Os objetivos deste estudo foram avaliar a concentração de Cd, Pb, Cr e Ni nos tecidos da cana-de-açúcar, constatar a presença de bactérias fixadoras de nitrogênio (BFN) na variedade IAC87-3396 cultivada em ambiente com altas concentrações de metais e avaliar a tolerância das bactérias metais pesados \"in situ\" e \"in vitro\". A cana-de-açúcar IAC87-3396 foi cultivada em área com altos teores de metais. Antes do plantio foram aplicados 5 mitigadores de metais pesados. Para detecção e quantificação de níquel, chumbo, cromo e cádmio foram realizadas análises em ICP-MS em amostras de tecidos da cana-de-açúcar (folha +1, raízes e tolete pré-germinado) obtidos na colheita da cana-planta e cana-soca. A quantificação das bactérias foram realizadas em amostras da parte aérea e das raízes, da cana-planta (colheita) e da cana-soca (6 meses e colheita), utilizando a metodologia do tolete pré-germinado. O ensaio \"in vitro\" consistiu em acrescentar ao meio de cultura 4 concentrações de Pb, Cd, Ni e Cr inseridos isoladamente e em combinações e proceder a inoculação em placa de petri de 4 bactérias (Herbaspirillum seropedicae, Gluconacetobacter diazotrophicus, Azospirillum amazonense e Burkholderia tropica). O comportamento nas diferentes concentrações foi avaliado atribuindo-se valores aos diferentes padrões de crescimento. Para os metais, a maior concentração foi encontrada nas raízes e a menor foi encontrado na folha +1. No campo os valores da folha +1 aumentaram da cana planta para a cana soca e os valores das raízes diminuíram. Comparando campo e tolete pré-germinado, na cana planta a concentração nas raízes foi menor do que o encontrado no campo e na parte aérea o tolete teve uma concentração maior para o Ni e Cd. Na cana soca o campo possui as maiores concentrações tanto para parte aérea como para raízes. Na quantificação das bactérias, a comparação entre os períodos mostrou que a quantificação no geral é maior na cana planta. Na cana planta a quantificação foi maior na parte aérea, no 6 meses da cana soca o predomínio é na raiz e na colheita da cana soca existe uma distribuição mais uniforme das bactérias no interior da planta. No ensaio \"in vitro\" a concentração máxima de metais tolerada foi a máxima estudada para Pb (248 mg L-1), Cd (8 mg L-1) e Ni (40 mg L-1). O Cr e a associação entre 2, 3 e 4 metais proporcionaram o não crescimento das bactérias. Para a maior parte das bactérias houve associação significativa entre os padrões de crescimento e as concentrações de metais no meio de cultura. Na variedade IAC87-3396 foram encontrados os 4 gêneros de BFN, mesmo nas raízes onde os teores de Pb, Ni, Cr e Cd foram maiores. A tolerância das BFN aos metais \"in situ\" diferiu da \"in vitro\". O cromo e a associação entre os metais limitaram o crescimento \"in vitro\" de todas as bactérias. A metodologia do tolete pré-germinado não refletiu as condições de concentração de metais em materiais coletados no campo. A cana-deaçúcar tem potencial para ser uma cultura fitoextratora e acumuladora de Pb, Ni, Cr e Cd / The objectives of this study were to evaluate the concentration of Cd, Pb, Cr and Ni in the tissues of sugarcane, noting the presence of the BFN in IAC87-3396 variety grown in contaminated environment and evaluate the BFN tolerance to heavy metals \"in situ\" and \"in vitro\". Sugarcane variety IAC87-3396 was grown in an soil contaminated by metals. Before planting, five mitigators of heavy metals were applied. Analysis were performed to detect nickel, lead, chromium and cadmium in tissues of sugarcane, including leaf +1, roots and pregerminated sett (shoot and root) at harvest of the plant cane and ratoon cane. To quantify the nitrogen-fixing bacteria, three tests were performed comprising the shoots and roots, one in the plant cane (at harvest) and two in ratoon cane (6 months and harvesting) using the methodology of pre-germinated sett. The test \"in vitro\" consisted of adding to the culture medium Pb, Cd, Ni, Cr, mixed metals and inoculated in a petri dish of 4 bacteria (Herbaspirillum seropedicae, Gluconacetobacter diazotrophicus, Azospirillum amazonense and Burkholderia tropica). The behavior in different concentrations was evaluated by assigning values to different growth patterns. For