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1.
Thirty-nine paired soil samples belonging to Inceptisols, irrigated with wastewater and well water, were examined to monitor
the combination of clay mineralogy, physicochemical properties, and trace metals (Zn, Cu, Cd, and Pb) following long-term
wastewater irrigation. Results of XRD analysis indicated that the quantity of clay minerals did not change by long-term wastewater
irrigation although some modifications in smectite were occurred in Fluvaquentic Endoaquepts compared to control (well water-irrigated
soil). Irrigation with wastewater was resulted in an increase in clay content from 3 to 17%, EC from 90 to 160%, organic carbon
from 13 to 44%, and CEC from 10 to 13%. In this context, improvement in total N was as 80–110%, available P as 270–330%, and
available K as 5–50% as compared to the control soil. Irrigation with wastewater was led to a significant enrichment in both
EDTA-extractable and total metals of Zn, Cu, Cd, Pb, mainly as result of the combination of their addition through wastewater
along with interaction between the used wastewater and its receiving soils. In the light of this, wastewater irrigation system
showed the relative enrichment (RE) for total-Zn, Cu, Cd, and Pb as 3.6–6.8, 2.8–4.9, 4.4–5.7, and 1.8–2.3, respectively.
Fine particle-size fraction (<0.002 mm), organic matter, and calcium carbonates were appeared as the main agents in retaining
the total trace metals as reflected in significant positive correlation among the physicochemical properties and the examined
metals. Degree of contamination (C d) for the four analyzed metals was in the range of 3–5. Based on C d values, the wastewater-irrigated soils were classified as moderate degree of contamination (2 ≤ C d < 4) to high degree of contamination (4 ≤ C d < 8). Fluvaquentic Endoaquepts highlighted to be a major contributor of the load and contamination rate of trace metals regarding
to geoaccumulation index, contamination factor, and Degree of contamination. 相似文献
2.
Application of untreated wastewater to irrigate urban vegetable gardens is raising serious concern about possible health risks
associated with the consumption of these vegetables particularly with regard to the concentrations of heavy metals (HM) in
their edible portions. The soil concentrations of cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc
(Zn), were investigated in seven vegetable gardens from the three West African cities of Kano (Nigeria), Bobo Dioulasso (Burkina
Faso) and Sikasso (Mali). Also determined were input–output balances of Cd and Zn from five vegetable gardens under 30 years
of wastewater irrigation in Kano. In these gardens Cd (2.3–4.8 mg kg −1) and Zn (13–285 mg kg −1) concentrations throughout the profile attained unsafe levels. The concentrations of Cu (0.8–18 mg kg −1), Cr (1.8–72 mg kg −1), Ni (0–17 mg kg −1) and Pb (0.6–46 mg kg −1) were below the safety thresholds for arable soils. Overall, concentrations of Zn, Cd, Pb and Ni were higher in Kano than
in Bobo-Dioulasso and Sikasso. Input–output analyses in Kano indicated that irrigation wastewater contributed annually 400–3,700 g
Cd ha −1 and 7,200–22,300 g Zn ha −1, fertilizer 30–2,100 g Cd ha −1 50–17,600 g Zn ha −1, harmattan dust 0.02–0.4 g Cd ha −1 and 40–200 g Zn ha −1 while 300–500 g Cd ha −1 and 2,700–4,700 g Zn ha −1 came from rainwater inputs. Input–output calculations subtracting the amounts of HM taken out in vegetable biomass and that
lost to leaching from total inputs yielded an annual net positive balance of 700–4,160 g Cd ha −1 and 9,350–39,700 g Zn ha −1. If such balances remain unchanged for another 10–20 years vegetables raised in these garden fields are likely to be unsuitable
for human consumption. 相似文献
3.
