一种改进的灰水足迹计算方法

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王丹阳, 李景保, 叶亚亚, 谭芬芳. .一种改进的灰水足迹计算方法.自然资源学报, 2015,30(12): 2120-2130
WANG Dan-yang, LI Jing-bao, YE Ya-ya, TAN Fen-fang. .An Improved Calculation Method of Grey Water Footprint.Journal of Natural Resources,2015,30(12): 2120-2130 复制到剪切板

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一种改进的灰水足迹计算方法

王丹阳¹, 李景保^1,^*, 叶亚亚¹, 谭芬芳^1,²

1. 湖南师范大学资源与环境科学学院,长沙 410081

2. 长沙市环境科学研究所,长沙 410001

第一作者简介：王丹阳（1990- ）,男,山东泰安人,硕士,研究方向为水污染和水资源保护。E-mail：danyang 144@163.com

*通信作者简介：李景保（1951- ）,男,湖南郴州人,教授,研究方向为水循环及水资源保护。E-mail：lijingbao 1951@126.com

收稿日期:2014-12-22 网络出版日期:2015-12-20

基金:国家自然科学基金项目（41571100）; 湖南省重点学科建设项目（地理学）

摘要

灰水足迹是为达到一定水质标准,将污染物稀释至该标准允许下最大浓度所需的水量。灰水足迹理论为定量评估水环境污染提供了新方法,但在实际计算中,由于未考虑对污染物的稀释实际由不同水体完成,且存在将污染物排放量大等同于产生的灰水足迹大的混淆,结果往往不够准确,也不能反映不同水体的污染程度。鉴于此,提出改进的灰水足迹计算方法,将污染物分解到不同水体,计算各水体的灰水足迹,再求和得到总灰水足迹,以湖南省为例进行实证分析。结果显示,近29 a来湖南省灰水足迹呈递增趋势,地表水与地下水灰水足迹之比约为7:3;地表水灰水足迹先后由氨氮和磷决定,地下水始终由磷决定;地表水环境荷载指数相对较低,环境状况优于地下水。

关键词: 水环境污染; 灰水足迹; 地表水; 地下水

中图分类号:X502;TV213.4 文献标志码:A 文章编号:1000-3037(2015)12-2120-11

An Improved Calculation Method of Grey Water Footprint

WANG Dan-yang¹, LI Jing-bao¹, YE Ya-ya¹, TAN Fen-fang^1,²

1.College of Resources and Environmental Science, Hunan Normal University, Changsha 410081, China

2.Changsha Institute of Environmental Science, Changsha 410001, China

Abstract

Presented by Hoekstra in 2002, grey water footprint is a method which describes the pollution status in quantitative way. Grey water footprint is defined as the fresh water volume needed to dilute the pollutant to the maximum concentration allowed by relevant water quality standards. Although this theory provides a new way to assess the condition of water environment pollution, it has several problems when taken in practical application. Firstly, the traditional grey water footprint computation does not consider the fact that the pollutant is usually diluted by different water bodies, so the result figured out only shows the total grey water footprint but fails to reflect the pollution severities of different water bodies; secondly, equating massive discharge of pollutant with large grey water footprint can lead to an incorrect computing result of grey water footprint. On account of these reasons, an improved computing method of grey water footprint is hereby presented. The improved method is a two-step ap-proach, which takes into consideration the fact that the same pollutant can be diluted by several water bodies, and attaches much importance to different demands on different pollutants by water quality standard, thus it can distinguish the two concepts of large grey water footprint and massive discharge of pollutant. The improved method firstly divides the whole quantity of discharged pollutant into several different water bodies and calculates the grey water footprint of each water body based on the “maximal counts” principle, and then sums up the grey water footprints of different water bodies to get the final grey water footprint. The concept of water environment load index is also introduced, and it is defined as the ratio between grey water footprint value of certain water body and volume of that water body. The improved method can not only describe the distribution of certain pollutant in different water bodies such as river, lake, sea, reservoir and underground water, etc. and demonstrate the combination structure of pollutants in certain water body, but also reflect the pollution severities of different water bodies, so it makes the result more accurate. After empirical analysis of Hunan province with the improved grey water footprint, the following results are obtained: during the years 1985-2013, the grey water footprint increased from 133.0 billion to 224.8 billion cubic meters with a steady annual growth rate of 1.89%, and the grey water footprint of surface water accounted for 70%, while the underground water for 30% approximately. The grey water footprint of surface water was determined by ammonia nitrogen in 1985-1991 and by phosphorus in 1992-2013, while the grey water footprint of underground water was always determined by phosphorus in 1985-2013. During the 29 years, the environment load index of surface water was always lower than that of underground water, and the difference between the two varied from 0.41 to 1.03 then to 0.76 demonstrating an inverted U shape. It means that the environment condition of surface water was better than that of underground water during the research time period, and the gap firstly increased and then decreased.

Keyword: water environment pollution; grey water footprint; surface water; underground water

Show Figures

灰水足迹是一种定量描述水环境污染状况的方法。Hoekstra^[1]于2002年最早提出其概念, 定义为以某类水质标准为基准, 将一定负荷的污染物稀释至该标准允许下的最大浓度时所需的淡水水量^[2]。传统的灰水足迹认为同一水体可以稀释不同污染物, 不同污染物所需的稀释水量不具有叠加性, 在计算中将灰水足迹确定为由需要最大稀释水量的污染物决定^{[3, 4, 5]}。但实际上, 同一污染物通常都是由不同水体分别稀释的。举例来说, 农业和工业生产都会产生氨氮, 但前者主要由土壤水和地下水稀释, 后者则一般由地表河湖水稀释^{[6, 7]}。如果按照简单的“ 最大决定” 原则计算灰水足迹, 可能会导致结果出现偏差, 并掩盖一些水体受到污染的严重程度。因此, 本文提出一种新的灰水足迹计算方法, 即先以某类水体中需要稀释水量最大的污染物确定该类水体的灰水足迹, 再将各水体的灰水足迹代数相加, 得到总的灰水足迹, 并以湖南省为例, 参考1985— 2013年的污染物排放数据, 使用新的方法计算该省近29 a来的灰水足迹, 进行实证分析。

1 传统灰水足迹

1.1 基本理论和计算

传统的灰水足迹理论认为水体对污染物的稀释并不唯一, 已稀释一种污染物的水体仍可继续稀释另一种污染物, 最终的灰水足迹由造成灰水足迹最大的污染物决定。根据Hoekstra等著的《水足迹评价手册》^[2], 现行灰水足迹计算方法如下：

