東華大學圖書館 |

Language: English

Help

回圖書館首頁

手機版館藏查詢

Back

Switch To: Labeled | MARC Mode | ISBD

Soil erosion and losses of nitrogen ...

Hamilton, Hugh.

Linked to FindBook

Google Book

Amazon

博客來

Soil erosion and losses of nitrogen and phosphorus in the Loess Plateau, Wangjiagou, Lishi, People's Republic of China.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Soil erosion and losses of nitrogen and phosphorus in the Loess Plateau, Wangjiagou, Lishi, People's Republic of China./
Author:	Hamilton, Hugh.
Published:	Ann Arbor : ProQuest Dissertations & Theses, : 1991,
Description:	227 p.
Notes:	Source: Dissertation Abstracts International, Volume: 53-02, Section: B, page: 7540.
Contained By:	Dissertation Abstracts International53-02B.
Subject:	Environmental science. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NN65819
ISBN:	9780315658196

Soil erosion and losses of nitrogen and phosphorus in the Loess Plateau, Wangjiagou, Lishi, People's Republic of China.
Hamilton, Hugh.

Soil erosion and losses of nitrogen and phosphorus in the Loess Plateau, Wangjiagou, Lishi, People's Republic of China. - Ann Arbor : ProQuest Dissertations & Theses, 1991 - 227 p.

Source: Dissertation Abstracts International, Volume: 53-02, Section: B, page: 7540.

Thesis (Ph.D.)--University of Toronto (Canada), 1991.

This study investigates the linkages between the processes of sediment transfer and the movement of nitrogen and phosphorus in the hilly loess region of China's Loess Piateau. Field work was carried out in a representative first-order drainage basin, the Yangdaogou, during 1987 and 1988. Soil loss in the Yandaogou equalled 203.4 Mg ha-1 in 1987 and 176.9 Mg ha-1 in 1988. The mean sediment concentration of the runoff was 505 kg m-3 and concentrations were observed to reach 1000 kg m-3. The principal sediment transfer process is hyperconcentrated overland flow that was observed to carry very large amounts of suspended sediment throughout the storm hydrograph. The majority of plotted discharge-concentration relationships showed counter-clockwise hysteresis where concentrations in the recession limb exceed the rising limb. Reductions in flow velocity resulted in only limited sediment deposition and virtually all entrained sediment is exported from the basin. Calculated Reynold's Numbers indicate that the hyperconcentrated flow is laminar. Sheet and rill erosion appears to be the most important sediment source followed by channel erosion, tunnel erosion, and the remobilization of sediments displaced by mass movement.

ISBN: 9780315658196Subjects--Topical Terms:

677245
Environmental science.

Soil erosion and losses of nitrogen and phosphorus in the Loess Plateau, Wangjiagou, Lishi, People's Republic of China.
LDR:03843nmm a2200325 4500 001 2123446
005 20171002064939.5
008 180830s1991 ||||||||||||||||| ||eng d
020 $a 9780315658196
035 $a (MiAaPQ)AAINN65819
035 $a AAINN65819
040 $a MiAaPQ $c MiAaPQ
100 1 $a Hamilton, Hugh. $3 3285366
245 1 0 $a Soil erosion and losses of nitrogen and phosphorus in the Loess Plateau, Wangjiagou, Lishi, People's Republic of China.
260 1 $a Ann Arbor : $b ProQuest Dissertations & Theses, $c 1991
300 $a 227 p.
500 $a Source: Dissertation Abstracts International, Volume: 53-02, Section: B, page: 7540.
502 $a Thesis (Ph.D.)--University of Toronto (Canada), 1991.
520 $a This study investigates the linkages between the processes of sediment transfer and the movement of nitrogen and phosphorus in the hilly loess region of China's Loess Piateau. Field work was carried out in a representative first-order drainage basin, the Yangdaogou, during 1987 and 1988. Soil loss in the Yandaogou equalled 203.4 Mg ha-1 in 1987 and 176.9 Mg ha-1 in 1988. The mean sediment concentration of the runoff was 505 kg m-3 and concentrations were observed to reach 1000 kg m-3. The principal sediment transfer process is hyperconcentrated overland flow that was observed to carry very large amounts of suspended sediment throughout the storm hydrograph. The majority of plotted discharge-concentration relationships showed counter-clockwise hysteresis where concentrations in the recession limb exceed the rising limb. Reductions in flow velocity resulted in only limited sediment deposition and virtually all entrained sediment is exported from the basin. Calculated Reynold's Numbers indicate that the hyperconcentrated flow is laminar. Sheet and rill erosion appears to be the most important sediment source followed by channel erosion, tunnel erosion, and the remobilization of sediments displaced by mass movement.
520 $a Nitrogen losses from the Yangdaogou in runoff were 76.4 kg ha-1 in 1987 and 44.1 kg ha-1 in 1988. These data are among the highest reported in the literature. Each year more than 98% of the total load was in the sediment-associated form. The presence of hyperconcentrated flow is significant as virtually all suspended solids are efficiently exported from the basin. Within-basin transfers of N appear to be slight. Nitrogen balance information suggests that the biological fixation of atmospheric N by the shrub Caragana korshinskii is a major N source to the non-cultivated part of the basin.
520 $a Total phosphorus losses were 73.7 kg ha-1 in 1988 with 99% of the load in particulate form. This rate is among the highest reported and is a function of the high rate of soil loss rather than of high P concentrations in the eroded sediment. Losses and concentrations of dissolved orthophosphate are comparable to those found elsewhere. However the available P content of the loess soils is low and any losses of soluble P should be considered serious.
520 $a In general, despite a rather significant influx of sediment from other processes, mass movement, channel erosion and tunnel erosion, it appears that the contribution of surface erosion to the sediment yield is large and the associated loss of nutrients is serious. Hyperconcentrated flow maintains eroded organic matter and sediment associated nutrients in suspension and the material is readily exported from basins. Conservation strategies that inhibit the initiation of hyperconcentrated flow on the upper slopes are thus critical for conserving both soil and nutrients.
590 $a School code: 0779.
650 4 $a Environmental science. $3 677245
650 4 $a Agronomy. $3 2122783
650 4 $a Physical geography. $3 516662
690 $a 0768
690 $a 0285
690 $a 0368
710 2 $a University of Toronto (Canada). $3 1017674
773 0 $t Dissertation Abstracts International $g 53-02B.
790 $a 0779
791 $a Ph.D.
792 $a 1991
793 $a English
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=NN65819