all metals, the highest concentration was found in the roots and the lowest values were found in leaf +1. This values in leaf +1 increased from plant cane to ratoon cane while in root it decreased. In relation to the pregerminated sett, metal concentration in root of plant cane was lower than that found in the field while the leaf had a higher concentration only for Ni and Cd. The field ratoon cane has the highest concentrations for both the aerial and root part. For the quantification of bacteria, the comparison between the measurement periods showed that in general it is greater in the plant cane. The location of bacteria inside the plant revealed that, in the plant cane, it was higher in the shoot. However, for the first six months of ratoon cane the predominance of bacterias was in the root. At harvest of the ratoon crop a more uniform distribution of bacteria was found inside the plant. In the \"in vitro\" essay the maximum concentration studied was the maximum tolerated for Pb (248 mg L-1), Cd (8 mg L-1) and Ni (40 mg L-1). The association between Cr and 2, 3 and 4 metals provided no growth of bacteria. For most of the bacteria a significant association was found between growth patterns and concentrations of metals in the culture medium. All the four kinds of NFB were found in IAC87-3396 even in roots where the levels of Pb, Ni, Cr and Cd were high. The tolerance of the NFB to these metals \"in situ\" is different from that \"in vitro\". The chromium and its association with other metals have limited growth \"in vitro\" of all bacteria. The methodology of pre-germinated sett did not reflect the conditions of metal concentration in material collected in the field. Sugarcane plant has the potential to be a culture of phytoextraction and accumulation of Pb, Ni, Cr and Cd

Estudos recentes constataram a existência de processos que permitem a atenuação natural dos contaminantes presentes nos lixiviados. O adequado entendimento destes processos pode originar benefícios possíveis de serem aplicados em aterros antigos, novos ou naqueles que ainda serão concebidos. O presente estudo avaliou o comportamento e a atenuação de contaminantes dos líxiviados no solo, por meio de experimento desenvolvido em colunas de percolação e, para a avaliação da atenuação este teste é indicado por refletir as condições naturais e as características adsortivas do solo, propiciando uma melhor simulação da atenuação. O lixiviado e o solo utilizados neste experimento são provenientes do aterro sanitário de São Carlos - SP. O solo utilizado foi caracterizado quanto à composição física, química, biológica e mineralógica para verificar o transporte do percolado nas colunas e a interação solo-contaminante. Na área do aterro foram feitas perfurações, ensaios de condutividade hidráulica e avaliação da geologia local, para conhecimento das características físicas, químicas, biológicas, mineralógicas e geológicas do solo in situ. Este foi classificado como arenoso, apresentando características físicas e químicas que não se enquadram nos parâmetros adequados para sua utilização em áreas de disposição de resíduos sólidos urbanos, pois, a capacidade de troca de cátions, superfície específica, potencial hidrogeniônico e classe textural arenosa, evidenciam que este solo possui deficiente capacidade de retenção e imobilização de contaminantes. Além disso, pela observação in situ, constata-se que a área de disposição de resíduos sólidos de São Carlos esta situado sobre rochas da Formação Botucatu, sendo que a mineralogia do solo presente no local é composta de quartzo, caulinita, goethita, hematita, gibsita e ilita. O ensaio de condutividade hidráulica indicou que o solo presente na base do Aterro sanitário não atende a valor de permeabilidade exigida por norma, o que poderá permitir a infiltração de água da chuva, aumentando a produção do lixiviado e sua movimentação no perfil, podendo atingir as águas subterrâneas. Assim, foram traçadas curvas características do transporte de contaminantes nas amostras efluentes monitoradas durante o processo de percolação, coletadas a cada 0,25 volume de poros até atingir 10,0 volume de poros percolados. As curvas características do transporte de contaminantes traçadas apresentaram baixas