总灰水足迹：

$\begin{matrix} G = \max {P g_{1}, P g_{2}, \dots, P g_{m}} \end{matrix}$ （1）

其中：

$\begin{matrix} P g_{i} = \frac{P l_{i}}{C_{i - \max} - C_{i - net}} (i = 1, 2, \dots, m) \end{matrix}$ （2）

式中：G为总灰水足迹（m³）, Pg_i为第i种污染物的灰水足迹（m³）, Pl_i为第i种污染物的排放量（kg）, $\begin{matrix} C_{i - \max} \end{matrix}$ 为水质环境标准允许的第i种污染物的最大浓度（kg/m³）, $\begin{matrix} C_{i - net} \end{matrix}$ 为第i种污染物在受纳水体中的初始浓度（kg/m³）, 一般以零计入^{[3, 8]}。

1.2 实际应用情况

灰水足迹理论提出后, 引起了包括联合国环境规划署（UNEP）、联合国粮农组织（FAO）和世界粮食计划署（WFP）等多个国际组织和相关领域内国内外学者的重视。UNEP^[9]在其公共网站公布了全球五大洲的人均灰水足迹; Chapagain等^[10]评估了世界范围内棉花生产的灰水足迹; 盖力强等^[11]讨论了华北地区小麦和玉米作物的灰水足迹。

在讨论造成灰水足迹的污染物时, 学者普遍从工业、农业和生活三个部门进行分析^{[12, 13, 14, 15, 16]}。在工业和生活部门, 由于化学需氧量（COD）在所有污染物排放量中占比重最大, 所以计算稀释COD所需的水量作为这两部门的灰水足迹。在农业部门, 一般认为化肥施用是主要污染源, 而氮肥施用量最多, 故计算稀释氮素污染消耗的水量作为农业部门的灰水足迹。其他工农业和生活产生的污染物则被认为因排放量相对较小, 造成的灰水足迹不会超过COD和氮素, 不会对总的灰水足迹计算结果产生影响, 所以不予考虑。之后, 比较工业和生活部门COD的灰水足迹和农业部门氮素的灰水足迹, 取较大者为总灰水足迹。

在确定水质环境标准时, 以往研究通常以《地表水环境质量标准》（GB 3838— 2002）^[17]（以下简称《地表水标准》）中的地表水III类水质规定的各类污染物的浓度上限作为C_max代入公式计算, 不考虑其他水体的水质标准。

1.3 存在的问题

传统的灰水足迹计算主要存在以下几个问题：

第一, 未考虑对污染物的稀释实际上是由不同水体完成。以居民生活中的衣物洗涤为例, 居住在河流附近的居民倾向于使用河水洗涤衣物, 洗衣粉中所含的磷酸盐多被河流带走, 而居住在湖泊附近的居民则多使用湖水, 磷酸盐多为湖泊所接纳。这样, 污染物同样是磷酸盐, 但却分别被河流水和湖泊水受纳和稀释。传统的灰水足迹在计算中并未区分不同水体对污染物的分别稀释, 这就有可能使计算结果不够准确, 并掩盖某些水体的实际污染状况。举例来说, 已知《地表水标准》中III类水质对氰化物浓度的要求为不超过0.2 mg/L（20 t/10⁸m³）, 假若有10 t和30 t的氰化物分别进入水量均为1× 10⁸m³的河流水和湖泊水中, 按照传统计算方法, 不考虑受纳污染物的水体不同, 要将这40 t氰化物稀释至20 t/10⁸m³, 刚好需要2× 10⁸m³的水量, 换句话说, 以现有的河流湖泊水体水量之和, 正好可以将这40 t氰化物稀释至达到III类水质标准。而若考虑实际上氰化物被不同水体稀释这一事实, 则会发现, 10 t氰化物进入1× 10⁸m³的河流水, 其浓度已然在III类水质标准之内, 而即使1× 10⁸m³的湖泊水全部用做稀释, 排入湖泊的氰化物浓度也无法达到标准。因此, 忽视对污染物的稀释由不同水体完成这一事实, 可能会掩盖某些水体的实际污染状况。

第二, 将污染物排放量大等同于产生的灰水足迹大。水质标准对不同污染物的浓度要求不同, 这可能会抵消污染物排放量的差别。举例来说, 《地表水标准》中III类水质对地表水中COD的浓度要求为不超过20 mg/L（2 000 t/10⁸m³）, 对汞的浓度要求为不超过0.000 1 mg/L（0.01 t/10⁸m³）, 假若实际排入河流的COD和汞类分别为20 t和0.1 t, 则稀释COD和汞类产生的灰水足迹分别为0.01× 10⁸m³和10× 10⁸m³, 所以尽管汞类的排放量仅为COD的0.5%, 但却成为了决定灰水足迹的污染物。可见, 如果简单将总排放量中占比例不大的污染物予以排除, 就有可能导致计算结果出现偏误。

第三, C_max的选择标准唯一化。由于未区分稀释污染物的水体的不同, 以往的研究都简单参照《地表水标准》确定C_max。而事实上, 不同水体的环境标准是有区别的, 以磷素为例, 要达到III类水质, 河流水中磷素的浓度需不超过0.2 mg/L, 而湖泊水库水则为0.05 mg/L, 倘若参考河流水的标准计算湖库水的灰水足迹, 会使结果偏小, 导致对湖库水体的污染状况估计较实际乐观, 而若参考湖库水体的浓度标准计算河流水的灰水足迹, 则会使得结果偏大, 导致对河流水体的污染状况估计较实际悲观。因此, 不同的水体使用同样的质量标准计算, 也会影响结果的准度。

2 改进的灰水足迹

2.1 基于不同受纳水体的灰水足迹计算

为解决上述问题, 考虑到同一污染物的受纳水体的不唯一性, 并且不同水体用于稀释污染物的水量即灰水足迹可以叠加, 本文提出一种基于不同受纳水体的改进的灰水足迹计算公式：

总灰水足迹由各水体灰水足迹求和得到：

$\begin{matrix} G = \sum W g_{j} (j = 1, 2, \dots, n) \end{matrix}$ （3）

某类水体的灰水足迹：

$\begin{matrix} W g_{j} = \max {P g_{1 j}, P g_{2 j}, \dots, P g_{mj}} \end{matrix}$ （4）

其中：

$\begin{matrix} P g_{ij} = \frac{P l_{ij}}{C_{ij - \max} - C_{ij - net}} (i = 1, 2, \dots, m ； j = 1, 2, \dots, n) \end{matrix}$ （5）