The application of commercial phosphate fertilizers containing Cd as an impurity is an important source of Cd to agricultural
soils. The changes in the Cd status and its bioavailability in soils taken from a field trial were investigated after several
years of application of fertilizers with a range of Cd contamination levels to soils. Various soil pH regimes were achieved
by liming. The isotopic dilution technique was used to determine both the plant available (L-value) and isotopically exchangeable
(E-value) Cd pools in soils. Firstly, we found that the L-values after 10 year of application were significantly higher at
pH 5.0 than at pH 6.0, and this was reflected in the increased Cd uptake by wheat at the lower pH. There was no significant
effect of the rate of soil Cd application on the L-values. Although long-term use of Cd enriched P-fertilizers increased the
total concentration of Cd in soil, the impact on wheat production was insignificant. Most cultivated soils in Norway are maintained
at soil pH between 5.5 and 6.5 by frequent liming. That brings up the second interesting finding, the possible impurity of
lime used in this experiment. The lime was not analysed, as it was unexpected that liming might raise the total content of
soil Cd substantially. That seems, however, to have been the case for this experiment since we find increase of total Cd even
in the low-Cd input blocks of the trial. 相似文献
4.
We conducted a pot experiment to investigate the effect of fertilizer additions on the solubility of Cd, Ni and Zn in soil
solution and their uptake by plants. Radish ( Raphanus sativus cv. Crystal Ball), oat ( Avena sativa cv. Thule) and water spinach ( Ipomoea aquatica cv. Kangkon) were grown in a naturally metal-rich soil. From day 7 after planting, fertilizers were added daily to each pot.
Additions of fertilizer nutrients affected the pH of soil and soil solution, soluble and tissue concentrations of Ca, Mg,
K, Cd, Ni and Zn differently in three plant species. The trend of soil and solution pH was in the order: water spinach < radish
< oats, that resulted highest soluble and plant tissue concentrations of Cd and Zn in the water spinach followed by radish
and then oats. However, Ni concentration in the soil solution increased in all pots and was not affected by pH changes. Soil
solution pH increased by more than 1unit in the pots with radish and oats, indicating that mechanisms other than acidification,
such as ion exchange and root exudation, may be responsible for the increased heavy metal uptake in these two plant species.
Paired t-test showed significantly higher uptake of Cd and Zn in the radish plants resulting in lower concentrations of these
elements in the solution. The contribution of mass flow to the supply of major cations and heavy metals varied among elements
and plant species. Cadmium, Zn and K were taken up rapidly by all plant species in response to the amount supplied by mass
flow. In contrast, the supply of Ni was in excess of its uptake by radish and water spinach. The uptake of all elements was
positively correlated (p<0.0001) with mass flow and the transpiration rate in individual plant species. The study suggests
that fertilizer cations increased the uptake of metals by improving growth conditions, but the magnitude of increase depended
on plant species.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
5.
Liming has widespread and significant impacts on soil processes and crop responses. The aim of this study was to describe the relationships between exchangeable cation concentrations in soil and the relative yield of spring barley. The hypothesis was that yield is restricted by the concentration of a single exchangeable cation in the soil. For simplicity, we focused on spring barley which was grown in nine years of a long-term experiment at two sites (Rothamsted and Woburn). Four liming rates were applied and in each year the relative yield (RY) and the concentrations of exchangeable cations were assessed. Liming had highly significant effects on the concentrations of most exchangeable cations, except for Cu and K. There were significant negative relationships (either linear or exponential) between the exchangeable concentrations of Mn, Cd, Cr, Al, Fe, Cu, Co, Zn and Ni in soil and soil pH. The relationships between RY and the concentrations of selected exchangeable cations (Mn, Ca and Al) were described well using log-logistic relationships. For these cations a significant site effect was probably due to fundamental differences in soil properties. At both sites the concentrations of exchangeable soil Al were excessive (>?7.5 mg kg?1) and were most likely responsible for reduced barley yields (where RY?≤?0.5) with soil acidification. At Rothamsted barley yield was non-limited (where RY?≥?1) at soil exchangeable Mn concentrations (up to 417 mg kg?1) greater than previously considered toxic, which requires further evaluation of critical Mn concentrations. 相似文献
6.
