保安湖大型水生植物在碳循环中的作用

通过全年的生物量调查的方法,对保安湖的优势种水草生产量进行调查;并进行两个月的优势种水草的分解实验,同时结合各优势水草的含碳量和保安湖的湖水溶解有机碳(DOC)和颗粒有机碳(POC)的动态,阐明大型水生植物在保安湖生态系统碳循环中的作用。同时在整个湖泊范围内,运用分形几何学对水草中的含碳量格局进行分析。       

CARBON DIOXIDE FROM THE NERVE CORD OF THE LOBSTER

1. The nerve cord of the lobster (Homarus americanus Milne-Edwards) is very delicate and can be used as a living preparation for only a few hours after its removal from the animal. 2. During the first hour or so after removal it discharges CO₂ at a steadily decreasing rate beginning at about 0.20 mg. CO₂ per gram of cord per minute and ending at about 0.07 mg. 3. This discharge exhibits a steady decrease in rate and is not divisible into a period of gush and a period of uniform outflow as with the lateral-line nerve of the dogfish. It terminates in a very few hours with the complete death of the cord. 4. Both handling and cutting the cord temporarily increase the rate of CO₂ output. 5. The stimulated cord discharges CO₂ at a rate about 26 per cent higher than that of the quiescent cord, an increase of about 1.6 times that of the increase observed in the lateral-line nerve of the dogfish under similar circumstances.     

THE PRODUCTION OF CARBON DIOXIDE BY NERVE

1. A modified Osterhout respiratory apparatus for the detection of CO₂ from nerve is described. 2. The lateral-line nerve from the dogfish discharges CO₂ at first with a gush for half an hour or so and then steadily at a lower rate for several hours. 3. Simple handling of the nerve does not increase the output of CO₂; cutting it revives gush. 4. The CO₂ produced by nerve is not escaping simply from a reservoir but is a true nervous metabolite. 5. The rate of discharge of CO₂ from a quiescent nerve varied from 0.0071 to 0.0128 mg. per gram of nerve per minute and averaged 0.0095 mg. 6. Stimulated nerve showed an increased rate of CO₂ production of 15.8 percent over that of quiescent nerve. 7. The results of these studies indicate that chemical change is a factor in nerve transmission.     

THE INCORPORATION OF ISOTOPIC CARBON 14C INTO THE CEREBRAL GLYCOGEN OF NORMAL AND X-IRRADIATED RATS

Maximal incorporation of ¹⁴C from labelled glucose into cerebral glycogen of the rat occurred at 3-6 h following intravenous injection of the precursor. A reduction of the rate of glycogen breakdown is the most likely cause of the glycogen accumulation observed in rat brain following exposure to 10 krad of X-radiation.     

THE DIFFUSION OF CARBON DIOXIDE IN TISSUES

1. Two methods are given for measuring the rate of diffusion of CO₂ in tissue membranes. Methods are also given for the determination of tissue thickness and the absorption coefficient for CO₂ in tissues. 2. The values obtained for the permeability constant (P x 10⁴) at 22°C. for CO₂ in the following tissues are:—frog skin, 3.05; connective tissue (dog), 2.65; smooth muscle (cat), 5.00; frog muscle, 5.29; striated muscle (dog), 4.70. P is expressed as cc. per cm.² per minute under a pressure gradient of one atmosphere per cm. 3. Evidence is presented to show that in a "steady state" bicarbonate contributes a negligible amount to the diffusion of CO₂. 4. The absorption coefficient for CO₂ in frog skin is 0.73 cc. per cc. and for frog muscle 0.78 cc. per cc. 5. In all of the tissues studied the diffusion of CO₂ is slower than in water. The diffusion coefficients (K x 10⁴ in cm.²/minute) at 22°C. for tissues as compared with water are:—water (16°C.), 9.5 (Hüfner, 1897); frog skin, 4.1; connective tissue, 3.7; frog muscle, 6.8; striated muscle (dog), 6.0; smooth muscle (cat), 6.4. 6. The time course of saturation of a tissue with CO₂ is altered in the presence of available base. Non-acidified tissues saturate more slowly than acidified tissues and the rate of saturation is dependent on the CO₂ tension.     

CARBON DIOXIDE FROM THE UNSEVERED VAGUS NERVE OF THE SNAKE

1. The vagus nerve of the gopher-snake, Drymarchon corais couperi (Holbrook), discharges carbon dioxide at an average rate of 0.00234 mgm. of gas per gram of nerve per minute. The extremes were 0.0032 mgm. and 0.0017 mgm. 2. These rates were maintained as well when the nerve was separated from its central and its peripheral connections as when these connections were intact showing that the resting metabolism of nerve is a local operation and is not immediately dependent upon distant connections. 3. These observations also point to the conclusion that the passage of normal impulses over a nerve call for an increase of activity that is unobservable by the method employed and that must be small in amount compared with that produced by artificial stimulation.     

黄河水系对流域碳分布的影响

本文利用区段模型并以土壤流失资料和水文资料为基础,计算黄河水系碳输运的诸特征量。结果表明：黄河水系的碳输运主要表现为无机离子态碳和悬浮态碳,它们的输运量主要受土壤流失量和径流量的影响,并可表示为相关性较高的线性回归函数;黄河流域各区段的碳的源汇功能状况取决于土壤流失与泥沙沉积的总效果,具体讲,河源至安宁渡段和河口至三门峡段为主要的碳输运之源,其余则为主要的碳输运之汇。