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1.
Anna Piotrowska Jacek Długosz Barbara Namysłowska-Wilczyńska Ryszard Zamorski 《Biology and Fertility of Soils》2011,47(1):101-109
We have studied spatial field-scale variability of soil dehydrogenase (DH) and cellulase activities (CEL) and their relationship
with variability of some physico-chemical properties at the surface horizon of the agricultural field. Soil samples were collected
at 50 points from the upper 20 cm of soil. The activity of DH ranged between 0.77 and 1.5 μM TPP·g−1·h−1 while CEL activity ranged from 0.8 to 1.94 μM glucose·g−1·24 h−1. Concentrations of CORG and TN varied from 8.5 to 31.7 g·kg−1 and from 0.94 to 3.56 g·kg−1, respectively. The soil data showed that spatial variability and semivariograms describe spherical and linear models with
the nugget effect (DH, CEL, CORG and TN). Dehydrogenase activity was in the strong variability class, while cellulase activity was situated in the week variability
class. Both CORG and TN concentrations and pHKCl values were strongly spatially dependent with the percentage of total variance (sill) presents as nugget variance ranging
from 8.9% to 16.1%. Kriged maps displayed the lowest values of CEL activities in the north-east of the area, while the south
area showed the highest CEL activity. The DH activity values were irregularly distributed in the surface horizon of the studied
soil and this behaviour did not correspond with the spatial distribution of other properties. 相似文献
2.
Jürgen Kern Hans Jürgen Hellebrand Michael G?mmel Christian Ammon Werner Berg 《Biology and Fertility of Soils》2012,48(1):1-8
Methane flux rates were measured on a loamy sand soil within perennial and annual energy crops in northeast Germany. The study
was performed in closed chambers between 2003 and 2005 with four measurements per week. A mixed linear model including the
fixed effects of year, rotation period, crop and fertilisation was applied to determine the influence of climatic factors
and soil management on the CH4 flux. Soil water content and air temperature were added as co-variables. With the exception of air temperature, all fixed
effects and the co-variable soil water content influenced the CH4 flux. The soil of annual crops consumed 6.1 μg CH4 m−2 h−1, significantly more than the soil of perennial crops with 4.3 μg CH4 m−2 h−1. It is suggested that soil water content plays the key role in CH4 flux between pedosphere and atmosphere. In the range of water contents between 5% and 15%, our model describes that a soil
water content increase of 1% induces a net emission of 0.375 μg CH4 m−2 h−1. As the soil of the experimental field was well-drained and aerobic, it represented a net sink for CH4 throughout the study period. 相似文献
3.
Some additional experiments checking out the extraction method recently developed for the determination of MeHg in biological
samples by Headspace Gas Chromatography with Microwave Induced Plasma atomic emission spectroscopy detection were performed.
In this method, the MeHg is cleaved from the biological tissue by H2SO4 and by addition of iodoacetic acid converted to the iodide form. These reaction steps take place in a closed headspace vial.
The H2SO4 concentration and the sample matrix have an important influence on the recovery of the MeHg from the sample and these effects
are discussed. The method was then applied to the determination of MeHg in cod fish caught in the North Sea. Levels found
ranged from 0.13 to 0.63 μg g−1 dw with a mean of 0.33 μg g−1 on the 25 samples analyzed. The total Hg content of these samples was also determined by Cold Vapour Atomic Absorption Spectrometry,
and all data pooled ranged from 0.19 to 0.90 μg g−1 with a mean of 0.40 μg g−1. A study of the ratio MeHg/total Hg revealed that MeHg always constituted more than 60 % of the total Hg level, with a mean
of 83 % on the 25 samples. The percentage MeHg did not increase or decrease markedly when the total Hg content increased.
It could be concluded that these North Sea samples are not much contaminated by Hg and are surely suitable for consumption. 相似文献
4.
Ana de Santiago José M. Quintero Eusebio Carmona Antonio Delgado 《Biology and Fertility of Soils》2008,44(6):875-883
The main objective of this work was to study the influence of humic substances (HS) on the effectiveness of Fe sulfate and
Vivianite in preventing Fe chlorosis in white lupin with a view of performing cost-effective methods to overcome the problem.