且：

$\begin{matrix} P l_{ij} = λ_{ij} \cdot TP l_{i} \end{matrix}$ （6）

式中：Wg_j为第j种水体的灰水足迹, Pg_ij为第i种污染物造成的第j种水体的灰水足迹, Pl_ij为第i种污染物在第j种水体中的排放量, C_ij_-max为环境水质标准允许的第i种污染物在第j种水体中的最大浓度, C_ij_-net为第i种污染物在第j种水体中的初始浓度, 仍以零计入, TPl_i为第i种污染物的总排放量, λ _ij为第i种污染物的总排放量分解到第j种水体中的比例系数。

此外, 由于大气圈、岩石圈和生物圈的阻滞, 一些污染物只以总排放量的一定比例进入各类水体, 记这一比例为流失率, 这时公式（6）变为：

$\begin{matrix} P l_{ij} = λ_{ij} \cdot μ_{i} \cdot TP l_{i} \end{matrix}$ （7）

其中μ _i为第i种污染物的流失率, 其他同上。

使用公式（3）至（7）计算灰水足迹, 先将污染物分解到不同的受纳水体, 再确定每一受纳水体稀释各类污染物所需的水量并以最大者作为该类水体的灰水足迹, 最后将所有水体的灰水足迹相加, 得到最终灰水足迹。相比传统的计算方法, 改进后的灰水足迹在计算过程中不仅能够描述某一污染物在江、河、湖、海、冰川、积雪、水库、池塘、地下水和大气水中的不同分布状况, 还能够描述造成上述这些水体污染的污染物组合特征; 而在计算结果上, 改进后的灰水足迹不仅使得到的结果更准确, 还能反映和比较不同水体环境受到污染的程度。

2.2 水环境荷载指数

为更好地通过灰水足迹反映各水体的污染程度, 提出水环境荷载指数（L_we）。定义水环境荷载指数为污染物对某类水体造成的灰水足迹（Wg）与该类水体水量（Q）的比值：

$\begin{matrix} L_{we} = \frac{Wg}{Q} \end{matrix}$ （8）

水环境荷载指数反映水体受到污染程度的大小, 取值范围为（0, +∞ ）。当这一指数大于1时, 说明对于某类水体来说, 现有的水量已无法将其中的污染物浓度稀释至环境标准以内。指数越大, 水体受到污染就越严重。

3 实证分析— — 以湖南省为例

3.1 研究区域概况和数据来源

湖南省地处我国中部, 长江中游地区, 属亚热带季风气候, 四季分明, 雨热同期, 年降水量在1 200~1 700 mm之间, 湘、资、沅、澧四水是其主要河流。全省面积约21.18× 10⁴km², 2013年总人口7 147.28× 10⁴人, 其中城镇人口3 427.84× 10⁴人; 实现地区生产总值24 500× 10⁸元, 公共财政收入3 315× 10⁸元, 三次产业比重为13:47:40; 排放化学需氧量（COD）124.9× 10⁴t, 氨氮15.77× 10⁴t。

受到资料数据的限制, 在下面计算中, 水体只区分为地表水和地下水, 即令j=2, 污染物只考虑工业、农业和居民生活三部门产生的可获得较全面数据的污染物, 地表和地下水体的水资源量以多年平均值计入。

我国《地下水质量标准》（GB/T 14818— 9）^[18]和《地表水环境质量标准》（GB 3838— 2002）对III类水定义为“ 以人体健康基准值为依据, 主要适用于集中式生活饮用水水源” , 并给出了该类水质下不同污染物的含量标准。本文基于此确定污染物在地表和地下水体中的环境浓度上限（C_max）。相关计算数据来自《湖南省统计年鉴》、《湖南农村统计年鉴》、《湖南省环境状况公报》和《湖南省水资源公报》。

3.2 污染物的选择及面向受纳水体的分解

理论上说, 考虑到排放量小的污染物造成的灰水足迹未必小, 应尽量将全部污染物纳入计算, 但是这就造成了工作量的增大。因此, 在计算前可以先按照下面的公式排除一些污染物：

$\begin{matrix} w = \frac{P l_{xj}}{P l_{yj}} - \frac{C_{xj - \max}}{C_{yj - \max}} \end{matrix}$ （9）

式中：Pl_xj和Pl_yj分别为x和y两种污染物排放到第j种水体的量, C_xj_-max和C_yj_-max分别为水质环境标准允许的x和y两种污染物在第j种水体中的最大浓度。若ω < 0, 排除污染物x, 即计算第j种水体的灰水足迹时不考虑污染物x; 若ω > 0, 排除污染物y; 若ω =0, 则意味着x和y两种污染物造成的第j种水体的灰水足迹相等, 需再与其他污染物进行比较。

根据公式（9）, 并考虑数据的可得性, 选取工业和生活部门的COD和氨氮（主要是NH₄⁺和NH₃）, 农业部门的硝态氮（NO₃^--N）、磷、石油类和COD共五类污染物进行分析。

工业生产和居民生活产生的主要是点源污染, 污染物由固定的排水管道进入河湖中。COD是以化学方法处理水样时消耗氧化剂的数量, 反映水体中还原性污染物的多少, 在工业和生活部门排放的污染物中所占比重最大, 除此之外氨氮也占有一定的比重。点源污染的污染物不存在部分流失情况, 因此在本文的计算中, 将工业和生活部门产生的COD和氨氮确定为全部流失, 即μ =1, 并全部由地表水体受纳。

化肥农药施用和畜禽养殖是主要农业污染源。在我国, 化肥施用以氮、磷、钾肥和复合肥料为主, 其中又以氮肥最多^[19]。考虑钾素在土壤中部分为土壤胶体所吸附, 部分存在于次生矿物层之间, 水溶性钾占比例较小, 且钾肥使用量相对较小的情况^{[20, 21, 22]}, 本文计算时排除了钾素的污染影响, 只考虑氮肥使用造成的硝态氮的灰水足迹和磷肥使用产生磷素的灰水足迹。复合肥料中氮、磷的比重参考中国农业科学院土壤肥料研究所主编的《中国肥料》^[23]提出的复合肥料中氮磷钾的合理配比1:0.5:0.4确定。

湖南省农业生产中主要施用的农药有毒死蜱（0.77%）、氟虫腈（1.13%）、吡虫啉（1.36%）、乙草胺（5.87%）、阿特拉津（20.74%）、有机磷素（30.78%）、酯类化合物（34.89%）和其他类（4.46%）^[24]。毒死蜱、氟虫腈、吡虫啉、乙草胺和阿特拉津均不溶、难溶或微溶于水且易被土壤阻滞, 故在计算时只考虑有机磷素和酯类化合物农药施用造成的磷素和石油类污染的灰水足迹。

