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Biotic indices have been used to assess water quality since the early twentieth century and thus pre-date the first water quality index based on physico-chemical characteristics by about 85 years. The early biotic indices were determined by the presence or absence of specific indicator species from a number of different groups and trophic levels (mainly bacteria, algae, protozoans and rotifers, but including some benthic invertebrates and fish) for which the tolerances to organic pollution were known. Selected components of the total aquatic community were thus, used as an indicator of the degree of organic pollution. Most modern biotic indices, on the other hand, are based on the presence and pollution tolerances of the community of organisms sampled from a particular group, such as benthic macroinvertebrates.

This chapter introduces the theme of the Part 2 of the book: Water quality indices based on bioassesment. It explains how bioassessment can give an ‘integrated’ picture of water quality in a manner not possible to obtain by indices based predominantly on physico-chemical characteristics of the water as described in Part 1 . It is also brought out that, notwithstanding certain special diagnostic attributes of bioassessment, it can't by itself be adequate for water quality assessment and ought to be used in conjunction with the indices based on physico-chemical parameters.

As the name suggests this chapter is specific to indices which have been developed to represent ground water quality. As all water quality indices (WQIs) are either developed with reference to standards, or are meant to assist in the setting of standards, the approaches to developing indices of ground water quality are very similar to the ones used for surface water quality. The difference lies mainly in parameter selection. Whereas parameters like coliforms and BOD feature in most of the surface WQIs they are rarely covered in ground WQIs. On the other had most ground WQIs incorporate minerals like boron and arsenic which are rarely included in surface WQIs.

This chapter highlights the uncertainties faced in achieving representativeness in water-quality sampling and attaining the desired levels of accuracy and precision in the subsequent analysis. As conventional indices are based on ‘crisp’ and ‘deterministic’ approaches, uncertainties in sampling and analysis can bring in substantial inaccuracies and imprecision in the index scores. The chapter serves as a preamble to the subsequent chapters in the book which describe approaches that have been attempted at combating the uncertainties mentioned above.

This chapter covers the state-of-the-art of water quality indices developed on the basis of the probability theory. It begins with a recapitulation of the seminal work of Landwher (1979) which had brought home the realization that the water quality constituents upon which all indices depend are essentially random variables. Hence, regardless of their construct, there is stochasticity associated with WQI. The chapter then describes all the probabilistic WQIs developed so far.

Even as biotic indices, described in Chapter 13 , are able to provide a better assessment of the overall status of the water quality in conjunction with ‘physico-chemical’ water quality indices than the latter can achieve in isolation, the former aren’t always adequately representative. The reason is that biotic indices are based on the sensitivity to stress of only a few indicator species or ecological group of species. In contrast, indices of biological integrity (IBIs) use a combination of univariate and biotic indices in an endeavor to capture with greater sensitivity the impacts of anthropogenic disturbances on aquatic ecosystems. Due to the use of multiple sub-indices, IBIs are also commonly referred as multimetric indices .

This chapter is devoted to ‘conventional’ water-quality indices. The distinguishing feature of the indices described in this chapter is that they are a) based on parameter selection, assignment of weightage, and aggregation by methods other than advanced statistical techniques, artificial intelligence or probability theory and b) deal predominantly with physico-chemical characteristics of water. Beginning with a reference to Horton's index, which was the first-ever modern WQI (introduced in 1985), the chapter introduces the WQI of the United State's National Sanitation Foundation (NSF-WQI) which is still used in several countries and has inspired several other WQIs. The chapter then presents the various ‘conventional’ WQIs developed and used in different countries through the years.

The impact of the application of compost/vermicompost obtained from water hyacinth (Eichhornia crassipes, Mart. Solms) on plants was assessed in terms of growth and flowering of the angiosperm crossandra (Crossandra undulaefolia). Overall nine morphological, size, and yield attributes were studied in crossandra saplings raised on water hyacinth compost or vermicompost as compared to the untreated saplings. Application of vermicompost led to statistically significant improvement in the growth and flowering of crossandra compared to the untreated plants. The impact of compost was also beneficial but a little less distinct than the positive impact of vermicompost. Qualitative studies were simultaneously conducted in five kitchen gardens owned by farmers near Pondicherry. In three of these locations water hyacinth vermicompost was applied-and no other fertilizer-for months to different species of vegetables. Water hyacinth compost was similarly applied in another two locations. In all the locations no adverse effect on any of the plant species was observed. We believe these studies would help in dispelling the apprehension of farmers that compost/vermicompost obtained form a pernicious weed like water hyacinth may have deleterious effect on other plants.