The Ruzyně Fertilizer Experiment (RFE, the Czech Republic) was established on a permanent arable field (illimerized Luvisol)
in 1955. The effects of long-term application of several organic fertilizers (dung water, farmyard manure, poultry litter)
and mineral N, P and K fertilizers on plant-available (extracted by CaCl 2), easily mobilizable (extracted by EDTA), potentially mobilizable (extracted by HNO 3) and total concentrations of trace elements were investigated in 2008. Concentrations of all analyzed trace elements in the
applied fertilizers did not exceed the limits permitted by Czech national legislation. Concentrations of As, Cd and Cr were
highest in single superphosphate, those of Cu, Mn and Ni were highest in poultry litter and those of Pb and Zn were highest
in dung water. Poultry litter had the second highest concentration of As and Zn. Poultry litter supplied the soils with considerable
amounts of Cu, Mn and Zn and increased their concentrations in the soil. There was also a significant increase in plant availability
of Mn, Ni and Zn and a decrease in soil pH. Although all fertilizers were applied for five decades, total concentrations of
As, Cr, Cu, Ni, Pb and Zn in soil remained far below Czech legislation limits. For Cu and Zn this was probably due to the
relatively low mean annual application rates of poultry litter. Total Cd concentrations in soil exceeded the legislative limit
even in the control (without any fertilizer inputs) and the effect of treatment was not significant. This indicates that fertilizers
were not the main source of Cd in the experimental area. Therefore, common cropping practices do not induce soil contamination
by trace elements even if they have been applied for more than 50 years. 相似文献
7.
The Rengen Grassland Experiment (RGE) was established in the Eifel Mts. (Germany) on a low productive Nardetum in 1941. Since then, the following fertiliser treatments have been applied along with a two cut system: unfertilised control,
Ca, CaN, CaNP, CaNP–KCl and CaNP–K 2SO 4 with basic slag (syn. Thomas phosphate) as the only P fertiliser. The effect of long-term fertilisation on plant-available
(extracted with 0.01 mol l −1 CaCl 2), easily-mobilisable (extracted with 0.05 mol l −1 EDTA), potentially-mobilisable (extracted with 2 mol l −1 HNO 3) and total concentrations of trace elements (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) in the top 0–10 and 10–20 cm of soil
were investigated in 2006. According to redundancy analysis (RDA), the effect of treatment on the concentrations of risk elements
was significant and explained 82.3 and 90.6% of the variability in the data in the 0–10 and 10–20 cm soil layers, respectively.
Basic slag supplied the soil with considerable amounts of As, Cr, Cu, Fe, Mn and Zn. Following 65 years of fertiliser application
the concentrations of risk elements in the soil profile had increased substantially, especially with basic slag. However,
threshold limits for total trace element concentration in soil permitted by Czech national legislation were exceeded only
in the case of As. The increase in plant-available As concentrations was most critical as it increased the potential uptake
of As by plants in plots fertilised with P. Although P treatments received more than 300 g of Cr ha −1 annually, no effect on plant-available Cr soil content was detected. This contrasted with the accumulation of total Cr in
the 0–10 and 10–20 cm soil layers. Furthermore, plant availability of Cd, Fe, Mn and Zn was affected by soil pH and generally
decreased with the application of quick lime. Plant availability of these elements was not correlated with amounts supplied
by fertilisers. 相似文献
8.
Information on fertilizer response in cassava in Africa is scarce. We conducted a series of on-farm and on-station trials
in two consecutive years to quantify yield responses of cassava to mineral fertilizer in Kenya and Uganda and to evaluate
factors governing the responses. Average unfertilized yields ranged from 4.2 to 25.7 t ha −1 between sites and years. Mineral fertilizer use increased yields significantly, but response to fertilizer was highly variable
(−0.2 to 15.3 t ha −1). Average yield response per kg applied nutrient was 37, 168 and 45 and 106, 482 and 128 kg fresh yield per kg of applied
N, P and K, respectively in 2004 and 2005. Fertilizer response was governed by soil fertility, rainfall and weed management,
but was not influenced by variety, pest and disease pressure and harvest age. Relative N and K yields were positively correlated
to SOC and exchangeable K, while response to fertilizer decreased on more fertile soils. Still, fertilizer response varied
widely on low fertility soils (e.g. on soils with <10 g kg −1 SOC, responses ranged from −8.6 to 24.4 t ha −1), indicating strong interactions between factors governing fertilizer response. Response to fertilizer was reduced if total
rainfall <1,500 mm or rainfall from 0 to 3 months after planting <400 mm. Fertilizer application promoted plant growth and
resulted in a better soil coverage and reduced weed competition. Yields in fertilized fields were independent of weed management,
unless growing conditions were unfavourable. 相似文献
9.
