خيارات البحث
النتائج 111 - 120 من 229
Element Concentrations in Soils and Plant Bioindicators in Selected Habitats of the Holy Cross Mountains, Poland النص الكامل
2001
Migaszewski, Zdzisław M. | Gałuszka, Agnieszka | Świercz, Anna | Kucharzyk, Jarosław
The objectives of this investigation in the HolyCross Mountain region of Poland were (1) to determineconcentration ranges and (2) mobility of elements within fivedetailed soil profiles and their apparent impact on thechemistry of some plant bioindicators, i.e. lichen thalli ofthe species Hypogymnia physodes (L.) Nyl. and Scotspine (Pinus sylvestris L.) bark. The results ofelemental determinations performed on soils and vegetationfrom the Holy Cross Mts show that some concentrations ofelements are elevated primarily due to air pollution.However, since 1994 a steady decrease in the content of S andsome heavy metals has been recorded in all the mediaexamined. Concentrations of many elements in H.physodes thalli and P. sylvestris needles of the Holy Cross Mountains are generally similarto those in other areas of Europe.
اظهر المزيد [+] اقل [-]An organizational guide to pollution prevention النص الكامل
2001
Migration and Chemical Availability of 137Cs and 90Sr in SwedishLong-Term Experimental Pastures النص الكامل
2001
Forsberg, Sverker | Strandmark, Mona
Migration and chemical availability of ¹³⁷Cs and⁹⁰Sr in the long-term was studied on a36-yr-old deposition experiment on pastureconsisting of a sandy soil and a clay soil,contaminated in 1961 with radionuclides in aqueoussolution. Comparisons were made with a study of thesame soils in 1967. Soil samples to 55 cm depth wereanalysed for ¹³⁷Cs and ⁹⁰Sr to establish thevertical distribution. Chemical availability wasstudied using sequential extractions with H₂O,NH₄Ac, NH₂OH·HCl, H₂O₂ andHNO₃. Both ¹³⁷Cs and ⁹⁰Sr were found atall depths in both soil types. Cs-137 waspredominantly retained within the upper 10 cm (70%)in both soils. For ⁹⁰Sr, the soils differedsignificantly, retention within the upper 10 cm was27% in sandy soil and 47% in clay soil. Migrationsince 1967 was faster in the sandy soil for bothnuclides. More than 95% of ¹³⁷Cs was bound inthe acid-digestible and residual fractions in bothsoils. The residual fraction was larger in clay soil.⁹⁰Sr was highly available in both soils. Noresidual fraction was found, and the easilyexchangeable fraction was 63–75%.
اظهر المزيد [+] اقل [-]Rainwater Composition at a Regional Representative Site of a Semi-Arid Region of India النص الكامل
2001
Singh, S. P. | Khare, P. | Satsangi, G. S. | Lakhani, A. | Maharaj Kumari, K. | Srivastava, S. S.
Rainwater samples (N = 51) were collected at Rampur, an areafree from anthropogenic activity during the monsoon of 1997 and1998. The concentration of ions follows a general pattern as Ca> NH₄ > Mg > SO₄ > Cl > F >Na > NO₃ > K > HCOO >CH₃ COO. The pH of precipitation ranges between 5.9 and 7.4. The levels of Ca and Mg at this site are higher than otherremote sites, probably dominated by particles of soil origin.Good correlation between Ca, NO₃, SO₄, HCOO and CH₃COO indicate that a fraction of NO₃, SO₄, HCOOand CH₃COO may be derived from soil or associated with Ca and Mg after neutralization. The order of neutralization factorCa (2.19) > NH₄ (1.26) = Mg (1.26) indicates that majorneutralization occurred by Ca. Factor analysis suggested thatCa, Mg, Na, K, NO₃, SO₄, HCOO and CH₃COO arecontributed by soil. NH₃ is known to exist as(NH₄)₂SO₄, NH₄NO₃ and NH₄Cl. Theymay be formed in the atmospheric water droplets by scavenging ofaerosols and reaction of gaseous species.
اظهر المزيد [+] اقل [-]A Study of Surface Water Quality in Macedonia, Greece: Speciation of Nitrogen and Phosphorus النص الكامل
2001
Voutsa, D. | Manoli, E. | Samara, C. | Sofoniou, M. | Stratis, I.
