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1.
The aim of the present study was to investigate the uptake of 16 PAHs by willow (Salix viminalis) from soil amended with contaminated sewage sludge. Uptake experiments were conducted on field plots using sludge applications of 0, 30, 75, 150, 300, and 600 Mg ha?1. The total PAH content of control soil and sludge were 49.6 μg kg?1 and 5713 μ g kg?1, respectively. The concentrations for the 16 PAHs listed as priority pollutants were measured for soil and plant tissue samples obtained at 0.5, 1.5, 2.5, and 3.5 years. Soil total PAH content decreased significantly within the first half year, followed by minimal changes over the subsequent three years of treatment. PAH analysis was carried out on a HPLC-UV. Total PAH content in control plants was 3.6–7.3 μ g kg?1 for shoots and 13–27 μ g kg?1 for leaves. Treated plant tissue content was higher with shoots and leaves containing ～5.5–17.6 and 13.5–33.8 μg kg?1, respectively. Plant total PAH content did not show a significant trend relative to controls with respect to time. However, uptake did increase in relation to an increased sludge application. Bioconcentration factors (BCF), adjusted by control values, were calculated for total PAH content. BCF values were highest for the initial sampling (6 months) and did not show a significant temporal relationship. BCF values did decrease with increasing sludge application. With respect to individual PAHs, elevated plant tissue concentrations were measured for “light” PAH (e.g. naphthalene, phenanthrene, acenaphthalene) with leaf BCF values correlated with solubility and organic partitioning coefficients.  相似文献   

2.
One of the main environmental impacts of concentrated animal feeding operations is soil degradation in the vicinity of the livestock breeding facilities due to substances such as ammonia emitted from the various stages of the process. In this research, the soil degradation effects of an intensive hog farming operation (IHFO) located at a Mediterranean limestone soil coastal area have been investigated. Soil samples of the upper mineral soil were taken in various distances and directions from the IHFO boundaries. Thirteen experimental cycles were carried out in the duration of 1.5?years starting in March 2009 until October 2010. The soil samples were analysed on total, exchangeable and water-soluble Ca, Mg and K as well as water-soluble ammonium concentrations. Significantly lower concentrations of the exchangeable and water-soluble base cations were observed on soil samples at increasing proximity downwind from the farm (south). Southern soil average concentrations of exchangeable base cations ranged between 78.6 and 128.52?mmol Ca2+?kg?1 soil, 8.42?C21.39?mmol?Mg2+?kg?1 soil and 4.25?C8.1?mmol?K+?kg?1 soil, respectively. Southern soil average concentrations of water-soluble base cations ranged between 0.57 and 2.17?mmol Ca2+?kg?1 soil, 0.16?C0.89?mmol?Mg2+?kg?1 soil and 0.48?C0.95?mmol?K+?kg?1 soil, respectively.  相似文献   

3.
Chemical extractions were tested to estimate the fraction of 15 polycyclic aromatic hydrocarbons (PAHs) in polluted soils degradable through bioremediation. Of 30 soil samples, differing in PAH concentrations, from 10 long‐term polluted sites, four were used in screening tests conducted with 14 different extractants. PAH extractability increased in the order salt solutions < surfactant solutions < organic solvents and organic solvent–water mixtures. Closest correlations (r = 0.73–0.91) and ratios of c. 1:1 of the extracted to the degradable PAH concentrations were found with aqueous solutions of two surfactants (Genapol UDD 88, Synperonic LF/RA 30). The PAH extractability by surfactant solutions increased with surfactant concentration (0–50 mg ml?1) and with decreasing degree of PAH condensation (6–2 rings). Kinetic behaviour of PAH solubilization by surfactants resembled the kinetics of PAH degradation (r = 0.84–0.99). With repeated extractions, a finite fraction of PAHs was extracted, which is thought to be the mobile and mobilizable PAH fraction, the latter being controlled by back‐diffusion from intra‐ and inter‐particle sites. Experiments with all 30 soil samples and a priori testing with an additional 10 soil samples confirmed that single extractions with surfactant solutions (5 mg ml?1; soil:solution ratio 1:20) were suitable for estimating the degradable fraction of PAHs in soil. With separate linear regression equations for PAHs grouped according to their degree of condensation, the extracted concentrations described the degradable concentrations with correlation coefficients (r) ranging from 0.62 to 0.80 (P < 0.001). PAH extractions with the surfactant solutions can be used to assess the prospects of bioremediation of PAH‐polluted sites.  相似文献   

