J. H. Kirkman

The potential of Thlaspi caerulescens for phytoremediation of contaminated soils

Uptake of Cd, Zn, Pb and Mn by the hyperaccumulator Thlaspi caerulescens was studied by pot trials in plant growth units and in populations of wild plants growing over Pb/Zn base-metal mine wastes at Les Malines in the south of France. The pot trials utilised metal-contaminated soils from Auby in the Lille area. Zinc and Cd concentrations in wild plants averaged 1.16% and 0.16% (dry weight) respectively. The unfertilised biomass of the plants was 2.6 t/ha. A single fertilised crop with the above metal content could remove 60 kg of Zn and 8.4 kg Cd per hectare. Experiments with pot-grown and wild plants showed that metal concentrations (dry weight basis) were up to 1% Zn (4% Zn in the soil) and just over 0.1% Cd (0.02% Cd in the soil). The metal content of the plants was correlated strongly with the plant-available fraction in the soils as measured by extraction with ammonium acetate and was inversely correlated with pH. Bioaccumulation coefficients (plant/soil metal concentration quotients) were in general higher for Cd than for Zn except at low metal concentrations in the soil. There was a tendency for these coefficients to increase with decreasing metal concentrations in the soil. It is proposed that phytoremediation using Thlaspi caerulescens would be entirely feasible for low levels of Cd where only a single crop would be needed to halve a Cd content of 10 μg/g in the soil. It will never be possible to remediate elevated Zn concentrations within an economic time frame (<10 yr) because of the lower bioaccumulation coefficient for this element coupled with the much higher Zn content of the soils.

The potential of the high-biomass nickel hyperaccumulator Berkheya coddii for phytoremediation and phytomining

Abstract Pot trials and tests in outside plots were carried out on the South African Ni hyperaccumulator plant Berkheya coddii in order to establish its potential for phytoremediation of contaminated soils and for phytomining of Ni. Outside trial plots showed that a dry biomass of 22 t/ha could be achieved after moderate fertilisation. Pot trials with varying soil amendments with nitrogen and phosphorus fertilisers showed enhanced uptake of Ni with increasing nitrogen addition, though there was no reaction to phosphorus. The Ni content of the plant was directly related to the ammonium acetate extractable fraction of Ni in a wide range of natural and artificial substrates. Excision of shoots induced a dramatic increase in the Ni content in the new growth (5500 μg/g compared with 1800 μg/g Ni). When plants were grown in pots with Ni added to the substrate (0–1%), the Ni content of the plants rose to a maximum value of about 1% dry mass. The data from this last experiment were used to calculate the probable Ni yield (kg/ha) of plants grown in nickel-rich soils in different parts of the world. It was calculated that moderately contaminated soils (100 μg/g Ni) could be remediated with only two crops of Berkheya coddii . The potential of this species for phytomining has also been evaluated and it is proposed that a yield of 100 kg/ha of Ni should be achievable at many sites worldwide. Phytomining is also discussed in general terms for other metals as well as Ni.

The distribution and fate of arsenic in the Waikato River system, North Island, New Zealand

Arsenic levels were determined in waters, sediments, aquatic macrophytes and other organisms taken from the Waikato River system, North Island, New Zealand. All water samples contained elevated lev...