concentrações de Chumbo, Cádmio, Ferro, Zinco, Manganês, Cálcio, Magnésio, Cobre, Cromo nas amostras fluentes. Já o Sódio, Potássio, Cloro, Níquel e Alumínio foram preferencialmente percolados com o lixiviado, evidenciando a variação da faixa de concentração de cada elemento no percolado. Os perfis de concentração dos metais pesados mostraram que existe uma frente de contaminação. As curvas de retenção de metais no solo mostraram que a preferência de sorção apresentada pelos solos nas colunas foi : Cobre > Cádmio > Cálcio > Zinco > Magnésio > Potássio > Manganês > Fósforo > Ferro > Níquel > Alumínio. Cujos valores retidos no solo das colunas podem estar evidenciando a capacidade deste solo em reter contaminantes.O solo em questão apresentou baixo potencial para retenção dos contaminantes presentes no lixiviado, classificado como arenoso e, com características químicas que não se enquadram nos parâmetros adequados para sua utilização em áreas de disposição de resíduos sólidos urbanos. / Recent studies had found the existence of processes that allow a natural attenuation of the leachates\'s cotaminants. An adequate understanding of these processes may originate benefits, that may be applied in ancient, new or to be created landfills. This work evaluated the contaminant\'s behavior and attenuation, contaminants existing in soil\'s leaching, throughout an experiment developed in percolation columns. This is the indicated examination for evaluate the attenuation, because it reflects soil\'s natural conditions and adsorptive characteristics, providing a better simulation of it\'s attenuation. The leachate and the soil used in this experiment came from Sao Carlos-SP landfill. The used soil has been characterized as its mineralogical\'s and physical chemical-biological\'s composition, looking for the percolated\'s transportation inside the columns, and for the interaction soil-contaminant. The landfill\'s area has been several times drilled, tested as it\'s hydraulic conductivity and assessment of local geology, in order to know the physical, chemical, biological, mineralogical and geological in situ soil\'s characteristics. This, has been classified as sandy, and, by presenting chemical characteristics that does not reach the adequated value for utilization on solid urban wastes, due to the values of CTC, SE, pH, and the textural sandy class, what shows a deficient buffering capacity in retaining and immobilisating contaminants. By observation in situ, has been found that Sao Carlos\'s solids disposal waste is located over rocks from the Botucatu formation, and the mineralogy of it is composed of quartz, caulinith, goethith, hematith, gibsith an ilith. The hydraulic conductivity test has indicated that the soil in the base of the sanitary landfill does not reaches the permeability values required by the standards, what may allow rain water\'s infiltration, and raises the amount of leachate and it\'s movement onto the ground, and even the leachete to reach the underground waters. So, has been drawn the characteristics curves of the contaminant\'s transportation in the effluents samples found during the percolation process, collected by every 0,25 VP until it reaches 10,0 VP percolated. The characteristical curves of the contaminant\'s transportation drawn showed low concentrations in the effluent samples of Lead, Cadmium, Iron, Zinc, Manganese, Calcium, Magnesium, Cooper, Chromium. Also, Sodium, Potassium, Chlorine, Nickel and Aluminium had been preferencially percolated within the leachate, what evidentiates the variation in the range of concentrations of every percolated element. The concentration profiles from heavy metal\'s had shown that there is a front of contamination. The retention curves from the soil\'s retaining metal showed that the preferency for the sorption was: Cooper > Cadmium > Calcium > Zinc > Magnesium > Potassium > Manganese > Phosphorus > Iron > Nickel > Aluminium, whose values may point the soil\'s ability in retaining contaminants. The studied soil has presented low potential in retain contaminants from the leachete, and is characterized as sandy, and it\'s chemical features shall not be framed according the standards parameters to be utilized in solid urban waste\'s disposal.