畜禽养殖是COD的另一个重要来源, 2007年全国COD排放3 028.96× 10⁴t, 畜禽养殖就贡献了41.87%^[25]。此外畜禽养殖也会造成少量的氮、磷污染, 但由于数据难以获得, 本文只将其造成的COD纳入计算。

化肥农药施用和畜禽养殖产生的污染物, 一部分残留在农作物和土壤中, 另一部分在自重力和外力作用下, 以一定的流失率转移到地表径流和地下水。根据相关研究和统计资料^{[7, 25, 26, 27, 28]}, 并在咨询专业人员的基础上, 确定农业生产中硝态氮、磷、石油类和COD的流失率分别为18%、15%、12%和22%。

农业生产是非点源污染的主要污染源, 没有固定的排污地点, 污染物通过地表径流或地下渗漏过程进入水体而造成污染^[29], 参考统计数据, 确定将农业生产污染物的60.68%分解到地表河流水, 39.32%分解到地下水^[25]。

综合上述分析, 共确定了工农业生产和居民生活三部门的5类污染物, 并将其分解到两种水体之中, 以计算灰水足迹（表1）。

表1 五类污染物的来源、流失率及在地表和地下水体中的分解 Table 1 Source, loss rate and distribution in surface/underground water of five pollutants

3.3 结果和分析

3.3.1 灰水足迹的变化趋势和构成

1985— 2013年间, 湖南省灰水足迹从1 801× 10⁸m³增长到3 072× 10⁸m³, 年平均增长率1.93%（图1）。以2000年为界, 1985— 2000年的年平均增长率为1.64%, 2001— 2013年为2.47%, 增速有所加快。除1989— 1991、1992— 1993、1994— 1996、2000— 2002年有4次幅度不超过4%的下降之外, 其余年份均为递增趋势。

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	图1 1985— 2013年湖南省灰水足迹变化趋势Fig. 1 Changing trend of grey water footprint in Hunan Province during 1985-2013

1985— 2013年间, 地表水灰水足迹从1 330× 10⁸m³增长到2 248× 10⁸m³, 年平均增长率约为1.89%, 略低于总灰水足迹的1.93%。地表水灰水足迹的变化趋势可以分为两个阶段, 1985— 1996年为波动增长阶段, 在这12 a间, 其环比增长率最高达到14.27%, 最低为-2.85%, 但总体保持了递增的态势; 1997— 2013年为稳定增长阶段, 在此期间, 地表水灰水足迹保持了年平均2.52%的增速, 超过整个研究时间段的平均增速, 并且没有出现负增长。

地下水灰水足迹在1985— 2013年间从471× 10⁸m³增长到824× 10⁸m³, 年平均增长率约为1.95%, 略高于总灰水足迹的1.93%。地下水灰水足迹的变化趋势也可以分为两个阶段, 1985— 2003年波动增长, 19 a间的年均增长率约为2.81%; 2004— 2013年的10 a低速稳定增长, 年均增长率约1.09%。

总的来说, 地表和地下水灰水足迹的变化趋势与总灰水足迹的变化趋势基本吻合, 即前期波动, 中后期稳定, 总体呈较低增长率的正增长。

从构成上看, 在研究时段内, 地表水灰水足迹和地下水灰水足迹对总灰水足迹的贡献稳定在7:3（约2.33）左右。1992年这一比值最小, 约为1.93, 说明该年地下水灰水足迹对总灰水足迹的贡献最大; 1985年这一比值最大, 约为2.82, 说明该年地表水灰水足迹对总灰水足迹的贡献最大。湖南省地表和地下多年平均水资源量分别为1 682× 10⁸m³和392× 10⁸m³, 地表和地下水量对总水量的贡献比约为4.29, 这一数字高于2.33, 说明地表水受到污染的严重程度要低于地下水。

3.3.2 各类污染物对地表和地下水造成的灰水足迹

1985— 1991年间, 地表水稀释氨氮所需的水量在所有污染物中最多, 因此氨氮是这一时段地表水灰水足迹的决定性污染物; 1992— 2013年间, 磷成为了地表水灰水足迹的决定性污染物, 地表水灰水足迹为将磷吸收至环境标准允许范围所需的水量（图2）。

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	图2 1985— 2013年各类污染物造成的地表水灰水足迹Fig. 2 Grey water footprint of surface water caused by pollutants during 1985-2013

COD和石油类造成的灰水足迹相对最少, 但原因不同。在所有污染物中COD的排放量是最大的, 但按环境标准, COD的最大允许浓度是20 mg/L, 分别是氨氮、硝态氮、磷和石油类的20、20、100和400倍, 因此尽管COD的排放量大, 但所需的稀释水量却较少。而对石油类污染物来说, 虽然其环境允许浓度在五类污染物中最低, 但由于排放量小, 所以造成的灰水足迹也较小。

氨氮、硝态氮和磷始终是造成地表水灰水足迹最大的三类污染物。地表水中的氨氮污染主要来自工业和生活, 而硝态氮则主要来自农业氮肥施用。环境标准对氨氮和硝态氮的浓度要求相同, 因此图2中氨氮和硝态氮造成的灰水足迹的变化趋势也就反映了进入地表水体中的氨氮和硝态氮的量的变化趋势, 即氨氮逐渐减少, 而硝态氮逐渐增加, 这与工业生活氨氮排放逐渐减少和氮肥施用不断增加的趋势一致。磷的污染主要来自农业磷肥施用, 由于环境标准要求其在水中的浓度为0.2 mg/L, 所以尽管排放量小于氨氮和硝态氮, 但1992年之后仍成为了地表水灰水足迹的决定性污染物。

1985— 2013年间, 地下水的灰水足迹始终由磷决定, 即在研究时段内, 稀释磷所需的地下水在所有污染物中最多（图3）。地下水的COD和石油类污染主要来自畜禽养殖的粪便排放和农药施用, 这两类污染物造成的灰水足迹始终不大, 原因与上面所述相同。相比磷素, 氮素造成的灰水足迹始终略低, 其原因在于尽管地下水水质标准对磷素浓度的规定是氮素的5倍, 但是实际化肥施用中, 氮肥施用量要接近磷肥的5倍, 故虽然未能成为地下水灰水足迹的决定性污染物, 氮素造成的灰水足迹也只是略低于磷素。

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	图3 1985— 2013年各类污染物造成的地下水灰水足迹Fig. 3 Grey water footprint of underground water caused by pollutants during 1985-2013