Two consecutive crops were performed using calcareous sand treated with different Fe sources (FeSO4·7H2O and Vivianite, at three different rates, and Fe-EDDHA) and five HS rates. Vivianite was more effective and persistent than
Fe sulfate in increasing Soils and Plant Analysis Development (SPAD) readings and lupin yield expressed as dry matter (DM),
probably due to the type of alteration products formed upon Vivianite oxidation. The effect of Fe sulfate and Vivianite in
preventing Fe chlorosis was significantly increased by HS, and the best results were obtained with Vivianite and HS applied
at 0.32 g Fe kg−1 and 0.06 g kg−1 growing media, respectively. SPAD readings with this treatment accounted for 85% and 70% of those obtained with Fe-EDDHA
in the first and second crop, respectively, whereas DM production was greater with the Vivianite + HS treatment than with
Fe-EDDHA. These results showed the potential effectiveness of treatments based on the application of Vivianite and HS in overcoming
Fe chlorosis. However, HS applied with Fe sources at rates of 0.5 and 1 g kg−1 growing media decreased SPAD readings and plant yield. These positive and negative effects of HS in preventing Fe chlorosis
were more evident with Fe sulfate and Vivianite than with chelated Fe, probably due to the effect of HS on the solubility
of Fe forms of the growing medium. 相似文献
5.
We compared, from 2004 through 2006, rates of soil–atmosphere CH4 exchange at permanently established sampling sites in a temperate forest exposed to ambient (control plots; ∼380 μL L−1) or elevated (ambient + 200 μL L−1) CO2 since August 1996. A total of 880 observations showed net atmospheric CH4 consumption (flux from the atmosphere to the soil) from all static chambers most of the time at rates varying from 0.02 mg m−2 day−1 to 4.5 mg m−2 day−1. However, we infrequently found net CH4 production (flux from the soil to the atmosphere) at lower rates, 0.01 mg m−2 day−1 to 0.08 mg m−2 day−1. For the entire study, the mean (±SEM) rate of net CH4 consumption in control plots was higher than the mean for CO2-enriched plots, 0.55 (0.03) versus 0.51 (0.03) mg m−2 day−1. Annual rates of 184, 196, and 197 mg m−2 for net CH4 consumption at control plots during the three calendar years of this study were 19, 10, and 8% higher than comparable values
for CO2 enriched plots. Differences between treatments were significant in 2004 and 2005 and nearly significant in 2006. Volumetric
soil water content was consistently higher at CO2-enriched sites and a mixed-effects model identified a significant soil moisture x CO2 interaction on net atmospheric CH4 consumption. Increased soil moisture at CO2-enriched sites likely increases diffusional resistance of surface soils and the frequency of anaerobic microsites supporting
methanogenesis, resulting in reduced rates of net atmospheric CH4 consumption. Our study extends our observations of reduced net atmospheric CH4 consumption at CO2-enriched plots to nearly five continuous years, suggesting that this is likely a sustained negative feedback to increasing
atmospheric CO2 at this site. 相似文献
6.
Balaji Rao Suhas Mohan Andreas Neuber William Andrew Jackson 《Water, air, and soil pollution》2012,223(1):275-287
Perchlorate (ClO4−), a thyroid hormone disruptor, is both naturally occurring and a man-made contaminant increasingly found in a variety of
terrestrial environments. The environmental presence of ClO4− is considered to be the result of atmospheric formation and deposition processes. The ultimate processes, particularly heterogeneous-based
reactions, leading to natural ClO4− formation are not well understood. Oxidation of chlorine species by an energetic source such as lightning is considered to
be one of the potential heterogeneous sources of natural ClO4−. Currently, there is very little information available on lightning-induced ClO4−. We designed a laboratory electrical discharge reactor capable of evaluating ClO4− formation by the oxidation of “dry” sodium chloride (NaCl) aerosols (relative humidity (RH) <70%) in electrical discharge
plasma at voltages and energies up to 24 kV and 21 kJ, respectively. Similar to other non-electrochemical ClO4− production processes, the amount of ClO4− produced (0.5–4.8 μg) was 3 orders of magnitude lower than the input Cl− (7.1–60.1 mg). The amount of ClO4− generated increased with peak voltage (V) and theoretical maximum discharge energy with ΔClO4−/ΔV = 0.28 × 10−3 μg V−1 (R
2 = 0.94) and ΔClO4−/ΔE = 0.44 × 10−3 μg J−1 (R
2 = 0.83). The total ClO4− generated decreased with an increase in relative humidity from 2.8 ± 0.1 μg (RH ∼46%) to 0.9 ± 0.1 μg (RH ∼62%) indicating
that the presence of moisture inhibits the formation of ClO4−. Additional modifications to the reactor support the hypothesis of ClO4− formation due to the action of plasma on Cl− aerosols as opposed to direct oxidation on the surface of the electrodes. Finally, the contribution of lightning-induced
ClO4− in North America is calculated to have a wide range from 0.006 × 105 to 5 × 105 kg/year and is within the range of the measured ClO4− depositional flux in precipitation samples obtained across the USA (0.09 × 105–1.2 × 105 kg/y). 相似文献
7.
