Plots of field corn established in Michigan and Arizona were fertilized with two industrial wastes of nitric acid as nitrogen fertilizers. Major contaminants before processing (greater than 1000 mg/l) were Cu, Pb, Ti, Zn, and Zr. Of these, only Cu and Zn were present in significant quantities after neutralization with ammonium hydroxide. Application rates of 0, 67, 135, and 202 kg N/ ha were used, and compared with commercial ammonium nitrate fertilizer at 202 kg N/ ha. No significant differences were found in Pb, Zr, and Ti concentrations in corn tissue or grain due to treatments. Higher Cu and Zn levels occurred in plants from plots receiving the spent acids, but the concentrations were not significantly different from those found using commercial ammonium nitrate. No significant differences were found in corn grain Cu and Zn levels due to treatments.

No description available.

No description available.

Heavy metal contamination of mangroves is of critical concern due to its accumulative and adverse effects in aquatic ecosystems. This study was undertaken to investigate the effects of mercury (Hg ), lead (Pb ), copper (Cu ) and zinc (Zn ) on plant responses, specifically growth and productivity, in Avicennia marina (Forssk.) Vierh. A. marina plants were grown for twelve months in pots contaminated with Hg +, Pb +, Cu2+ and Zn2+ at concentrations of 0, 40, 80, 120 and 160 ppm (1 ppm = 1 (agmf1). Accumulation and distribution of the heavy metals in shoot and root tissues were determined using atomic absorption spectroscopy (Perkin-Elmer Model 303) while secretion of the heavy metals from leaves was studied using scanning electron microscopy and energy dispersive X-ray microanalysis. I hypothesized that heavy metals have deleterious effects on plant growth and that they are absorbed by roots and secreted from salt glands present on the leaves. SEM X-ray microanalyses confirmed secretion of Cu + and Zn + ions as well as salt (NaCl) from glandular structures on both the adaxial and abaxial surfaces of leaves; however Hg2+ and Pb2+ were not detected in the secretion. Ion concentrations were significantly higher in plant roots than in shoots, particularly at 160 ligml"1 for all heavy metals. In addition, toxic levels of Hg and Pb were detected in the shoot tissue; however, Cu2+ and Zn2+ were within the normal ion concentration in the shoots. Plant height, number of leaves, biomass accumulation and chlorophyll content were significantly lower at 160 ugml" than the control values for all heavy metals. Carbon dioxide exchange, transpiration and leaf conductance generally decreased with increasing metal concentration. CO2 exchange at a concentration of 160 (J-gmf1 was significantly lower than the control for all metals. CO2 exchange at 160 ugml"1 for Hg2+, Pb2+, Cu2+ and Zn were 49.6 %, 55 %, 47.6 % and 63.6 % respectively lower than the control values. Photosystem II (PS II) quantum yield, photochemical efficiency of PSII (Fv/Fm) and electron transport rate (ETR) through PS II generally decreased with increasing concentration for all heavy metals. XV This study has shown that A. marina experiences dose-dependent stress responses to Cu2+, Zn2+, Hg2+ and Pb2+ in shoot and root tissue at a concentration of 160 lagmi"1, evidenced by decreases in growth and photosynthetic performance. The results also ~)A- "7-1- 9-1- "J-\-indicate that CuZT, Znz\ HgZT and PbZT are taken up by roots and transported to shoots. In addition, only Cu and Zn are secreted via the glands while Hg and Pb accumulate within the shoots. / Thesis (M.Sc.)-University of KwaZulu-Natal, 2008.

This thesis reviews literature relating both to the treatment of metal rich wastewaters by the use of constructed wetlands and the use of slurry analytical procedures for the determination of heavy metals in environmental micro-samples. A survey of metal contaminated wetland sites showed that aquatic plants maintain low levels of metals in aerial parts despite some very elevated sediment metal concentrations and extreme acidity. A series of greenhouse trials investigated the uptake of metals into aerial sections of Typha, Phragmites and Equisetum in long term hydroponic experiments. Phragmites was shown to accumulate zinc to a higher level than Typha. The toxicity of zinc supplied in the nutrient solution at 5 mg.dm-3 over long periods was found to limit the viability of such non-sediment based systems. A reliable routine analytical procedure was developed along with a program of quality control for the study of metal uptake into aquatic plants. A micro sampling technique, eminently suited for the analysis of small plant sections was developed. This technique uses ozone to ash the plant samples at a low temperature and following suspension in a liquid medium provides a sample ready for slurry determinations by a variety of analytical instrumentation. It is proposed that this method may also be suitable for the determination of metals in individual invertebrates and other zoological micro-samples as well as potential applications in the medical field.

No description available.