A 2-yr (1997–1998) survey aiming at the establishment of national data bases concerning the quality of surface waters has been conducted in the major river systems of Macedonia, N. Greece. This paper presents the physicochemical parameters(pH, conductivity, total suspended solids, temperature and DO),the organic pollution parameters (BOD₅, COD) and the major N and P species (NO₃ ⁻, NO₂ ⁻,NH₄ ⁺,organic N, orthophosphates and total P) determined at 25 sampling sites located on main rivers, tributaries, streams andditches that drain the major rural, agricultural, urban and industrial areas of N. Greece. Use of multivariate statistics is also made to identify the principal factors which influencethe chemistry of the water in individual river systems.The eutrophication status of the examined systems was evaluatedby means of N/P ratios. Mean N/P ratios showed large variationsamong sampling sites ranging from potential N- to P-limitationconditions. N/P ratios at particular sampling sites showed also great temporal variability thus suggesting temporary states of N- or P- limitation. Most frequently, highest ratio values wereobserved during winter and early spring. Comparisons are made between data from this study region and literature on rivers elsewhere.
اظهر المزيد [+] اقل [-]An Analysis of Soil and Plant (Taraxacum Officinale) Contamination with Heavy Metals and Polycyclic Aromatic Hydrocarbons (PAHs) In the Area of the Railway Junction Iława Główna, Poland النص الكامل
2001
Malawska, M. | Wiołkomirski, B.
Polycyclic aromatic hydrocarbon and heavymetal (Pb, Cd, Cu, Zn, Hg, Fe, Co, Cr, Mo) contentswere established in soil and plant samples collectedin different areas of the railway junction IławaGłówna, Poland. Soil and plant samples werecollected in four functional parts of the junction, i.e. the loading ramp, platform area, rolling stockcleaning bay and the railway siding. It was found thatthe PAH contamination of soil and plants was thehighest in the platform area and near the railwaysiding and lowest in the loading ramp and cleaning bayareas. The contamination exceeded control levels up toalmost twenty fold. The heavy metal contaminationpattern was different. The soil and plants were veryhighly contaminated in the cleaning bay and side trackareas while the loading ramp and platform areas wereless contaminated. A particularly high pollution levelwas observed for mercury in the cleaning bay area.Also lead, zinc and copper pollution levels wererelatively high in the cleaning bay and side trackareas. No significant increase in molybdenum contentwas observed in comparison with the control area.
اظهر المزيد [+] اقل [-]The Impact of Road De-Icing Salts (NaCl) on Colloid Dispersion and Base Cation Pools in Roadside Soils النص الكامل
2001
Norrström, A.-C. | Bergstedt, E.
The maintenance of safe-drivingconditions in snow and ice-affected areas in thewintertime includes the use of sodium chloride (NaCl)as de-icing salts. In this study, the impact of NaClon soil-colloid mobilisation and exchangeablebase-cation leaching has been evaluated. The chemistryof groundwater samples below an infiltration trenchfor highway runoff and leachate from column studiessuggested that soil-colloid mobilisation had occurred,as the exchangeable sodium (Na) concentration and theelectrical conductivity (EC) in the groundwater/columnleachate reached the threshold values for colloiddispersion. Generally, samples with no dispersionproblems had high Na and calcium (Ca) concentrations,suggesting that the initial effect of the de-icingsalt was to stabilise the colloids. In the columnstudy there was a good agreement between the degree ofcolloid dipersion problems and lead (Pb) concentrationwhen the pH value was above 7.0. Significant negativecorrelations between Na/CEC (cation exchange capacity)and Ca/CEC in roadside soils from three sitesindicated that Na preferentially displaces Ca from theexchange sites. However, the groundwater dataindicated that Na ions also displace potassium (K) andmagnesium (Mg). A positive effect of NaCl seen at onesite was an increase in the K concentration, which ishighly likely an effect of Na ions displacing fixed Kbetween the layers of 2:1 type clay minerals. In soilslacking these types of clay minerals, severe Kshortage may result from a high plant demand combinedwith the low K concentration in the readily availablefractions in the original soil and a highsusceptibility to leaching. The most significantimpact on soil exchange processes was found to occurwithin 6 m from the road.
اظهر المزيد [+] اقل [-]Ammonium Losses Through Subsurface Drainage Effluent from Rice Fields of Coastal Saline Sodic Clay Soils النص الكامل
2001
Singh, Man | Bhattacharya, A. K. | Nair, T. V. R. | Singh, A. K.