C. Alejandra Villamar Teresa Cañuta Marisol Belmonte Gladys Vidal 《Water, air, and soil pollution》2012,223(1):363-369
Since swine wastewater is used by farmers for soil fertilization, evaluation of toxic compounds or micro-contaminants of separate
streams is required. This paper uses the toxicity identification evaluation (TIE) procedure for the physicochemical and ecotoxicological
characterization of swine wastewater. To distinguish the most important toxic compounds, a physicochemical characterization
and phase I-TIE procedure were performed. The acute toxic effect of swine wastewater and treated fractions (phase II-TIE)
were evaluated using Daphnia magna determining 48-h LC50. Results show a high level of conductivity (23.5 μS cm−1), which is explained as due to the concentration of ions, such as ammonium (NH4+–N 1.6 g L−1), sulfate (SO42− 397.3 mg L−1), and chlorine (Cl− 1,230.0 mg L−1). The acute toxicity of the swine wastewater was evaluated on D. magna (48-h LC50 = 3.4%). Results of the different water treatments indicate that anionic exchange treatments could reduce 22.5% of swine
wastewater’s acute toxicity by reducing chlorine (to around 51%) and conductivity (8.5%). On the other hand, cationic exchange
treatment increased acute toxicity on D. magna (% RT = −624.4%), by reducing NH4+–N (around 100%) and total nitrogen (95.5%). This finding suggests that part of the toxicity comes from anionic compounds,
such as chlorine. 相似文献
8.
Ilya Yevdokimov Andreas Gattinger Franz Buegger Jean Charles Munch Michael Schloter 《Biology and Fertility of Soils》2008,44(8):1103-1106
The changes in size, activity and structure of soil microbial community caused by N fertilization were studied in a laboratory
incubation experiment. The rates of N fertiliser applied (KNO3) were 0 (control), 100 and 2,000 μg N g−1 soil. Despite no extra C sources added, a high percentage of N was immobilized. Whereas no significant increase of microbial
C was revealed during incubation period, microbial growth kinetics as determined by the substrate-induced growth-response
method demonstrated a significant decrease in the specific growth rate of microbial community in soil treated with 2,000 μg
N g−1 soil. Additionally, a shift in microbial community structure resulting in an increase in fungal biomarkers, mainly in the
treatment with 2,000 μg N g−1 soil was visible. 相似文献
9.
Stylianos Liodakis Charalampos Michalopoulos Elpida Efthymiou Georgios Katsigiannis 《Water, air, and soil pollution》2012,223(1):169-179
One of the main environmental impacts of concentrated animal feeding operations is the soil degradation in vicinity with the
livestock breeding facilities due to substances such as ammonia emitted from the various stages of the process. Owing to the
high temperatures of the Mediterranean ecosystems, the evolution of gasses is more extensive and the soil degradation is consequently
more severe than those obtained in northern Europe. In this research, the soil degradation effects of a large meat-producing,
processing, and packaging unit have been investigated. The investigated intensive hog farming operation (IHFO) is located
at a limestone soil coastal area with sea to the north and hills to the south. 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 analyzed on pH and electrical conductivity (EC)
values as well as NH4
+ and NO3
− concentrations. Significantly higher concentrations of the two nitrogen forms were observed on samples at increasing proximity
downwind from the farm (south). Southern soil average NH4
+ and NO3
− concentrations ranged between 0.4–118 μg NH4
+-N g−1 soil and 6.1–88.4 μg NO3
−-N g−1 soil, respectively. The variation of emitted gasses depositions was clearly reflected in the average pH and EC values. Average
pH and EC values downwind from IHFO boundaries varied between 7.1–8.2 and 140–268 μS/cm, respectively. 相似文献
10.