The epigeic earthworm species Eudrilus ugeniae, Eisenia fetida, Perionyx excavatus, and an anecic arthworm species Lampito mauritii were explored separately for the vermicomposting of Ipomoea leaves in reactors that were operated for four months. The earthworm species which consistently produced more vermicast was E.eugeniae followed by E.fetida, P.excavatus, with L.mauritii being the least producer. Seen from the standpoint of average of vermicast production per gram of earthworm body weight, E. eugeniae scored over E.fetida but the difference is very less.The average zoomass of E.fetida, E.eugeniae, and P.excavatus increased over time but decreased in L.mauritii decreased. In terms of fecundity, the performance of E.fetida (29 juveniles, 16 cocoons) was similar to that of E. eugeniae (20 juveniles, 10 cocoons) followed by P.excavatus. L.mauritii respectively. The results indicate that E.fetida and E. eugeniae are the most suitable among the four species screened for vermicomposting of Ipomoea leaves; their performance in terms of efficiency of vermicomposting, zoomass gain, and being close to each other. P. excavates is not suitable for the vermicomposting because of mortality. The anecic L. mauritii came out a poor fourth and is clearly unsuitable for the vermicomposting of Ipomoea carnea leaves as it didn't gain weight on feeding upon Ipomoea carnea. Due to this fact, and the animal's poor fecundity in Ipomoea-based vermireactors, this species will not be able to provide sustainable vermicast output.

We report, for the first time, shape-tuned and sizetuned synthesis of silver nanoparticles using extracts of the weed lantana (Lantana camara). The purity, crystal structure and possible biomolecules responsible for the nanoparticle formation were explored with SEM, Hr-SEM, TEM, EDAX, XRD, zetasizer and FTIR techniques. The distinguishing feature of the present study is that it enables the fabrication of silver nanoparticles with a non-hazardous, energy-saving, and cost effective method. Simultaneously the study enables gainful utilization of an obnoxious invasive weed, which is otherwise not only worthless but also seriously harmful to the environment.

Green nanoparticle synthesis has been achieved using the extracts of leaves/stem/roots of mimosa (Mimosapudica) as the reducing and capping agent. The study utilizes the highly pernicious and otherwise worthless terrestrial weed mimosa. Nanoparticles were rapidly synthesized at ambient temperature and shape/size control was made possible by controlling the extract: metal proportions. The results of UV-visible spectrophotometric, Fourier transform infrared, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy support the biosynthesis and characterization of the nanoparticles. One of the distinguishing features of the study is that it employs the whole plant unlike most previous studies which are confined to the use of leaves.

The virtues of biogas as a clean fuel have been known since the late nineteenth century but the great resurgence of interest in biogas capture – hence methane capture – is due to the rapidly growing spectre of global warming (GW). Anthropogenic causes, which directly or indirectly release methane into the atmosphere, are responsible for as much as a third of the overall additional GW that is occurring at present. Hence the dual advantage of methane capture – generating energy while controlling GW – have come to the fore.

The aim of this chapter is to explain the difference between the so-called “biogas digesters” popular in the developing countries and the broader terms of “anaerobic digesters/reactors/fermenters.” The chapter also deals with the difference between “low-rate” and “high-rate” anaerobic systems, and describes the techniques with which the former can be converted to the latter.

Prior to the 1970s, the principle use of anaerobic digestion across the world was in manure management. Whereas developing countries – principally India and China – used “biogas technology” to extract fuel from manure, developed countries used anaerobic digestion mainly to stabilize the manure, with little concern for the methane that was generated in the bargain.

Sanitary landfills begin releasing biogas within a few weeks of being laid out and continue to do so for several decades. It has been estimated that as much as 12% of the total global methane emission is contributed by sanitary landfills. Till recently sanitary landfills were predominantly located in developed countries but as developing countries also begin taking resort to sanitary landfills, the landfill-based methane emissions are expected to rise.