4.
The present study was conducted with an objective to estimate the distribution of boron (B) application in various soil fractions and their plant response for assessing the availability in the soil. Two soils (alluvial and red soil) and five levels of B (0, 0.5, 1, 2 and 3?mg B kg?1 soil) were applied in the pot experiment, and pots were sown with cauliflower (Sabour Agrim) arranged in a completely randomized block design (CRD) with three replications. Result showed that the curd yield of cauliflower increased significantly upto 2?mg B kg?1 soil irrespective of soils. The percent yield increase was 14.78 and 15.01 in alluvial and red soil over the control, respectively. The initial total B content was 35.88 (alluvial soil) and 15.51 (red soil) mg·kg?1. The mean content of Fraction I, II, III, IV and V in alluvial soil was 1.11, 1.54, 0.65, 1.49, and 95.18% and in red soil was 2.68, 4.47, 6.62, 2.50, and 83.59% of the total soil B, respectively. For changes in amount of B fractions due to B applications there was significant effect on all the fractions except Fraction II. The increase in apparent B uptake was 0.43?mg B kg?1 in alluvial soil and 0.25?mg B kg?1 in red soil over the control (0?mg B kg?1 soil). Regression equation of yield and B fractions showed the relationship between first four fractions to the yield. Residual fraction was found to be collinear during calculation. Overall the study predicted the bioavailability and dynamics of B in the two distinct soils.  相似文献   

5.
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6.

Purpose

The choice and timing of microorganisms added to soils for bioremediation is affected by the dominant bioavailable contaminants in the soil. However, changes to the concentration of bioavailable PAHs in soil are not clear, especially when several PAHs coexist. This study investigated the effects of PAH concentration and chemical properties on desorption in meadow brown soil after a 1-year aging period, which could reflect changes of PAH bioavailability during bioremediation.

Materials and methods

Based on the percentage of different molecular weights in a field investigation, high-level contaminated soil (HCS) and low-level contaminated soil (LCS) were prepared by adding phenanthrene (PHE), pyrene (PYR) and benzo(a)pyrene (BaP) to uncontaminated meadow brown soil. The concentrations of HCS and LCS were 250 mg?kg?1 (PHE, PYR, and BaP: 100, 100, and 50 mg?kg?1) and 50 mg?kg?1 (PHE, PYR, and BaP: 20, 20, and 10 mg?kg?1) respectively. The soils were aged for 1 year, after which desorption was induced by means of a XAD-2 adsorption technique over a 96-h period.

Results and discussion

The range of the rapidly desorbing fraction (F rap) for PHE, PYR, and BaP in HCS and LCS was from 1.9 to 27.8 %. In HCS, desorption of PYR was most difficult, and the rate constant of very slow desorption (K vs) of PYR was 8 orders of magnitude lower than that of BaP, which had similar very slow desorbing fractions (49.8 and 50.5 %, respectively). However, in LCS, desorption of PYR was the easiest; the Kvs of PYR was 8–10 orders of magnitude higher than those of PHE and BaP. In HCS, the time scale for release of 50 % of the PAHs was ranked as BaP?>?PYR?>?PHE, while in LCS this was BaP?>?PHE?>?PYR.

Conclusions

The combined effect of PAH concentrations and properties should be taken into account during desorption. The desorption of PAH did not always decrease with increasing molecular weight, and the desorption of four-ring PAHs might be special. These results are useful for screening biodegrading microbes and determining when they should be added to soils based on the dominant contaminants present during different periods, thus improving the efficiency of soil bioremediation.  相似文献   

7.
Ozone and UV irradiation were used for oxidative decomposition of EDTA-Cu complexes in washing solution obtained during multi-step leaching of Cu (344,1?±?36.5 mg kg?1) contaminated vineyard soil with EDTA as a chelant. The released Cu was absorbed from the washing solution on a commercial mixture of metal absorbing minerals, and the treated washing solution then reused for removal of soil residual Cu-EDTA complexes in a closed-loop process. Six consecutive leaching steps (6?×?2.5 mmol kg?1 of EDTA) removed 38.8 % of Cu from soils, and reduced Cu soil mobility, determined using the toxicity characteristic leaching test (TCLP), by 28.5%. The final washing solution obtained after soil remediation was colourless, with a pH close to neutral (7.5?±?0.2) and with low concentrations of Cu and EDTA (0.51?±?0.22 mg L?1 and 0.083 mM, respectively). The proposed remediation method has therefore potential not just to recycle and save process water, but also not to produce toxic wastewaters. Soil treatment did not substantially alter the soil properties determined by pedological analysis, and had relatively little impact on soil hydraulic conductivity and soil water sorption capacity.  相似文献   

