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1.
Sandstorms which distribute a great number of particles are a special atmospheric occurrence and are uncommon in northern China. This study was conducted to determine, for the first time, the concentration of organochlorine pesticides (OCPs) in sandstorm depositions. Samples were collected from urban areas of Beijing and a total of eight OCPs were measured. All samples contained OCP residues. The total hexachlorocyclohexane (HCHs) concentration ranged from 20.6 to 59.8ng g ?1 and the total dichlorodiphenyltrichloroethane (DDTs) concentration ranged from 12.0 to 14.3ng g ?1. Furthermore, increasing HCH contamination was observed from the northwest to the southeast and a uniform distribution of DDT contamination was discovered in Beijing. Analysis of the sources of contamination showed that HCHs in the sandstorm depositions were derived from a relatively old source of lindane, and DDTs mainly originated from an old source of dicofol in Beijing. The preliminary pollution assessment of the samples indicated that HCH levels might be categorized as low pollution and DDT levels might be categorized as no pollution. The present study suggests that sandstorm depositions may not produce the special risk of adverse health effect from OCPs for the residents of Beijing, China. 相似文献
2.
PurposeSummer pasture development and tourism near and around Lake Son-Kul in the western Tian Shan Mountains has resulted in a local source of organochlorine pesticides (OCPs) that lack monitoring and evaluation. Materials and methodsTwenty-eight soil samples were collected from the Lake Son-Kul Basin (SKB) and Naryn River Valley (NRV) to measure OCP concentrations and evaluate their composition, transport processes, and ecological risks. Results and discussionExcept for the high OCP concentration measured at one location, site 7 (145.32 ng/g dw), total OCP concentrations in the SKB ranged from 2.36 to 24.13 ng/g dw, slightly higher than concentrations in the NRV (1.69–7.45 ng/g dw) and similar to values in polar regions. Among the OCPs, HCHs and methoxychlor were the predominant compounds that accumulated in soils, followed by DDTs and Aldrins, whereas Chlors and Endos displayed lowest concentrations, indicating that animal husbandry is the main agricultural activity in the study area. Most of the less volatile pesticides, including β-HCH, p,p-DDT, and Chlors, represent past use from local sources, for instance the pesticides warehouse at site 7. More volatile compounds such as α-HCH, γ-HCH, and p’p-DDE represent exogenous atmospheric transport to the study area, as demonstrated by their isomeric ratios. Ecological risk assessment showed that the surface environment of the study area remains in good condition. ConclusionsFindings from this study provided a snapshot of the current status of OCP contamination in soils of the Lake Son-Kul region. Although historical OCP contamination has impacted the lake’s ecology, catchment soils display low levels of OCP contamination. 相似文献
3.
Surficial sediments were sampled with a light-weight gravity corer at 175 sites in 73 Ontario and Québec lakes and Zooplankton was collected with a 225 μm mesh size net in 24 lakes. Hg concentrations in surficial sediments (0–2 cm) ranged from 3 to 267 ng g ?1 dry weight with a mean of 80 ng g ?1 dry weight for all sites. A regression model including organic content of sediments and the ratio of the catchment area/lake surface explained 60% of the variation in sediments Hg concentrations. Hg in Zooplankton ranged from about 25 to 377 ng g ?1 dw with a mean of 108 ng g ?1 dw and was weakly correlated with catchment area, primary productivity and TOC. Our data indicate that an important fraction of Hg originates from the catchments, but do not show a clear west-east regional gradient for Hg concentrations in surficial sediments or in zooplankton. 相似文献
4.
Total Hg levels were determined in 17 harbour porpoises Phocoena phocoena collected in the North Sea and the Kattegat (muscle, liver and kidney), as well as in a sperm whale Physeter macrocephalus, a common dolphin Delphinus delphis and two bottle-nose dolphins Tursiops truncatus collected in Belgium. Juvenile porpoises (total body length less than 140 cm) were characterized by total Hg concentrations increasing with length (t.i. with age) with median values of 3.1 μg g ?1 dw in muscle, 6.2 in liver and 5.7 in kidney, and liver to muscle resp. liver to kidney ratios varying between 1 and 2. In adults, liver concentrations were higher (up to 500 μg g ?1 dw) with liver to muscle and to kidney ratios up to 20. Median McHg concentrations in 5 of the porpoises were 4.0 μg g ?1 dw in muscle and 6.9 in liver. These values did not increase as strongly with length (t.i. with age, at least for juveniles) as total Hg did; as a consequence, the relative McHg levels decreased from 100% in juveniles to 2 or 3 % in the liver of adults. Such results seem to reflect the existence of a slow mineralization phenomenon and storage of inorganic Hg, mainly in the liver. 相似文献
5.
