Many drainage schemes and salinity control projects have been executed world wide. Pipe drainage has widely been used in Pakistan,
Egypt and India to control waterlogging. The impact of pipe drainage on land and water was evaluated in this paper using data
of three pipe drainage projects in Pakistan namely Khushab Salinity Control and Reclamation Project, Fourth Drainage Project
in Faisalabad and Swabi Salinity Control and Reclamation Project. Data by regular monitoring of these projects were collected.
The effect of pipe drainage on water table depth at these three locations has been compared. Water quality and soil salinity
improvement due to the pipe drainage has also been investigated. Data, related to water table depths and discharges from drain
pipes/wells, was collected. Observation wells, installed at various places by the Water and Power Development Authority, were
used for collection of this data. To evaluate the impact of the projects on salinity, soil samples from all the three locations
were tested. A questionnaire was prepared to get the view of the people about the projects. It was revealed that in these
areas, due to subsurface pipe drainage, the percentage of the abandoned land has been considerably decreased. Over drainage
was observed in a few places of the projects. The farmers at such places were asked to change their cropping patterns. Ultimately,
there has been an increase in area under cultivation, crop yields and cropping intensity in the projects’ area. 相似文献
The heavy metal (Pb, Cd, Cr, and Ni) content of a fish species consumed by the Sistan population and its associated health risk factors were investigated. The mean concentrations of Pb, Cd, and Cr were slightly higher than the standard levels. The Ni content of fish was below the maximum guideline proposed by the US Food and Drug Administration (USFDA). The average estimated weekly intake was significantly below the provisional tolerable intake based on the FAO and WHO standards for all studied metals. The target hazard quotients (THQ) of all metals were below 1, showing an absence of health hazard for the population of Sistan. The combined target hazard quotient for the considered metals was 26.94 × 10?3. The cancer risk factor for Pb (1.57 × 10?7) was below the acceptable lifetime carcinogenic risk (10?5). The results of this study reveal an almost safe level of Pb, Cd, Cr, and Ni contents in the fish consumed by the Sistan population.
Thirty-three organic acids and furfural metabolites were examined for their nematicidal activity against plant-parasitic, free-living and predacious nematodes. Propionic acid, 2-methylhexanoic acid, lactic acid, maleic acid, and furic acid were the most effective nematicides among normal chain organic acids, branched organic acids, hydroxy/keto-acids, dicarboxylic acids and furfural metabolites, respectively. Seven of the tested compounds were found to have more than 90% mortality thus designating them as highly active nematicides. Of the highly active tested compounds, an average octanol/water log P of 0.97 was observed with a range from 0.28 to 2.64, and a Henry's Law constant averaging 2.6 x 10(- 7) atm.m3/mole. Tested chemicals with minor or low nematicidal activity showed an average log P of 1.76 with a range from 0.15 to 3.42 and a Henry's Law constant averaging 16.6 x 10(- 7) atm.m3/mole. 相似文献
Nanocrystalline titanium dioxide was injected into sand columns to simulate subsurface injection for creation of a permeable treatment barrier. Past usage of this material as an ex situ pilot scale treatment filter has shown that it has a high adsorption capacity for a number of heavy metals and therefore would be a good candidate for injection technology. Three suspension concentrations (50, 75 and 100 mg l(-1)) were pumped through packed sand columns at different flow velocities (3.0, 6.8 and 14.1 cm min(-1)). Little to no particles was detected in the effluent. Most of the nanoparticles remained in the sand columns, with an increasing then decreasing retained solids pattern. Application of a one-dimensional advection-dispersion flow model, that included two empirical kinetic terms to account for particle retention in the porous media, produced data fits that followed the general trend of the data, but did not truly capture the concentration maxima in the data sets. Discussion of these results highlights the limited ability of existing models to aid in predicting particle retention of non-ideal materials for engineering purposes. 相似文献
Persistent organochlorine pesticides (OCPs), such as dichlorodiphenyltrichloroethane (DDT) and its metabolites, hexachlorobenzene (HCB), alpha, beta and gamma-hexachlorocyclohexane (HCH) isomers, together with polychlorinated biphenyl (PCB) congeners (IUPAC Nos. 28, 52, 101, 138, 153 and 180), were determined in tail feathers from 37 birds belonging to 18 species, all originating from the South-West of Iran (Khuzestan, coast of the Persian Gulf). This is the first report on organochlorine contaminants in feathers from museum collections and it is an indication of the concentrations of OCPs and PCBs in the past (1991-1996). Median concentrations of HCHs, DDTs, PCBs and HCB were 22, 14, 11 and 10 ng/g feather, respectively. Significant correlations (p<0.05) were calculated between OCPs (except HCB) and PCBs in the bird feathers. p,p'-DDE and gamma-HCH were the most abundant OCPs, while CB 180, CB 138 and CB 101 were the predominant PCB congeners in almost all species. Significant differences (p<0.05) in the mean concentrations of DDTs and PCBs were detected among species grouped according to their feeding habits. Levels of DDTs and PCBs were highest in the carnivorous species and lowest in the herbivorous species. Levels of OCPs and PCBs in feathers of bids in the 1990s were generally below the thresholds reported to affect reproduction. 相似文献
Environmental Science and Pollution Research - Numerous studies have determined the adverse effects of air pollution on the health, welfare, and comfort of humans. More recently, the effects of air... 相似文献
Variations in breeding success of the Whiskered Terns (Chlidonias hybrida) were studied in two wetlands; Anzali (2005 and 2008) and Zarivar (2007–2008) in north and west Iran. Nesting success was
modeled and compared using information-theoretic approach implemented in program Mark in order to assess effects of colony
locations, years and nest initiation dates on the probability of daily nest survival. Clutch size did not vary between colonies
and years. Breeding success varied between colonies (Zarivar > Anzali), and years only in Anzali (2005 > 2008). Overall daily
nest survival was 0.977. (95% LCI 0.973, UCI 0.981), equivalent to a Mayfield nest survival of 0.317. (95% LCI 0.255, UCI
0.387). Egg-laying periods and colony site were important covariates affecting the daily survival rates (Σωi = 0.86 and Σωi = 0.83, respectively), while, the support for the effect of year was less (Σωi = 0.41). We concluded that Lake Zarivar provides a more favorable nesting location for Whiskered Terns probably because of
little changes in rainfall and water depth during the breeding seasons which influence breeding performance. 相似文献
Seeds of Enterolobium contortisiliquum were subjected to steam distillation to obtain a light yellow essential oil in a yield of 3 ml/kg of seeds. The major components of the oil were identified using gas chromatography/mass spectrometry (GC-MS) and were furfural, limonene, linalool, estragole, carvone, and apiole with carvone representing more than 50% of the total composition. Antimicrobial activities of the essential oil were determined against four species of gram positive bacteria (Bacillus subtilis, Bacillus cereus, Staphylococcus aureus, Micrococcus luteus) and two gram negative bacteria (Klebsiella pneumoniae, Serratia Marcescencs). The essential oil inhibited the growth of all tested bacteria but was most effective against the gram positive bacteria. Chemicals that are responsible for the antibacterial effect of the essential oil were determined using the bio-autography thin layer chromatography (TLC) technique. The active compounds responsible for the activity were found to be carvone and estragole. 相似文献