Soil pH and Eh play an important role in reducing heavy metal solubility in paddy soils. To assess the effects of flooding
and organic matter application on changes in Eh, pH and solubility of Cd, Ni and Zn in contaminated soils, a growth chamber
experiment with rice plants( Oryza sativa L.) was conducted. Eh values decreased with flooding time in all three soils. The changes of Eh values were more negative
in the tannery and alum shale contaminated soils and stabilized after 30 days of submergence. The Eh changes were not so large
in the city sewage contaminated soil as in the other two soils. Soil pH increased with flooding time. During the 65 days of
submergence, pH increase was about 2, 1 and 0.6units in the tannery, city sewage and alum shale soils, respectively. In all
three soils, organic matter treated soil showed lower Eh and higher pH values compared to untreated soil. Concentration of
Cd, Ni and Zn in soil solution decreased with flooding time. The solution concentration of Cd and Zn in the city sewage soil
and of Ni in the tannery soil was higher than in the alum shale soil. The soluble metal concentration in all three soils was
lower inorganic matter treated soils. Reduced solubility of metals in the organic matter treated soils was related to larger
changes of Eh and pH values in these soils. Correlation coefficient calculations also showed that metal solubility decreased
with decreased Eh and increased pH in the soil solution.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
10.
Conservation agriculture (CA) characterised by minimal soil disturbance, permanent soil surface cover by dead or living plants
and crop rotations is one way of achieving higher soil organic carbon (C) in agricultural fields. Sandy loam and loamy soil
samples from zero tillage (ZT) and conventional tillage (CT) plots were taken from farmers’ fields during the dry season in
August 2006. Soil organic carbon (SOC) and soil organic nitrogen (SON), microbial biomass carbon (MB-C) and microbial biomass
nitrogen (MB-N), C mineralization and SOC distribution in particle size fractions in 0–20 cm layer were evaluated. Forty eight
farmers’ fields were randomly sampled at four different locations in Central and Northern Malawi, representing ZT plots maintained
for a different number of years, and ten fields under CT with similar soil type and crop grown were selected. SOC and SON
in ZT fields were 44 and 41 % (4 years ZT) and 75 and 77 % (5 years ZT) higher, respectively, than CT plots. MB-C and MB-N
in ZT fields were 16 and 44 % (4 years ZT) and 20 and 38 % (5 years ZT) higher, respectively, than CT plots. However, MB-C
and MB-N in ZT fields were 27 and 25 % (2 years ZT) and 17 and 9 % (3 years ZT) lower than in CT plots. The proportion of
the total organic C as microbial biomass C was relatively higher under CT than ZT treatments. The higher SOC and MB-C content
in the ZT fields resulted in 10, 62, 57 % higher C mineralization rate in ZT plots of 3, 4 and 5 years of loamy sand soils
and 35 % higher C mineralization rate in ZT plot of 2 years than CT of sandy loam soils in undisturbed soils in the laboratory.
Simulating plough from the undisturbed soils that were used for C mineralization experiment resulted in linear curves indicating
that all organic C was already depleted during the first incubation period. The relative distribution of soil organic matter
(SOM) in silt and clay size fractions was strongly correlated ( r = 0.907 and P ≤ 0.01) with silt percentages. Easily degradable carbon pool (C A,f) was correlated ( r = 0.867 and P ≤ 0.05) with organic carbon in sand size fraction. In developing viable conservation agriculture practices to optimize SOC
content and long-term sustainability of maize production systems, priority should be given to the maintenance of C inputs,
crop rotations and associations and also to reduced soil disturbance by tillage. 相似文献
11.