ABSTRACT Broccoli sprouts ( Brassica oleraceae var. italica) have been attributed health protective effects based on their glucosinolate content, and thus, are recommended in diets. However, no information is available on the mineral content of this novel product and how fertilization might influence it. The influence of nitrogen (N) and sulfur (S) applications (0, 14, and 28 mg· N dish ?1 and 0, 4.5, and 9 mg· S dish ?1) on the mineral content [N, S, potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), chloride (Cl), and silicon (Si)] of broccoli sprouts ( Brassica oleraceae var. italica cv. ‘Marathon’) was determined 11 d after sowing. It was found that N and S fertilization significantly ( P < 0.001) influenced the uptake of all elements except phosphorus (P). Sulfur concentrations in broccoli sprouts varied between 11.4 and 15.2 mg· g ?1 (dw), while the Ca, Mg, P, K, and Na concentrations were below 10 mg· g ?1 (dw). The Cl contents ranged from 13.6 to 23.1 mg· g ?1 (dw). The highest S concentration was found when 9 mg· dish ?1 S and 14 mg· dish ?1 N was applied. A higher N rates of 28 mg· dish ?1, N yielded no higher S uptake. The significantly ( P < 0.05) highest Ca, Mg, and Na concentrations were found in the control treatments, while this effect proved to be not consistent for P. The results clearly revealed that N and S fertilization increased biomass production even in the early growth stages. With view to maintaining high Ca concentrations an application in the form of ammonium sulfate would be preferable. 相似文献
6.
We determined the concentrations and residue patterns of 20 persistent organochlorine pesticides (OCPs), including hexachlorocyclohexanes (HCHs), hexachlorobenzene, dichlorodiphenyltrichloroethanes (DDTs), chlordane-related compounds (CHLs), mirex, dieldrin, endrin, and aldrin, in muscle of rainbow trout from Lake Mashu, Japan. Total concentrations of OCPs varied from 1.0 to 132 ng g ?1 lipid weight. α-HCH was the most prevalent OCP contaminant in the fish muscle. Using the daily fish consumption in Japan (95.2 g), the mean weight of a Japanese adult (50.0 kg), and residual pesticide concentrations, we calculated the estimated daily intakes of γ-HCH, DDTs, CHLs, and dieldrin for humans to be 0.39, 0.48, 0.68, and 0.08 ng kg ?1 day ?1, respectively. Judging from acceptable daily intakes established by the Food and Agriculture Organization of the United Nations and the World Health Organization, we believe that these OCP levels would not adversely affect human health. 相似文献
7.
PurposeThe purpose of this study is to study the major sources, concentrations, and distributions of polycyclic aromatic hydrocarbons (PAHs) in three different types of green space in Shanghai. In addition, we will quantitatively assess the burden of PAHs in the soil, as well as the potential carcinogenic risk of PAHs in humans. These results will provide valuable information for soil remediation and human health risk management. Materials and methodsA total of 166 surface soil samples were collected in parks, greenbelts, and woodlands. Soils were extracted using accelerated solvent extraction (ASE). PAHs were analyzed by gas chromatography-mass spectrometry (GC-MS). The positive matrix factorization (PMF) model was used to identify major PAH emission sources and quantitatively assess their contributions to PAHs. The incremental lifetime cancer risk (ILCR) was used to quantify the potential health risk of PAHs. Results and discussionThe average concentrations of ∑15 PAHs are 227?±?95 ng g?1, 1632?±?251 ng g?1, and 1888?±?552 ng g?1 in the woodland, park, and greenbelt soils, respectively. The PMF results show that biomass (33%), coal (21%), vehicles (17%), natural gas (14%), oil (9%), and coke (7%) are the dominant sources of PAHs in the park soils. Diesel (40%), tire debris (30%), biomass (15%), gasoline (9%), and oil (5%) are the main sources in the greenbelt soils. Biomass (48%), vehicles (37%), and coal (15%) are the main sources in the woodland soils. The ILCRs of adults and children who are exposed to PAHs in soils range from 9.53?×?10?8~1.42?×?10?5. ConclusionIn three types of green space in Shanghai, the dominant PAHs are high–molecular weight (HMW) compounds (≥?4 rings). This may be due to the proximity of the sampling site to emission sources. In addition, low–molecular weight (LMW) PAHs (with 2–3 rings) are relatively unstable, and these compounds are prone to volatilization and degradation. Source identification indicates that biomass combustion is the most dominant PAH source in the park and woodland soils, while vehicles are the dominant PAH source in the greenbelt soils. The ILCRs of adults and children indicate potential health risks, and children have a greater health risk than adults. 相似文献
8.