Morphology and structure of halloysite in New Zealand tephras

As shown by scanning and transmission electron microscopy, halloysite in three rhyolitic tephras occurs as squat and elongate ellipsoids. Both morphologies are presumed to result from a similar lattice building mechanism. The squat ellipsoids form from allophane; the elongate ellipsoids form from feldspars. The squat ellipsoids do not possess flattened faces or spaces between books of layers at field moisture levels. Outgrowths from the squat ellipsoids are possibly due to inclusions of allophane, glass, ferrihydrite, or feldspar crystallites. Possible spiral growth of halloysite, giving curved surfaces, may be due to a continuous distribution of crystal dislocations.РезюмеС помощью сканирующего и трансмиционного электронного микроскопа было показано, что галлоизит в трех реолитовых тефрах встречается в виде сплющенных и вытянутых эллипсоидов. Обе морфологии предположительно являются результатом подобного механизма построения решетки. Сплющенные эллипсоиды формируются из аллофана, вытянутые эллипсоиды—из фельдшпата. В условиях полевого уровня влажности сплющенные эллипсоиды не имеют ни плоских поверхностей, ни расстояний между «книгами» слоев. Отростки сплющенных эллипсоидов вываны, возможно, инклюзиями аллофана, стекла, ферригидрита, или кристаллитов фельдшпата. Возможный спиральный рост галлоизита, который приводит к искривлению поверхности, может быть вызван сплошным распределением кристаллических дислокаций. [Е.С.]ResümeeRaster- und transmissionselektronenmikroskopische Untersuchungen zeigten, daß Halloysit aus drei rhyolithischen vulkanischen Lockerprodukten als gedrungene oder längliche Ellipsoide auftritt. Es wird angenommen, daß beide Formen durch einen ähnlichen Gitterbildungsmechanismus entstehen. Die gedrungenen Ellipsoide bilden sich aus Allophan; die länglichen Ellipsoide entstehen aus Feldspäten. Die gedrungenen Ellipsoide haben bei Bergfeuchte keine glatten Flächen oder Zwischenräume zwischen Schichtpaketen. Auswüchse auf den gedrungenen Ellipsoiden sind wahrscheinlich durch Einschlüsse von Allophan, Glas, Ferrihydrit, oder Feldspatkristalliten bedingt. Ein mögliches Spiral—wachstum von Halloysit, das gebogene Oberflächen ergibt, könnte von einer kontinuierlichen Verteilung von Versetzungen im Kristall herrühren. [U.W.]RésuméLa microscopie électronique balayante et à transmission montre que l’halloysite dans trois tephres est présente sous la forme d’ellipsoides trappus et élongés. On présume que les deux morphologies résultent d’un mécanisme semblable de construction de l’édifice cristallin. Les ellipsoides trappus sont formés à partir d’allophane, ceux qui sont élongés sont formés à partir de feldspars. Les ellipsoides trappus n’ont pas de faces aplaties ou d’espaces entre les livres de couches à des niveaux d’humidité naturels. Des protrusions des ellipsoides trappus sont possiblement dus à des inclusions d’allophane, de verre, de ferrihydrite, ou de cristallites de feldspars. La croissance en spirale possible d’halloysite, donnant des surfaces recourbées, peut être due à une distribution continuelle de dislocations de cristaux. [D.J.]

A 4300 year palynological and sedimentological record of environmental change and human impact from Wharau Road Swamp, Northland, New Zealand

The palynology and sedimentology of the late Holocene Wharau Road Swamp, Northland, are described Organic sediment began accumulating ca 4300 yr B P ma valley as a result of damming by a basaltic lava flow from nearby Mount Te Puke Mixed conifer‐hardwood forest dominated the region until major anthropogenic forest clearance dated by radiocarbon at ca 600 yr B P Dacrydium cupressinum was the dominant taxon Agathis austrahs was always present until European clearance, with peaks in the pollen record at inferred ages of ca 3700 yr B P and ca 1800 yr B P Climate changes similar to those registered in other pollen diagrams from northern New Zealand are evident, and suggest that climate was wetter and warmer than at present before 4000 yr B P From about 2600 yr B P climate became drier and cooler, indicated by a decline in Ascanna lucida and D cupressinum A period of milder and wetter climate from ca 2000 yr B P is suggested by increases m D cupressinum A lucida and Cvathea Major forest disturbance at ca 600 yr...

Edaphic influences on a New Zealand ultramafic (“serpentine”) flora: a statistical approach

Ultramafic (“serpentine”) soils from and adjacent to the Dun Mountain Ophiolitic Belt, South Island, New Zealand were analysed for 11 elements in order to establish to what degree edaphic factors influenced the character of the overlying vegetation. Using principal components analysis with a mutual plot of the first two principal components, involving the total elemental concentrations in the soils, it was possible to divide the soils into 6 virtually non-overlapping fields, each of which represented a specific vegetation community. Component 1 was essentially an “ultramafic plot” with heavy loadings from the elements chromium, cobalt, iron, magnesium, manganese, and nickel. Component 2 was a “non ultramafic” plot with heavy loadings from aluminium, copper and zinc. For elements extracted from the soils at pH 5.9, discrimination was somewhat poorer but confirmed the great importance of magnesium and nickel as controlling elements for the serpentine vegetation. It was concluded that the results indicated the overriding importance of edaphic factors in controlling the serpentine vegetation.