Submitted in partial fulfillment of the requirements for the degree in Masters of Technology: Chemistry, ML Sultan Technikon, Durban, 2003. / The pollution of water bodies by heavy metals is a serious threat to humanity. The technique known as phytoremediation is used to clean up these polluted water bodies. The accumulation of heavy metals by aquatic plants is a safer, . cheaper and friendlier manner of cleaning the environment. The aquatic plants -studied in this project are A.sessilis, P.stratiotes, R.steudelii and T.capensis. The accumulation of heavy metals in aquatic plants growing in waste water treatment ponds was investigated. The water, sludge and plants were collected from five maturation ponds at the Northern Waste Water Treatment Works, Sea Cow Lake, Durban. The samples were analysed for Zn, Mn, Cr, Ni, Pb and Cu using ICP-MS. In general it was found that the concentrations of the targeted metals were much lower in the water (0.002 to 0.109 mg/I) compared to sediment/sludge (44 to 1543mg/kg dry wt) and plants (0.4 to 2246 mg/kg dry wt). These results show that water released into the river from the final maturation pond has metal concentrations well below the maximum limits set by international environmental control bodies. It also shows that sediments act as good sinks for metals and that plants do uptake metals to a significant extent. Of the four plants investigated it was found that }t.sessi[ir (leaves, roots and stems) and }A.sessilis (roots and stems) are relatively good collectors of Mn and Cu respectively. These findings are described in the thesis. The concentration of heavy metals in the stems, leaves and roots of the three plants were compared to ascertain if there were differences in the ability of the plant at different parts of the plant to bioaccumulate the six heavy metals studied. / M

