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1.
The effects of copper pollution on the soil fungal flora was investigated. Soils treated with 100, 200, 400, 800 or 1600 μg Cu g?1 were used for experiments to study changes in fungal populations, especially the development and dominance of copper-tolerant fungi. Fungi were sampled 1, 3 and 5 months after copper treatment.All the correlation coefficients between the copper contents and the number of fungal colonies plated were positive. The higher the copper concentration in soil, the more 1000 μ Cu ml?1 tolerant fungi were isolated. The relative number of 1000 μg Cu mr?1 tolerant fungi from the soil treated with 1600 μg Cu g?1 was about 30% of those of the control 14 days after treatment. Within the limits of this experiment, the increase in fungal populations was directly correlated with the increase of dominant Cu-tolerant fungi.From control soils, containing low quantities of copper, 1000 μg Cu ml?1 tolerant fungi were also isolated; whereas, from soils containing high amounts of copper, some Cu-sensitive fungi were isolated. Most of the 1000 μg Cu ml?1 tolerant fungi were Penicillium spp. It was concluded that the genus Penicillium may be dominant in soils polluted with copper.  相似文献   

2.
The aquatic vascular plant (Ceratophyllum demersum L.) was investigated as a potential biological filter for removal of Cd from wastewaters. Plants were grown in and harvested weekly from 0.10 M Hoagland nutrient solutions containing concentrations of Cd from 0.01 to 1.03 μg Cd mL?1. Tissue Cd was positively correlated to increased concentrations of Cd in solution. Concentration factors (CFs) of Cd in plants after one week were 13.3 for the 0.01 μg Cd mL?1 treatment; 451.4 for plants treated with 0.04 μg Cd mL?1, and 506.5 for plants treated with 1.03 μg Cd mL?1. Plants treated with 0.01 μg Cd mL?1 sustained tissue Cd concentrations almost 9-fold over those at week 1. However, after 5 weeks tissue Cd concentration in plants exposed to 1.03 μg Cd mL?1 had decreased 97% compared to the week 1 concentration. Growth measurements of dry weight, stem lengths, and lateral shoot growth were nagatively correlated to increased Cd treatments. Our results suggest that Coontail exposed to very low Cd concentrations (0.01 μg Cd mL?1) can take up and accumulate Cd. However, plants exposed to Cd at 0.04 μg Cd mL?1 or above did not accumulate Cd past one week.  相似文献   

3.
One of the characteristics of soils located within the cores of stockpile storage mounds at opencast mine sites is their accumulation of ammonium-nitrogen. Two areas of restored land were constructed from soil stockpiled for 3 years; one consisted of mound-surface (‘aerobic zone’) soil, and the other of deeply buried (‘anaerobic zone’) soil. In that constructed from mound-surface soil, concentrations of both ammonium- and nitrate-nitrogen remained fairly stable throughout the first 6 months of restoration at about 12–20 μg g?1, but in the site constructed from deeply buried soil, concentrations of ammonium-N decreased from an initial high of 160 to 14 μg N g?1 soil after 14 weeks, and increased again to 42 μg N g?1 soil by week 29. In contrast, concentrations of nitrate-nitrogen at the latter site increased from an initial 9 μg to a maximum recorded level of 77 μg N g?1 soil by week 14, before subsiding to 9 μg N g?1 soil by week 29. Nitrate was considered to have been lost from the restored soils by a combination of leaching and denitrification, as no vegetation was established at these sites. After a short-term stimulation following restoration, soil microbial biomass levels remained fairly constant, though soils (up to 3 years after restoration) were characterized by a very small ratio of biomass C: organic C.  相似文献   

4.
The energy content of the mycoparasite Sporidesmium sclerotivorum mycelium was 18,389 J g?1 and 16,334 J g?1 for macroconidia on a dry weight basis. The energy content of Sclerotinia minor sclerotia, the host of the mycoparasite, was 16,485 J g?1. In liquid culture, the economic coefficient for the conversion of glucose to mycelium (mycelial dry wt ÷ glucose consumed × 100) was 51–60 whereas the mycelial energy coefficient, [mycelial energy (J) ÷ substrate energy (J) × 100] was 65–75. In soil, the conidial energy coefficient [conidial energy (J) ÷ substrate energy (J) × 100] for the conversion of host sclerotial energy to the macroconidia of the mycoparasite was 19.8, which was 2–9 times that for the conversion of glucose in liquid culture. The conidial energy coefficient when grown on a liquid medium on vermiculite was 23.0. S. sclerotivorum, as an obligate parasite of sclerotia in soil, was most efficient in the conversion of energy in a system where there was a high surface: energy ratio. In liquid culture S. sclerotivorum is more efficient than most other fungi.  相似文献   

