated very well with soil pH (r 2 = 0.72). Introducing soil organic matter content as a second parameter improved the correlation some (r 2 = 0.79). No further improvements were obtained by introducing traditional soil parameters as clay, silt, fine sand, coarse sand and CEC or ‘reactive’ parameters as oxyhydroxides of Mn, Fe and Al. The identified regression equation for predicting K d values indicates that K d approximately doubles for each 0.5 unit increase in pH or 2% increase (weight basis) in organic matter content.  相似文献   

14.
土壤主要理化性质对湘粤污染农田镉稳定效果的影响   总被引：3，自引：0，他引：3  
崔旭  吴龙华  王文艳 《土壤》2019,51(3):530-535
利用盆栽试验研究了稳定剂(石灰、海泡石联合施用)对湖南、广东两省区不同性质土壤上生长的小青菜(Brassica chinensis L.)生物量、重金属吸收以及土壤pH和重金属提取态含量的影响,探讨了影响镉(Cd)稳定修复效果的土壤性质参数。结果表明:施加稳定剂对增加酸性土壤上小青菜生物量效果显著,土壤pH、有机质(OM)、全量Cd和黏粒是影响小青菜生物量变化的主要因素;土壤pH、阳离子交换量(CEC)、OM、黏粒是影响小青菜Cd含量变化的主要因素;土壤pH、CEC、全量Cd和黏粒是影响土壤提取态Cd含量变化的主要因素。  相似文献   

15.
Abstract

Selected chemical properties of an artificially acidified agricultural soil from northern Idaho were evaluated in a laboratory study. Elemental S and Ca(OH)2were used to manipulate the soil pH of a Latahco silt loam (fine‐silty, mixed, frigid Argiaquic Xeric Argialboll), which had an initial pH of 5.7. A 100 day incubation period resulted in a soil pH manipulation range of 3.3 to 7.0. Chemical properties evaluated included: N mineralization rate, extractable P, AI, Mn, Ca, Mg and K and CEC. N mineralization rate (assessed by anaerobic incubation) decreased with decreasing soil pH. Nitrification rate also decreased as NH4 +‐N accumulated under acid soil conditions. Sodium acetate extractable P was positively linearly correlated (R2= 0.87) with soil pH over the entire pH range evaluated. Potassium chloride extractable Al was less than 1.3 mg kg‐1of soil at pH values higher than 4.4. Consequently, potential Al toxicity problems in these soils are minimal. Extractable Mn increased with decreasing soil pH. Soil CEC, extractable Mg, and extractable K all decreased with increasing soil pH from 3.3 to 7.0. Extractable Ca levels were largely unaffected by changing soil pH. It is likely that the availability of N and P would be the most adversely affected parameters by soil acidification  相似文献   

16.
Mean NH3 losses after nine days incubation at 18°C and 60% FC were 3.1±2.9% and 7.6±6.0% of applied urea-N from the pasture and tillage counterparts of 10 soil series. These losses were highly correlated with buffered CEC and maximal pH values (pHm) generated three days after urea application. NH3 volatilization was apparently controlled by buffered CEC and initial pH (R2= 72–87%) and was related to variations in soil organic matter and texture (R2= 77–81%). Losses in the acid pasture soils were attributed largely to initial pH differences, and in the tillage soils to buffered CEC only. Evolution was greater from the tillage than from the pasture equivalent in eight series. This was attributed to differences in CEC, including buffered CEC and pH-dependent charge, caused by differences in OM content primarily but also in texture between the two soil groups. Differences in NH3 evolution from urea in pasture and tillage soils, in general, are not related to pH differences.  相似文献   

17.
Summary The aim of this study was to provide data to evaluate the short- and long-term effects of heavy metals on arylsulphatase activity in five soils. The effects are fitted on a logistic dose-response model and are presented graphically as the ecological dose (heavy metal concentration corresponding to 50% inhibition; ED50) and ecological dose range (heavy metal concentration range corresponding to 10–90% inhibition; EDR). In 7 out of 22 comparable soil-metal combinations the ED50 decreased significantly over 6 weeks to 18 months of incubation and in two cases the ED50 increased. Toxicity (defined as ED50) was highest in sand and sandy loam and lowest in sandy peat. Cd toxicity in sand, silty loam, and clay varied from 1.08 to 9.04 mmol kg-1. Both Cr and Ni toxicity varied strongly and decreased with time in some soils while increasing in others. The Cu toxicity ranged from 4.51 to 2 mmol kg-1 in sand and silty loam, respectively, but remained fairly constant over time. Pb was the least toxic element (14.5 to 59.9 mmol kg-1). The toxicity of Zn ranged from 5.73 to 148 mmol kg-1 in sand and sandy peat, respectively. At critical concentrations set by the Dutch Soil Protection Act, Cr, Cu, Ni, and Zn inhibited arylsulphatase by 53, 35, 48 and 97%, respectively.  相似文献   

