environmental toxicology wright and welbourn pdf

Environmental Toxicology Wright And Welbourn Pdf

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This paper reviews the current state-of-the-art, limitations, critical issues, and new directions in freshwater plant ecotoxicology. We selected peer-reviewed studies using relevant databases and for each 1 publication year, 2 test plant species, 3 reference plant group microalgae, macroalgae, bryophytes, pteridophytes, flowering plants , 4 toxicant tested heavy metal, pharmaceutical product, hydrocarbon, pesticide, surfactant, plastic , 5 experiment site laboratory, field , and 6 toxicant exposure duration.

Indoor air pollution is ranked as one of the world's greatest public health risks Wolverton, The United Nations Development Program estimated in that over 2 million humans die each year due to the persistence of deleterious indoor air Brennan and Withgott,

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Environmental Toxicology

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Temperature, pH, total dissolved solid, conductivity, salinity, dissolved oxygen, biological oxygen demand BOD , chemical oxygen demand COD , total hardness, sulfate, nitrate, and phosphate were determined in surface water.

Particle size, total organic matter TOM , and pH were also determined in the sediments. The parameters were within permissible limits except the mean values of BOD, COD, total hardness, and sulfate that exceeded levels permissible for domestic use. The sediments consisted mainly of sand, with TOM ranging from 0.

The latter were higher than World Health Organization recommended permissible levels for both surface and drinking water. Human activities can alter the geochemical cycles of metals resulting in increased contamination. Although metals enter water bodies from many natural and anthropogenic sources, an important one is oil spills, which occur almost daily in the Niger Delta, Nigeria's hub of oil and gas production.

Bodo is a network of brackish water creeks on the upper reaches of the Andoni—Bonny river system in the lower Niger Delta basin affected by incessant crude oil spills from abandoned pipelines, criminal damage sabotage , and lack of maintenance of oil facilities Legborsi On 28 th August , a fault in the Trans-Niger pipeline resulted in a significant oil spill into Bodo Creek.

The oil poured into the swamp and creek for weeks finally stopped on 7 November , covering the area with a thick slick of oil that killed aquatic organisms.

A second major spill was reported on 2 nd February Amnesty International Bodo Creek is a strong livelihood supporting base for the people of Bodo community and their neighbors. It is a major source of drinking and bathing water, especially for fisherfolks of Ogoni who are in close contact with the water. The creek is also used for fishing, transportation, cassava fermentation, recreation, waste disposal, small-scale aquaculture, and sand dredging.

In a recent report, UNEP stated that the drinking water sources in Ogoni community may have been affected by pollution from oil spills, and drinking water sampled from 28 wells in 10 communities were oil-contaminated. Some trace metals with relatively high toxicity and potential for bioaccumulation are high priority pollutants. These metals tend to accumulate in sediments, which may act as short- or long-term sinks in aquatic systems and sources of further contamination. Accumulation of metals is controlled by granular composition of the sediments and the physico-chemical properties of the water.

Sediment grain size and organic matter content are two critical factors influencing their distribution and their capacity for pollution Liaghati, Preda, and Cox ; Selvaraj et al. Grain size determines the surface area, the settling velocity, and the deposition rate of suspended solids in the water column, as well as the degree of chemical partitioning between sediment and water Lin, Chen, and Su ; Aprile and Bouvy Since the major oil spills of and , minor oil spills have continued to occur in Bodo Creek and there is urgent need to assess their effect on the metal concentrations and physico-chemical properties of the sediment and water.

Knowledge about the changing concentrations and the distribution of metals between various compartments helps to provide evidence of the health quality of a wetland system and is needed for conceiving good environmental management programs for the Niger Delta. Bodo Creek is a brackish water that adjoins the Bodo community in Ogoni land.

Onwugbuta-Enyi, Zabbey, and Erondu have described the creek's structure and hydrology. It is characterized by tidal flats, influenced by a semi-diurnal tidal regime. The water level and salinity increase and decrease depending on the lunar cycle RPI The area experiences heavy rainfalls from April to October and sporadic rainfalls from November to March. Three sampling stations were georeferenced through global positioning system.