5.
The effect of 50, 100, 150, and 400 μg sodium pentachlorophenate (Na-PCP) per gram soil was studied in nonsterile soil incubated under aerobic and anaerobic conditions, and in sterilized soil inoculated withAzotobacter sp. isolated from the soil. N2 fixation was determined by acetylene reduction. Pentachlorophenate at a concentration of 50 μg g?1 had an inhibitory effect in nonsterile soil incubated aerobically while strong inhibition of dinitrogen fixation in nonsterile soil occurred in the presence of 100 μg g?1 and above. The EC50 values for the inhibition of nitrogenase activity in nonsterile soil incubated aerobically and anaerobically and in sterilized soil inoculated withAzotobacter sp. suspensions were 49.8±1.4 μg Na-PCP g?1, 186.8±2.8 μg Na-PCP g?1, and 660.8±29.3 μg Na-PCP g?1, respectively.  相似文献   

6.
The effects of four concentrations (0.5, 1, 5 and 10 μg mL?1) of the heavy metals Hg, As, Pb, Cu, Cd, and Cr on some senescence variables of Cuscuta reflexa Roxb. were studied. All of the treatments, except 0.5 μg mL?1, decreased Hill reaction activity, chlorophyll and protein contents and dry matter percentage in biomass and increased tissue permeability over control data. The harmful effects of the metals were best visible at 10 μg mL?1. The general order of sensitivity was As > Cd > Pb > Hg > Cu > Cr (absolute metal concentration). The data suggest that Cuscuta reflexa shows tolerance to the heavy metals tested up to 0.5 μg mL?1.  相似文献   

7.
Barley (Hordeum vulgare L.) was grown on a sandy soil given different doses of cadmium carbonate (salt), copper carbonate (malachite), lead carbonate (cerussite), and zinc carbonate (smithsonite) in a pot experiment conducted in a greenhouse. The element compounds were added to the soil in amounts equivalent to the following levels of the metals: Cd 5, 10, 50 μq ?1; Cu and Pb 50, 100, 500 μg g?1; Zn 150, 300, 1500 μg g?1. Sequential extraction was used for partition these metals into five operationally-defined fractions: exchangeable, bound to carbonates, bound to Fe-Mn oxides, bound to organic matter and residual. The residue was the most abundant fraction in the untreated soil for all the metals studied (43 to 61% of the total contents). The concentration of exchangeable Cd (0.2 μg g?1), Cu (0.01 μg g?1), Pb (0.1 μg g?1), and Zn (1.4 μg g?1) were relatively low in the untreated soil but increased markedly in the treated soils for Cd (up to 31 μg g?1) and Zn (up to 83 μg g?1), whereas only small changes were observed for Cu and Pb. The pot experiment showed a significant increase in the Cd and Zn contents of barley grown on the treated soils, but only small changes in Cu and Pb concentrations.  相似文献   

8.
Respiratory methods to estimate the amount of C in the soil microbial biomass and the relative contributions of procaryotes and eucaryotes to the biomass were used to evaluate the influence of pesticides on the soil microflora. Experiments were conducted with 5 and 50 μg·g?1 of three fungicides, captan, thiram and verdasan. At 5 μg·g?1 they caused significant decreases (40%) in the biomass; the organomercury fungicide verdasan also caused a shift from fungal to bacterial dominance. Within 8 days, biomass in captan- and thiram-amended soils had recovered to that of the controls. Although the fungal to bacterial balance was restored in verdasan-amended soils, biomass recovery was not complete. At 50 μg·g?1 the fungicides caused long-term decreases in the biomass and altered the relative proportions of the bacterial and fungal populations. Verdasan had the greatest effect on soil microbial biomass and composition.  相似文献   