Starting with the introduction of anaerobic filter in 1967, a string of breakthroughs in anaerobic reactor design occurred during the late 1960s and early 1970s. These breakthroughs made it possible to extend the reach of anaerobic digestion from highly concentrated (in volatile organics content) manure slurry or sewage-sludge to much less concentrated industrial wastewaters. Later the reach was further extended to dilute wastewaters like domestic sewage and wash-waters.

“Biogas” is the name popularly used to denote the flammable mixture of gases that are generated when organic material undergoes anaerobic decomposition. The mixture contains 40–70% (usually 55–65%) methane, carbon dioxide, and traces of other gases. “Biogas” has good calorific value and can be directly used as fuel or indirectly used to generate electricity.

Among the most vexing of environmental problem being faced by the world is that of solid waste, of which a major component is biodegradable solid waste (BSW). When left to rot in the open, or when disposed in sanitary landfills, BSW undergoes anaerobic digestion leading to generation of methane. It translates to lost energy but also to global warming. This realization, and the failure of other methods, such as incineration and composting, to handle BSW without generating newer problems of pollution, has focused global attention towards the use of anaerobic digestion to treat BSW with concomitant generation of energy in the form of biogas.But whereas a number of processes have been developed, principally in Europe, to treat large quantities of BSW, and increasingly larger quantities of BSW are being treated by anaerobic digestion all over the world, a number of technological problems still remain to be solved before the processes can become profitable. The present chapter discusses all these aspects and issues alongside presenting latest information on the penetration of anaerobic digestion-based processes in BSW treatment.

This chapter briefly traces the history of anaerobic digestion from the time the existence of this phenomenon was first recorded four centuries ago to its rapidly increasing popularity at present. The extent of adaptation of biogas technology across the world is also briefly reviewed. Whereas China and India lead the initiative from among developing countries, the thrust of the developed world is mainly coming from Western Europe.

The Oussudu watershed is situated at 11°57' North and 77°45 ' East on either side of the border separating the Union Territory of Puducherry and the Indian state of Tamil Nadu (Figure 1). Apart from playing a crucial role in recharging the ground water aquifers, the Oussudu watershed also harbors rich flora and fauna (Chari and Abbasi, 2000; 2002; 2005). This watershed supports Puducherry's largest inland lake Oussudu which is also called Ousteri (a Tamil language hybrid of Oussudu and eri, meaning Oussudu lake) with a surface area of 8.026 Km2 and shore line length of 14.71 Km2. Oussudu lake is such an important wintering ground for migratory birds that it has been identified as one of the heritage sites by IUCN (Interactional Union for Conservation of Nature) and has been ranked among the most important wetlands of Asia (Scott 1989). In the recent past, Oussudu lake and its watershed have been subject to enormous pressures due to the increasing population, industrialization and urbanization. The resultant inputs of pollutants – rich in nitrogen and phosphorous – has provided aquatic weeds an opportunity to grow uncontrollably in the lake to the exclusion of other flora. This has led to a defacing of the lake by large patches of ipomoea (Ipomoea carnia) and other weeds.

Whereas a myriad of possible factors have been reported which effect the formation of granules in a upflow anaerobic sludge blanket (UASB) reactor and influence their properties, there is no study on the effect of vitamins on the granulation of UASB reactor sludge. The present study was undertaken to bridge this gap. It was seen that vitamins helped in better granule formation—as reflected by favorable size distribution, sludge volume index, and settling velocity—compared to controls. The vitamin-spiked reactors also achieved >85 % COD removal efficiency in half the number of days the unspiked reactors took. The vitamin supplements were effective at concentrations ≤ 1 mg/l. Hence, their use in expediting granule formation as also in developing better-quality granules appears economically viable.

Pistia stratiotes , an aquatic weed, was investigated as a substrate for biogas production in batch digestion. An inoculum was necessary to obtain biogas production from the weed. With Pistia only, production of carbon dioxide alone was high during the first five days of digestion but began to level off thereafter. With inoculated Pistia , a high rate of biogas production was sustained for nearly 10 days and the average methane content was 58–68%. The digesters charged with Pistia alone had significant concentrations of propionic, butyric, isobutyric, valeric, and isovaleric acids. These acids were not present in detectable concentrations, in the digesters running with inoculated Pistia , except during the first 4 days of the digestion when propionic acid was formed. When an inoculum was added to a ‘soured’ digester the performance of the latter improved dramatically.