These were upstream, downstream, and midstream from locations that have had some history of oil pollution or are close to oil production facilities Figure 1. Shore and water surface were slightly coated with oil. The area is close to agricultural land and homesteads.

Samples were collected from September to January At each site, four sediment sub-samples were collected using a plastic trowel at a depth of 2 to 30 cm from four randomly selected nodes. These sub-samples were homogenized to form a representative sample. The composite samples were transferred to aluminum sampling packs and sealed. Care was taken not to disturb the fine surface algal flock that was scraped off during the sampling process.

Water samples were collected against the flow of current using precleaned mL polyethylene bottles. Particle size analysis was carried out using a laser granularmeter LS with P. Aliquots of 0. The cool digest solution was filtered through the Whatman 42 filter paper and made up to mL in a volumetric flask by adding deionized water. All chemicals and reagents used were of analytical grade and of highest purity possible.

Analytical blanks were prepared with each batch of the digestion set and analyzed one blank for every set of 12 samples in the same way as the samples. The spatial variations in physico-chemical parameters of the water are presented in Table 1. Water temperature varied from The exact temperature depends on the time of day and of the sunlight absorbed by the water. Spatial variations of pH values were identical among the stations and varied from 8.

Variations in physico-chemical parameters of Bodo Creek in comparison with national standards in Nigeria. AMCS — average means concentration of the sampling stations. Dissolved oxygen mean values ranged from 4. Lower values were obtained in station 3 when compared with the two other stations Table 1. Inflow of fresh water tends to reduce the salinity and conductivity in station 3 but nitrate 0. Except for temperature, phosphate, and pH, physico-chemical parameters of station 3 were significantly different from the two other stations.

The mean values of salinity, temperature, and pH showed a gradual increase from September until January , coinciding with the onset of the dry season. Decreases in DO and total hardness were observed during this period. The other parameters did not show any particular trend. The sediments of Bodo Creek exhibit fluctuating pH values that ranged from 5.

Sediments from station 3 had pH values of 7. The clay—silt fractions in the sediments ranged from 0. TOM ranged from 0. Particle size plays an important role in nutrient accumulation in the sediments because fine-grained particles often have greater surface to volume ratio and more organic matter Aprile and Bouvy ; Wang, Liu, and Tang Metals are released to the water column through sediment resuspension, adsorption—desorption, reduction—oxidation reactions, and the action of degrading organisms Barakat et al.

Except for cadmium, the study results indicated that the metal contents appeared higher than international quality criteria for public surface water or drinking water WHO ; FEPA WHO did not established guidelines for Fe, Mn, and Zn because they are not of health concern at levels found in drinking water. Cu and Zn values at station 3 were significantly different.

The metal values of Bodo Creek reported here were higher than those reported for Ikot Ada Udo with a history of oil spills in the Niger Delta Udo Cu, Zn, and Pb are closely associated with crude oil and municipal wastes disposal Chindah, Braide, and Sibeudu These metals tend to increase in less saline and highly turbid media Selvaraj et al.

This could explain the high concentrations of these metals observed at station 3, which is near the oil pipeline, and the homesteads. The metal concentrations in the sediments from Bodo Creek are summarized in Table 2.

Iron is the fourth most abundant element in the earth's crust and is considered as a main factor determining the adsorption capacity Wright and Welbourn The Mn concentrations found here are higher than those 0. The Cu concentrations of 8. Similar trends were observed for Ni and Co, their concentrations being highest at station 2 and lowest at station 3. They did not show much variation when compared with other rivers in the Niger Delta Ayotunde, Offem, and Ada ; Chindah et al.

Low levels of Pb recorded in this study 0. Concentrations of Cr varied from 4. The reason for the low values have been affirmed to the high energy of current and the volume of water that ensures proper flushing of the system Chindah, Braide and Sibeudu The hydrodynamic and chemical complexity of a particular river, which is peculiar to the behavior of each metal, makes it difficult to compare concentrations from one water body to another.

Nevertheless, the values in this study were higher or similar to those reported previously for the Niger Delta Issa et al. The spatial variations observed in metal contents were due to differences in physico-chemical parameters, silt and clay contents of different sites. This implies that the concentrations of the metals analyzed were not high enough to suggest serious contamination in the sediment. However, the higher concentration of metals in Bodo water suggests that it is not fit for domestic use.