Heavy metals are highly persistent in water and have a particular significance in ecotoxicology. Heavy metals loading from the Pearl River are likely to cause significant impacts on the environment in the South China Sea and the West Pacific. In this study, using monthly monitoring data from a water quality monitoring campaign during 2006–2012, the temporal variation and spatial transfer of six heavy metals (lead (Pb), copper (Cu), cadmium (Cd), zinc (Zn), arsenic (As), and mercury (Hg)) in the Pearl River were analyzed, and the heavy metal fluxes into the sea were calculated. During this period, the annual heavy metal loads discharged from the Pearl River into the South China Sea were 5.8 (Hg), 471.7 (Pb), 1524.6 (Cu), 3819.6 (Zn), 43.9 (Cd), and 621.9 (As) tons, respectively. The metal fluxes showed a seasonal variation with the maximum fluxes occurring from June to July. There is a close association between metal fluxes and runoff. The analysis of the heavy metal transfer from the upstream to the downstream revealed that the transfer from the upstream accounted for a major portion of the heavy metals in the Pearl River Delta. Therefore, earlier industry relocation efforts in the Pearl River watershed may have limited effect on the water quality improvement in surrounding areas. It is suggested that watershed-based pollution control measures focusing on wastewater discharge in both upstream and downstream areas should be developed and implemented in the future.

Thesis (M.Sc. (Biochemistry)) --University of Limpopo, 2005 / Refer to document

A range of chemical pollutants now contaminate drinking water sources and present a public health concern, including organic compounds, such as pharmaceuticals and pesticides, and both metalloids and heavy metals, such as arsenic and lead. Metalloids and heavy metals have been detected in private drinking water wells, which do not fall under federal drinking water regulations, as well as in urban tap water, due to the introduction of contamination to the drinking water distribution system. Further, many so-called “emerging organic contaminants,” which are present in drinking water sources at detectable levels but have unknown long-term health implications, do not fall under federal drinking water regulations. To protect the health of consumers, drinking water treatment at the point-of-use (POU) (i.e., the tap) is essential. Next-generation POU treatment technologies must require minimal energy inputs, be simple enough to permit broad application among different users, and be easily adaptable for removal of a wide range of pollutants. Nanomaterials, such as carbon nanotubes and iron oxide nanoparticles, are ideal candidates for next-generation drinking water treatment, as they exhibit unique, high reactivity and necessitate small treatment units. However, concerns regarding water pressure requirements and nanomaterial release into the treated supply limit their application in traditional reactor designs. To bridge the gap between potential and practical application of nanomaterials, this study utilizes electrospinning to fabricate composite nanofiber filters that effectively deploy nanomaterials in drinking water treatment. In electrospinning, a high voltage draws a polymer precursor solution (which can contain nanomaterial additives, in the case of nanocomposites) from a needle to deposit a non-woven nanofiber filter on a collector surface. Using electrospinning, we develop an optimized, macroporous carbon nanotube-carbon nanofiber composite that utilizes the sorption capacity of embedded carbon nanotubes, and achieves a key balance between material strength and reactivity towards organic pollutants. Additionally, via single-pot syntheses, we develop two optimized polymer-iron oxide composites for removal of heavy metal contamination by inclusion of iron oxide nanoparticles and either cationic or anionic surfactants in the electrospinning precursor solution. In hybrid materials that contain a well-retained quaternary ammonium surfactant (tetrabutylammonium bromide) and iron oxide nanoparticles, ion exchange sites and iron oxide sites are selective for chromate and arsenate removal, respectively. We demonstrated that a sulfonate surfactant, sodium dodecyl sulfate, acted as a removable porogen and an agent for surface segregation of iron oxide nanoparticles, thus enhancing composite performance for removal of lead, copper, and cadmium. Notably, nanoparticles embedded in composites exhibited comparable activity to freely dispersed nanoparticles. Collectively, the composites developed in this work represent a substantial advance towards the overlap of effective nanomaterial immobilization and utilization of nanomaterial reactivity. Outcomes of this work advance current knowledge of nanocomposite fabrication, and contribute to the responsible and effective deployment of nanomaterials in POU drinking water treatment.