3.3.3 地表和地下水环境荷载指数

从增速上看, 2003年之前, 地表水环境荷载指数处于不稳定上升阶段, 增长率在 -2.53%到14.29%之间波动, 2003年之后没有再发生负增长, 保持年均3.28%的速度稳定从0.97上升至1.34（图4）。从数值上看, 1985— 2003年间, 地表水环境荷载指数始终小于1, 说明在这19 a里, 以湖南省地表水资源总量, 能够将所有排放入地表水体的污染物稀释直至达到III类水的水质标准; 2004年后该指数突破1并不断增长, 这意味着自2004年后, 以湖南省现有的地表水资源总量, 已无法保证地表水体水质均处在III类及III类以上, 并且地表水质还有恶化的趋势。

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	图4 1985— 2013年地表和地下水环境荷载指数Fig. 4 Surface/underground water environment load index during 1985-2013

地下水环境荷载指数在研究时段内从1985年的1.20上升至2013年的2.10, 总体上保持了较为平稳的增势, 但1989— 1996年间的波动性较为明显, 这8 a间的增长率最高达到15.06%, 最低则为 -5.69%, 相差超过20个百分点。地下水环境荷载指数在研究时段内始终大于1, 表明稀释进入地下水的污染物所需的水量始终超过地下水的总水量, 即在研究时段内, 全部地下水水质均在III类及III类之上的情况没有发生。

对比两条曲线, 地下水环境荷载指数始终高于地表水环境荷载指数, 这主要是因为地下水资源量有限, 而地表水资源量较丰富。分析地下水与地表水环境荷载指数之差可以发现, 1985年, 地下水与地表水环境荷载指数之差最小, 为0.41, 说明在这一年地下水环境状况最接近地表水; 之后这一差值逐渐增大, 至1994年达到拐点最大值1.03后出现缩小趋势, 到2013年缩小为0.76。这一倒U型的变化轨迹表明地下水与地表水的水质差别经历了先扩大再缩小的过程, 并且在这一过程中, 地表水水质始终优于地下水。

此外, 以2003年为界, 地表水和地下水环境荷载指数在1985— 2003年间的增长率分别为1.15%和2.18%, 而在2004— 2013年间则分别为3.28%和1.72%, 这意味着在2003年之前, 地表水环境的恶化速度要低于地下水, 而2003年之后则相反。

4 讨论

使用传统方法计算湖南省1985— 2013年的灰水足迹, 并与本文方法进行对比（表2）, 在不影响分析的前提下, 限于篇幅, 仅列出近10 a数据。

表2 两种方法计算的灰水足迹对比 Table 2 Comparison of grey water footprints calculated by two methods

近10 a, 使用改进方法计算得到的灰水足迹始终超过传统方法, 超出比例在11.70%~17.70%之间。这是因为使用传统方法计算时, 仅考虑了排放量大的COD和氮, 没有考虑虽然排放量小但环境标准要求浓度更低的磷, 而实际上近10 a的灰水足迹正是由磷素决定的。但是, 由于氮素和磷素造成的灰水足迹差别不大, 所以反映在数据上差别也不大。此外, 传统的灰水足迹计算结果只能给出宏观上的水污染状况, 无法具体到某类水体, 计算得到的数据缺乏可比性。可见, 改进的灰水足迹计算在保留了原始逻辑过程的同时, 在污染物的选取、不同水体对污染物的分别稀释和不同水体的环境标准浓度上进行了完善, 所得结果更加准确, 反映信息更加全面。

5 结论

传统灰水足迹在计算时没有考虑不同受纳水体对同一污染物的稀释, 并以排放量的多少为依据选择纳入灰水足迹计算的污染物, 忽视了同一水质标准对不同污染物浓度要求的不同可能抵消排放量的差别。这些问题都可以导致结果出现偏差, 并掩盖某些水体受到污染的严重程度。本文提出基于不同受纳水体的改进灰水足迹计算方法, 按照先最大再加总的原则, 以各类水体的灰水足迹之和作为总的灰水足迹, 能够使计算结果更加准确, 并反映不同水体的污染情况。

使用改进的灰水足迹计算方法, 以湖南省为例进行了实证分析。结果显示, 湖南省的灰水足迹总体呈增长态势, 地表水和地下水的灰水足迹比例维持在7:3左右; 地表水灰水足迹先后由氨氮和磷决定, 地下水灰水足迹始终由磷决定; 地表水环境荷载指数小于地下水, 但差值逐渐缩小, 说明地表水体的环境状况优于地下水, 但两者差距在不断缩小。值得一提的是, 差距缩小的原因在于地表水质的恶化速度快于地下水, 而并不是地下水的环境质量在逐渐变好。

灰水足迹能够从总体上对水环境状况进行评价, 但具体到某一区域, 还需结合当地污染排放情况、水体自净能力和环境质量要求等因素进行具体分析。基于灰水足迹, 从水质水量综合的角度进行水环境评价, 是后续可深化的一个研究方向。

The authors have declared that no competing interests exist.