Eight common aquatic weeds Salvinia molesta, Hydrilla verticillata, Nymphaea stellata, Azolla pinnata, Ceratopteris sp. Scirpus sp. Cyperus sp. and Utricularia reticulata were digested anaerobically to produce methane. The carbon to nitrogen (C/N) ratio, carbon to phosphorus (C/P) ratio, and the volatile solids (VS) content of the weeds varied widely. No trend between these factors and the methane yield was discernable; the possible reasons are discussed. The energy potential of the weeds per unit area of the weed crop was worked out. Natural stands of salvinia, such as the one employed in the present investigation, would yield energy (methane) of the order of 108 Kcal ha−1 year−1.

A chip for high speed two bit error correction in the received signal has been designed and implemented on a Xilinx FPGA using VHDL. The design is based on a modified step-by-step decoding algorithm which does not require the calculation of the error location polynomial. The use of complex computation intensive inverse operations is also avoided. Efforts have been made for reducing the complexity of the decoder. A modified circuit has been used for multiplication of field elements within the Galois field. For squaring the field elements within the Galois field, a modified square circuit with much less complexity has been successfully designed. The average operation cycle for decoding each received word is just equal to the block length of the coded word.

The feasibility of using upflow anaerobic sludge blanket (UASB) reactors for the treatment of dairy wastewaters was explored. Two types of UASBs were used––one operating on anaerobic sludge granules developed by us from digested cowdung slurry (DCDS) and the other on the granules obtained from the reactors of M/s EID Parry treating sugar industry wastewaters. The reactors were operated at HRT of 3 and 12 h and on COD loading rates ranging from 2.4 kg per m 3 of digester volume, per day to 13.5 kg m −3 d −1 . At the 3 h HRT, the maximum COD reduction in the DCDS-seeded and the industrial sludge-seeded reactors was 95.6% and 96.3%, respectively, better than at 12 h HRT (90% and 92%, respectively). In both the reactors, the maximum, the second best, and the third best COD reduction occurred at the loading rates of 10.8, 8.6 and 7.2 kg m 3 d −1 , respectively. At loading rates higher than 10.8 kg, the reactor performance dropped precipitously. Whereas in the first few months the reactors operating on sludge from EID Parry achieved better biodegradation of the waste, compared to the reactors operated on DCDS, the performance of the latter gradually improved and matched with the performance of the former.

Vermicomposting of neem (Azadirachta indica A. Juss) was accomplished in "high-rate" reactors operated at the earthworm (Eudrilus eugeniae) densities of 62.5 and 75 animals per litre of reactor volume. Contrary to the fears that neem--a powerful nematicide--might not be palatable to the annelids, the earthworms fed voraciously on the neem compost, converting upto 7% of the feed into vermicompost per day. Indeed the worms grew faster and reproduced more rapidly in the neem-fed vermireactors than in the reactors fed with mango leaf litter earlier studied by the authors (Gajalakshmi et al., 2003). Another set of experiments on the growth, flowering, and fruition of brinjal (Solanum melongena) plants with and without fertilization with vermicompost, revealed that the vermicompost had a significantly beneficial impact.

In an attempt to develop a system with which the aquatic weed water hyacinth (Eichhornia crassipes, Mart. Solms) can be economically processed to generate vermicompost in large quantities, the weed was first composted by a 'high-rate' method and then subjected to vermicomposting in reactors operating at much larger densities of earthworm than recommended hitherto: 50, 62.5, 75, 87.5, 100, 112.5, 125, 137.5, and 150 adults of Eudrilus eugeniae Kinberg per litre of digester volume. The composting step was accomplished in 20 days and the composted weed was found to be vermicomposted three times as rapidly as uncomposted water hyacinth [Bioresource Technology 76 (2001) 177]. The studies substantiated the feasibility of high-rate composting-vermicomposting systems, as all reactors yielded consistent vermicast output during seven months of operation. There was no earthworm mortality during the first four months in spite of the high animal densities in the reactors. In the subsequent three months a total of 79 worms died out of 1650, representing less than 1.6% mortality per month. The results also indicated that an increase in the surface-to-volume ratio of the reactors might further improve their efficiency.

