Measuring Asset Values and Flow Benefits of Non-Traded Products and Ecosystems Services of Forest and Woodland Resources in South Africa

Conventional measures of economic output, national income and wealth highly underestimate the value and contribution of natural resources to economic welfare. This paper makes estimates of the asset values and flow benefits of non-traded goods and services from forests and woodland resources in South Africa. Four benefit categories were included, namely direct consumptive use values (timber and non-timber products), non-consumptive use values (recreation for example), indirect use values (environmental services such as carbon sequestration, watershed protection, etc.), and non-use values (based on contingent valuation by tourists). Asset values were calculated knowing the change in physical stocks and the relevant prices. In South Africa, the increase in assets was equivalent to 1.1% of gross domestic product (GDP) (forests were improving, but fynbos deteriorating), and the flow benefits were equivalent to 0.8% of GDP. These are large magnitudes.     

Potential of 2, 4‐dichlorophenoxyacetic acid conjugates as promutagens in the salmonella/microsome mutagenicity test

Abstract

Hepatic S9 preparations from Aroclor 1254 induced rats and 3‐methylcholanthrene induced woodchucks were used to investigate, in vitro, the mutagenic potential of five amino acid conjugates of 2, 4‐Dichlorophenoxyacetic acid (alanine, aspartic acid, leucine, methionine and tryptophan). Five strains of Salmonella typhimurium (TA97, TA98, TA100, TA1535, TA1538) were utilized for this purpose. Dose‐response effects producing a two‐fold increase of revertants over spontaneous levels were not observed with either S9 preparation indicating that the amino acid conjugates are not promutagens in these assays.     

Reactions between aqueous zinc,aluminium and iron with increasing solutionpH

Solutions of zinc, aluminium and/or iron, as chlorides in NaCl of ionic strength 0.13 mol/l atpH 3, were mixed to give initial concentrations of 0–5, 5–50 and 10–100 g/ml, respectively. Sodium hydroxide was then added to increase thepH in a range up to 7. Turbidity was measured and equilibrium concentrations were determined after filtration (< 0.1 m). Decrease inpH on mixing suggested an immediate reaction, with the release of protons. At allpH values Zn concentration decreased with increasing initiai concentrations of Fe and Al. Adsorption and/or nucleation of Zn with Fe and Al was highlypH dependent and increased markediy with increasingpH. The particle size of the products increased with increasingpH and initial concentration of the elements. Increasing Al concentration decreased the size of Fe nucleates at a given Fe concentration. The results suggest that co-precipitation may be involved as well as adsorption. This has important consequences for the availability of Zn to plants, especially in Zn-deficient soils, and is of relevance to the products of mixing acid drainage waters with streams and lakes.     

Evaluation of chlordimeform and degradation products for mutagenic and DNA-damaging activity in Salmonella typhimurium and Escherichia coli

The mutagenic activity of chlordimeform and two of its breakdown products, 4-chloro-o-toludine and 4-chloro-N-formyl-o-toluidine were determined with five histidine dependent strains of Salmonella typhimurium (TA1535, TA1537, TA1538, TA98, TA100) and five tryptophan dependent strains of E. coli WP2 (WP2, WP2uvrA, WP67, CM611, CM571) with and without rat liver microsomal enzymes. 4-chloro-o-toluidine increased the number of the reversions of the S. typhimurium strain TA1535 more than two fold over spontaneous at the concentration of 400 micrograms/plate. The results of the DNA repair tests in the Salmonella TA1538/TA1978 and E. coli multirepair deficient systems showed that both breakdown products were active in inducing damage not repaired in at least one repair deficient strain while chlordimeform itself was inactive.     

Field-scale application of oily food waste and nitrogen fertilizer requirements of corn at different landscape positions

Oily food waste (FOG; fat + oil + greases) containing high concentrations of fat, oil and grease is produced by the food service, production, and processing industries. It has a high C to N ratio (90:1) and can recycle soil available N through immobilization and remineralization during its decomposition. Experiments were conducted at a farm (Hillsburg fine sandy loam; Typic Hapludalf) having rolling topography (5 and 9% slope) during 1995 and 1996. Objectives of this study were to (i) examine the variability of available N and corn (Zea mays L.) grain yield at different landscape positions of FOG-amended fields and (ii) determine whether N fertilizer management could be improved by considering the spatial variability of soil NO(3)-N at different landscape positions in FOG-amended fields. A spatial and temporal variability in soil NO(3)-N was observed during both years. Corn grain yields at all N fertilizer application rates were affected by slope position and followed the pattern: lower > upper > or = middle. Nitrogen fertilizer requirements for corn production in conjunction with FOG management were also affected by slope position. Essentially no additional fertilizer N was required for corn production at the lower landscape position. It was estimated that site-specific fertilizer N management on FOG-amended fields could result in an average savings of 51 and 63 kg N ha(-1) (with a potential economical savings of US 42 dollars and US 52 dollars ha(-1)) during 1995 and 1996, respectively.     

OPTIMAL MANAGEMENT OF A REGIONAL AQUIFER IN EASTERN SAUDI ARABIA1

ABSTRACT: This paper describes the formulation and application of a ground-water hydraulic management model to determine the optimal development and operating policies of a regional aquifer in the Eastern Province of Saudi Arabia. The hydraulic response of the aquifer system is represented by a simulation model that is linked to an optimization management model using response functions. Yearly optimal ground-water extraction rates over a planning horizon of 15 years are determined for four scenarios, each reflecting alternative ground-water development policies. The results are presented in the form of tradeoff curves, relating drawdowns to optimal pumpage, which may enhance the decisionmaker's ability to select the best development policy from a set of alternatives. The results illustrate how various optimal management schemes can be devised to increase the total withdrawal from the aquifer while preventing excessive de-watering.     

Recovery of gas waste from the petroleum industry: a review

Environmental Chemistry Letters - Globally, 150–170 billion cubic metres of gas are being flared annually from petroleum refineries, petrochemical industries and from landfills. In this...     

Use,exposure, and environmental impacts of pesticides in Pakistan: a critical review

Environmental Science and Pollution Research - The excessive use of pesticides is posing major threats to humans and the environment. However, the environmental exposure and impact of pesticides in...     

Induction of apoptosis in A431 cells via ROS generation and p53-mediated pathway by chloroform fraction of Argemone mexicana (Pepaveraceae)

Environmental Science and Pollution Research - Argemone mexicana(Pepaveraceae) is an important medicinal plant commonly known as ‘maxican prickly poppy’ and is traditionally used to...