Potassium‐supplying power of selected Pallic soils of New Zealand: 1. Pot trial study

Abstract Examination of the non‐exchangeable K (K nex ) supplying power of selected Pallic soils of the North and South islands, New Zealand, revealed a wide variation in the measured reserve K (K c ) values. A glasshouse pot trial showed that the supply of K nex to ryegrass grown on 13 North Island Pallic soils ranged from 0 to 409 mg kg‐1 and from 33 to 353 mg kg‐1 on 6 South Island Pallic soils. There were lower levels of K nex supply in developed soils that had been used for agriculture compared with corresponding undeveloped soils for the South Island soils. The results have implications for the fertiliser models that are used in New Zealand to assist prediction of the fertiliser K requirements of pastures.

Lime-aluminium-phosphorus interactions and the growth of Leucaena leucocephala. I. Plant growth studies.

The effects of lime and P addition on the amounts of soil extractable P and Al, and on the growth of the tropical legume Leucaena leucocephala were investigated in a factorial experiment under controlled climate conditions using 4 (Koronivia, Nadroloulou, Batiri, and Seqaqa) highly-weathered, acid (pH initially 3.9 to 4.9) soils from Fiji. Resin-extractable P increased with lime addition and then decreased above pH 5.5, whereas M KCl-extractable Al decreased to undetectable levels at or above pH 5.2. Plant growth was usually adversely affected at low and high pH, even in the presence of added P. The pH (in M KCl) at which maximum growth occurred in the 4 soils varied from approximately 4.4 to 5.2; values somewhat lower than those reported in the literature. Changes in dry matter yield with increasing soil pH were strongly influenced by P status and a positive lime × P interaction was obtained with 3 of the 4 soils. Above pH 5.2, liming decreased the yield of both tops and roots, for reasons which are discussed in part II. The data obtained for extractable soil P and plant P concentrations indicate that P deficiency is a major problem on these soils.

Effect of liming on phosphate extracted by two soil-testing procedures

Lime and phosphate (P) additions had a variable effect on Olsen- and Mehlich-extractable P in 4 acid soils from Fiji. Olsen-extractable P was at a minimum between pH values of 5.5–6.0, on either side of which it increased, particularly in soils which received large amounts of added P. The initial decrease in Olsen-extractable P is attributed to the removal of P from solution by precipitation during the Olsen extraction. The increase at higher pH values is thought to be due to the slow release of P from precipitated Ca-P compounds. There was a consistent decrease in Mehlich-extractable P with increasing soil pH. When the pH of the Mehlich reagent was kept constant, using an autotitrator, there was no decrease in Mehlich-extractable P, suggesting that in the absence of pH control the decrease in extractable P was largely due to the neutralizing effect of lime on the Mehlich reagent.

Potassium‐supplying power of selected Pallic soils of New Zealand: 2. Soil testing procedures

Abstract A previous study showed that there were large differences in the uptake of non‐exchangeable K (K nex ) by ryegrass grown in a glasshouse trial between 19 selected Pallic soils from both North and South islands. The present study evaluated a range of soil testing procedures for K for their ability to explain the variability between the 19 soils in both the uptake of total K from the soil and also the apparent uptake of K nex . A new, simple soil testing procedure, involving extraction of soil K with dilute nitric acid (HNO 3 ‐K), was found to be superior to a number of other published procedures, including estimates of exchangeable K (such as Quick Test K) and reserve K (involving multiple extractions with nitric acid), when correlated with dry matter yield and K uptake. An estimate of step K, calculated as the difference between HNO 3 ‐K and Quick Test K, proved to be better than reserve K in explaining variations in K nex uptake. The proposed HNO 3 extraction procedure is simple, cheap, and effective. Its validity should be tested under field conditions.