9.
Bone fluoride concentration was measured in field voles (Microtus agrestis) trapped throughout a year at a moderately polluted site 1 km south of an Al reduction plant at Holyhead, Anglesey. Fluoride values ranged from 300 to 4800 μg g?1, with a mean of 2074 μg g?1 and increased with age as judged by dried eye-lens weight and body weight. At a heavily polluted site about 250 m from the pot-room of the reduction plant field voles had bone fluoride concentrations which ranged from 910 to 11000 μg g?1 with a mean of 7148 μg g?1. Wood mice (Apodemus sylvaticus) at this same location had a mean bone fluoride concentration of 8430 μg g?1 and ranged from 1800 to 17 200 μg g?1. The difference in mean bone fluoride concentration between these two species at this location was not significant (P > 0.1). A sample of field voles from presumed unpolluted sites in other parts of Britain had bone fluoride concentrations which ranged from 23 to 540 μg g?1 with a mean of 168 jig g?1. There was a high positive correlation (r > 0.97) between fluoride concentrations in different parts of field vole skeletons. There was no correlation between bone fluoride concentration in field voles and their femur diameters (r < 0.2).  相似文献   

10.
This study evaluated the toxic effects of arsenic (As) on the growth, total antioxidant activity, total content of phenolic compounds, and content of photosynthetic pigments of Azolla filiculoides. The aquatic fern was propagated and exposed to Yoshida nutrient solution contaminated with sodium arsenate (Na2HAsO4??7H2O) at six concentrations (5, 10, 20, 30, 60, and 120???g?As?mL?1), including the control without As contamination. Azolla cultures were kept under environmental chamber conditions?26??C, 12?h photoperiod and 80% HR for 96?h. Increased As concentrations (>30???g?mL?1) significantly diminished growth of A. filiculoides and the total content of chlorophyll and total phenolic compounds, but significantly enhanced of total carotenoid?+?xanthophylls content. The concentrations of 5 and 10???g?As?mL?1 significantly stimulated the growth of A. filiculoides. This aquatic fern tolerates As concentrations lower than 30???g?mL?1, and its maximum As accumulation (28???g?g?1 dry weight) was achieved when exposed to 60???g As mL?1, but showing clear symptoms of As toxicity.  相似文献   

11.
The effect of increasing concentrations of Cd and Zn in a sandy soil on spring wheat (Triticum vulgare L.) yields and the metal contents of the plants was examined in a pot experiment to establish critical levels of these metals in soil. The metals were added (individually and jointly) to the soil as sulfates in the following doses (in μg g?1, dry wt.): Cd — 2, 3, 5,10, 15, 25, and 50; Zn ?200, 300, 500, 1000, 1500, 2500, and 5000. Cadmium added to soil did not affect yields of wheat. The Zn dose of 1000 μg g?1 strongly reduced crop yields; at 1500 μg g? Zn dose wheat did not produce grain. The metal contents of wheat increased with increasing concentrations of Cd and Zn in soil up to 10.3 and 1587 μ g? of Cd and Zn in straw, respectively. The concentrations of both metals were higher in straw than in grain by factors of 3–7 and 1.5–2 for Zn and Cd, respectively. The relationships between Cd and Zn contents of the plants and soils were best expressed by exponential equations. High concentrations of Zn in soils (1042 and 1542 μg g?1) enhanced uptake of Cd by plants. The tested threshold concentrations of the metals in soils (3 μg g?1 for Cd and 200–300 μg g?1 for Zn) are safe for Zn but are too high for Cd in terms of protecting plants from excessive metal uptake. The critical Cd content of sandy soil should not exceed 1.5 μg g?.  相似文献   

12.
Research was conducted to determine the environmental effects of Cr residues from a chromite-ore processing plant (Cromatos de México) on the human population living in the surrounding area. The results of this study provided the first quantitative evidence of the transfer of Cr to the atmosphere, soil and subsequently to ground water. The atmospheric concentration of Cr ranged from 0.25 to 0.39 μg m?3, seven times higher than the level found in the control area. Most of the well water samples (90%) had a higher Cr concentration than the threshold limit value for drinking water of 0.05 mg L?1. The high Cr concentration in the environment may be responsible for the high concentration of this metal in urine (18.6 ng mL?1) and hair (4.3 μg g?1) found in the residents of this polluted area. These results were compared with those of people living in a Cr free zone through statistical analysis (Wilcoxon's signed-ranks test). A significant difference of p<0.01 was found between these two populations. In relation to the average concentrations in hair (1.4 μg g?1) and urine (2.0 to 6.0 ng mL?1) considered as normal for a non exposed population in the USA, 70 to 80% of the residents in the Mexican urban-industrial area registered higher values. The high Cr concentration in urine found in workers from the chromite-ore processing plant show the lack of an efficient pollution control system. Therefore the Cr levels found in urine and hair can be used as indicators of environmental exposure.  相似文献   