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[17]	GB3838—2002GB3838—2002. 中华人民共和国国家标准——地表水环境质量标准 [S]. 北京: 中国标准出版社, 2002. [GB3838-2002GB3838-2002. Environmental Quality Stand ards for Surface Water. Beijing: Stand ards Press of China, 2002. ] [本文引用:1]
[18]	GB/T14848—93. 中华人民共和国国家标准——地下水质量标准 [S]. 北京: 中国标准出版社, 2002. [GB/T14848-93. Environmental Quality Stand ards for Underground Water. Beijing: Stand ards Press of China, 2002. ] [本文引用:1]
[19]	栾江, 仇焕广, 井月, 等. 我国化肥施用量持续增长的原因分解及趋势预测[J]. 自然资源学报, 2013, 28(11): 1869-1877. [LUAN Jiang, QIU Huan-guang, JING Yue, et al. Decomposition of factors contributed to the increase of China’s chemical fertilizer use and projections for future fertilizer use in China. Journal of Natural Resources, 2013, 28(11): 1869-1877. ] [本文引用:1]
[20]	占丽平, 李小坤, 鲁剑巍, 等. 土壤钾素运移的影响因素研究进展[J]. 土壤, 2012, 44(4): 548-553. [ZHAN Li-ping, LI Xiao-kun, LU Jian-wei, et al. Research advances on influence factors of soil potassium movement. Soils, 2012, 44(4): 548-553. ] [本文引用:1]
[21]	谢建昌, 周健民. 我国土壤钾素研究和钾肥使用的进展[J]. 土壤, 1999, 31(5): 244-254. [XIE Jian-chang, ZHOU Jian-min. Study progress of potassium and potash fertilizer using in the soil. Soils, 1999, 31(5): 244-254. ] [本文引用:1]
[22]	廖育林, 郑圣先, 鲁艳红, 等. 长期施钾对红壤水稻土水稻产量及土壤钾素状况的影响[J]. 植物营养与肥料学报, 2009, 15(6): 1372-1379. [LIAO Yu-lin, ZHENG Sheng-xian, LU Yan-hong, et al. Effects of long-term K fertilization on rice yield and soil K status in reddish paddy soil. Plant Nutrition and Fertilizer Science, 2009, 15(6): 1372-1379. ] [本文引用:1]
[23]	中国农业科学院土壤肥料研究所. 中国肥料 [M]. 上海: 上海科学技术出版社, 1994. [Soil and Fertilizer Institute, Chinese Academy of Agricultural Sciences. Fertilizer of China. Shanghai: Shanghai Science and Technology Press, 1994. ] [本文引用:1]
[24]	大通湖区第一次农业污染源普查小组. 大通湖区第一次农业污染源普查公报 [R]. 2009. [Agricultural pollution census team for the first time in Datonghu region. Bulletin of first agricultural pollution census in Datonghu region. 2009. ] [本文引用:1]
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[26]	李学平, 邹美玲. 农田土壤磷素流失研究进展[J]. 中国农学通报, 2010, 26(11): 173-177. [LI Xue-ping, ZOU Mei-ling. Advance of farmland soil phosphorus running off. Chinese Agricultural Science Bulletin, 2010, 26(11): 173-177. ] [本文引用:1]
[27]	陈欣, 王兆骞, 杨武德, 等. 红壤小流域坡地不同利用方式对土壤磷素流失的影响[J]. 生态学报, 2000, 20(3): 374-377. [CHEN Xin, WANG Zhao-qian, YANG Wu-de, et al. Effects of sloping land use patterns on phosphorus loss in a micro watershed of red soil area, Southern China. Acta Ecologica Sinica, 2000, 20(3): 374-377. ] [本文引用:1]
[28]	杨飞, 杨世琦, 诸云强, 等. 中国近30年畜禽养殖量及其耕地氮负荷污染分析[J]. 农业工程学报, 2013, 29(5): 1-9. [YANG Fei, YANG Shi-qi, ZHU Yun-qiang, et al. Analysis on livestock and poultry production and nitrogen pollution load of cultivated land during last 30 years in China. Transactions of the CSAE, 2013, 29(5): 1-9. ] [本文引用:1]
[29]	葛继红, 周曙东. 农业面源污染的经济影响因素分析——基于1978—2009年的江苏省数据[J]. 中国农村经济, 2011(5): 72-80. [GE Ji-hong, ZHOU Shu-dong. Analysis of non-point source pollution effected by economic factors—based on data of Jiangsu province in1978 -2009. Chinese Rural Economic, 2011(5): 72-80. ] [本文引用:1]

2003

0.0

... Hoekstra^[1]于2002年最早提出其概念,定义为以某类水质标准为基准,将一定负荷的污染物稀释至该标准允许下的最大浓度时所需的淡水水量^[2] ...

2011

0.0

... Hoekstra^[1]于2002年最早提出其概念,定义为以某类水质标准为基准,将一定负荷的污染物稀释至该标准允许下的最大浓度时所需的淡水水量^[2] ...

... 根据Hoekstra等著的《水足迹评价手册》^[2],现行灰水足迹计算方法如下： ...

2013

0.0

曾昭, 刘俊国. 北京市灰水足迹评价[J]. 自然资源学报, 2013, 28(7): 1169-1175.

[ZENG

Zhao

, LIU

Jun-guo

. Historical trend of grey water footprint of Beijing, China. Journal of Natural Resources, 2013, 28(7): 1169-1175. ]

Beijing is an international metropolis with serious shortage of water resources. Water scarcity in addition to serious water pollution has made water a major constraint for future socio-economic development and ecological security. In this study, we use grey water footprint as an indicator to quantify the effects of water pollution on the amount of freshwater resources from agricultural, industrial and domestic sectors in Beijing during 1995-2009. These effects are presented as the volume of water that is needed to dilute the water pollutants. The results show that: 1) Grey water footprint of Beijing in 2009 is 4.95 billion m 3 /a, about 2.3 times that of the total amount of water resources in the same year; 2) domestic sector has the largest grey water footprint, followed by agricultural. Industrial sector has the smallest grey water footprint; 3) the grey water footprint of Beijing has declined year by year. Since 1995, the grey water footprints of agricultural, industrial and domestic sectors have decreased by 45%, 93% and 62%, respectively; and 4) although the grey water footprint of Beijing has dropped gradually, the ratio of water bodies reaching water quality standard has shown a decreasing trend. The grey water footprint is much higher than the amount of water resources, leading to accumulation of pollutants in the water bodies. It is not possible to dilute such a large amount of pollutants emitted into natural water bodies only by relying on the self-purification capacity of water bodies. So the residual grey water footprint has a positive sign and the accumulation of residual grey water footprint has increased year by year. As a result, water quality continues to deteriorate. The growth of the accumulation of residual grey water footprint explains the reasons why the quality of water becomes worse even with decreasing grey water footprint. The grey water footprint should be controlled in order to improve the aquatic environment in the Beijing city.

北京市属于重度资源型缺水地区,加上严重的水污染情况,使得水问题成为制约当地社会经济发展和生态安全的关键性因素。研究采用灰水足迹理念将北京市1995-2009年间不同部门产生的污染物以"稀释水"的形式进行量化。研究表明:①北京市2009年灰水足迹为49.5×10 8 m 3 ,约为北京当年水资源量的2.3倍;②生活部门的灰水足迹最大,农业部门次之,工业部门的灰水足迹最小;③北京市灰水足迹呈现逐年下降的趋势,农业、生活和工业部门的灰水足迹在1995-2009年间分别下降了45%、62%和93%;④虽然北京市灰水足迹逐年减小,水体水质却呈现逐年恶化的趋势,剩余灰水足迹(即灰水足迹与水资源的差值)累积值的增加,是北京市水质逐年恶化的直接原因。严格控制灰水足迹是实现水环境总体改善的重要途径。

... 传统的灰水足迹认为同一水体可以稀释不同污染物,不同污染物所需的稀释水量不具有叠加性,在计算中将灰水足迹确定为由需要最大稀释水量的污染物决定^[3,4,5] ...