Joseph C. Fetter Rebecca N. Brown Josef H. Görres Chong Lee José A. Amador 《Water, air, and soil pollution》2012,223(4):1531-1541
Consumer demand for cleaned squid generates a substantial amount of waste that must be properly disposed of, creating an economic
burden on processors. A potential solution to this problem involves converting squid by-products into an organic fertilizer,
for which there is growing demand. Because fertilizer application to lawns can increase the risk of nutrient contamination
of groundwater, we quantified leaching of NO3–N and PO4–P from perennial ryegrass turf (Lolium perenne L.) amended with two types of fertilizer: squid-based (SQ) and synthetic (SY). Field plots were established on an Enfield
silt loam, and liquid (L) and granular (G) fertilizer formulations of squid and synthetic fertilizers were applied at 0, 48,
146, and 292 kg N ha−1 year−1. Levels of NO3–N and PO4–P in soil pore water from a depth of 60 cm were determined periodically during the growing season in 2008 and 2009. Pore
water NO3–N levels were not significantly different among fertilizer type or formulation within an application rate throughout the
course of the study. The concentration of NO3–N remained below the maximum contaminant level (MCL) of 10 mg L−1 until midSeptember 2009, when values above the MCL were observed for SQG at all application rates, and for SYL at the high
application rate. Annual mass losses of NO3–N were below the estimated inputs (10 kg N ha−1 year−1) from atmospheric deposition except for the SQG and SYL treatments applied at 292 kg N ha−1 year−1, which had losses of 13.2 and 14.9 kg N ha−1 year−1, respectively. Pore water PO4–P levels ranged from 0 to 1.5 mg P L−1 and were not significantly different among fertilizer type or formulation within an application rate. Our results indicate
that N and P losses from turf amended with squid-based fertilizer do not differ from those amended with synthetic fertilizers
or unfertilized turf. Although organic in nature, squid-based fertilizer does not appear to be more—or less—environmentally
benign than synthetic fertilizers. 相似文献
11.
Comparison of community structures of microbiota at main habitats in rice field ecosystems based on phospholipid fatty acid analysis 总被引:1,自引:0,他引:1
The present study compares the community structures of microbiota at different habitats in Japanese rice fields by comparing their phospholipid fatty acid (PLFA) compositions to understand the contribution of different habitats to microbiological diversity. The data were collected from four neighboring rice fields. Comparison was made for the PLFA compositions extracted from the floodwater, percolating water, rice soils under flooded and drained conditions, rice straw (RS) placed in flooded and drained rice soils, RS in the composting process, and RS compost placed in a flooded rice field. Average amounts of PLFAs were 33 μg L−1 in the floodwater, 17.1 μg L−1 in the percolating water from plow layers, 34.6 μg L−1 in the percolating water from subsoil layers, 108 μg g−1 dry weight basis (dw) in flooded rice soils, 382 μg g−1 dw in RS materials, 2,510 μg g−1 dw in RS composts, 2,850 μg g−1 dw in RS composts after application to a flooded rice soil, 222 μg g−1 wet weight basis (ww) in RS in drained rice soils, and 284 μg g−1 ww in RS in flooded rice soils. The total amount of PLFAs to the soil depth of 10 cm was estimated to be about 12 g m−2. The PLFA compositions were different from each other depending on the habitats. Rice soils were characterized by the predominance of actinomycetes and Gram-positive bacteria in comparison with the other habitats. In contrast, the microbial communities in the floodwater and percolating water were characterized by the predominance of Gram-negative bacteria and eukaryotes (presumably algae), and Gram-negative bacteria, respectively. The microbial community of RS materials was dominated by fungi. Gram-positive bacteria became predominant in RS after application to flooded rice soils, while RS placed in a drained rice field after harvesting rice was characterized by the predominance of Gram-negative bacteria and fungi. The community structures at respective habitats were stable and specific, irrespective of the season of sampling and the duration of decomposition of RS. 相似文献
12.