As pollution becomes an ever-increasing threat to the global environment pressure is being placed upon industry to "clean-up" its act, both in terms of reducing the possibility of new pollution and cleaning up already contaminated areas. It was with this in mind that Amplats embarked on a phytoremediation project to decontaminate nickel-polluted soils at one of their mine sites in Rustenburg, using the nickel hyperaccumulating plant, Berkheya coddii, which is endemic to the serpentine areas near Barberton, Mpumalanga. Besides the applied aspects pertaining to the development of the phytoremediation process we were also interested in more academic aspects concerning the transport and storage of nickel within the plant tissues. In order that the progress of nickel could be followed through the plant, a radio-tracer of ⁶³nickel was placed in the soil and its movement within the plant followed by analysing the plant material, at set intervals, using a liquid scintillation counter. From these studies it was found that the nickel appeared to be transported from the roots to the leaves of the plant via the xylem. It appeared that the nickel was not confined to the leaf to which it was initially transported and so movement of nickel within the phloem also appears to occur in B. coddii. As nickel is generally toxic to most plants, hyperaccumulators contain elements that nullify the toxic effect of nickel. In the case of Berkheya coddii it is thought that the accumulated nickel is bound to malate to form a harmless nickel complex. With this in mind an assay for L-malic acid was developed in order that any effect on L-malic acid, caused by growing Berkheya coddii on soils containing various concentrations of nickel, could be determined. This method also enabled comparisons of L-malic acid concentrations to be made between hyperaccumulators and non-hyperaccumulators of various plant species. From the L-malic acid comparisons it was found that the nickel concentration within soils affected the levels of L-malic acid within B. coddii and that the levels of L-malic acid within B. coddii were greater than that of a closely related non-hyperaccumulator, suggesting that L-malic acid is indeed involved in the hyperaccumulation mechanism within B. coddii. B. coddii was chosen as the tool in nickel phytoremediation at Rustenburg Base Metal Refineries as it was found to accumulate up to 2.5% nickel in the dry biomass, it grows rapidly and has a large above-ground biomass with a well developed root system, and it is perennial and so does not need to be planted each season. Earlier work had shown that the nickel levels in the roots were comparatively low (up to 0.3% nickel in the dry material) and thus, for ease of harvesting and to ensure the continued vegetative growth of the plant on the planted sites, it was decided that the leaves and stems of the plants would be harvested at the end of each growing season. The plant was also found to accumulate low levels (0.006 - 0.3 %) of precious metals, including platinum, palladium and rhodium, within its above ground biomass, making it attractive for the remediation of certain soils that contain low levels of these metals. Before B. coddii could be introduced to the Rustenburg area a comparison of the climatic and soil conditions of Barberton, the area to which B. coddii is endemic, and Rustenburg needed to be made to ensure that the plant would be able to survive the new conditions. These comparisons showed that Rustenburg receives on average, 484 mm less rain per year than Barberton, indicating that irrigation was required when the Rustenburg sites were planted out with B. coddii, in order to reduce water stress. Rustenburg was also found to be, on average, 4.6°C warmer than Barberton, but as B. coddii growth responds to wet/dry seasons, as opposed to hot/cold seasons, it was not felt that this temperature difference would have a negative effect on the growth of the plants. The soil comparisons showed the contaminated Rustenburg sites to be serpentine-like in nature, with respect to Barberton, again giving confidence that the plant would adapt to the conditions occurring at the contaminated sites. However, to ensure optimal growth, nutrient experiments were also performed on B. coddii to ascertain the ideal macronutrient concentrations required, without inhibiting nickel uptake. These trials indicated that the individual addition of 250 mg/l ammonium nitrate, 600 mg/l calcium phosphate, 2 000 mg/l calcium chloride, 600 mg/l potassium chloride and 250 mg/l magnesium sulphate enhanced plant growth and nickel uptake, suggesting that, for phytoremediation purposes, these nutrients should be added to the medium in which the plants are growing. The growth-cycle of naturally occurring B. coddii plants in Barberton was also studied in order that seedlings could be germinated, in greenhouses, at the correct time of year so that the plants could be sown as the naturally occurring plants were germinating. From this information the seeds of the plants could be collected at the correct time of year and the above ground biomass harvested when the nickel concentrations were at their highest. It was found that the plants began to germinate as the first rains fell, which was generally at the beginning of September, and plant maturity was reached at about five months, after which flowers were produced. Seeds were produced from the flowers and these matured and were wind-dispersed one month to six weeks after full bloom, usually during February. The plants then started to die back and dry out and dormancy was reached about nine months after germination, generally in about mid- to late- May. It was found that the nickel concentration was at its highest about one month after the plants had begun to dry out and thus it was decided that the above ground biomass would usually be harvested at the end of April each season, in order to achieve maximum nickel recovery. Finally, in order that the plant's potential for use in phytoremediation could be fully assessed, field trials at the contaminated sites in Rustenburg were performed. Germination procedures were developed for the mass production of B. coddii and it was found that, although fully formed plants could be propagated in tissue culture, it was cheaper and faster to germinate the seeds in speedling trays, containing a zeolite germination mix, in greenhouses. It was also found that the seeds had a low germination rate, due to dehydration of the embryos and thus, in order to obtain the number of plants required, four to five times the amount of seeds needed to be sown. The two-month-old seedlings were transferred to potting bags, containing a mixture of potting soil and RBMR soil, and grown up in the greenhouse for a further three months. This growth period allowed B. coddii to adapt to the RBMR soil and also ensured that the plants were relatively healthy when transplanted into three prepared sites at RBMR. The plants were allowed to grow for the entire season after which the above ground biomass, comprising the leaves and stems, was harvested, dried and then ashed in an ashing vessel designed by the author, with the help of Mr K Ehlers. The ashed material was acid-leached with aqua regia in order that the base metals (mainly nickel) and precious metals could be removed from the silicates and carbonised material. The acid solution was then neutralised, causing the base metals (mainly nickel) and precious metals to be precipitated. This precipitate was then smelted with a flux in order that nickel buttons could be formed. Thus, from all the phytoremediation trials it was found that this process is highly successful in employing B. coddii for the clean-up of nickel-contaminated sites. This constitutes the first time that such a complete phytoremediation process has ever been successfully developed with B. coddii as the phytoremediation tool. It also appears to be the first time that phytoremediation has been performed "commercially" to produce a saleable metal product. The success of this project has stimulated Amplats to continue with, and expand it, to include more studies on phytoremediation as well as in the biomining of certain areas containing very low levels of precious metals which, with conventional techniques, were previously not worth mining. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1998.

In this thesis, the uptake kinetics of Cd by the liverwort D. hirsuta and the moss A. androgynum were investigated. In preliminary experiments, the toxicity of Cd to the bryophytes was investigated by characterising the effects of Cd on photosynthesis and K loss. Experiments were carried out to explain the existence of variation between different collections observed in uptake kinetics in the liverwort D. hirsuta. Photosynthesis in D. hirsuta was more sensitive to Cd than photosynthesis in A. androgynum. The sensitivity was directly related to intracellular Cd concentrations. D. hirsuta accumulated considerably higher concentration of intracellular Cd than A. androgynum. Cd caused intracellular K loss in D. hirsuta but not in A. androgynum. Extracellular Cd uptake was rapid and independent of metabolism. Intracellular Cd uptake as a function of Cd concentrations followed Michael is-Menten kinetics. Intracellular Cd uptake in D. hirsuta was affected by age of the plant, K pretreatment and the site where plants were collected. The moss A. androgynum displayed Cd uptake acclimation when uptake was measured at low temperatures. The results indicated that uptake kinetics could be affected by seasonal variation. Tolerance of Cd in the moss A. androgynum could be induced by pretreating the plants with low concentrations. The moss possibly excludes Cd from the cytoplasm and thus reduces the concentration of Cd in the cytoplasm to below toxic level. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 1997.

Thesis (M. Phil.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 359-374).