13.
Volume regulation (weight change) correlates with varying salinity — Cu regimes in whole worms. Decapitation removed this correlation. Regulation of volume and Cu ion uptake are not coupled. Whole worms when exposed to Cu levels of 0.15 to 0.45 mg L?1 accumulated Cu which ranged from 48.9 to 145 μg g?1 dry weight within four days. Decapitated worms exposed to similar doses of Cu accumulated from 77.3 to 405.4 μg g?1 dry weight Cu within three days. Volume regulation appears to be both passive and active processes mediated by the nervous system.  相似文献   

14.
A cloud point extraction (CPE) procedure has been developed for the determination of available cadmium (Cd) and lead (Pb) in soil by flame atomic absorption spectrometry. The proposed method was based on the CPE of a complex from ammonium pyrrolidine dithiocarbamate (APDC) and metal Cd and Pb using emulsifier octyl polyethylene glycol phenol ether (OP) as surfactant. Conditions that would affect the complex formation and separation were researched in detail, including extraction conditions as well as pH, amount of the chelating agent, concentration of the surfactant, equilibration temperature and time, and salt effect. Under the optimized conditions, both of the calibration graphs were linear in range of 0–1.0 μg mL?1 with detection limits of 0.29 ng mL?1 for Cd and 2.10 ng mL?1 for Pb. The relative standard deviation (RSD) for 11 replicate measurements at 0.10 μg mL?1 of Cd and Pb were 2.18% and 4.04%, respectively. The enhancement factors were 48.8 and 61.6 for Cd and Pb, respectively. The recoveries of Cd and Pb at the spiking level of 0.10 μg g?1 in soil samples were from 91.7% to 115% and from 91.0% to 115%, respectively. The proposed method has been applied to the determination of available Cd and Pb in soil.  相似文献   

15.
稻米和土壤微量元素的空间变异   总被引：1，自引：0，他引：1  
Consumption of rice is the main source of micronutrients to human in Asia. A paddy field with unknown anthropogenic contamination in Deqing County, Zhejiang Province, China was selected to characterize the spatial variability and distribution of micronutrients in rice grain and soil. A total of 96 paired soil and rice grain samples were collected at harvest. The micronutrients in the soil samples were extracted by diethylenetriamine pentaacetic acid (DTPA). The mean micronutrient concentrations in rice grain were 3.85 μg Cu g-1, 11.6 μg Fe g-1, 39.7 μg Mn g-1, and 26.0 μg Zn g-1. The mean concentrations were 2.54 μg g-1 for DTPA-Cu, 133.5 μg g-1 for DTPA-Fe, 30.6 μg g-1 for DTPA-Mn, and 0.84 μg g-1 for DTPA-Zn. Semivariograms showed that measured micronutrients in rice grain were moderately dependent, with a range distance of about 110 m. The concentrations of the DTPA-extractable micronutrients all displayed strong spatial dependency, with a range distance of about 60 m. There was some resemblance of spatial structure between soil pH and the grain Cu, Fe, Mn, and Zn. By analogy, similar spatial variation was observed between soil organic matter (SOM) and DTPA-extractable micronutrients in the soil. Kriging estimated maps of the attributes showed the spatial distributions of the variables in the field, which is beneficial for better understanding the spatial variation of micronutrients and for potentially refining agricultural management practices at a field scale.  相似文献   

16.
The effect of adding cobalt, as 60Co, to the food source of the earthworm Eisenia foetida was studied. Cobalt was retained with a half-life of 387 ± 43 (SD) days in the worm. After 172 days more cobalt was concentrated in the gut than the body wall. 60Co was not transmitted from adults to cocoons. Prolonged studies involving the addition of CoCl2 (0, 8.2, 16.5 and 82.5 μg Co g?1) to a food source low in Co indicated that total Co concentrations of 17.6 and 25.9 μg g?1 resulted in significantly increased maximum weights compared to the control worms which were exposed to 9.4 μg Co g?1. The highest Co addition (82.5 μg g?1, total 91.9 μg g?1) caused no increase in maximum weight over controls, but resulted in a statistically significant lag in early growth compared to that of all other groups. Significantly more cocoons were produced by worms fed 17.6 or 25.9 μg Co g?1 compared with those fed 9.4 or 91.9 μg Co?1 Co.  相似文献   