Six-month long trials were conducted on different vermireactors fed with one of the following forms of water hyacinth: (a) fresh whole plants, (b) dried whole plants, (c) chopped pieces of fresh plants, (d) 'spent' weed taken from reactors after extracting volatile fatty acids (VFAs), (e) precomposted fresh weed and (f) precomposted spent weed. The first four forms were studied with and without cowdung. The experiments revealed three clear trends (i) of the various forms of the weed assessed, the precomposted forms were the most favoured as feed by Eudrilus eugeniae, Kinberg, while the fresh whole form was the least favoured, (ii) the different forms of spent weed were favoured over the corresponding forms of fresh weed, and (iii) blending of cowdung (approximately 14% of the feed mass) with different forms of water hyacinth had a significant positive impact on vermicast output, growth in worm zoomass, and production of offspring relative to the corresponding unblended feed. In all reactors, the 'parent' earthworms steadily grew in size over the six-month span, and produced offspring. There was no mortality. The experiments thus confirm that water hyacinth can be sustainably vermicomposted in any of the forms with E. eugeniae.

As it is conventionally done, strategies for incorporating accident--prevention measures in any hazardous chemical process industry are developed on the basis of input from risk assessment. However, the two steps-- risk assessment and hazard reduction (or safety) measures--are not linked interactively in the existing methodologies. This prevents a quantitative assessment of the impacts of safety measures on risk control. We have made an attempt to develop a methodology in which risk assessment steps are interactively linked with implementation of safety measures. The resultant system tells us the extent of reduction of risk by each successive safety measure. It also tells based on sophisticated maximum credible accident analysis (MCAA) and probabilistic fault tree analysis (PFTA) whether a given unit can ever be made 'safe'. The application of the methodology has been illustrated with a case study.

Dairy wastewaters are rich in organic carbon and nutrients. When disposed without proper treatment they cause severe pollution of water and land. But if treated by anaerobic fermentation such wastewaters can yield useful clean energy in the form of methane. The systems commonly used for such fermentation throughout the world are Continuously Stirred Tank Reactors (CSTRs). We describe attempts to upgrade CSTR performance by incorporating biofilm support systems (BSSs) within the existing reactors. The focus of the work has been to find inexpensive and easy-to-install BSS which could significantly enhance the rate of waste treatment as well as quantum of energy recovery (as methane). Our experiments with various BSS options have revealed that rolls of nylon mesh (-1 mm openings), of 5 cm height and 2 cm dia, when incorporated in CSTRs at the biofilm-surface: digester-volume ratio of 0.3 cm2 cm-3, enabled the CSTRs to perform better with up to 25% improvement in methane yield. The studies, thus, reveal that simple devices of the type used by us as BSS can significantly improve the performance of CST anaerobic digesters treating dairy wastes. The enhancement is evidently due to the development of active biofilms on the BSS which not only enhance the contact of the water with micro-organisms but also reduce microbial washout. Further, such devices are inexpensive and very easy to incorporate--the gains are thus achieved with very little cost and effort. BSSs were also found by us to enhance conversion of volatile fatty acids--derived earlier by us from aquatic weed water hyacinth--into methane-rich biogas.

The potential of two epigeic species (Eudrilus eugeniae Kinberg, and Perionyx excavatus Perrier) and two anecic species (Lampito mauritii Kinberg and Drawida willsi Michaelson) of earthworms was assessed in terms of efficiency and sustainability of vermicomposting water hyacinth (Eichhornia crassipes, Mart. Solm.). In different vermireactors, each run in duplicate with one of the four species of earthworms, and 75 g of 6:1 water hyacinth: cowdung as feed, vermicasts were produced with steadily increasing output in all the reactors. E. eugeniae was by far the most efficient producer of vermicasts, followed by the other epigeic P. excavatus. The two anecics came next, with D. willsi being the least effective which could generate only about half the quantity of vermicasts achieved in a corresponding time by E. eugeniae. In all the reactors, the earthworms grew well, increasing their weights by more than 250%. The maximum net gain of weight (average 30.7 g) was by E. eugeniae, followed by P. excavatus, L. mauritii and D. willsi. This trend, which followed the efficiency of vermicast production, was also shown in terms of reproductive ability as measured by the number of offspring produced by the four species.