In southern Africa, tillage research has focused on rainfed smallholder cropping systems, while literature on high-input irrigated
cropping systems is limited. We evaluated the effects of conventional (CT), minimum (MT) and no-till (NT) tillage systems
on soil organic carbon (SOC), bulk density, water-stable aggregates (WSA), mean weighted diameter (MWD) and crop yields in
an irrigated wheat–cotton rotation. Soil data were monitored in the first and final year, while yields were monitored seasonally.
Average bulk densities (1.5–1.7 Mg m −3) were similar among tillage systems, but often exceeded the critical limit (1.60 Mg m −3) for optimum root growth. Conversion from CT to MT and NT failed to ameliorate the high bulk densities associated with the
alluvial soil. SOC (g kg −1) at 0–15 cm was higher ( P < 0.05) under MT (3.9–5.8) and NT (4.2–5.6) than CT (2.9–3.3). Corresponding horizon SOC stocks (Mg C ha −1) for the tillage treatments were; 9.3–13.9 (MT), 9.3–13.5 (NT) and 7.3–7.7 (CT). In the final year, significant ( P < 0.05) tillage effects on SOC stocks were also observed at 15–30 cm. Cumulative SOC stocks (Mg C ha −1) in the 0–60 cm profile were higher ( P < 0.05) under MT (32.8–39.9) and NT (32.9–41.6) than CT (27.8–30.9). On average, MT and NT sequestered between 0.55 and 0.78 Mg C ha −1 year −1 at 0–30 cm depth, but a net decline (0.13 Mg C ha −1 year −1) was observed under CT. At 0–30 cm, MT and NT had higher ( P < 0.05) MWD (0.19–0.23 mm) and WSA (2.3–3.5%) than CT (MWD: 0.1–0.12 mm, WSA: ≈1.0%). Both MWD and WSA were significantly
( P < 0.05) correlated to SOC. Seasonal yields showed significant ( P < 0.05) tillage effects, but 6-year mean yields (t ha −1) were similar (CT: 4.49, MT: 4.33, NT: 4.32 for wheat; CT: 3.30, MT: 2.82, NT: 2.83 for cotton). Overall, MT and NT improved
soil structural stability and carbon sequestration, while impacts on crop productivity were limited. Therefore, MT and NT
are more sustainable tillage systems for the semi-arid regions than conventional tillage.
S. Chakanetsa—Deceased. 相似文献
12.
Experiments were conducted in the laboratory, greenhouse and on farmers’ fields to determine, the potassium (K) supplying
capacity of some soils in Ogun State, Nigeria, using equilibrium parameters as measured by quantity, intensity and activity
indices. The result showed that the potassium status of the soils varied widely. Total K varied from 14.2 to 104 cmol kg −1 in the green house soils and 46.05 to 89.1 cmol kg −1 in the field soils. On the average, exchangeable and solution K constituted 0.39 and 0.09% of the total K, respectively in
the greenhouse soils. The potential buffer capacity (PBC), which measures the ability of the soil to maintain the intensity
of K in the soil solution, varied from 12.24 to 39.25 (ML −1/2). About 50% of the soils studied in the green house and in the field have high PBC indicating slow release of K to the soil
solution. The specifically bonded K which constituted the bulk of the labile K (K L) that is immediately available is generally low. It ranged from 0.10 to 0.29 cmol kg −1 with a mean of 0.18 cmol kg −1 in the greenhouse soils, and mean of 0.16 cmol kg −1 in the field soils. These low values accounted for the appreciable responses to K application by soybean in most of the soils
studied. The change in Gibb’s free energy (Δ G) values, which measures the intensity of exchangeable K relative to other cations, is moderate in most of the soils. Correlation
analysis showed that all the forms of K correlated positively and significantly with soybean dry matter yield at the first
cropping harvest. However, soybean K concentration in the first harvest was only positively correlated with available K, exchangeable
K, solution K and fixed K ( P < 0.01). The clay content of the soil is also positively and significantly correlated with K forms. The prediction equation
showed that the soil’s clay content is a major determinant of labile K, equilibrium activity ration (EAR) and the potential
buffering capacity. The EAR is also strongly determined by the ECEC and the K saturation ( R
2 = 0.990, 0.996, P < 0.01). The critical level of soil labile K, available K and specifically bonded K are 0.21, 0.35, and 0.19 cmol kg −1, respectively. Thus, with the use of available K as the index of K fertility, about 50% of the soils are K deficient. Hence
potassium fertilization is necessary for enhanced production of soybean in these sites. 相似文献
13.