Balaji Anandha Rao Cameron P. Wake Todd Anderson William Andrew Jackson 《Water, air, and soil pollution》2012,223(1):181-188
Temporal depositional rates are important in order to understand the production and occurrence of perchlorate (ClO4−) as limited information exists regarding the impact of anthropogenic production or atmospheric pollution on ClO4− deposition. Perchlorate concentrations in discrete ice core samples from the Eclipse Icefield (Yukon Territory, Canada) and
Upper Fremont Glacier (Wyoming, USA) were analyzed using ion chromatography tandem mass spectrometry to evaluate temporal
changes in the deposition of ClO4
− in North America. The ice core samples cover a time period from 1726 to 1993 and 1970 to 2002 for the Upper Fremont Glacier
(UFG) and Eclipse ice cores, respectively. The average ClO4
− concentration in the Eclipse ice core for the time period from 1970 to 1973 was 0.6 ± 0.3 ng L−1, with higher values of 2.3 ± 1.7 and 2.2 ± 2.0 ng L−1 for the periods 1982–1986 and 1999–2002, respectively. All pre-1980 ice core samples from the UFG had ClO4
− concentrations <0.2 ng L−1, and the post-1980 samples ranged from <0.2 ng L−1 to a maximum of 2.6 ng L−1 for the year 1992. A significant positive correlation (R = 0.75, N = 15, p < 0.001) of ClO4− with SO42− was found for the annual UFG ice core layers and of ClO4
− with SO42− and NO3− in sub-annual Eclipse ice samples (R > 0.3, N = 121, p < 0.002). The estimated yearly ClO4− depositional flux for the Eclipse ice core ranged from 0.6 (1970) to 4.7 μg m−2 year−1 (1982) and the UFG from <0.1 (pre-1980) to 1.4 μg m−2 year−1 (1992). There was no consistent seasonal variation in the ClO4− depositional flux for the Eclipse ice core, in contrast to a previous study on the Arctic region. The presence of ClO4− in these ice cores might correspond to an intermittent source such as volcanic eruptions and/or any anthropogenic forcing
that may directly or indirectly aid in atmospheric ClO4− formation. 相似文献
13.
David Fangueiro Henrique Ribeiro João Coutinho Laura Cardenas Henrique Trindade Cristina Cunha-Queda Ernesto Vasconcelos Fernanda Cabral 《Biology and Fertility of Soils》2010,46(4):383-391
The following six pig slurries obtained after acidification and/or solid/liquid separation were used in the research: original
(S) and acidified (AS) pig slurry, nonacidified (LF) and acidified (ALF) pig slurry liquid fraction, and nonacidified (SF)
and acidified (ASF) pig slurry solid fraction. Laboratory incubations were performed to assess the effect of the application
of these slurries on N mineralization and CO2 and N2O emissions from a sandy soil. Acidification maintained higher NH4
+-N contents in soil particularly in the ALF-treated soil where NH4
+-N contents were two times higher than in LF-treated soil during the 55–171-day interval. At the end of the incubation (171 days),
32.9 and 24.2 mg N kg−1 dry soil were mineralized in the ASF- and SF-treated soils, respectively, but no mineralization occurred in LF- and S-treated
soils, although acidification decreased N immobilization in ALF- (−25.3 mg N kg−1 soil) and AS- (−12.7 mg N kg−1 soil) compared to LF- (−34.4 mg N kg−1 soil) and S-treated (−18.6 mg N kg−1 soil) soils, respectively. Most of the dissolved CO2 was lost during the acidification process. More than 90% of the applied C in the LF-treated soil was lost during the incubation,
indicating a high availability of the added organic compounds. Nitrous oxide emissions occurred only after day 12 and at a
lower rate in soils treated with acidified than nonacidified slurries. However, during the first 61 days of incubation, 1,157 μg N
kg−1 soil was lost as N2O in the AS-treated soil and only 937 in the S-treated soil. 相似文献
14.