N-alkanes were measured both in dissolved and particulate-adsorbed phases of water samples collected from five stations located along Shatt al-Arab River in Iraq. The aim of this study was to provide a background information on the presence, origin, and distribution of n-alkanes in the waters of Shatt al-Arab River. Total concentrations of n-alkanes were lower in the dissolved phase (29.37 (μg L ?1) than in the particulate-adsorbed fraction (17.62 μg g ?1 dw). Distribution of n-alkanes in both fractions is characterized by two distinct patterns. First, for C compounds numbered C 14 to C 22, the ‘odd’ numbered hydrocarbons were slightly more abundant with C 17 being the most concentrated. The second is shown within n-alkanes greater than C 22. In these the ‘odd’ numbered hydrocarbons show even greater predominance indicating that much of the n-alkanes in the waters of Shatt al-Arab, may have originated from aquatic biogenic sources; i.e., diatoms, algal forms, bacterial activities, and higher plants. The CPI values were found to be from 0.99 to 1.98 in the dissolved fraction and from 0.70 to 2.10 in the particulate fraction. Petroleum hydrocarbon inputs and urban related oil discharges (anthropogenic pollution) may also have contributed to the input of n-alkanes in Shatt al-Arab, particularly near the city of Basrah (St. IV). Total concentrations at station IV were much higher (8.40 μg L ?1 and 5.80 μg g ?1) than that for the most upstream station, # I, (3.20 μg L ?1 and 1.48 μg g ?1) and decreased again further downstream at station V (7.10 μg L ?1 and 4.32 μg g ?1). The CPI values were around 1.0 in station IV. In a conclusion, results obtained in this study indicate that the n-alkanes in the waters of Shatt al-Arab River are of aquatic biogenic and anthropogenic (petroleum related) origins. 相似文献
9.
利用GC-ECD对环鄱阳湖区11个县市蔬菜地土壤中有机氯农药测定的数据,研究蔬菜地土壤中有机氯农药残留状况,并进行生态风险评价。结果显示,蔬菜地土壤中HCHs、DDTs、氯丹和六氯苯均有检出,且DDTs、HCHs的残留量较高,总有机氯农药含量范围为2.39～47.28μg·kg-1。从整体上分析,处于工业分布区域的土壤中有机氯农药含量高于其他区域。有机氯农药组成特征研究表明,该地区土壤中除个别采样点有机氯农药主要来自于早期残留外,大部分地区有新的污染源输入。与国内其他地区蔬菜地土壤相比,环鄱阳湖区蔬菜地土壤中有机氯农药含量较低。生态风险分析显示,环鄱阳湖区蔬菜地土壤中HCHs残留对于土壤生物的风险较低,而DDTs可能对鸟类和土壤生物具有一定的生态风险。 相似文献
10.
Mercury concentrations were measured in samples of peat soils, sediments and clams ( Rangia cuneata) from a peatland region of the Albemarle-Panlico Peninsula of North Carolina. Total Hg concentrations in peat cores ranged from 40 to 193 ng g ?1 (dw); no depth-related trends were noted. Mercury concentrations in surface sediments from canals draining the peatlands and from the Pungo River that receives this drainage ranged from 8 to 20 ng g ?1 (dw). Selective extractions of these peat and sediment samples revealed that the bulk of the Hg was associated with organic matter-associated fractions (particularly humic/fulvic acid bound and organic-sulfide bound fractions). No Hg was detected in the relatively mobile and bioavailable water-soluble or ion-exchangeable fractions. Total Hg concentrations in the soft tissues of clams from the Pungo River ranged from 25 to 32 ng g ?1 (ww). No concentrations of methyl Hg above the detection limit of a 25 ng g ?1 were measured in soils, sediments, or clams. These data indicate that Hg concentrations in this region are at the low end of the distribution of levels reported for uncontaminated systems and that mining of these peatlands is unlikely to significantly elevate Hg concentrations in the receiving estuarine system. 相似文献
11.