在分析我国农田土壤重金属污染状况的基础上,阐述了腐植酸与铬、镉、锌等金属离子在土壤中的作用机理研究现状,认为通过范德华力、氢键、静电吸附、阳离子键桥等形成土壤有机-无机复合体,使腐植质的胶团被吸附在土壤颗粒表面,使带正电的金属离子更牢固地与土壤结合,从而有效防止被农作物吸收。文章指出,腐植物质的结构及其与金属离子作用机理的研究,对于促进腐植酸土壤环境保护领域的应用与相关的技术开发具有重要意义。 相似文献
14.
Recent concerns about global warming due to accumulations of atmospheric CO 2 have encouraged the achievement of better understanding of the roles of animal agriculture in mitigating CO 2 emissions. Grazing can accelerate and alter the timing of nutrient transfers, and increase the amount of nutrients cycled
from plant to soil. Our reason for conducting this study is to test whether cattle congregation sites (CCS) typical on most
Florida ranches, such as mineral feeders (MF), water troughs (WT), and shaded areas (SA) have higher soil organic carbon (SOC)
than in other locations of pasture under foraged-based system. Baseline soil samples around the congregations zones (MF, WT,
and SA) and grazing zones in established (>10 year), grazed cow–calf pastures were collected in the spring and fall of 2003,
2004, and 2005, respectively. Soil samples were collected from two soil depths (0–20 and 20–40 cm) at different locations
around the CCS following a radial (every 90 degrees: N, S, E, and W) sampling pattern at 0.9, 1.7, 3.3, 6.7, 13.3, 26.7, and
53.3 m away from the approximate center of MF, WT, and SA. The levels of SOC varied significantly with CCS ( P ≤ 0.001), distance away from the center of the CCS ( P ≤ 0.05), sampling depth ( P ≤ 0.001), sampling year ( P ≤ 0.001) and the interaction of CCS and soil depth ( P ≤ 0.001). Sampling orientations did not significantly affect the levels of SOC. The SA sites had the highest level of SOC
of 3.58 g kg −1, followed by WT sites (3.47 g kg −1) and MF sites (2.98 g kg −1). Results of our study did not support our hypothesis that cattle congregation sites typical on most ranches, such as MF,
WT and SA, may have higher concentrations of SOC. The levels of SOC (averaged across CCS) within the congregation zone (3.42 g kg −1) were not significantly ( P ≤ 0.05) different from the concentrations of SOC at the grazing zone (3.16 g kg −1). 相似文献
15.
Contaminated land may in many cases still be used for agriculture, provided that crops are chosen appropriately, as the accumulation
of contaminants varies greatly among cultivars and also plant parts. We aimed to determine whether maize ( Zea mays), sunflower ( Helianthus annuus) and tobacco ( Nicotiana tabaccum) grown on a heavy-metal contaminated soil containing copper (540 mg Cu kg −1), zinc (680 mg Zn kg −1) and cadmium (1.4 mg Cd kg −1) could be used to gradually remediate the soil, while producing valuable biomass. The soil was treated with either a normal
fertiliser regime (control), elemental sulphur (S), or the biodegradable chelant NTA (nitrilotriacetic acid), to test how
soil acidification or chelating organic compounds would affect the uptake and allocation of selected elements (Ca, Cd, Cu,
Fe, K, Mg, Mn, P, S and Zn). The highest concentrations of Cd, Cu and Zn occurred in the leaves and/or roots, while seeds
and grains contained much lower concentrations of these elements. All these concentrations, however, were still in the ranges
considered normal for the respective plant parts grown on uncontaminated soil. While sunflower and maize could be safely used
as food and feed, tobacco would better be used for bioenergy than for cigarette production because of its relatively high
foliar Cd concentration. The two treatments (S and NTA) had only slight effects on the uptake and allocation of plant nutrients
and Cd. Thus, there was little benefit of these treatments for phytoextraction purposes at this site. 相似文献
16.
