『Abstract
Phosphorus has a number of indispensable biochemical roles, but
it does not have a rapid global cycle akin to the circulations
of C or N. Natural mobilization of the element, a part of the
grand geotectonic denudation-uplift cycle, is slow, and low solubility
of phosphates and their rapid transformation to insoluble forms
make the element commonly the growth-limiting nutrient, particularly
in aquatic ecosystems. Human activities have intensified releases
of P. By the year 2000 the global mobilization of the nutrient
has roughly tripled compared to its natural flows: Increased soil
erosion and runoff from fields, recycling of crop residues and
manures, discharges of urban and industrial wastes, and above
all, applications of inorganic fertilizers (15 million tonnes
P/year) are the major causes of this increase. Global food production
is now highly dependent on the continuing use of phosphates, which
account for 50-60％ of all P supply; although crops use the nutrient
with relatively high efficiency, lost P that reaches water is
commonly the main cause of eutrophication. This undesirable process
affects fresh and ocean waters in many parts of the world. More
effectively controlled, such measures are often not taken, and
elevated P is common in treated wastewater whose N was lowered
by denitrification. Long-term prospects of inorganic P supply
and its environmental consequences remain a matter of concern.
Key Words: biogeochemical cycling; phosphates; fertilizers; eutrophication』
Contents
1. An essential element of life
2. Biogeochemical cycling of phosphorus
2.1. Natural reservoirs of phosphorus
2.2. Annual fluxes
3. Human intensification of phosphorus flows
3.1. Accelerated erosion, runoff, and leaching
3.2. Production and recycling of organic wastes
3.3. Sewage and detergents
3.4. Inorganic fertilizers
3.5. Summarizing the human impact
4. Phosphorus in agriculture
4.1. Phosphorus uptake and applications
4.2. Phosphorus in soils
5. Phosphorus in waters
5.1. Losses of dissolved phosphorus
5.2. Eutrophication
6. Reducing anthropogenic impacts
7. Long-term perspectives
Literature cited
| リンのリザーバ | 全量（１００万トンP） |
| 海洋 | 93000 |
| 表層 | 8000 |
| 深層 | 85000 |
| 土壌 | 40-50 |
| 無機リン | 35-40 |
| 有機リン | 5-10 |
| 植物体 | 570-625 |
| 陸上 | 500-550 |
| 海洋 | 70-75 |
| 動物体 | 30-50 |
| 人間体 | 3 |
| リンのフラックス |
（１００万トンP／年） |
| 大気沈着 | 3-4 |
| 浸食および流出 | 25-30 |
| 粒子状リン | 18-22 |
| 溶存リン | 2-3 |
| 植物摂取 | |
| 陸上 | 70-100 |
| 海洋 | 900-1200 |
| 海洋堆積物への埋没 | 20-35 |
| 構造運動による隆起 | 15-25 |
| 成分 | 頭字語 | 化学式 |
栄養分 （％P） |
|
Monocalcium phosphateまたは ordinary superphosphate |
MCP OSP |
Ca(H2PO4)2 | 8-9 |
| Dicalcium phosphate | DCP | CaHPO4・H2O | 17 |
| Triple superphosphate | TSP | Ca(H2PO4)2 | 19-20 |
| Monoammonium phosphate | MAP | NH4H2PO4 | 21-24 |
| Diammonium phosphate | DAP | (NH4)2HPO4 | 20-23 |
| Monopotassium phosphate | MKP | KH2PO4 | 17 |
| フラックス | 天然 |
産業化以前 （1800年） |
現在 （2000年） |
| 人間活動によって増加した天然フラックス | |||
| 浸食 | ＞10 | ＞15 | ＞30 |
| 風 | ＜2 | ＜3 | ＞3 |
| 水 | ＞8 | ＞12 | ＞27 |
| 河川運搬 | ＞7 | ＞9 | ＞22 |
| 粒子状リン | ＞6 | ＞8 | ＞20 |
| 溶存リン | ＞1 | ＜2 | ＞2 |
| 生物体燃焼 | ＜0.1 | ＜0.2 | ＜0.3 |
| 人為源フラックス | |||
| 農作物摂取 | - | 1 | 12 |
| 動物排泄物 | - | ＞1 | ＞15 |
| 人間排泄物 | - | 0.5 | 3 |
| 有機リサイクリング | - | ＜0.5 | ＞6 |
| 無機肥料 | - | - | 15 |
| 作物 |
収穫高 （100万トン） |
リン （％） |
作物残渣 （100万トン） |
リン （％） |
リン摂取 （100万トンP） |
| 穀物 | 1670 | 0.3 | 2500 | 0.1 | 7.5 |
| 砂糖作物 | 450 | 0.1 | 350 | 0.2 | 1.2 |
| 根、塊茎 | 130 | 0.1 | 200 | 0.1 | 0.3 |
| 野菜 | 60 | 0.1 | 100 | 0.1 | 0.2 |
| 果物 | 60 | 0.1 | 100 | 0.1 | 0.2 |
| 豆 | 190 | 0.5 | 200 | 0.1 | 1.1 |
| 油脂作物 | 110 | 0.1 | 100 | 0.1 | 0.2 |
| その他の作物 | 80 | 0.1 | 200 | 0.1 | 0.3 |
| 飼料 | 500 | 0.2 | 1.0 | ||
|
|
3250 | 3750 | 12.0 |
| フロー |
年間フロー （100万トンP） |
| インプット | 24-29 |
| 風化 | 2 |
| 大気沈着 | 1-2 |
| 有機リサイクル | 7-10 |
| 作物残渣 | 1-2 |
| 動物肥やし | 6-8 |
| 合成肥料 | 14-15 |
| 除去 | 11-12 |
| 作物 | 8-9 |
| 作物残渣 | 3 |
| ロス | |
| 浸食 | 13-15 |
| バランス | 0-2 |
| インプット・シェア（％） | |
| 有機リサイクル（7/24-10/29） | 29-34 |
| 無機肥料（14/24-15/29） | 52-58 |
| 摂取効率（％）（11/24-12/29） | 41-45 |