An analytical model for heavy gas dispersion based on the modifications in plume path theory has been developed. The model takes into account the variations in temperature, density, and specific heat during the movement of heavy gas plume. The model has been tested for three hazardous gases - chlorine, natural gas and liquefied petroleum gas. The results have been compared with the recently generated experimental data as also with the outputs of other models. A good agreement is observed qualitatively as well as quantitatively. A study has also been carried out to simulate the effect of the wind speed, density of the gas, and venting speed on dispersion. Based on the simulation study a set of empirical equations has been developed. The equations are validated by theoretical as well as experimental studies.

Litter of the mango ( Mangifera indica ) tree leaves was composted and then converted into vermicast by the action of the earthworm Eudrilus eugeniae Kinberg. After over nine months of continuous operation the vermireactors with 62.5 animals l −1 generated ∼13.6 g vermicast per litre of reactor volume (l) per day (d) whereas the reactors with 75 animals l −1 produced ∼14.9 g vermicast l −1 d −1 . This difference in performance of the reactors operating in duplicate at the two different earthworm densities was statistically significant (⩾90% confidence level) for most of the nine-month span. The animals grew well in all reactors, increasing their zoomass by ∼103% and producing ∼157 offspring. Not a single of the 1100 animals died during the first four months. In the subsequent five months a total of 122 worms died, representing a loss of ∼2% per month. We attribute this to the normal process of ageing. The ability of the earthworms to survive, grow and breed in the vermireactors fed with composted mango tree leaves, and a rising trend in vermicast output inspite of the death of a few worms after four months of reactor operation, indicate the sustainability of this type of vermireactors. The studies also indicate that even better vermireactor efficiency may be possible by modifying the reactor geometry. Studies on changes in C:N ratio during composting and vermicomposting revealed that whereas composting helped in lowering the ratio due to loss of carbon in bacterial metabolism, vermicomposting had no such effect on the ratio.

Neither R. Mashelkar's Editorial (“India's ‘science for all’ academy,” 24 February, p. [891][1]) nor the News Focus story by R. Stone (“India rising,” 24 February, p. [904][2]) touched upon the biggest shortcoming of Indian science: its inability to reward, and hence inspire, excellence

Systemic and inhaled dexamethasone treatments have been shown to improve lung mechanics in preterm infants with chronic lung disease. 253 infants were enrolled in a multicenter randomized, placebo-controlled, double-blind clinical trial of early administration of beclomethasone (40μg/kg/day, tapered over 4 weeks) or placebo given by metered dose inhaler and aerochamber® (Mongahan Medical Corp., Inc). These infants were < 33 wks GA and

Retinopathy of Prematurity (ROP), Cerebral Palsy (CP) Serum Bilirubin (SB) and Vitamin E (VE). † 925

Kernicterus in seemingly healthy but jaundiced term and near term newborns has reemerged in this decade. About 1-2% of the Well Baby (WB) population is at risk for SB 3 20mg/dl and about 5% for SB 3 17mg/dl; these groups are at risk for bilirubin induced neurologic dysfunction (BIND). We hypothesize 1) that Universal SB analyses at the time of the predischarge metabolic screen, when plotted on the SB nomogram shown below will predict the high risk groups and 2) use of the predictive SB nomogram will facilitate cost effective, individualized follow-up. Based upon a previously reported database of hour-specific SB values in 1097 WB, we developed this nomogram for the first week of life. At ≈ 24 hours age, SB 3 8mg/dl was at 95th percentile and the likelihood ratio for SB 3 17 was 19.4; whereas, for SB

A highly sensitive, selective, and rapid method for the spectrophotometric determination of trace amounts of vanadium(V) is described. Vanadium(V) is extracted from 4–8 M hydrochloric acid solutions as its violet complex with N-p-methoxyphenyl-2-furohydroxamic acid (MFHA) in chloroform. The extract shows maximum absorbance at 545 run (E = 7.3 × 103 L.mole−1 cm−1) and obeys Beer's law over the range 0–12 ppm of vanadium; Sandell's sensitivity being 0.007 μg/cm2. The method has been applied for the analysis of vanadium in pond water, rock phosphates, and steels.