The photochemical degradation of two widely used organophosphorothioate insecticides, fenitrothion and diazinon, was investigated
in aqueous solutions containing three separate dissolved constituents commonly found in natural waters (NO3−, CO32− and dissolved organic matter (DOC)). The effect of these constituents on pesticide photodegradation was compared to degradation
in “constituent-free” pure water. Solutions were irradiated in an Atlas solar simulator fitted with a UV-filtered Xenon arc
lamp with light irradiances (500 W m−2) measured using a spectral radiometer to allow derivation of quantum yields of degradation. Fenitrothion absorbs light within
the solar UV range (λ, 295–400 nm) and underwent direct photolysis in pure water whereas diazinon (λ
max ∼250 nm) showed no observable loss over the experimental period. However, photodegradation conforming to pseudo-first-order
kinetics was observed for both chemicals in the presence of the dissolved constituents (at concentrations typically observed
in natural waters), with the rates of photodecay observed in the order of NO3− > CO32− ≅ DOC, with the highest rates observed in the 3 mM NO3− solutions (k
Fen = 0.155 ± 0.041 h−1; k
Dia = 0.084 ± 0.0007 h−1). For diazinon this rate was comparable to fenitrothion photolysis in pure water (k
fen 0.072 ± 0.0078 h−1), highlighting the importance of NO3− on a non-photolabile pesticide, with indirect photodegradation probably attributable to the light-induced release of aqueous
hydroxyl radicals (·OH) from NO3−. Suwannee river fulvic acid (serving as DOC) did not statistically affect the rate of photodecay for fenitrothion relative
to its photolysis in MilliQ water, although measured rates in DOC solutions were slightly lower. However, measurable rates
of photodecay were apparent for diazinon in the DOC solutions, indicating that fulvic acid, possibly in the form of “excited”
triplet-state-DOC plays a role in diazinon transformation. Hydrolysis was not apparent for fenitrothion (in buffered solutions
of pH 5–9) but was notable for diazinon at the lower pHs of 5 and 3 (k
Dia-hyd 0.3414 h−1 at pH 3 and 0.228 h−1 at pH 5), resulting in the formation of the degradate, 2-isopropyl–6-methyl–4-pyrimidinol. This work highlights the importance
of dissolved constituents on abiotic photodegradation of pesticides and it is recommended that these constituents be incorporated
into laboratory-based fate-testing regimes. 相似文献
15.
Application of feedlot manure (FLM) to cropping and grazing soils could provide a valuable N nutrient resource. However, because
of its high but variable N concentration, FLM has the potential for environmental pollution of water bodies and N2O emission to the atmosphere. As a potential management tool, we utilised the low-nutrient green waste compost (GWC) to assess
its effectiveness in regulating N release and the amount of N2O emission from two Vertisols when both FLM and GWC were applied together. Cumulative soil N2O emission over 32 weeks at 24°C and field capacity (70% water-filled pore space) for a black Vertisol (Udic Paleustert) was
45 mg N2O m−2 from unamended soil. This increased to 274 mg N2O m−2 when FLM was applied at 1 kg m−2 and to 403 mg N2O m−2 at 2 kg m−2. In contrast, the emissions of 60 mg N2O m−2 when the soil was amended with GWC 1 kg m−2 and 48 mg N2O m−2 at 2 kg m−2 were not significantly greater than the unamended soil. Emission from a mixture of FLM and GWC applied in equal amounts (0.5 kg m−2) was 106 mg N2O m−2 and FLM applied at 0.5 kg m−2 and GWC at 1.5 kg GWC m−2 was 117 mg N2O m−2. Although cumulative N2O emissions from an unamended grey Vertisol (Typic Chromustert) were only slightly higher than black Vertisol (57 mg N2O m−2), FLM application at 1 kg m−2 increased N2O emissions by 14 times (792 mg N2O m−2) and at 2 kg m−2 application by 22 times (1260 mg N2O m-2). Application of GWC did not significantly increase N2O emission (99 mg N2O m−2 at 1 kg m−2 and 65 mg N2O m−2 at 2 kg m−2) above the unamended soil. As observed for the black Vertisol, a mixture of FLM (0.5 kg m−2) and GWC (0.5 or 1.5 kg m−2) reduced N2O emission by >50% of that from the FLM alone, most likely by reducing the amount of mineral N (NH4+–N and NO3−–N) in the soil, as mineral N in soil and the N2O emission were closely correlated. 相似文献
16.
