Soils and Groundwater Pollution and Remediation

Asia, Africa, and Oceania

P. M. Huang, I.K. Iskandar

• Publisher: CRC Press
• Year: 2020
• ISBN:
  9781000157987
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Agriculture
• Index: Technology & Engineering

The increasing population densities of Asia, Africa and Oceania are in conflict with the ecosystem. A growing demand for food and fiber causes agriculture to rely heavily upon chemical fertilization, herbicides and pesticides. Rising industrial output creates higher contamination from cadmium, lead, selenium, and other metals.
Soils and Groundwater Remediation explores the toxic levels of metals, radionuclides, inorganics, and anthropogenic organic compounds found in the soils and groundwater of Asia, Africa and Oceania. This 14 chapter book reviews the distribution, transformation, and dynamics of the pollutants. The authors also reflect on the impact of Acid-rain.
The contributors to this book are well-known scientists from Japan, China, Korea, Malaysia, New Zealand, Australia, and Kenya. The authors address their findings to researchers, educators, government regulators, and students.
As the title suggests, the book is ultimately concerned with remediation. Huang and Iskandar feel "the potential for restoring ecosystem health... in these areas is enormous." The contributions of Soils and Groundwater Remediation will bring science closer to achieving that possibility.

CHAPTER 1

ENVIRONMENTAL IMPACTS OF HEAVY METALS IN AGROECOSYSTEMS AND AMELIORATION STRATEGIES IN OCEANIA

K.G. Tiller, M.J. McLaughlin, and A.H.C. Roberts

INTRODUCTION

The agroecosystems of Australia and New Zealand encompass an enormous range of both soil types and climatic conditions. The main feature that they have in common is a relative freedom from influences of urban and industrial pollution. Soil and associated crop contamination has primarily resulted from agricultural practices arising from fertilizers, agricultural sprays, and organic wastes. Atmospheric contamination arising from industrial emissions has only influenced relatively small areas near a few regional centers. This review will discuss background concentrations of heavy metals in Australian and New Zealand soils and crops, sources of contamination, their environmental impact, some amelioration strategies especially in relation to farm management practices, and regulatory controls. Data on heavy metals in groundwater are few and will not be discussed. Those available are of questionable quality because of the likelihood of contamination from access tubes and bore casings. Information on a range of heavy metals will be presented; most research has been carried out on cadmium (Cd) in particular, as well as lead (Pb), arsenic (As), copper (Cu), and zinc (Zn), with less work still on nickel (Ni), mercury (Hg), and chromium (Cr).

BACKGROUND CONCENTRATIONS OF HEAVY METALS IN AUSTRALIAN AND NEW ZEALAND SOILS

Initially we will outline our attitude on the topic of background values. Background values are often used to determine if a soil has become enriched with an undesirable substance; such soils with values exceeding the local normal background values are then deemed “contaminated.” If the soil becomes so contaminated that it has an observed environmental impact, it is deemed “polluted.” As discussed by Tiller (1992), there is a continuum of soil concentrations from the natural or pristine state through to highly polluted soils. The level at which a soil is deemed polluted therefore depends on the contaminant of interest, its bioavailability and toxicity, and the pathways through which health or environmental risk are exercised.

Table 1.1. Background Concentrations (mg kg⁻¹) of Heavy Metals in New Zealand Soil Types (Data for the 0 to 7.5-cm layer)^a

Element	Nat./Past.	Soil Type^b
		YBL	YBP	YBE	YGE	GLEY	PEAT	BGL	ALLUV	MEAN
As	Native	3.9	7.0	4.2	2.1	5.3	8.4	5.3	3.0	4.3
	Pasture	7.4	7.8	3.0	2.4	5.1	15.1	5.4	3.6	4.9
Cd	Native	0.23	0.31	0.16	0.13	0.24	0.22	0.19	0.13	0.18
	Pasture	0.70	0.75	0.22	0.12	0.42	0.69	0.49	0.16	0.44
Cu	Native	26.9	7.2	14.6	8.0	17.9	20.4	19.4	11.5	17.0
	Pasture	32.1	10.9	12.3	8.9	18.2	27.0	25.5	17.3	17.7
Pb	Native	11.6	6.8	13.7	12.5	17.6	16.9	18.0	15.0	13.3
	Pasture	19.3	7.4	7.6	9.3	11.6	10.0	19.1	10.9	11.7
Zn	Native	77	37	65	54	92	51	56	72	65
	Pasture	97	47	55	61	66	43	82	78	68

^aSource: Roberts et al. (1996).

^b Soil types (Taylor and Pohlen, 1970): YBL = yellow-brown loam; YBP = yellow-brown pumice soil; YBE = yellow-brown earth; YGE = yellow-grey earth; GLEY = gleys; PEAT = peats; BGL = brown granular loam; ALLUV = alluvial soils. Sites sampled = 398.

In the view of most health authorities where urban and industrial pollution are the main concern, “background” values for metals in soil are often assessed in relation to rural soils. These normal background values will therefore include soils with mildly elevated metal concentrations due to normal agricultural fertilization practices. To assess the impact of farm management practice, metal concentrations in native (uncultivated) soils must be compared to their farmed or pastoral equivalents. For the purposes of this review, therefore, background values will be referred to in terms of the range of rural soils without distinction between native (i.e., unfertilized) and agricultural soils. These are the “normal” ...