Polluted stormwater, if not treated, can compromise water quality throughout our hydrologic cycle, adversely affecting aquatic ecosystems. Common stormwater pollutants, copper and zinc, have been identified as primary toxicants in multiple freshwater and marine environments. For small-scale generators, stormwater management can be cumbersome and implementation of common BMPs impractical thus catch basins are popular though not the most environmentally conscious and sustainable option. This study aims to characterize the potential of a mobile media filter operation for the treatment and on-site recycling of catch basin stormwater. The removal capacities of various commercially available filter media (e.g. a common perlite; Earthlite™, a medium largely composed of biochars; and Filter33™, a proprietary porous medium) were measured using binary injection solutions modeled after local catch basin stormwater characteristics. The results of filtration experiments, rapid small-scale column tests (RSSCTs), indicate that the transport of metals in Perlite is primarily impacted by nonspecific sorption whereas in Earthlite™ and Filter33™ both nonspecific and specific sorption are present. For all media and experimentation, there was a consistent preferential uptake of copper such that copper displayed delayed arrival and/or greater removal than zinc. Moreover, the observed snow plow effects and concentration plateaus in Earthlite™ and Filter33™ RSSCTs suggest rate limited ion exchange and specific sorption in addition to ion competition. Earthlite™ exhibited an approach velocity dependent removal efficiency in the RSSCTs and pseudo second order uptake behavior for zinc in kinetic batch experiments. At the lab scale equivalent of the proposed field scale flow rate, Filter33™ displayed the greatest average zinc removal of 8.6 mg/g. In all, this research indicates that test parameters (i.e. pH, competitive ions solutions, empty bed contact time, flow rate) based on the natural environment and field scale operation can greatly impact removal efficiency in filter media.

Les Kazakhs sont des consommateurs traditionnels de lait d'espèces non-conventionnelles comme la chamelle. Pour autant, les régions d'élevage camelin dans ce pays, bien que basées sur un mode extensif et un accès à des ressources naturelles, n'en sont pas moins fragilisées par les risques de pollution, l'environnement du pays étant affectées par la présence de métaux lourds, pesticides et radionucléides. L'objectif de la thèse a été (a) d'évaluer l'impact de cette pollution sur la qualité du lait de chamelle et du shubat (lait fermenté), et (b) d'évaluer les capacités de détoxification des produits laitiers.Pour aborder la question de l'impact de la pollution, plusieurs niveaux d'analyses ont été mis en œuvre:(i) A l'échelle régionale, des cartes d'indice de pollution ont été établies autour de 13 fermes de zones polluées (Almaty, Sud Kazakhstan, Atyraou et Kyzylorda) afin de comparer le niveau de pollution des différentes matrices (sol, eau, plante) selon la distance aux sources de pollution.(ii) A l'échelle des matrices environnementales (sol, plante, eau), deux métaux lourds majeurs (Pb et Cd) ont été déterminés dans les échantillons de sols (7,76-131,08 ppm et 0,08-0,39 ppm, respectivement), l'eau (Pb entre 5,9-13,6 ppm et Cd 0,05-0,25 ppm), les plantes (0,50-2,30 ppm et >0,05-0,56 ppm, respectivement). Un lien entre indice de pollution et métaux dans les sols a été observé, montrant l'impact de la proximité et de la nature des sources de polluants sur la contamination des sols. On observe également une corrélation étroite entre teneur en Pb et Cd au sein des différentes matrices. Cependant, les teneurs dans le sol sont indépendantes des teneurs dans l'eau ou les plantes. Les teneurs en pesticides dans l'eau sont inférieures à celles des normes internationales. Dans les fourrages, le DDT et ses dérivés ont été plus élevés que dans le sol. Cela signifie que les résidus de pesticides peuvent être également d'origine atmosphérique et donc inhalés par les animaux(iii) Dans le lait et le shubat, la concentration en métaux lourds dans cinq régions (Almaty, Atyraou, Kyzylorda, Taraz et Sud Kazakhstan) a été en moyenne faible en Cu (< 0,05 ppm), normale en Zn (près de 5 ppm) et Cd, mais un peu élevée pour Pb. Nos résultats ont été relativement élevés pour le DDT total dans le lait de toutes les régions sauf Kyzylorda et supérieurs pour le HCH total dans le lait des régions d'Almaty et d'Atyraou.