8.
The 137Cs and 40K activities and transfer factors from soil to vegetables, grass, and milk from villages located around Tarapur Atomic Power Station (TAPS) were determined using high-resolution gamma spectrometry. A total of 32 soil, 21 vegetable, 23 dry paddy grass, and 23 milk samples were collected from 23 different agricultural farms from various villages around TAPS to determine transfer factors for natural environment. The mean concentration values for 137Cs and 40K in soil, grass, and milk were 2.39?±?0.86 Bq kg?1, 0.31?±?0.23 Bq kg?1, and 12.4?±?5.7 mBq L?1 and 179?±?31 Bq kg?1, 412?±?138 Bq kg?1, and 37.6?±?9.3 Bq L?1, respectively, for soil?Cgrass?Cmilk pathway. In the soil?Cvegetation pathway, the mean concentrations values for 137Cs and 40K were 2.15?±?1.04 Bq kg?1, 16.5?±?7.5 mBq kg?1, and 185?±?24, 89?±?50 Bq kg?1, respectively. The evaluated mean transfer factors from soil?Cgrass, grass?Cmilk, and soil?Cvegetation for 137Cs were 0.14, 0.0044, and 0.0073 and that of 40K were 2.42, 0.0053, and 0.49, respectively. Only 15 out of total 44 milk and vegetable samples were detected positive for 137Cs, indicating a very low level of bioavailability.  相似文献   

9.
Concentrated Animal Feeding Operation activities lead to soil degradation in vicinity with the livestock breeding facilities, mainly due to ammonia emissions from the various stages of the process. In this research, the soil degradation effects of an intensive hog farming operation (IHFO) located at a Mediterranean limestone soil coastal area, have been investigated. Soil samples of the upper mineral soil were taken in various distances (10?C1,500?m) and directions from the IHFO boundaries. Thirteen experimental cycles were carried out in the duration of 1.5?years starting in March 2009 until October 2010. The soil samples were analysed on total, exchangeable and water-soluble Al, Fe and Mn. Significantly higher concentrations of the exchangeable and water-soluble Al, Fe and Mn were observed on soil samples at increasing proximity downwind from the farm (south). Southern soil average concentrations of exchangeable Al3+, Fe3+ and Mn2+ ranged between 3.56 and 7.45?mmol Al3+ kg?1 soil, 5.85 and 7.11?mmol Fe3+ kg?1 soil and 2.36 and 5.03?mmol Mn2+ kg?1 soil, respectively. Southern soil average concentrations of water-soluble Al, Fe and Mn forms ranged between 1.1 and 4.6?ppm Al, 0.5 and 0.8?ppm Fe and 0.4 and 1?ppm Mn, respectively.  相似文献   

10.
Abstract

In intensive agricultural systems, efficient nutrient use is necessary for high crop yields as well as for sustainable environmental management. Recent studies in temperate regions indicate that non-exchangeable NH4 +-N (NEA), which is fixed in clay minerals, may affect crop productivity and soil N dynamics more than previously thought. To estimate the quantity and plant availability of NEA in Swedish soils, ryegrass (Lolium perenne) was grown in a pot experiment using 18 soils that were collected (0–20?cm depth) from two long-term agricultural experiment series at five locations. Initial NEA, total N and soil K contents were measured, as well as NEA content 56, 112 and 168?days after planting of ryegrass. The results show that the soils (0–20?cm) contained 21–217?mg?NEA?kg?1 sieved soil (5–300?kg?NEA?ha?1) estimated as corresponding to 0.1–5.1% of the total soil N. Long-term application of farmyard manure (FYM) did not increase contents of soil NEA. Long-term application of K fertilizer increased soil contents of AL-extractable K, but there was no significant correlation with NEA content. Concurrent with ryegrass growth, NEA content decreased on average by 16% between day 0 and day 112, indicating that NEA was released from the soil and taken up by the plants.  相似文献   

