Interactions of tillage and rainfall on atrazine leaching under field and laboratory conditions

Laboratory studies were conducted to evaluate effects of tillage reversal and rainfall on ¹⁴C-atrazine (2-chloro4-ethylamino-6-isopropylamino- -triazine) leaching patterns. Twelve intact soil cores (16 cm dia x 20 cm deep) were collected from 8-yr no-till (NT) fields. Half the cores were tilled (5 cm deep) prior to ¹⁴C-atrazine treatment (2.7 mg core⁻¹) to all cores. All cores received two rains (27 mm rain in 1.5 h, one day after application followed, two days later, by a 17 mm rain in 2.5 h) and leachate was collected and analyzed for atrazine. These rains simulated the timing, amount and duration of natural rainfall events from a tillage reversal field study. During the first high inte ity rainfall event, a pulse (2.1 μg L-1) of atrazine leached through tilled cores while leaching rate was linear and decreased (1.25 to 0.9 μg L-1) through un-tilled cores. Leaching rate was linear for both the tilled and un-tilled cores during the second rain. Less atrazine was left in the surface 5 cm of tilled soil than un-tilled after the two rains. Results confirmed field observations and suggested that when tillage is reversed on well structured soils, pesticide leaching may increase relative to un-tilled soil but these effects are probably confined to the first rain events after application only.     

Conservation of biodiversity in western India

Director of environmental studies at the Indira Gandhi Centre for Human Ecology, Environmental and Population Studies at the University of Rajasthan. This paper describes the biodiversity in the north-western Indian State of Rajasthan, its relationship with the environment and the existing human and livestock populations. As the biodiversity is depleting in this area due to zoogenic and anthropogenic reasons, certain pragmatic conservation strategies are advocated. The north-western part of India is occupied by a desert ecosystem, the Thar Desert. Animal husbandry is the major livelihood in the region, followed by agriculture. The vegetation, which is predominantly xerophytic and quite sparse, occurs in great variety. Six hundred and eighty-two plant species and 390 animal species have been identified from the Thar Desert. Many plant and animal species have become endangered due to zoogenic and anthropogenic activities. Plants such as Calligonum polygonoides, Tecomella undulata and Prosopis cineraria urgently require conservation.     

GROUND WATER SIMULATION USING A ONE DIMENSIONAL FLOW MODEL1

ABSTRACT: In projects involving ground water problems, dependence on the mathematical modeling of the ground water flow phenomena is inescapable. At present, two dimensional flow models, which require tremendous amounts of computer time and storage, are generally used. When such bulky models are used for planning purposes, the two requirements (computer time and storage) can severely limit the number of alternatives that can be considered. A simple quantity and quality simulation model is developed here which requires considerably less computer time and storage and gives reasonably accurate results. The model was applied to simulate a ground water basin in San Luis Rey River in Southern California. The results were compared with those obtained by a USGS model. It was found that the simple model gave results which were consistentaly within five percent of the USGS model results, while the requirements on computer time and storage were drastically reduced.     

The international natural rubber agreement 1979

The International Natural Rubber Agreement (INRA) 1979 is the first, and so far the only, commodity agreement to emerge from the negotiations under the Integrated Programme for Commodities (IPC). The agreement is examined in the context of the issues relating to international stock and as an indicator for future development. The author concludes that while the principle of joint responsibility for financing international stock has been for the first time accepted in INRA, this has been achieved at the cost of reducing the scope of the regulatory mechanism, and that the single-instrument pattern that the agreement has adopted may not be suitable or acceptable in other commodities.     

Reproduction in mice treated with crufomate: effects of dermal treatments on female mice and on their progeny.

Dermal treatments with crufomate 100 or 50 mg/kg or crufomate vehicle 100 mg/kg were applied to mice either on days 35 and 21 before mating or on days 70, 56, 35, and 21 before mating. Two, but not four dermal treatments, with both doses of crufomate reduced the mating reponse and conception rate in mice. The mice either did not produce a litter or the litter died before the age of 7 days. Four treatments with crufomate 100 mg/kg, but not with 50 mg/kg, reduced the weaning weight of progeny weaned at the age of 21 days. The vehicle had no effects on reproduction and increased the weights at maturity of female and male progeny of mice given two and four treatments, respectively.     