Raúl Zornoza Dora M. Carmona Jose A. Acosta Silvia Martínez-Martínez Niels Weiss Ángel Faz 《Water, air, and soil pollution》2012,223(2):519-532
This work aims to identify and characterize heavy metal contamination in a fluvial system from Cartagena–La Unión mining district
(SE Spain). In order to assess the dynamics of transport and the accumulation of heavy metals, sediments, surface water and
vegetation, samples along “El Avenque” stream were collected. The former direct dumps of wastes and the presence of tailing
ponds adjacent to the watercourse have contributed to the total contamination of the stream. Total Cd (103 mg kg−1), Cu (259 mg kg−1), Pb (26,786 mg kg−1) and Zn (9,312 mg kg−1) in sediments were above the limits of European legislation, being highest where tailing ponds are located. Bioavailable
metals were high (3.55 mg Cd kg−1, 6.45 mg Cu kg−1, 4,200 mg Pb kg−1 and 343 mg Zn kg−1) and followed the same trend than total contents. Metals in water were higher in sampling points close to ponds, exceeding
World Health Organization guidelines for water quality. There is a direct effect of solubilisation of sediment metals in water
with high contents of SO42−, product of the oxidation of original sulphides. The mobility of metals varied significantly with shifts in pH. Downstream,
available and soluble metals concentrations decreased mainly due to precipitation by increments in pH. As a general pattern,
no metal was bioaccumulated by any tested plant. Thus, native vegetation has adopted physiological mechanisms not to accumulate
metals. This information allows the understanding of the effect of mining activities on stream contamination, enforcing the
immediate intervention to reduce risks related to metals’ mobility. 相似文献
17.
Long-term effects of mineral fertilization on microbial biomass C (MBC), basal respiration (R
B), substrate-induced respiration (R
S), β-glucosidase activity, and the r–K-growth strategy of soil microflora were investigated using a field trial on grassland established in 1969. The experimental
plots were fertilized at three rates of mineral N (0, 80, and 160 kg ha−1 year−1) with 32 kg P ha−1 year−1 and 100 kg K ha−1 year−1. No fertilizer was applied on the control plots (C). The application of a mineral fertilizer led to lower values of the MBC
and R
B, probably as a result of fast mineralization of available substrate after an input of the mineral fertilizer. The application
of mineral N decreased the content of C extracted by 0.5 M K2SO4 (C
ex). A positive correlation was found between pH and the proportion of active microflora (R
S/MBC). The specific growth rate (μ) of soil heterotrophs was higher in the fertilized than in unfertilized soils, suggesting the stimulation of r-strategists, probably as the result of the presence of available P and rhizodepositions. The cessation of fertilization with
320 kg N ha−1 year−1 (NF) in 1989 also stimulated r-strategists compared to C soil, probably as the result of the higher content of available P in the NF soil than in the C
soil. 相似文献
18.
Prakash C. Srivastava Ajay P. Singh Surendra Kumar V. Ramachandran Manoj Shrivastava S. F. D’souza 《Biology and Fertility of Soils》2008,44(8):1035-1041
Laboratory and greenhouse investigations were carried out with 65Zn-labeled sources to study the kinetics of desorption, transformation, and availability of Zn applied to soil as zinc-enriched
biosludge from distillery molasses (ZEMB) or as zinc sulfate heptahydrate (ZSH). Desorption (0.5 to 72 h) of added Zn by the
column method followed a biphasic kinetics with an initial (up to 12 h) faster phase followed by a slower desorption phase.