11.
Foliar Cd and Zn concentrations in Salix, Populus and Zea mays grown on freshwater tidal marshes were assessed. Soil metal concentrations were elevated, averaging 9.7 mg Cd kg?1 dry soil, 1100 mg Zn kg?1 dry soil and 152 mg Cr kg?1 dry soil. Cd (1.1–13.7 mg kg?1) and Zn (192–1140 mg kg?1) concentrations in willows and poplars were markedly higher than in maize on impoldered tidal marshes (0.8–4.8 mg Cd kg?1 and 155–255 mg Zn kg?1). Foliar samples of maize were collected on 90 plots on alluvial and sediment‐derived soils with variable degree of soil pollution. For soil Cd concentrations exceeding 7 mg Cd kg?1 dry soil, there was a 50% probability that maize leaf concentrations exceeded public health standards for animal fodder. It was shown that analysis of foliar samples of maize taken in August can be used to predict foliar metal concentrations at harvest. These findings can therefore contribute to anticipating potential hazards arising from maize cultivation on soils with elevated metal contents.  相似文献   

12.

Purpose

The best method for determining soil organic carbon (SOC) in carbonate-containing samples is still open to debate. The objective of this work was to evaluate a thermal gradient method (ThG), which can determine simultaneously inorganic carbon (SIC) and SOC in a wide range of soil samples.

Materials and methods

The determination of SOC by ThG (SOCThG) was compared to the following widespread standard methods: (1) acidification (ACI) as pretreatment and subsequent dry combustion (SOCACI) and (2) volumetric quantification of SIC by a calcimeter (CALC) and subtraction of the total carbon content as determined by dry combustion (SOCCALC). Precision (F test) and bias (t test) were tested on a subset of seven samples (n?=?3). Comparison of the ThG and CALC methods was performed by regression analysis (n?=?76) on samples representing a wide range of SOC (5.5 to 212.0 g kg?1) and SIC (0 to 59.2 g kg?1) contents.

Results and discussion

Tests on the replicated subset showed that the precision of ThG was not significantly different from ACI or CALC (F values?<?39, n?=?3) for SOC and SIC measurements. However, SOCACI and SOCCALC contents were systematically and significantly lower compared to SOCThG contents. The positive bias for SOCThG relative to SOCCALC contents appeared also in the regression analysis (given numbers?±?standard errors) of the whole data set (y?=?(4.67?±?0.70)?+?(0.99?±?0.01)x, R 2?=?0.99, n?=?76). When performing a regression with carbonate-free samples, the bias between the methods was negative (?2.90?±?0.63, n?=?29) but was positive in the set with carbonate-containing samples (3.95?±?1.41, n?=?47). This observation corroborated the suspicion that the use of acid for carbonate decomposition can lead to an underestimation of SOC.

Conclusions

All methods were suitable for differentiation between SIC and SOC, but the use of acid resulted in lower estimates of SOC contents. When comparing soil samples with different carbonate concentrations, the use of the ThG method is more reliable.  相似文献   

13.
Abstract

Good and balanced citrus nutrition is important for high fruit yields and improved tree performance. A study was conducted for 2?years to investigate the effect of soil application of boron (B) on leaf nutrient content, canopy size, and root length density (RLD). The study was conducted on 10-year-old Candidatus Liberibacter asiaticus (CLas)-infected Vernia sweet orange on Rough Lemon rootstock in a commercial grove east of St. Cloud, FL planted at 375 trees ha?1 on a traditional soluble dry nutrition and spray programs. Treatments were supplied with various ground-applied controlled-release fertilizer treatments containing B. Boron was applied at 0×, 2×, and 4× current University of Florida recommendation where 1×?=?1.12?kg ha?1. Data collected included leaf B nutrient content, soil B concentration, trunk diameters, canopy volumes, soil electrical conductivity, and soil pH. The 0×, 2×, and 4× application rates corresponded with leaf nutrient contents ranging from 56?mg kg?1 and 88?mg kg?1 in March 2017, 162?mg kg?1 and 288?mg kg?1 in September 2017, and 122?mg kg?1 and 320?mg kg?1 in May 2018. Temporary, RLD decreased with time from March to September 2017 by 13, 30, and 37% at the 0, 2.24, and 4.48?kg B ha?1 and increased by 309, 258, and 306% at the 0, 2.24, and 4.48?kg B ha?1, respectively, from September 2017 to May 2018. No consistent pattern was established between soil B application with canopy size.  相似文献   

