Soil factors associated with zinc deficiency in crops and humans.

Zinc deficiency is the most ubiquitous micronutrient deficiency problem in world crops. Zinc is essential for both plants and animals because it is a structural constituent and regulatory co-factor in enzymes and proteins involved in many biochemical pathways. Millions of hectares of cropland are affected by Zn deficiency and approximately one-third of the human population suffers from an inadequate intake of Zn.

Effects of short-term pH fluctuations on cadmium, nickel, lead, and zinc availability to ryegrass in a sewage sludge-amended field.

In this field experiment, sewage sludge was applied at 0, 5, 10, and 50tha(-1), and the availability of Cd, Ni, Pb, and Zn was assessed both by ryegrass uptake and by DTPA extractions. The aim was to investigate the role of important soil parameters, particularly pH, on heavy metal availability. It was found that metal uptake and extractability increased significantly in the 50tha(-1) treatment.

Trace element partitioning and soil particle characterisation around mining and smelting areas at Tharsis, Ríotinto and Huelva, SW Spain.

Trace elements may present an environmental hazard in the vicinity of mining and smelting activities. However, the factors controlling trace element distribution in soils around ancient and modern mining and smelting areas are not always clear. Tharsis, Ríotinto and Huelva are located in the Iberian Pyrite Belt in SW Spain.

Genotypic variations in the accumulation of Cd, Cu, Pb and Zn exhibited by six commonly grown vegetables.

Metal contaminants in garden and allotment soils could possibly affect human health through a variety of pathways. This study focused on the potential pathway of consumption of vegetables grown on contaminated soil. Five cultivars each of six common vegetables were grown in a control and in a soil spiked with Cd, Cu, Pb and Zn.

Soil mobility of sewage sludge-derived dissolved organic matter, copper, nickel and zinc.

A soil (sandy loam) column leaching study aimed to determine the extent of mobility and co-mobility of Cu, Ni, Zn and dissolved organic matter (DOM) released from a surface-application (equivalent to 50 t ds ha(-1) of anaerobically-digested sewage sludge. Leaching of DOM through the soil column was found to be almost un-retarded. Decidedly similar behaviour was exhibited by Ni suggesting that it migrated as organic complexes.

The illusion of environmental iodine deficiency.

The distribution of endemic goitre in England and Wales was compared with the distribution of environmental iodine (atmospheric deposition, soil, surface water). Despite a very clear goitre belt through the west of England and Wales there was no patterning in the environmental iodine distribution. A clear seasonal variation in depositional iodine exists, with an unusually high concentration of iodine in March 1997.

An inventory of heavy metals inputs to agricultural soils in England and Wales.

An inventory of heavy metal inputs (Zn, Cu, Ni, Pb, Cd, Cr, As and Hg) to agricultural soils in England and Wales in 2000 is presented, accounting for major sources including atmospheric deposition, sewage sludge, livestock manures, inorganic fertilisers and lime, agrochemicals, irrigation water, industrial by-product 'wastes' and composts. Across the whole agricultural land area, atmospheric deposition was the main source of most metals, ranging from 25 to 85% of total inputs. Livestock manures and sewage sludge were also important sources, responsible for an estimated 37-40 and 8-17% of total Zn and Cu inputs, respectively.

Field trials to assess the uptake of arsenic by vegetables from contaminated soils and soil remediation with iron oxides.

The uptake of arsenic (As) by plants from contaminated soils presents a health hazard that may affect the use of agricultural and former industrial land. Methods for limiting the hazard are desirable. A proposed remediation treatment comprises the precipitation of iron (Fe) oxides in the contaminated soil by adding ferrous sulfate and lime.

Reduction of arsenic uptake by lettuce with ferrous sulfate applied to contaminated soil.

Soil contamination by arsenic (As) presents a hazard in many countries and there is a need for techniques to minimize As uptake by plants. A proposed in situ remediation method was tested by growing lettuce (Lactuca sativa L. cv.

The role of dissolved organic carbon in the mobility of Cd, Ni and Zn in sewage sludge-amended soils.

A pot experiment was conducted to investigate the effect of application of naturally derived dissolved organic compounds (DOC) on the uptake of Cd, Ni and Zn by Lolium perenne L. from mixtures of soil and sewage sludge and on their extractability with CaCl2. DOC was applied at concentrations of 0, 285 and 470 mg l(-1) to a loamy sand (LS) and a sandy clay loam (SCL) soil mixed with sewage sludge at rates equivalent to 0, 10 and 50 t ha(-1).

Changes in the leachability of metals from dredged canal sediments during drying and oxidation.

The behaviour of metals in canal sediments after their disposal to land has important implications for the environmental management of canal dredgings. The leaching behaviour of trace metals was investigated in a laboratory-based experiment using sediment from a canal in the UK (139 mg Zn kg-1dry sediment, 1.1 mg Cd, kg-1dry sediment 31.

Towards the characterisation of heavy metals in dredged canal sediments and an appreciation of 'availability': two examples from the UK.

Canal sediments can act as sinks for a wide range of contaminants including heavy metals from various sources (e.g. industrial and waste water discharges).

The problem of arsenic interference in the analysis of soils for cadmium by inductively coupled plasma-optical emission spectrometry.

Cadmium determination in soils that contain arsenic may be subject to interference. When this problem is not appreciated spurious results may be accepted as correct. Spectrometric methods for the quantitative determination of cadmium in the presence of arsenic were compared.

The behaviour of heavy metals in sewage sludge-amended soils.

Soils amended with sewage sludges generally contain elevated concentrations of a wide range of heavy metals and are therefore of interest with regard to their potential impact on human health. This review considers the concentrations of heavy metals in sewage sludges and in the soils amended with them. The effects of sludge amendments on soil properties, the speciation of heavy metals and their bioavailability are reviewed.

The accumulation of cadmium by vegetables grown on soils contaminated from a variety of sources.

The accumulation of cadmium by four crops (cabbage, carrot, lettuce and radish) grown on soils contaminated from a variety of sources was investigated in greenhouse pot experiments. Stepwise multiple regression analyses of the data revealed that, out of the 23 soil variables determined, only eight were significantly related to cadmium accumulation in the edible plant tissues. The most frequently occurring soil parameter was total cadmium, which was inversely related to plant cadmium accumulation (CdPlant tissue/CdSoil).