Chemical analyses performed on the invasive weed Phytolacca americana (pokeweed) growing in industrially contaminated (Ulsan) and noncontaminated (Suwon) sites in South Korea indicated that the
levels of phenolic compounds and various elements that include some heavy metals (Al, As, B, Cd, Co, Cu, Fe, Mn, Ni, Pb, and
Zn) were statistically higher in Ulsan soils compared to Suwon soils with Al being the highest (>1,116 mg/l compared to 432 mg/l).
Analysis of metals and nutrients (K, Na, Ca, Mg, Cl, NH 4, N, P, S) in plant tissues indicated that accumulation occurred dominantly in plant leaves with Al levels being 33.8 times
higher in Ulsan plants (PaU) compared to Suwon plants (PaS). The ability of PaU and PaS to tolerate stress was evaluated under
controlled conditions by varying atmospheric CO 2 and temperature and soil pH. When grown in pH 6.4 soils, the highest growth rate of PaU and PaS plants occurred at elevated
(30°C) and non-elevated (25°C) temperatures, respectively. Both PaU and PaS plants showed the highest and lowest growth rates
when exposed to atmospheric CO 2 levels of 360 and 650 ppm, respectively. The impact of soil pH (2–6.4) on seed germination rates, plant growth, chlorophyll
content, and the accumulation of phenolics were measured to assess the effects of industrial pollution and global-warming-related
stresses on plants. The highest seed germination rate and chlorophyll content occurred at pH 2.0 for both PaU and PaS plants.
Increased pH from 2–5 correlated to increased phenolic compounds and decreased chlorophyll content. However, at pH 6.4, a
marked decrease in phenolic compounds, was observed and chlorophyll content increased. These results suggest that although
plants from Ulsan and Suwon sites are the same species, they differ in the ability to deal with various stresses. 相似文献
17.
In some areas of southern Australia, cadmium (Cd) concentrations in excess of the Australian maximum permitted concentration (0.05 mg kg –1 fresh weight) have been found in tubers of commercially grown potato ( Solanum tuberosum L.) crops. Field experiments were therefore conducted in various regions of Australia to determine if Cd uptake by potatoes could be minimised by changes in either phosphorus (P), potassium (K) or zinc (Zn) fertilizer management.Changing the chemical form in which either P fertilizer (monoammonium phosphate, diammonium phosphate, single superphosphate and reactive rock phosphate) or K fertilizer (potassium chloride and potassium sulfate) were added to crops had little influence on tuber Cd concentrations. Fertilizer Cd concentrations also had little influence on tuber Cd concentrations, suggesting that residual Cd in the soil was a major contributor to Cd uptake by the crops on these soils.Addition of Zn at planting (up to 100 kg Zn ha –1) significantly reduced tuber Cd concentrations at four of the five sites studied. However, the largest variation was between sites rather than between treatments, with site mean tuber Cd concentrations varying tenfold (from 0.018 to 0.177 mg Cd kg –1 fresh weight). Factors associated with irrigation water quality at the sites, in particular the chloride concentration, appeared to dominate any effects of changing fertilizer type or Cd concentration. 相似文献
18.