14.
Maize (Zea mays L.) is the most widely grown crop in Bosnia and Herzegovina especially in Northwest part of the country. Considering that, the maize is extremely sensitive to micronutrient deficiency the main aim of this study was to asses: (1) micronutrient availability in soil, (2) micronutrient status in silage maize; and (3) the relationship between micronutrient soil availability and maize plant concentration. Soil samples for micronutrient availability (n?=?112) were collected from 28 farms in 7 municipalities. Plant available micro- and macro- nutrients in soil were extracted using Mehlich-3, except plant available Se was extracted using 0.1M KH2PO4. Result showed that on average there was no significant difference between different soil types regarding their potential in plant available nutrients. P deficiency was present both, in soil and plants in whole region. Soil extractable P was ranging from 0.003–0.13?g?kg?1 and total plant P was ranging from 0.79–4.95?g?kg?1. Zinc deficiency was observed in two locations both in soil (0.71?mg?kg?1; 0.79?mg?kg?1) and plant (11.5?mg?kg?1; 15.8?mg?kg?1). Potential Se soil deficiency was observed on some locations, while Se plant status is not high enough to meet daily requirements of farm animals. Extractable soil nutrients could be used as relatively good predictor of potential soil and plant deficiencies, but soil nutrient interactions and climate conditions are highly effecting the plant uptake potential.  相似文献   

15.
The influence of atmospheric fluoride deposits on the soil microbial biomass and its enzyme activities was investigated near the aluminium smelter at Ranshofen, Upper Austria. Soil samples at various distances from the emission source were analyzed for water-extractable F and microbial activity. The water-extractable F contents at the sites examined reflected the gradient of F exposure (10 to 189 mg F kg?l dry soil). The microbial activities increased with distance from the emission source and were inversely correlated with the degree of F contamination. The linear correlation coefficients between the water-extractable F concentrations and the microbial biomass, dehydrogenase and arylsulphatase activity were r=?0·8, ?0·86 and ?0·84, respectively. In the most contaminated soil (up to 189 mg F kg?1), the microbial activities were only 5–20% of those in the unpolluted soil. The microbial biomass and dehydrogenase activity decreased substantially where the concentration of F exceeded 100mgkg?1, whereas arylsulphatase activity was already inhibited at 20 mg kg?1. The accumulation of organic matter near the smelter (123 mg F kg?1) also indicated severe inhibition of the microbial activity by F. Our investigations show that the ratio of arylsulphatase to microbial biomass can be used as a sensitive index for evaluating environmental stress such as F Contamination.  相似文献   

16.
The vertical distribution of mercury along a weathering profile derived from a diabase was compared to the main geochemical and mineralogical characteristics of the soil and its parental rock. The sampling site was in a metropolitan area, nearby to an active quarry and relatively close to an industrial park. The samples of a 6-m-deep fresh exposure of the soil profile and also of fresh rock were collected during the dry season. Kaolinite, goethite, hematite, and residual primary minerals were identified in the soil samples. Typically, the concentrations of Hg in the soil are low. Whole samples contained between 1 (rock) and 37 ??g kg?1 Hg, while the?<?63-??m soil fraction had up to 52 ??g kg?1 Hg. The higher values of Hg corresponded to the upper layers of A (0?C10 cm) and B (200?C220 cm) soil horizons. Elemental gains and losses calculated against Zr resulted in the following order: Hg>>Pb?>?Zr?>?LREE?>?Nb?>?HREE?>?Al?>?Ti?>?Fe?>?Cr. Total organic carbon in soil samples varied between 0.2 and 5.1 g dm?3, and correlation with Hg concentrations was moderate. The acid pH (4.2?C5.5) of the soil samples favors the sorption Hg species by predominant secondary phases like goethite and kaolinite. The Hg concentration of the rock is insufficient to explain the large enrichment of Hg along the soil profile, indicating that exogenic Hg, via atmospheric deposition, contributed to the measured Hg concentrations of the soil.  相似文献   