18.
Most studies on phosphatase activity in soils have been concerned with acid phosphatase. This study was conducted to determine the activity of phosphomonoesterases (acid and alkaline phosphatases), phosphodiesterase, and “phosphotriesterase”. The results indicate that acid phosphatase is predominant in acid soils and that alkaline phosphatase is predominant in alkaline soils. With universal buffer, the pH optima of phosphodiesterase and phosphotriesterase were at pH 10. The activities of these phosphatases in soils were much lower than those of the acid and alkaline phosphatases. Studies on the effects of various soil treatments on the activity of phosphatases in soils indicated that air-drying increased the activity of acid phosphatase and phosphotriesterase, decreased the activity of alkaline phosphatase, but did not affect the activity of phosphodiesterase. Steam sterilization of soils at 121 C for 1 h inactivated alkaline phosphatase, phosphodiesterase, and phosphotriesterase, but did not completely inactivate acid phosphatase. Addition of toluene to the incubation mixture did not markedly affect the activity of acid phosphatase, alkaline phosphatase, phosphodiesterase, but increased the activity of phosphotriesterase in soils.Studies of the kinetic parameters of phosphatases in the soils studied showed that the Km values ranged from 1.11 to 3.40 mm for acid phosphatase. from 0.44 to 4.94 mm for alkaline phosphatase, and from 0.25 to 1.25 mm for phosphodiesterase. Expressed as μg p-nitrophenol released·h?1·g?1 soil, the Vmax values ranged from 200 to 625 for acid phosphatase, from 124 to 588 for alkaline phosphatase, and from 46 to 127 for phosphodiesterase. The substrate of phosphotriesterase (tris-p-nitrophenyl phosphate) is insoluble in water; hence, the Km and Vmax values of this enzyme in soils could not be determined.  相似文献   

19.
Risk assessment of the nitrification inhibitors (NIs) 3,4-dimethylpyrazole phosphate (DMPP), 4-chloromethylpyrazole (ClMP), and dicyandiamide (DCD) on nontarget microbial activity in soils was determined by measuring dehydrogenase and dimethyl sulfoxide reductase activity (DHA, DRA, respectively) in three differently textured soils under laboratory conditions. Dehydrogenase activity was measured with standard procedure recommended to evaluate side effects of environmental chemicals on general microbial activity in soils. The kinetic of inhibition were obtained by dose–response relationships and used to calculate the no observable effect levels (NOEL values) and the effective doses at 10% and 50% inhibition (ED10 and ED50), respectively. Negative effects on DHA and DRA, respectively, were observed only at rates approximately 40–100 times higher than the concentrations recommended in the field. Both DHA and DRA were affected more in the sandy than in the silty or clayey soil. Consequently, NOEL, ED10, and ED50 values were considerably higher in the clayey than in the silty or sandy soil. The heterocyclic N compounds DMPP and ClMP, respectively, were more effective in inhibiting DHA and DRA than DCD. At application rates used in the field as well as at concentration up to 25 to 90 times higher, the NIs concerned failed to affect general soil microbial activity in soils. Among the three NIs tested, the not marketed ClMP exhibited the strongest negative effects on soil microbial activity. At recommended application rates, the NIs tested should be considered as enviromentally safe.  相似文献   

20.
Summary The acute toxicity of Cd (chloride), chloroacetamide, 3,4-dichloroaniline and pentachlorophenol to the earthworm Eisenia fetida andrei was determined using the OECD (1984) artificial soil and contact testing procedures. To investigate the influence of two soil characteristics (pH and organic-matter content), the toxicity of the chemicals was also determined in two natural sandy soils. It is concluded that the filter-paper contact test cannot be recommended to predict earthworm toxicity of these chemicals in soil. Toxicity in soil was influenced by both pH and organic-matter content. Differences between LC50 values in the high-organic-matter artificial soil and in an acid, low-organic-matter sandy soil were, however, not greater than a factor of 3–4. The results of this study therefore support the use of a well-defined artificial soil substrate for standardized earthworm toxicity tests.  相似文献   

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