A method is presented for the spectrophotometric microdetermination of cobalt (II) in fresh waters, aquatic weeds, and animal tissues employing 7-nitroso-8-hydroxyquinoline-5-sulfonic acid. the method enables direct determination of cobalt (II) in presence of a large number of anions and cations commonly associated with cobalt, and is adequate for determining the metal in the concentration range of 0.001–10 ppm, which is commonly encountered in environmental samples.

The paper describes a new hydroponic system which is easy to fabricate and is inexpensive and effective. The system is especially suitable for studying the impact of water quality and other environmental factors on the germination and growth of the angiosperms (seed bearing plants).

The status of niobium in the environment is briefly reviewed and a new method suitable for the trace analysis of the metal in ores, alloys, plant tissues, animal tissues, and natural waters is presented. The method is based on the selective extraction of niobium as its complex with N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) in organic solvents. For molecular absorption spectrophotometric analysis chloroform is used in extraction and a ternary complex is formed in the extract by adding 4-(2-pyridylazo) resorcinol (PAR). The ternary complex has an absorbance maximum at 550nm (e=3.6 × 104 1 mole−1 cm−1). Solvent extraction from the aqueous phase to lower volumes of organic phase enables up to 20-fold enrichment of niobium(V) and the method is capable of determining niobium levels down to 10−4 ppm (0.1 ppb). For the atomic absorption spectrometric determination, methyl isobutyl ketone is used as extracting solvent and a sensitivity of 0.3 ppm, which is over 3 times higher than attained so ...

A method for the detection ofμg amounts of carboxylic acids, based on the conversion of carboxylic acids to hydroxamic acids using ethylene glycol or dicyclohexylcarbodiimide and subsequent detection as reddish-violet vanadium(V) complex, is presented. The method tolerates the presence of anions and cations including SO4 2−, Br−-, PC4 3−, Mg(II), Ca(II), Na(I), Fe(II), Fe(III), Cu(II). The test for benzoic acid was independent of the presence of benzene, aniline, diethyl ether, benzenesulfonic acid and phenol. Aryl chlorides, esters, amides and anhydrides interfere with the test.

Tungsten (VI) was selectively extracted from 2–8 M HCI or 15–20 M H2SO4 media with N-p-methoxyphenyl-2-furylacrylohydroxamic acid (MFHA) in methyl isobutyl ketone (MIBK) and determined atomic absorption spectrometrically at 400.9 nm employing nitrous oxide-acetylene flame. The method was significantly more selective and sensitive than the prevailing methods for tungsten (VI) based on flame-AAS, and was successfully applied to the trace analysis of the metal in alloys, ores, plant tissues, animal tissues, and freshwaters. MFHA was chosen from amongst eleven new hydroxamic acids.

Experiments on frog tadpoles exposed to chromium (VI) revealed a marked teratogenic effect of the element. The toxicity of chromium also led to abnormal behavioral responses and death. The results of this study support our earlier findings with Annelids that the permitted levels of chromium in irrigation waters are harmful to terrestrial and aquatic organisms.

A rapid, sensitive and accurate method is presented for the atomic absorption spectrophotometric determination of manganese after extractive separation from aqueous media as its ternary complex with nicotinohydroxamic acid and trioctyl-methylammonium cation into methyl isobutyl ketone. The method permits determination of up to 0.002 ppm (2ppb) of manganese without any pretreatment and up to 0.1 ppb with pretreatment. The method was applied to the determination of manganese in natural waters and industrial effluents.

Fifteen new hydroxamic acids were explored in conjunction with trioctyimethylammonium cation for the extractive separation of manganese into MIBK from the anions and cations commonly associated with the metal in environmental samples. The most rapid extraction with the maximum selectivity and sensitivity for the atomic absorption spectrometric determination of the metal in the MIBK extract was achieved with N-p-aminophenyl-2-furylacrylohydroxamic acid. The method enabled the determination of manganese at sub-ppb levels and was applied in the analysis of coal, manganese ore, plant tissue, animal tissue and natural waters.