17.
Abstract

Biochar application to soils can mitigate carbon dioxide (CO2) by increasing soil carbon (C) sink, but also causes increased CO2 released from soils through priming effects of soil organic carbon (SOC). However, priming effects of biochar application on SOC are complex, showing inconsistent results, and further complicated when applied with other substrates such as organic amendment (OA). Incubation experiments were conducted using Typic Durudand with bamboo (Phyllostanchys edulis Carrière) biochar (400°C) and OA (crotalaria) applied individually, simultaneously or with biochar applied 5 weeks prior to OA application. After 56 d of incubation, cumulative CO2 released from soils with no amendments (control), biochar only (BC), OA only (OA), simultaneous (BC+OA), and differently timed (BCP+OA) applications reached 313, 326, 1270, 1535 and 1311 mg CO2 kg?1, respectively. The OA application distinctly increased CO2 released from the soils due to its decomposition. The OA decomposition rates were comparable with OA and BC+OA, while those with BCP+OA were lower than those with other treatments during early incubation. Net CO2 (CO2-(treatment) ? CO2-control) from soils with BC, OA, BC+OA and BCP+OA yielded 13, 957, 1222 and 998 mg CO2 kg?1, respectively. Primed CO2-BC of 13 mg CO2 kg?1 was equivalent to 4.2% of priming effect relative to CO2-control. Primed CO2-BC+OA [net CO2-BC+OA ? (net CO2-BC + net CO2-OA)] and primed CO2-BCP+OA were 252 and 28 mg CO2 kg?1, equivalent to 26% and 2.9% of priming effects relative to sum of net CO2-BC + net CO2-OA, respectively. The priming effect with BC was negligible likely because of limited amounts of biochar labile C to induce co-metabolism, while BC+OA showed a modest priming effect most likely as a result of co-metabolism induced by additional mineralization of presumably SOC and/or biochar, because the OA decomposition rates were not affected by biochar application. The priming effect with BCP+OA was comparable to that with BC likely due to changes in soil properties caused by biochar application prior to OA, likely from slowed decomposition rates of OA.  相似文献   

18.
Abstract

This study investigated whether small additions to soil of primary paper-mill sludge, a wood fibre residue from paper production (fibre sludge), caused temporary N immobilization and thereby reduced the amount of inorganic nitrogen leached from agricultural land. This was achieved by measuring respiration and immobilization of N in incubation studies at 8°C, with fibre sludge added at rates varying from 63 to 1000?mg?C?kg?1 soil. Glucose added at rates of 63–250?mg?C?kg?1 soil was used as a reference. Respiration in soil after glucose addition followed an exponential course with the highest rates on days 2–4. During this period maximum peaks of net N immobilization were measured. Even addition of only 63?mg glucose-C?kg?1 soil caused significant immobilization of N in soil. Fibre sludge additions to soil caused lower respiration activities, characterized by two initial peaks followed by somewhat higher respiration rates during the remaining incubation than for glucose. It was likely that hemicellulose, which amounted to 14% of the total C, was the initial available energy source in the sludge as concentrations of water-soluble C were very low. Addition of at least 250?mg?C?kg?1 soil as fibre sludge was required to cause significant N immobilization in soil corresponding to 5?kg?N?ha?1. Both nitrate and ammonium were immobilized. Relating maximum N immobilization data during days 2 to 10 to corresponding respiration data for glucose and fibre sludge revealed that microbes utilised similar amounts of C per unit N immobilized. On average, 175.6±74.8?mg CO2-C were respired to immobilize 1?mg?N and the relationship between C respiration and N immobilization was linear (R 2=0.984). To make soil application of fibre sludge a realistic counter-measure against N leaching from agricultural soils, pre-treatment is necessary to increase the content of energy readily available to microbes.  相似文献   