PurposeCurrently, the distribution characteristics and transport processes of the radionuclides 137Cs and 239?+?240Pu in the sediments of estuaries are still a controversial issue. Thus, in the present study, we investigated the distribution characteristics, sources and migration path of 137Cs and 239?+?240Pu in sediment cores of the Liao River estuary (LRE), China, and evaluated the relative contributions of the Pacific Proving Grounds (PPG) and riverine sources of Pu for the sediments in this area. We used 137Cs and Pu isotopes for dating the sediments and estimated the sedimentation rates by the two radionuclides in the LRE. Materials and methodsSeven sediment samples were collected using a box corer from the Liao River estuarine wetland and tidal flat in the LRE in October 2012 and April 2015, respectively. The activities of 137Cs in the various samples were determined by γ spectrometry using HP-Ge detectors with 60% relative counting efficiency. Approximately 2–5 g of sediment were spiked with 242Pu (ca. 1 mBq) as a chemical yield tracer for Pu isotopic analysis at the School of Radiation Medicine and Protection, Soochow University. The measurement of Pu isotopes (239Pu, 240Pu, 242Pu) was performed by a sector field ICP-MS. In order to quantitatively differentiate the relative proportions of global fallout and PPG, we employed a two-end member mixing model to estimate their contributions. Results and discussionThe average values of 137Cs, 239?+?240Pu activity concentrations, and 240Pu/239Pu atom ratios in the surface sediment samples of the LRE were 6.727?±?0.251 mBq g?1, 0.294?±?0.024 mBq g?1, and 0.188?±?0.049 (1σ), respectively. The average 240Pu/239Pu atom ratios ranged from 0.180?±?0.034 to 0.199?±?0.021 in sediment cores from the east and west sides of the LRE. For core LT-2 values for 137Cs and 239?+?240Pu concentrations were from below the detection limit: 3.380?±?0.414 and 0.036?±?0.007 to 0.105?±?0.007 mBq g?1. The mean 240Pu/239Pu atom ratio 0.217?±?0.050 (1σ) in sediment core LT-2 lies between the global fallout and PPG close-in fallout. ConclusionsWe found that atmospheric fallout is the main source of Pu in sediment cores from the east and west sides of the LRE. For core LT-2, atmospheric fallout and riverine input (~?73.4%) are the major sources of Pu with the source of the rest of Pu (~?26.6%) attributed to the PPG via the Tsushima Warm Current and the coastal water of the East China Sea. The sedimentation rates (means 0.62–0.8 cm year?1) estimated by the two radionuclides were in good agreement and without any statistically significant difference. 相似文献
12.
Abstract The diurnal net photosynthesis of Ficus benjamina L., cultivar Cleo, was studied at different daylengths (12, 18 and 24 h day ?1), photosynthetic photon flux densities (40 and 120 μmol m ?2 s ?1 PPFD) and CO 2 concentrations (350 and 700 μmol mol ?1). Net photosynthesis increased to a maximum after 5–6 and 6–7h of light at 12 and 18h day ?1photoperiods, respectively, followed by a decrease towards the end of the photoperiod. At a photoperiod of 18 h day ?1 similar diurnal curves were found at 350 and 700 μmol mol ?1 CO 2, and at 40 and 120 μmol m ?2 s ?1 PPFD. Five days after the photoperiod was changed from 18 to a 24h day ?1the diurnal rhythm disappeared. Transpiration followed the same diurnal rhythm as that for photosynthesis. The water-use efficiency was enhanced by raising the CO2 concentration. A decrease in the CO 2 concentration from 700 to 350 μmol mol ?1after six days at high CO 2 first significantly decreased the photosynthesis, but three days later it reached the same level as that at high CO 2. 相似文献
13.
Chicory ( Cichorium intybus L.) and dandelion ( Taraxacum officinale Web.) were demonstrated to be potential indicator plants for heavy metal contaminated sites. Chicory, grown with 0.5–50 μM cadmium (Cd) in nutrient solution, accumulated 10–300 μM Cd g ?1 in shoots and 10–890 μg Cd μg ?1 in roots and rhizomes. With dandelion, 20–410 μg Cd μg ?1 was found in shoots and 20–1360 μg Cd μg ?1 in roots and rhizomes. An inverse correlation existed between chlorophyll and Cd concentrations in shoots of both species. Accumulation of Cd from nutrient solution was similar with the counter-anions SO 4 2?, Cl 1? and NO 3 ? in chicory. In chicory grown in Cd-amended (11.2 kg Cd ha ?1 applied five years previously) soils, Cd concentrations were substantially higher than in controls in all plant parts following the order: leaf > caudex > stem > root and rhizome. The above trend was the opposite of that observed in solution culture, where Cd accumulation was higher in roots and rhizomes than in shoots. Higher cadmium accumulation was found from a Cd-treated sand (Grossarenic Paleudult) than from a loamy sand (Typic Kandiudult) soil type. Chicory and dandelion are proposed indicator plants of cadmium contamination, and both have the potential to be an international standard heavy phytomonitor species of heavy metal contaminantion. 相似文献
14.