(iv) Les relations entre environnement et lait ont été testées montrant l'absence de lien entre contamination de l'environnement en métaux lourds et celle du lait et shubat. Aucune relation non plus n'a été observée pour les pesticides, à l'exception du lindane et 4,4-DDD.Pour tester l'effet détoxifiant, il a été procédé en deux étapes. D'abord l'isolement et l'identification des souches de bactéries lactiques (BAL) du shubat afin de tester leur capacité à fixer Pb et Cd. Au total, 138 souches ont été isolées à partir de 25 échantillons laitiers. Une étude qualitative pour détecter la capacité des BAL à fixer les métaux lourds a été réalisée. Parmi 118 souches testées, seules 5,1% d'entre elles n'ont poussé ni sur Pb ni sur Cd, 36 % ayant eu la capacité de fixer Pb ou Cd, et 9% les deux. Les 52 souches montrant les meilleurs résultats ont été retenues pour identification par des méthodes moléculaires (rRNA16S). Selon les résultats de séquençage, la plupart de souches étaient de genre Enterococcus et Lactobacillus, secondairement Lactococcus et Leuconostoc.Dans un second temps, un test physiologique (in vivo) a été réalisé sur 80 cobayes divisés en 8 groupes traités par le Pb et des souches de BAL. La quantité de Pb dans les fèces des groupes traités par le lait fermenté ayant contenu ou pas du Pb était relativement élevé par rapport aux groupes témoin et celui recevant de l'eau enrichie de Pb (groupe EauPb). La distribution du Pb dans les organismes de cobayes du groupe EauPb s'est révélée dans l'ordre croissant: rate / The Kazakh people are traditional consumers of milk from non-conventional species like camel. However, the camel-rearing areas in this country, although based on an extensive mode and an access to natural resources, are affected by the risks of pollution, the environment of the country being affected by the presence of heavy metals, pesticides and radionuclides. The objective of the thesis was (a) to evaluate the impact of this pollution on the quality of the camel milk and shubat (fermented milk), and (b) to evaluate the abilitiy of detoxification by the dairy products. To answer to the question of the impact of pollution, several levels of analyses were implemented:(i) At the regional level, maps of pollution index were established around 13 farms from polluted zones (Almaty, Southern Kazakhstan, Atyraou and Kyzylorda) in order to compare the level of pollution of the various matrices (soil, water, plant) according to the distance to the polluting sources.(ii) On environmental matrix level (soil, plant, water), two major heavy metals (Pb and Cd) were determined in the soil (7,76-131,08 ppm and 0,08-0,39 ppm, respectively), water (Pb 5,9-13,6 ppm and Cd 0,05-0,25 ppm), the plants (0,50-2,30 ppm and >0,05-0,56 ppm, respectively) samples. A correlation between pollution index and metals in soils was observed, showing the impact of the proximity and the nature of the polluting sources on the contamination of the soils. A close correlation between Pb and Cd content within the various matrices was also observed. However, the contents in the soil were independent of the contents in water or plants. The contents of pesticides in water were lower than those of the international standards. In fodder, the DDT and its derivatives were higher than in the soil. That means that the pesticides residues can be also of atmospheric origin and thus inhaled by the animals(iii) In milk and shubat, the heavy metal concentration in five areas (Almaty, Atyraou, Kyzylorda, Taraz and Sud Kazakhstan) was on average low in Cu (< 0,05 ppm), normal for Zn (nearly 5 ppm) and Cd, but a little high for Pb. Our results were relatively high for the total DDT in the milk of all the areas except Kyzylorda and superiors for the total HCH in the milk of Almaty and Atyraou areas.