19.
Current non-invasive biomonitoring techniques to measure heavy metal exposure in free ranging birds using eggs, feathers and guano are problematic because essential metals copper (Cu) and zinc (Zn) deposited in eggs and feathers are under physiological control, feathers accumulate metals from surface contamination and guano may contain faecal metals of mixed bioavailability. This paper reports a new technique of measuring lead (Pb), Cu and Zn in avian urate spheres (AUS), the solid component of avian urine. These metal levels in AUS (theoretically representing the level of metal taken into the bloodstream, i.e. bioavailable to birds) were compared with levels in eggs (yolk and shell), feathers and whole guano from chickens (Gallus gallus domesticus) exposed to a heavy metal-contaminated soil (an allotment soil containing Pb 555?mg?kg?1 dry mass (dm), Cu 273?mg?kg?1?dm and Zn 827?mg?kg?1?dm). The median metal levels (n?=?2) in AUS from chickens exposed to this contaminated soil were Pb 208???g?g?1 uric acid, Cu 66???g?g?1 uric acid and Zn: 526???g?g?1 uric acid. Lead concentrations in egg yolk and shell samples (n?=?3) were below the limit of detection (<2?mg?kg?1), while Cu and Zn were only consistently detected in the yolk, with median values of 3 and 70?mg?kg?1 (dm), respectively, restricting the usefulness of eggs as a biomonitor. Feathers (n?=?4) had median Pb, Cu and Zn levels respectively of 15, 10 and 140?mg?kg?1 (dm), while whole guano samples (n?=?6) were 140, 70 and 230?mg?kg?1 (dm). Control samples were collected from another chicken flock; however, because they had no access to soil and their diet was significantly higher in Cu and Zn, no meaningful comparison was possible. Six months after site remediation, by top soil replacement, the exposed chickens had median Pb, Cu and Zn levels respectively in whole guano (n?=?6) of 30, 20 and 103?mg?kg?1 (dm) and in AUS (n?=?4) of 147, 16 and 85???g?g?1 uric acid. We suggest the persistent high Pb level in AUS was a consequence of bone mobilised for egg production, releasing chronically sequestered Pb deposits into the bloodstream. In contrast, AUS levels of Cu and Zn (metals under homeostatic control and sparingly stored) had declined, reflecting the lower current exposure. However because pre- and post-remediation samples were measured using different methods carried out at different laboratories, such comparisons should be guarded. The present study showed that metals can be measured in AUS, but no assessment could be made of availability or uptake to the birds because tissue and blood samples were not concomitantly analysed. A major short coming of the study was the inappropriate control group, having no access to uncontaminated soil and being fed a different diet to the exposed birds. Furthermore guano and urine analysis should have been carried out on samples from individual birds, so biological (rather than just technical) variation of metal levels could have been determined. Future studies into using AUS for biomonitoring environmental heavy metals must resolve such experimental design issues.  相似文献   

20.

Purpose

A major challenge to phytoremediation of co-contaminated soils is developing strategies for efficient and simultaneous removal of multiple pollutants. A pot experiment was conducted to investigate the potential for enhanced phytoextraction of cadmium (Cd) by Sedum alfredii and dissipation of polycyclic aromatic hydrocarbons (PAHs) in co-contaminated soil by application of pig manure vermicompost (PMVC).

Materials and methods

Soil contaminated by Cd (5.53?mg?kg?1 DW) was spiked with phenanthrene, anthracene, and pyrene together (250?mg?kg?1 DW for each PAH). A pot experiment was conducted in a greenhouse with four treatments: (1) soil without plants and PMVC (Control), (2) soil planted with S. alfredii (Plant), (3) soil amended with PMVC at 5?% (w/w) (PMVC), and (4) treatment 2?+?3 (Plant?+?PMVC). After 90?days, shoot and root biomass of plants, Cd concentrations in plant and soil, and PAH concentrations in soil were determined. Abundance of PAH degraders in soil, soil bacterial community structure and diversity, and soil enzyme activities and microbial biomass carbon were measured.

Results and discussion

Application of PMVC to co-contaminated soil increased the shoot and root dry biomass of S. alfredii by 2.27- and 3.93-fold, respectively, and simultaneously increased Cd phytoextraction without inhibiting soil microbial population and enzyme activities. The highest dissipation rate of PAHs was observed in Plant?+?PMVC treatment. However, neither S. alfredii nor PMVC enhanced PAH dissipation when applied separately. Abundance of PAH degraders in soil was not significantly related to PAH dissipation rate. Plant?+?PMVC treatment significantly influenced the bacterial community structure. Enhanced PAH dissipation in the Plant?+?PMVC treatment could be due to the improvement of plant root growth, which may result in increased root exudates, and subsequently change bacterial community structure to be favorable for PAH dissipation.

Conclusions

This study demonstrated that remediation of Cd and PAHs co-contaminated soil by S. alfredii can be enhanced by simultaneous application of PMVC. Long-term evaluation of this strategy in co-contaminated field sites is needed.  相似文献   

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