Abstract A greenhouse experiment was conducted at the University of lbadan, Nigeria to determine the optimum sulphur (S) rate for Celosia (Celosia argentia L. CV. TLV 8) production under hydroponic growing conditions. Average temperature and light intensity in the greenhouse was 27.7°C and 1.32 x 10 3 μEinstein M‐2 S‐1 (PAR), respectively. Five rates of S(0, 13.5, 27, 40.5, and 54 ug g ?1 of sand) in a series of nutrient solutions were imposed in a completely randomized design. Application of S significantly increased leaf number, plant height, leaf area, weights of leaf, stem, root, and raised contents of leaf sulphate (SO 4)‐S, chlorophyll, vitamins A and C, and crude protein. The optimum S rate for leaf formation, plant height at harvest (seven weeks after transplanting‐WAT), shoot production, SO 4‐S, vitamin A, and crude protein synthesis was 40.5 μg S g ?1 of sand in the applied nutrient solution, while that for maximum leaf production, chlorophyll, and vitamin C synthesis was 54 ug S g ?1 of sand. These results indicate that S nutrition is necessary for the optimum growth, yield, and yield attributes of Celosia. 相似文献
15.
The literature on heavy metal toxicity to vascular plants is reviewed. Special attention is given to forest plant species, especially trees, and effects at low metal concentrations, including growth, physiological, biochemical and cytological responses. Interactions between the metals in toxicity are considered and the role of mycorrhizal infection as well. Of the metals reviewed, Zn is the least toxic. Generally plant growth is affected at 1000 μg Zn L ?1 or more in a nutrient solution, though 100 to 200 µg L ?1 may give cytological disorders. At concentrations of 100 to 200 μg L ?1, Cu and Cd disturb metabolic processes and growth, whereas the phytotoxicity of Pb generally is lower. Although a great variation between plant species, critical leaf tissue concentrations affecting growth in most species being 200 to 300 μg Zn g ?1 dry weight, 15 to 20 μg Cu g ?1 and 8–12 μg Cd g ?1. With our present knowledge it is difficult to propose a limit for toxic concentrations of Zn, Cu, Cd and Pb in soils. Besides time of exposure, the degree of toxicity is influenced by biological availability of the metals and interactions with other metals in the soil, nutritional status, age and mycorrhizal infection of the plant. 相似文献
16.
Sodium chloride, at rates up to 100 mg g ?1, was added to a Sassafras sandy loam amended with finely-ground alfalfa to determine the effect of NaCl on CO 2 evolution, ammonification, and nitrification in a 14-week study. A NaCl concentration of 0.25 mg g ?1 significantly reduced CO 2 evolution by 16% in unamended soil and 5% in alfalfa-amended soil. Increasing NaCl progressively reduced CO 2 evolution, with no CO 2 evolved from the soil receiving 100 mg NaCl g ?1. A 0.50 mg NaCl g ?1 rate was required before a significant reduction in decomposition of the alfalfa occurred. The NO ?2-N + NO ?3-N content of the soil was significantly reduced from 40 to 37 μg g ?1 at 0 and 0.25 mg NaCl g ?1, respectively in the unamended soil. In the alfalfa amended soil, nitrification was significantly reduced at 5 mg NaCl g ?1. At 10 mg NaCl g ?1, nitrification was completely inhibited, there being only 6 and 2 μg NO ?2-N + NO ?3-N g ?1 in the alfalfa amended and unamended soil, respectively. In the alfalfa amended soil NH +4-N accumulated from 6 μg g ?1 at the 0 NaCl rate to a maximum of 54 μg g ?1 with 25 mg NaCl g ?1. These higher NH +4-N values resulted in a 0.5 unit increase in the pHw over that of the 0 NaCl rate in the alfalfa amended soil. At NaCl concentrations above 25 mg g ?1 there was a reduction in NH +4-N. The addition of alfalfa to the soil helped to alleviate the adverse affects of NaCl on CO 2 evolution and nitrification. 相似文献
17.