The desorption rate coefficient (K) of the latter phase and the amount of Zn desorbed during 12 to 72 h were significantly
higher with ZEMB than with ZSH. Sequential extraction of Zn added as ZEMB and ZSH showed that Zn added as ZEMB was present
in higher proportion as water soluble + exchangeable, carbonate bound, organically bound, and reducible fractions than Zn
applied as ZSH, which showed a higher proportion of residual fraction. Under greenhouse conditions, dry matter yield (35 days)
and total Zn uptake by rice fertilized with ZSH applied at 5 kg Zn ha−1 were statistically similar to those of rice treated with 2.5 kg Zn ha−1 supplied as ZEMB. The highest Zn uptake (167.08 μg pot−1) by rice was recorded in the treatment with 5 kg Zn ha−1 as ZEMB. For wheat plants grown after the harvest of rice, significantly higher dry matter yield over control was recorded
in the treatment with ZEMB applied at 5 kg Zn ha−1 to rice. Total Zn uptake by wheat was statistically similar for both ZEMB and ZSH treatments at 5 kg Zn ha−1 dose. Both zinc derived from fertilizer and the percent utilization of fertilizer Zn by rice and by the subsequent wheat
crop were significantly higher with ZEMB than with ZSH.
Patent filed No. 757/MUM/2007 dated 19.04.2007 相似文献
19.
Girisha K. Ganjegunte Leo M. Condron Peter W. Clinton Murray R. Davis Nathalie Mahieu 《Biology and Fertility of Soils》2006,43(2):199-207
Composition and effects of additions of fibric (Oi) and hemic/sapric (Oe + Oa) layer extracts collected from a 20-year-old stand of radiata pine (Pinus
radiata) on soil carbon dioxide (CO2) evolution were investigated in a 94-day aerobic incubation. The 13C nuclear magnetic resonance spectroscopy indicated that Oi layer extract contained greater concentrations of alkyl C while Oe + Oa layer extract was rich in carboxyl C. Extracts from Oi and Oe + Oa layers were added to a forest soil at two different polyphenol concentrations (43 and 85 μg g−1 soil) along with tannic acid (TA) and glucose solutions to evaluate effects on soil CO2 efflux. CO2 evolution was greater in amended soils than control (deionized water) indicating that water-soluble organic carbon (WSOC) was readily available to microbial degradation. However, addition of WSOC extracted from both Oi and Oe + Oa layers containing 85 μg polyphenols g−1 soil severely inhibited microbial activity. Soils amended with extracts containing lower concentrations of polyphenols (43 μg polyphenols g−1 soil), TA solutions, and glucose solutions released 2 to 22 times more CO2-C than added WSOC, indicating a strong positive priming effect. The differences in CO2 evolution rates were attributed to chemical composition of the forest floor extracts. 相似文献
20.
Plant growth-promoting rhizobacteria (PGPR) play an important role in the biodegradation of natural and xenobiotic organic
compounds in soil. They can also alter heavy metal bioavailability and contribute to phytoremediation in the presence or absence
of synthetic metal chelating agents. In this study, the inhibitory effect of Cd2+ and Ni2+ at different concentrations of Ca2+ and Mg2+, and the influence of the widely used chelator EDTA on growth of the PGPR Pseudomonas brassicacearum in a mineral salt medium with a mixture of four main plant exudates (glucose, fructose, citrate, succinate) was investigated.
Therefore, the bacteriostatic effect of Cd2+, Ni2+ and EDTA on the maximum specific growth rate and the determination of EC50 values was used to quantify inhibitory impact.
At high concentrations of Ca2+ (800 μmol L-1) and Mg2+ (1,250 μmol L-1), only a small inhibitory effect of Cd2+ and Ni2+ on growth of P. brassicacearum was observed (EC50 Cd2+, 18,849 ± 80 μmol L−1; EC50 Ni2+, 3,578 ± 1,002 μmol L−1). The inhibition was much greater at low concentrations of Ca2+ (25 μmol L−1) and Mg2+ (100 μmol L−1) (EC50 Cd2+, 85 ± 0.5 μmol L−1 and EC Ni2+, 62 ± 1.8 μmol L−1). For the chosen model system, a competitive effect of the ions Cd2+ and Ca2+ on the one hand and Ni2+ and Mg2+ on the other hand can be deduced. However, the toxicity of both, Cd2+ and Ni2+, could be significantly reduced by addition of EDTA, but if this chelating agent was added in stoichiometric excess to the
cations, it also exhibited an inhibitory effect on growth of P. brassicacearum. 相似文献