Higher accumulation of toxic heavy metals in rice grown in contaminated soils may lead to health disorder in humans in tropical
countries as rice is a staple diet. A pot experiment was conducted in a growth chamber to investigate the effect of flooding
and non-flooding conditions in three soils added with4% organic matter on the concentration and uptake of Cd, Ni and Zn by
rice plants ( Oryza sativa L.). In flooding condition, the level of standing water was at a height of 2.5 ± 0.5 cm above the soil surface and in non-flooded
culture80 ± 5% of water holding capacity was maintained. Flooding condition significantly( p < 0.05) reduced the concentration and uptake of Cd, Ni and Zn in rice grown in all three soils. The overall reduction of
metal concentration in shoot at vegetative stage, and straw and polished rice at maturity, under flooding conditions was 84,
89, and 79% for Cd; 21,63and 65% for Ni; and 52, 78 and 16% for Zn, respectively. Organic matter addition significantly reduced
the Ni concentration in plant parts but no such reduction was seen for Cd and Zn. Accumulation index of Cd and Zn was 82and
55% higher than that of Ni in the plant and the index of all three metals was higher in the tannery soil than the other two
soils. Polished rice contained significantly lower amounts of Cd, Ni and Zn than shoot and straw. Cadmium and Ni uptake in
polished rice was > 20% of the total uptake and thus it may be a concern for human health.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
19.
A new three-step fractionation scheme was applied to study the distribution of Al, As, Cd, Cr, Cu, Fe, Mn, Mo, Ni, Pb, S, Sb, Ti, V and Zn in fly ashes collected in the electrostatic precipitator of a thermal power plant in the city of San Nicolás (Argentina). Seven samples were collected during one week of operation in 2005. For the fractionation, the scheme applied consisted of extracting the elements in three fractions: (i) soluble and exchangeable elements, (ii) carbonates, oxides and reducible elements and (iii) residual elements. Metals and metalloids at μg g −1 level were determined in each fraction by plasma based techniques namely, inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS). For validation, a certified reference materials NIST SRM 2711 (Montana soil) was subject to the same chemical sequential extraction procedure. X-ray diffraction powder (XRD) analysis and scanning electron microscopy (SEM) were used to characterize the major minerals present in the matrix. The predominant phases found in the total samples were mullite, quartz, iron oxides and lime. Total analyte concentration varied (in μg g −1) from 1.54 for Cd to 30 600 for Al. The leachability of the 15 elements under study proved to be different. All the elements (except Cd and Pb) were detected in the soluble fraction in the order: Cu (0.10%) ∼ Mn (0.13%) < Ni (0.17%) ∼ Ti (0.19%) ∼ Fe (0.20%) ∼ As (0.21%) < Zn (0.86%) < Al (1.3%) < Cr (2.9%) < V (3.9%) < Sb (6.9%) < Mo (45.1%) < S (58.0%). Percentages higher than 20% of S (24.1%) < V (27.5%) < Mn (29.0%) were detected in the second fraction. Al, As, Cr, Cd, Cu, Fe, Ni, Pb, Sb and Zn were mostly associated to the residual fraction. Recoveries of the overall procedure varied between 106% (Mo) and 72% (Cr). 相似文献
20.
The objective of this study is to determine influence of Treated Sewage Sludge (TSS) rates as organic matter and nutrient
resource on temporal variations of some macronutrients and micronutrients and heavy metals concentrations in a Typic Xerofluvent
soil. The experiment was conducted in Menemen Plain, in the Western Anatolia Region of Turkey in 2003–2005. Moist TSS was
added to the soil at the rates of 0, 30, 60 and 90 Mg ha −1 on May 1, 2003. Peanut ( Arachis hypogaea) was planted as the first crop. On the other hand, mixture of green barley ( Hordeum vulgare) and common vetch ( Vicia sativa L.) was planted as the second crop. During the experiment, soil samples were taken five times. Increasing TSS applications
to this soil resulted in significantly increased concentrations of total N, Cu, Pb and Ni, and available P, K, Ca, Fe, Cu,
Zn, Mn concentrations in soil. However, concentrations of available Mg and Na, total Fe, Zn, Mn, Cd, Co and Cr in soil did
not significantly change. Micronutrients and heavy metals concentrations in soil were found under threshold values in all
sampling periods in this study. Available nutrient concentrations in the soil decreased particularly in the last sampling
periods because of plant uptake of nutrients from the applied TSS. It is recommended that 90 Mg ha −1 moist TSS can be added once in a 2-year period for improving nutrient concentrations in Typic Xerofluvent soil. 相似文献
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