This implies that there is need for policy makers to initiate processes of restoration of this water body to meet internationally acceptable standard for domestic use. No potential conflict of interest was reported by the authors. Read article at publisher's site DOI : Environ Monit Assess , 1 , 21 Dec Zabbey N , Olsson G. Glob Chall , 1 5 , 13 Jul To arrive at the top five similar articles we use a word-weighted algorithm to compare words from the Title and Abstract of each citation.

Cited by: 3 articles PMID: Environ Monit Assess , , 22 Oct Cited by: 6 articles PMID: Mar Pollut Bull , 42 10 , 01 Oct Cited by: 13 articles PMID: Ecotoxicol Environ Saf , , 17 Jun Environ Monit Assess , 7 , 29 Jul Take part in our Impact Survey 15 minutes.

Effectiveness of Houseplants in Reducing the Indoor Air Pollutant Ozone

Either your web browser doesn't support Javascript or it is currently turned off. In the latter case, please turn on Javascript support in your web browser and reload this page. Temperature, pH, total dissolved solid, conductivity, salinity, dissolved oxygen, biological oxygen demand BOD , chemical oxygen demand COD , total hardness, sulfate, nitrate, and phosphate were determined in surface water. Particle size, total organic matter TOM , and pH were also determined in the sediments. The parameters were within permissible limits except the mean values of BOD, COD, total hardness, and sulfate that exceeded levels permissible for domestic use. The sediments consisted mainly of sand, with TOM ranging from 0. The latter were higher than World Health Organization recommended permissible levels for both surface and drinking water.

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This content was uploaded by our users and we assume good faith they have the permission to share this book. If you own the copyright to this book and it is wrongfully on our website, we offer a simple DMCA procedure to remove your content from our site. Start by pressing the button below! Environmental Toxicology Home Environmental Toxicology. The text is arranged in four tiers and covers most aspects of environmental toxicology, from the molecular to the ecosystem level. Early chapters deal with basic and advanced concepts, methods, and approaches for environmental toxicology.

Aquatic plants and ecotoxicological assessment in freshwater ecosystems: a review

Environmental toxicology is a multidisciplinary field of science concerned with the study of the harmful effects of various chemical, biological and physical agents on living organisms. Rachel Carson is considered the mother of environmental toxicology, as she made it a distinct field within toxicology in with the publication of her book Silent Spring , which covered the effects of uncontrolled pesticide use. Carson's book was based extensively on a series of reports by Lucille Farrier Stickel on the ecological effects of the pesticide DDT. Organisms can be exposed to various kinds of toxicants at any life cycle stage, some of which are more sensitive than others.

Росио улыбнулась: - Todo bajo el sol. Чего только нет под солнцем. - Это был девиз туристского бюро Севильи.

Беккер непроизвольно снова и снова вглядывался в его странно деформированные руки. Он присмотрелся внимательнее. Офицер выключил свет, и комната погрузилась в темноту. - Подождите, - сказал Беккер.  - Включите на секунду.

Environmental toxicology

Introduction

Машина упала на бок и замерла. На затекших ногах Беккер прошел через вращающуюся дверь. Больше никаких мотоциклов, пообещал он. Ярко освещенное помещение аэровокзала сияло стерильной чистотой. Здесь не было ни души, если не считать уборщицы, драившей пол. На противоположной стороне зала служащая закрывала билетную кассу компании Иберия эйр-лайнз. Беккеру это показалось дурным предзнаменованием.

Мужчина нерешительно кивнул. Беккер заговорил на чистейшем немецком: - Мне нужно с вами поговорить. Мужчина смотрел на него недовольно. - Was wollen Sie. Что вам .

Я просто добивался своей цели, - мысленно повторил. Ты лжешь, - ответил ему внутренний голос. Да, это. Он - лжец. Он вел себя бесчестно по отношению ко многим людям, и Сьюзан Флетчер - одна из. Он очень о многом ей не сказал - о многих вещах, которых теперь стыдился.

 Боюсь, что .

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