Abstract Radlands Crimson strawberries were grown in a glasshouse with 7 rates of applied boron. Wood shavings mulches with different boron concentrations were also applied as separate treatments. Boron toxicity symptoms were produced in leaves by boron rates of 0.32 kg ha ‐1 and greater on a soil containing 1.6 ug B g ‐1 of hot water extractable boron. Concentrations greater than 123 μg B g ‐1 in old leaves were associated with boron toxicity symptoms. In the B rate experiment, soil boron concentrations greater than 1.9 μg B g ‐1 soil were associated with leaf toxicity symptoms which increased in severity with increasing soil boron concentrations up to 4.1 μg B g ‐1 soil. Wood shavings mulch containing 17 μg B g ‐1 caused boron toxicity symptoms in older leaves whereas mulches containing less than 6 μg B g ‐1 did not produce toxicity symptoms. 相似文献
18.
Three months after neutralization concentrations of methylmercury (MeHg) were higher in the water of the limed than in the control basin of a small lake. After two years, the concentrations in the limed basin were somewhat lower than in the control (0.056–2.19 ng L ?1 and 0.129–2.65 ng L ?1, respectively). The highest concentrations were found in the anoxic hypolimnia. The total amount of MeHg in the water mass of the lake varied from 19 to 68 mg, showing a drop after spring and autumn overturns and a maximum during stratification periods. The total Hg concentrations of fish in L. Iso Valkjärvi varied from 0.06 to 0.14 μg g ?1 (ww) in whitefish to 0.1 to 0.7 μg g ?1 in perch and to 0.2 to 1.4 μg g ?1 in pike. The total amount of MeHg bound in the fish of the lake was quite similar to that in the water column, 43 to 59 mg in 1990–1993, 33 to 47 mg of which was in the perch population. 相似文献
19.
PurposeThe purpose of the study was to determine the levels of polychlorinated dibenzo-p-dioxin and polychlorinated dibenzofuran (PCDD/F), two types of persistent organic pollutant (POP), in an urban retention reservoir located in an industrial zone within a coal-mining region. It also assesses the potential ecological risk of the PCDDs/Fs present in bottom sediments and the relationship between their content and the fraction of organic matter. Materials and methodsThe sediment samples were collected from Rybnik Reservoir, located in the centre of the Rybnik Coal Region, Silesia, one of Poland’s major industrial centres. Seventeen PCDD/F congeners in the surface of the sediments were analysed using high-resolution gas chromatography and high-resolution mass spectrometry (HRGC/HRMS). Results and discussionThe toxic equivalency (TEQ) of the PCDDs/Fs in the sediments ranged from 1.65 to 32.68 pg TEQ g?1. PCDDs constituted 59–78% of the total PCDDs/Fs, while the PCDFs accounted for 22–41%. The pattern of PCDD/F congeners in the sediments was dominated by OCDD. However, the second-most prevalent constituents were OCDF and ∑HpCDFs in the low TOC sediment (< 10 g TOC kg?1), but HpCDD in the rich TOC samples (> 10 g TOC kg?1). PCDD/F concentrations in the sediment samples were 2- to 38-fold higher than the sediment quality guidelines limit, indicating high ecological risk potential. Although a considerable proportion of PCDDs/Fs in the bottom sediments from the Rybnik Reservoir were derived from combustion processes, they were also obtained via transport, wastewater discharge, high-temperature processes and thermal electricity generation. The PCDD/F concentrations were significantly correlated with all fractions of organic matter; however, the strongest correlation coefficients were found between PCDDs/Fs and humic substances. Besides organic matter, the proportions of silt/clay fractions within sediments played an important role in the transport of PCDDs/Fs in bottom sediments. ConclusionsThe silt/clay fraction of the bottom sediments plays a dominant role in the movement of PCDDs/Fs, while the organic matter fraction affects their sorption. The results indicate that the environmental behaviour of PCDDs/Fs is affected by the quantity and quality of organic matter and the texture of sediments. 相似文献
20.
Summary An automatic method for the colorimetric determination of Al in soil extracts using catechol violet was developed. The method is very reproducible and precise. The manifold arrangement covers a range of 0–1 μg ml ?1. By using a dilution loop, solutions containing up to 10 μg ml ?1 can be analysed. The method compares favourable with a manual catechol violet method and the alumin on method. 相似文献
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