(iv) The relations between environment and milk were tested showing the absence of link between environmental contamination of the heavy metals and that of milk and shubat. No relation either was observed for the pesticides, except for lindane and 4,4-DDD.To test the detoxification effect, it was proceeded in two stages: initially the isolation and identification of the strains of lactic bacteria (LAB) of the shubat in order to test their capacity to fix Pb and Cd. On the whole, 138 strains were isolated starting from 25 dairy samples. A qualitative study to detect the capacity of the LAB to fix heavy metals was carried out. Among 118 tested strains, only 5.1% of them pushed neither on Pb nor on Cd, 36% having had the capacity to fix Pb or Cd, and 9% both. The 52 strains showing the best results were retained for identification by molecular methods (rRNA16S). According to results' of sequencing, the majority of strains were of genus Enterococcus and Lactobacillus, secondarily Lactococcus and Leuconostoc. In the second time, a physiological test (in vivo) was carried out on 80 guinea-pigs divided into 8 groups treated by strains of LAB containing or not some Pb. The quantity of Pb in feces of the groups treated by fermented milk having contained or not Pb was relatively high compared to the reference groups and that receiving from the water enriched by Pb (WaterPb group). The distribution of Pb in the organes of guinea-pigs of the WaterPb group appeared in the ascending order: spleen> blood> heart> lungs> liver> kidneys. There was no significant correlation between organs.The results obtained on the identification of the isolated strains, gave the possibilities of studying

Small amounts of chromium (VI) are carcinogenic in mammals. Concentrations of Cr in marine algae and seagrasses range from 0.06-7.17 /g DW and 0.1-30.6 g/g DW respectively. To test for an effect of these concentrations, production (change in organic material), righting response, feeding rates, absorption efficiency and fecal production were measured in Lytechinus variegatus from Sarasota fed prepared diets containing 0, 4.1, and 32g Cr/ g DW and individuals from Ft. DeSoto fed diets containing 0, 41 and 82g Cr/ g DW. The urchins were fed for 4-5 weeks, with weekly measurements of their feeding rates, absorption efficiency and fecal production. At the end of the experiment the urchins were righted to note any changes in behavior. Their gonads, gut, lantern and test with spines were weighed and ashed to calculate gonadal and gut indices and inorganic and organic percentage and content. After five weeks individuals in all treatments from experiment one showed no significant results. Urchins in all treatments from experiment two showed a significant decrease Individuals in all treatments had a significant increase in wet (P<0.001) and dry (P=0.005) weights as well as total organic material (P<0.001) in the gut of the urchins recieveing 82µg Cr/ g DW. There was significant decrease in the feeding rate (P<0.001) and absorption efficiency (P<0.001), countered by a significant increase in fecal production. The righting times were significantly different between the 0µg Cr/ g dry weight, 82µg Cr/ g DW and initial (P=0.031), but not the 41µg Cr/ g DW. Chromium in the feed at the concentrations used in this experiment does not affect the production or absorption efficiency of Lytechinus variegatus, but it does affect feeding rates, fecal production and righting response.

No description available.

No description available.