... 式中：G为总灰水足迹（m³）,Pg_i为第i种污染物的灰水足迹（m³）,Pl_i为第i种污染物的排放量（kg）, Ci-max为水质环境标准允许的第i种污染物的最大浓度（kg/m³）, Ci-net为第i种污染物在受纳水体中的初始浓度（kg/m³）,一般以零计入^[3,8] ...

2014

0.0

曹连海, 吴普特, 赵西宁, 等. 内蒙古河套灌区粮食生产灰水足迹评价[J]. 农业工程学报, 2014, 30(1): 63-70.

[CAO

Lian-hai

, WU

Pu-te

, ZHAO

Xi-ning

, et al. Evaluation of grey water footprint of grain production in Hetao irrigation district, Inner Moreongolia. Transactions of the CSAE, 2014, 30(1): 63-70. ]

随着面源污染和土壤盐渍化成为重要的环境污染源和粮食安全的制约要素,如何评价和量化农业生产的负面效应,成为亟需解决的问题。水足迹理论的出现使该负面效应的量化成为可能,水足迹包括蓝水、绿水和灰水足迹,灰水足迹可以表征不同类型负面效应的大小,粮食生产灰水足迹反映了单位粮食产量的负面效应。该文应用水足迹理论,以内蒙古河套灌区为研究区,给出粮食生产灰水足迹的计算方法,选取环境最大允许浓度Cmax和本底浓度Cnat,逐项计算各项灰水足迹,并根据短板原理得出总灰水足迹, 计算分析河套灌区粮食生产灰水足迹。结果表明:2005-2008年面源污染的灰水足迹为0.55~0.58亿m3;积盐的灰水足迹从2005年的 4.570亿m3减少到2008年的1.825亿m3。总灰水足迹从2006年的5.872亿m3,减少到2008年的1.825亿m3,总灰水足迹在总水足迹中比例小于10%,有逐年降低的趋势。2005-2008年粮食生产灰水足迹分别为0.129、0.159、0.062和0.043 m3/kg,粮食生产灰水足迹有逐年降低的趋势,2008年的粮食生产灰水足迹仅相当于2006年的27.04%。节水灌溉等新技术的推广是其主要原因, 节水灌溉可以减少无效灌溉水量和水分的无效蒸发量,从而减小粮食生产灰水足迹。在此基础上,给出减少粮食生产灰水足迹的措施,即节水灌溉、种植业结构调整、合理确定地下水位和合理使用化肥、农药。研究成果较好地量化了大型灌区粮食生产的负面效应和粮食生产灰水足迹,可为其他粮食主产区农业可持续发展及制定农业产业政策提供参考。

2013

0.0

张郁, 张峥, 苏明涛. 基于化肥污染的黑龙江垦区粮食生产灰水足迹研究[J]. 干旱区资源与环境, 2013, 27(7): 28-32.

[ZHANG

, ZHANG

Zheng

, SU

Ming-tao

. Research on grey water footprint based on chemical fertilizer use in the grain production in Heilongjiang reclamation area. Journal of Arid Land Resources and Environment, 2013, 27(7): 28-32. ]

化肥在促进粮食增产的同时,也是造成农业面源污染的主要来源.文中以东北地区重要的商品粮基地-黑龙江垦区为例,应用灰水足迹方法,对基于化肥污染造成的粮食生产灰水足迹进行研究.结果表明:粮食产量与灰水足迹、化肥施用量与灰水足迹均高度相关,相关系数分别为0.987、0.975；水稻生产对灰水足迹的贡献率为56％,所占比重最大,水稻高产地区同时也是高污染地区,并通过国际、国内比较,指出黑龙江垦区降低灰水足迹的空间,为"绿色垦区"建设提供科学决策的参考.

2006

0.0

贾蕊, 陆迁, 何学松. 我国农业污染现状、原因及对策研究[J]. 中国农业科技导报, 2006, 8(1): 59-63.

[JIA

Rui

, LU

Qian

, HE

Xue-song

. Present situation, reasons and countermeasures of the agriculture pollution of China. Review of China Agricultural Science and Technology, 2006, 8(1): 59-63. ]

集约化的农业生产模式在提高农产品产量的同时,也给我国带来了严重的农业污染.由于"小农经济"难以实现绿色生产等原因,农业污染已成为制约我国农业可持续发展的主要障碍.通过绿色扶持政策提高农民从事绿色生产的积极性等措施是控制农业污染问题的有效途径.

... 举例来说,农业和工业生产都会产生氨氮,但前者主要由土壤水和地下水稀释,后者则一般由地表河湖水稀释^[6,7] ...

1996

0.0

王家玉, 王胜佳, 陈义, 等. 稻田土壤中氮素淋失的研究[J]. 土壤学报, 1996, 33(1): 28-35.

[WANG

Jia-yu

, WANG

Sheng-jia

, CHEN

, et al. Study on the nitrogen leaching in rice fields. Acta Pedologica Sinica, 1996, 33(1): 28-35. ]

Nitrogen leaching loss from double cropping rice fields was observed using a lysimeter system during 1991-1994. The main results are summarized as follows:1.The basic form of nitrogen leached from rice fields-was nitrate nitrogen(NO 3 - -N) rather than ammonium nitrogen (NH 4 + -N),so the N fertilizer applied in rice fields could result in the nitrate pollution to underground water due to N leaching.2. N application showed an obvious effect on NH 4 -N concentrations in the percolateing soil depth of at 10-16cm, and a rather high NH 4 + -N concentration occurred in urea plot compared with the NH 4 HC0 3 plot, suggesting the possibility of more N-leaching in NH 4 HC0 3 plot than in urea plot.3. The NO 3 - -N level in the percolating at water soil depth of 90-96cm was consistently higher in the NH 4 HCO 3 plot than in the urea plot, which may be ascribed to the obvious dif ference of transformation dynamics between NH 4 HCO 3 and urea. 4. Under the conditions of an application rate of 300 kg urea-Nha -1 and a percolation of 540 mm, a NO 3 - -N leaching of about 23 kg ha -1 and a NO 3 - -N+NH 4 + -N leaching load of nearly 27 kg ha -1 were estimated for double-rice cropping paddy. 5. Based on the observed peak levels of 9 to 11 mg NO 3 - -N L -1 during a certain period of time and the limit of 10 mg NO 3 - -N L -1 in drinking water derived from underground water, we recommended a application limit of 150 kg Nha -1 per rice-cropping season.