Bioavailability to rats of bound [14C] pirimiphos-methyl in stored wheat.

Stored wheat treated with radiolabelled pirimiphos-methyl (0-2-diethyl-amino-6-methyl-pyrimidin-4-yl 0,0-dimethyl phosphorothioate) formed bound (nonextractable) 14C residues. Supercritical fluid extraction, gas chromatography and mass spectrometric techniques were used to identify and quantitate the 14C bound residues in wheat grains. The amount of bound 14C residues present after 28 weeks of storage was about 9.9% of the applied radioactivity. Pirimiphos-methyl accounted for 80% of the bound residue. Grain-bound residues were fed to rats for 5 days. After a total period of 8 days a substantially large percentage of the administered bound 14C residues (72.9%) was eliminated in urine while feces contained only 17.9%. Bound pirimiphos-methyl in wheat grain was metabolized in rats by processes involving hydrolysis, N-dealkylation and 0-demethylation. The results indicate that wheat-bound residues of pirimiphos-methyl are highly bioavailable to the rat and may possess a toxicological potential as manifested by a significant reduction in body weight gain.     

Limitation of communal latrines in changing the prevalence of parasites and diarrhoeal attack rate in Dhaka Peri-urban slums

A study of the effects of communal latrines on diarrhoeal incidence and parasite prevalence rates was conducted in 1983 at Tongi, which had five communal Oxfam latrines with a manual flushing system for 924 people; and at Kalsi, which had 39 open fit latrines for 823 people. Inhabitants' stool samples were tested initially and also after twelve months to see the reinfection rates. All inhabitants were dewormed with pyrantel, and were visited weekly to obtain diarrhoea histories. In both communities, there were high prevalence rates of roundworm, hookworm, Trichuris trichiura, Entamoeba histolytica, Giardia lambia and Strongyloides stercoralis. Following the dewormings, the prevalence rates of roundworm, hookworm and Trichuris infection came down significantly, in both areas. The prevalence or reinfection rates remained identical in both communities. There was also no difference in diarrhoea incidence rate for the two areas. It is found that keeping all other variables unchanged, use of communal latrines, without strict disposal of everyone's excreta, does not affect parasite prevalence and diarrhoea rates. People must be educated about the use of communal latrines and the safe disposal of all excreta, including that of children.     

Decision making for multiple utilization of water resources in New Zealand

The Clutha is the largest river in New Zealand. The last two decades have witnessed major conflicts centered on the utilization of the water resources of the upper Clutha river. These conflicts have by no means been finally resolved. The focus of this article is on institutional arrangements for water resource management on the Clutha, with particular reference to the decision-making processes that have culminated in the building of the high dam. It critically evaluates recent experiences and comments on future prospects for resolving resource use conflicts rationally through planning for multiple utilization in a climate of market led policies of the present government.The study demonstrates the inevitable conflicts that can arise within a public bureaucracy that combines dual responsibilities for policy making and operational functions. Hitherto, central government has been able to manipulate the water resource allocation process to its advantage because of a lack of clear separation between its two roles as a policy maker and developer. The conflicts that have manifested themselves during the last two decades over the Clutha should be seen as part of a wider public debate during the last two decades concerning resource utilization in New Zealand. The Clutha controversy was preceded by comparable concerns over the rising of the level of Lake Manapouri during the 1960s and has been followed by the debate over the think big resource development projects during the 1980s.The election of the fourth Labour government in 1983 has heralded a political and economic policy shift in New Zealand towards minimizing the role of public intervention in resource allocation and major structural reforms in the relative roles of central and regional government in resource management. The significance of these changes pose important implications for the future management of the Clutha.     

The international tin agreement, 1976: An assessment of its regulatory machinery as an instrument of international policy

The author examines the provisions of the New International Economic Order (NIEO), and maintains that with or without a Common Fund, International Commodity Agreements are, and will remain, a recognized instrument for achieving the objectives of the NIEO. Because of various factors conducive to effective organization — including the convergence of interests among producing and consuming countries — the International Tin Agreement (ITA) has made some useful contributions. But wider objectives can only be achieved by appropriate structural reforms in commodity organization.