Environmental policy and human capital inequality: A matter of life and death

This paper analyzes the economic implications of an environmental policy when we account for the life expectancy of heterogeneous agents. In a framework in which everyone suffers from pollution but health status also depends on individual human capital, we find that the economy may be stuck in a trap in which inequality rises steadily, especially when the initial pollution intensity of production is too high. We emphasize that such inequality is in the long run costly for the economy in terms of health and growth. Therefore, we study whether a tax on pollution associated with an investment in pollution abatement can be used to address this situation. We show that a stricter environmental policy may allow the economy to escape from the inequality trap while enhancing the long-term growth rate when the initial inequality in human capital is not too large.     

花果期持续受渍对油菜生长、产量与含油量的影响

油菜是江汉平原广泛栽培的越冬作物，在春季雨水较多时常遭遇持续受渍胁迫，对产量有明显影响。为了探索春季油菜田的排水管理，取得较高产量，通过测坑试验和小区试验，初步研究了花果斯持续受渍对油菜生长，产量和含油量的影响。结果表明：油菜花果期持续受渍，主要是通过单株的有效角果数，千粒重等因素影响产量；随着持续受渍时间的延长，各受渍处理的单株有效角果数减少，千粒重降低，产量下降，与对照相比，较短时间（比如2天）持续受渍对油菜生长发育，产量形成以及籽粒含油量影响不大，但较长时期持续受渍会对油菜的这些方面产生不良影响，此类水分胁迫是生产上重点防治的对象。因此，在考虑地下水位动脉及其作用时间对油菜影响的排渍指标研究中，应主要从持续受渍程度对产量的影响方面建立关系，确定适宜的新型排渍指标。     

DISTRIBUTED RUNOFF FORMULATION DESIGNED FOR A PRECISION AGRICULTURAL LANDSCAPE MODELING SYSTEM1

A precision scale landscape model designed for agricultural applications is described in this paper. The Precision Agricultural Landscape Modeling System (PALMS) is a combination of two process‐based models: a diffusive wave runoff model with ponding (described in detail) and a biosphere model with a crops module (briefly reviewed). Several innovations, including numerical formulations for the hydrologic properties of the soil surface with crusting, slope/tillage angle interactions, and change of roughness and detention storage with cumulative precipitation have been included. The model is compared to observations on one 1.8 ha field planted with maize and soybeans during four growing seasons, and one 24 ha field planted with maize during one growing season. Daily average soil moisture is simulated well (within 5 percent volumetric), except in extended runoff/ponding episodes. Physical processes not simulated in the model suggest possible explanations for model errors. Planned improvements for PALMS are also presented.     

胭脂鱼仔幼鱼的摄食习性及其生长

胭脂鱼幼鱼具有明显的昼夜摄食节律.仔鱼以适口的浮游动物为食,并随着口位下移,转而摄食底层生物.文中分别对140日幼鱼的日龄与全长、全长与体重以及全长和全长/体高的关系作了曲线回归方程,反映了幼鱼的生长特点.本工作为增殖该种珍稀鱼类资源提供了基础资料,并对其观赏价值进行了评价.     

The need for growth promoting compounds in poultry meat production

Modern strains of broiler chicken are capable of achieving a 2.4 kg liveweight at 42d of age. This extremely fast growth is accomplished in part by balanced diets containing pharmaceutical growth promoting compounds. Over the last few years, a number of ethical questions have arisen regarding the use of such compounds. Such fast growth rate is accompanied by reduced bird welfare related to morbidity and mortality of a proportion of the birds. In two trials we have shown that acceptable growth rate can be achieved in diets without these compounds, and that economics of production are not adversely affected. It is concluded that future management programs for broiler chickens should consider a tempering of growth rate and that this could lead to improved bird well-being.     

RESPONSE FUNCTIONS OF CROPS YIELD TO SOIL MOISTURE STRESS1

: A methodology for determining an optimal irrigation policy to obtain maximum economic yield of crops is presented. The method is based on an empirical response function, relating crop yield to soil moisture stress in different stages of plant growth. The function was developed from data obtained in field experiments on several crops and may be useful in determining when and how much to irrigate. Additionally, a mathematical expression is derived from that function which estimates the economic loss if irrigation is not applied in the opportune moment.     

Environmental risk: Management strategies in the developing world

This paper describes a heuristic model which helps to relate a developing nation's environmental risk to the level of sophistication appropriate in adjusting management strategy to dealing with environmental hazards. The model takes into account three factors: the degree of risk, the stage of economic growth, and the sophistication of adjustment. The interrelationship of these factors is examined, and the role of international cooperation in establishing strategies is outlined.     

THE LETHAL AND SUB LETHAL EFFECTS OF A ZIRCONIUM PROCESS EFFLUENT ON JUVENILE SALMONIDS1

ABSTRACT: An effluent (ZPE), with high concentrations of ammonia was compared with solutions of ammonium chloride in both lethal and sublethal tests. The ZPE was more toxic than were solutions of ammonium chloride in acute toxicity tests, although ammonia was shown to be the major toxicant. The secondary toxicants present in the effluent were not identified. Growth was used as a sublethal test parameter and ZPE was again more toxic than ammonium chloride solutions at the same ammonia concentration. Concentrations of ammonia less than 3 mg/liter in ammonium chloride solutions actually stimulated the growth of juvenile chinook salmon. Concentrations of ZPE in the river at extreme low river flow could have sublethal effects on juvenile salmonids below the outfall.     

ZONES OF NITRIFICATION1

ABSTRACT: This paper advances the hypothesis that nitrification exists in shallow streams as a result of surface activity and in estuaries due to growth in the water phase. Between these zones no significant levels of nitrification occur. Field measurements of ammonia, nitrite and nitrate nitrogen, enumerations of Nitrosomonas and Nitrobacter, and respirometry on two small streams and two moderately large rivers are presented. The appropriate mathematical models to describe nitrification must be based on the mechanisms involved - bacterial growth kinetics for estuaries and zero kinetics for the surface activity in shallow streams.     

Perspectives on the landmark decision designating the northern spotted owl (Strix occidentalis caurina) as a threatened subspecies

Following an extensive legal battle challenging its original decision to not extend the protection of the Endangered Species Act to the northern spotted owl (Strix occidentalis caurina), the US Fish and Wildlife Service was ordered by the 9th District Court of Appeals to reassess the status of the owl. As a result of the revised analysis, the service proposed the northern spotted owl for threatened status throughout its range. Because of the complex biological issues involved and the perceived potential for economic disruption in timber-dependent communities of the Pacific Northwest, this proposal generated more controversy and interest than any previous one. In this article I discuss the rationale for the service’s decision, public involvement in the process, and the mechanisms now available to conserve the northern spotted owl and its habitat under the Endangered Species Act.