17.
The effect of added Pb on the respiration and dehydrogenase activity of two sandy soils, a clay soil and a peat soil, (all with different physico-chemical properties), was studied.A concentration of 375 μg Pb· g? inhibited the respiration of the sandy soil by ca. 15%, 1500 μg Pb· g?ca. 50%. In the clay soil 1500 μg Pb· g? caused a 15% reduction in respiration. The inhibition of respiration in the sandy soil was still ca. 30% 40 months after the addition of Pb. Respiration of the peat soil was not affected by even 7500 μg Pb· g?.Dehydrogenase activity was affected by Pb in a similar way to soil respiration. In the sandy soil a considerable reduction occurred, while in the clay and peat soils dehydrogenase activity was not reduced.It was concluded, that a relationship exists between the inhibitory effects of Pb and the buffering capacity of the soil as expressed by its cation-exchange capacity. Because of these different effects of the same Pb concentration on the various soil types, no single value for the permitted concentration of lead pollution in soil could be established.  相似文献   

18.
Forest floor and mineral soil samples were collected from subalpine spruce-fir forests at 1000 m above mean sea level on 19 mountains in the northeastern United States to assess patterns in trace metal concentrations, acidity, and organic matter content. The regional average concentrations of Pb, Cu, and Zn in the forest floor were 72.3 (2.9 s.e.) μg g?1, 8.5 (0.7) μg g?1, and 46.9 (2.0) μg g?1, respectively. The regional average concentrations of Pb, Cu, and Zn in the mineral soil were 13.4 (0.8) μg g?1, and 18.2 (1.2) μg g?1, respectively. The regional average pH values of the forest floor and mineral soil were 3.99 (0.03), and 4.35 (0.03), respectively. The Green Mountains had the highest concentrations of Pb (105.7 μg g?1), and Cu (22.7 μg g?1), in the forest floor. They also had the highest concentrations of Cu (18.0 μg g?1), in the mineral soil. Site aspect did not significantly influence any of the values. Concentrations of Pb were lower than concentrations reported earlier in this decade at similar sites while concentrations of Cu and Zn remained the same. We believe that these lower Pb concentrations reflect real changes in forest Pb levels that have occurred in recent years.  相似文献   

19.
The earthworms Allolobophora catiginosa and Lumbricus rubellus were used to study the toxicity of 2,3,7,8-TCDD (dioxin) for earthworms. The earthworms were exposed to soil containing concentrations ranging from 0.05 to 5.0 μgg?1. No worms were killed or showed any other observable toxicological effects when exposed to concentrations up to 5 μg g?1 for 85 days in soil. The lethal threshold concentration for TCDD to earthworms falls between 5 and 10 μg g?1 in this study. In soils containing 0.05 μg g?1 earthworms accumulated TCDD up to 5 times the original soil concentration within 7 days. Worms were also exposed to TCDD on filter paper to study the behaviour of earthworms and the uptake of TCDD after surface contact. The earthworms did not avoid TCDD in their environment, indicating an indifference to it. No active penetration of TCDD into the body occurred where earthworms were exposed to surface concentrations. No indication was found of possible biological breakdown of TCDD on passing through the earthworm gut, although the search for metabolites was limited to the mono-, bi- and trichlorinated dioxins. There was a steady decrease (a T12-value of 80–400 days) in the amount of TCDD recovered from worm-worked soil compared to soil without worms.  相似文献   

20.
Toxicity of heavy metals (Zn,Cu, Cd,Pb) to vascular plants   总被引：1，自引：0，他引：1  
The literature on heavy metal toxicity to vascular plants is reviewed. Special attention is given to forest plant species, especially trees, and effects at low metal concentrations, including growth, physiological, biochemical and cytological responses. Interactions between the metals in toxicity are considered and the role of mycorrhizal infection as well. Of the metals reviewed, Zn is the least toxic. Generally plant growth is affected at 1000 μg Zn L?1 or more in a nutrient solution, though 100 to 200 µg L?1 may give cytological disorders. At concentrations of 100 to 200 μg L?1, Cu and Cd disturb metabolic processes and growth, whereas the phytotoxicity of Pb generally is lower. Although a great variation between plant species, critical leaf tissue concentrations affecting growth in most species being 200 to 300 μg Zn g?1 dry weight, 15 to 20 μg Cu g?1 and 8–12 μg Cd g?1. With our present knowledge it is difficult to propose a limit for toxic concentrations of Zn, Cu, Cd and Pb in soils. Besides time of exposure, the degree of toxicity is influenced by biological availability of the metals and interactions with other metals in the soil, nutritional status, age and mycorrhizal infection of the plant.  相似文献   

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