Subsurface tile drainage systems with drainspacings of 15 m in 0.4 ha and 25 m in 3.2 ha wereinstalled at the farmers' field in 1986 and 1987,respectively, to study their effect on the reclamationof the coastal saline sodic clay soils. The system'sperformance in terms of the changing physical andchemical properties of the soil and rice yield wascontinuously monitored for a decade. Field datasuggested the possibility of adopting wider drainspacings and thus, drainage system with 35 and 55 mspacings was laid in 1997 in a 4 ha area. On theseinstallations the losses of NH₄ ⁺-N throughsub-surface drainage effluent were estimated. Thearea under 25 m drain spacing was the control with nocrops, fertilization and irrigation. Analysis ofwater samples collected daily for 10 days startingfrom 40 DAT from the drain laterals revealed thatthere were no trace of NH₄ ⁺-N in theeffluent from 15 and 25 m drain spacings. However,the effluent from 35 and 55 m spacings contained anaverage of 6.704 mg L⁻¹ and 4.205 mg L⁻¹ of NH₄ ⁺-N, respectively, before irrigation and2.438 and 1.650 mg L⁻¹ after irrigation. Themagnitudes of the losses of NH₄ ⁺-N duringthe crop season were 6.43 kg ha⁻¹ in 35 m spacingwith a drainage rate of 5.6 mm d⁻¹ and 2.14 kgha⁻¹ in 55 m spacing with a drainage rate of 3.5 mm d⁻¹. The rice yield was 6.5 Mg ha⁻¹ in15 m drain spacing where no ammonium losses throughsubsurface drainage effluent occurred. The rice yieldsunder 35 and 55 m drain spacings were 1.9 and 1.8 Mgha⁻¹, respectively. The poor yield was due tosignificant loss of ammonium form of nitrogen throughthe drainage effluent and lesser availability of totalnitrogen to the plants. The plant uptake of nitrogen in the unreclaimed area with 55 m spacing was half ofthat in the reclaimed area with 15 m spacing.
اظهر المزيد [+] اقل [-]Rhodophyta Seaweed Species as Bioindicators for Monitoring Toxic Element Pollutants in the Marine Ecosystem of Ghana النص الكامل
2001
Serfor-Armah, Y. | Nyarko, B. J. B. | Osae, E. K. | Carboo, D. | Anim-Sampong, S. | Seku, F.
Six seaweed species of the Rhodophyta family were sampled for atwo-year period from June 1996 to August 1998 along the Atlanticcoast of Ghana (part of the Atlantic Ocean). The species wereanalysed to determine the levels of eleven chemicalelements namely: Al, As, Br, Cd, Fe, La, Mn, Ni, Hg, V and Zn byInstrumental Neutron Activation Analysis (INAA). Al, Br, Ni, andZn were measured in all the seaweed species studied. The elementAl generally showed the highest concentrations in most of thespecies analysed while Hg levels were the lowest. Precision andaccuracy of the method have been evaluated and the detectionlimits also calculated. The results showed high variability inand between species, among sampling sites and times ofcollection. The high values of metal concentrations in themacroalgae suggest that these marine organisms can be used asbiological indicators for studing marine pollution.
اظهر المزيد [+] اقل [-]Identification of an Assemblage of Indicator Organisms to Assess Timing and Source of Bacterial Contamination in Groundwater النص الكامل
2001
Conboy, M. J. | Goss, M. J.
Bacterial contamination of drinking water wells is a commonproblem in many rural areas. Some of this contamination may berelated to manure spreading or housing of livestock; another source is on-site septic systems. Current indicator organisms are able to detect the presence of fecal contamination, but where there may be more than one potential source of fecal material, the current indicators are unable to ascertain the origin. This laboratory investigation was undertaken to determine the longevity and reliability of a selected suite of indicator organisms. Total coliform, fecal coliform, fecal streptococci and Clostridium perfringens were monitoredin a simulated contaminated groundwater environment for 6 months. All four indicator organisms were present at the end of6 months. The number of fecal streptococi bacteria decreased most noticeably, allowing assessment of relative age of contamination. C. perfringens was found to be a reliableindicator of contamination from animal manure. Fecal material from 28 different animals and three septic systems were assessed for the presence of the indicator organisms. Totalcoliform, fecal coliform and fecal streptococci were present in the fecal material of all animals tested including reptiles.C. perfringens was detected in feces from all but two of the animals assessed. Using an assemblage of indicator organisms provides more information regarding source and timingof contamination than just testing for total coliform and fecalcoliform bacteria.
اظهر المزيد [+] اقل [-]