本文应用稻田大型原状土柱渗漏计,研究了双季稻田土壤中氮素随渗漏水流淋失的形态、数量、季节性变化以及若干农化因子的影响。明确了稻田中氮素淋失的基本形态是硝态氮(NO 3 - -N),估算出双季稻田中氮素淋失总量可接近30kgN/ha,同时肯定了农田施用氮肥对地下水体环境可能的NO 3 - -N污染,建议双季稻田中每季水稻的氮肥用量宜控制在150kgN/ha;本文还证实氮肥用量对氮素淋失有明显影响,不同氮肥品种的氮素淋失是碳铵高于尿素,采用涂层包膜处理似可减少氮肥的淋失。

... 举例来说,农业和工业生产都会产生氨氮,但前者主要由土壤水和地下水稀释,后者则一般由地表河湖水稀释^[6,7] ...

... 根据相关研究和统计资料^{[7,25,26,27,28]},并在咨询专业人员的基础上,确定农业生产中硝态氮、磷、石油类和COD的流失率分别为18%、15%、12%和22% ...

0.0

王来力, 丁雪梅, 吴雄英. 纺织产品的灰水碳足迹核算[J]. 印染, 2013(9): 41-43.

[WANG

Lai-li

, DING

Xue-mei

, WU

Xiong-ying.

Assessment of grey water footprint of textile products. China Dyeing and Printing, 2013(9): 41-43. ]

水足迹是一种衡量水资源消耗、水源类型、污染量和污染类型的多维指标,为水资源管理提供了新的思路和方法.文中结合纺织产品的生产加工特点,参照水足迹理论,提出了初始灰水足迹、残余灰水足迹、工序灰水足迹和整体灰水足迹的概念和核算方法,对纺织产品灰水足迹的核算进行了讨论.

0.0

... UNEP^[9]在其公共网站公布了全球五大洲的人均灰水足迹 ...

2006

0.0

... Chapagain等^[10]评估了世界范围内棉花生产的灰水足迹 ...

2010

0.0

盖力强, 谢高地, 李士美, 等. 华北平原小麦、玉米作物生产水足迹的研究[J]. 资源科学, 2010, 32(11): 2066-2070.

[GAI

Li-qiang

, XIE

Gao-di

, LI

Shi-mei

, et al. A study on production water footprint of winter-wheat and maize in the north China plain. Resources Science, 2010, 32(11): 2066-2070. ]

Water footprint is an indicator of freshwater use that accounts for not only the direct water consumption of a consumer or producer, but also the indirect water consumption. In general, water footprint can be regarded as a comprehensive indicator of freshwater resources appropriation, close to the traditional and restricted measure of water withdrawal. Based on the concept and calculation methods of water footprint, this paper estimates virtual water and water footprint of the production of major crops (i.e., winter wheat and summer maize) of the North China Plain, Hebei Province, Beijing and Tianjin Municipalities, in year 2007. Furthermore, the study clarifies three types of impacts, i.e., evaporation of infiltrated rainwater for crop growth (green water use), withdrawal of ground- or surface water for irrigation or processing (blue water use), and water pollution during growth. The latter impact was quantified in terms of the dilution volume necessary to abate pollution. Results showed that the total crop production water footprint was roughly 345.07 billion m 3 per year, 2.2 times of the total local water resources, from which it is clear that reduction in wheat and maize crop production water footprint seemed to be significant over the North China Plain. Of the total crop production water footprint, wheat accounted for 172 billion m 3 , and that of maize took up 173.07 billion m 3 . As for the wheat production water footprint, 30.85 billion m 3 was considered green water footprint, 102.5 billion m 3 was blue water footprint, and 38.65 billion m 3 was grey water footprint. Concerning maize production water footprint, about 101.06 billion m 3 was green water footprint, 26.92 billion m 3 was blue water footprint, and 45.09 billion m 3 was grey water footprint. The major volume of water to sustain wheat plant growth was from blue water, and the major volume of water to sustain maize plant came from green water (rainwater). In general, utilization of blue water can affect the environment more than does the green water use. Furthermore, green water use shows relatively few negative environmental impacts in that there is only a slight difference between the evapotranspiration from the crop field and the evapotranspiration that would take place in presence of natural vegetated cover. Therefore, the green water footprint seems to be of more importance in water resources management and environmental protection. The portion of the water footprint mitigating water requirements deserves attention as well.

本文借助水足迹的概念，计算了华北平原地区（河北、北京、天津）小麦、玉米的虚拟水含量及其生长生产水足迹，并就绿水的重要性和灰水对环境的不利影响进行了相关分析。结果显示：2007年华北平原主要地区小麦虚拟水含量为1.054 m3/㎏，生长用水以蓝水为主；玉米虚拟水含量为0.808 m3/㎏，生长用水以绿水为主；小麦生产水足迹为172×10 8 m 3 ，其中绿水足迹30.85×10 8 m 3 ，蓝水足迹102.5×10 8 m 3 ，灰水足迹38.65×10 8 m 3 ；玉米生产水足迹为173.07×10 8 m 3 ，其中绿水足迹101.06×10 8 m 3 ，蓝水足迹26.92×10 8 m 3 ，灰水足迹45.09×10 8 m 3 。通过分析表明：绿水在当地农作物生产中占有重要的地位，绿水的使用与作物的生长特点及作物生长周期有关；小麦、玉米总水足迹约为当地水资源总量的2.2倍，减少小麦、玉米作物生产水足迹对华北平原具有重要的意义。

... 盖力强等^[11]讨论了华北地区小麦和玉米作物的灰水足迹 ...

2013

0.0

孙才志, 陈栓, 赵良仕. 基于ESDA的中国省际水足迹强度的空间关联格局分析[J]. 自然资源学报, 2013, 28(4): 571-580.

[SUN

Cai-zhi

, CHEN

Shuan

, ZHAO

Liang-shi

. Spatial correlation pattern analysis of water footprint intensity based on ESDA model at provincial scale in China. Journal of Natural Resources, 2013, 28(4): 571-580. ]

Water footprint intensity is an index that can comprehensively reflect the water use efficiency, this paper firstly estimated the water footprint of 31 provinces, municipalities and autonomous regions in China (excluding Hong Kong, Macao and Taiwan due to no data) from 1995 to 2009, and the water footprint intensity was then calculated, the ESDA (Exploratory Spatial Data Analysis) model was applied to study the spatial correlation pattern and changing tendency of water footprint intensity, the results show that: 1) the water footprint intensity has a decreasing tendency in general which means that the water use efficience are increasing in the 15 years, but the decreasing amounts of water footprint intensity are imbalance among the 31 provinces (regions), the regions located in the west China have a larger decreasing amount than the regions located in the east China in general. 2)From the aspect of global spatial difference, the water footprint intensity has a positive correlation characteristics, which means that there exists a spatial cluster feature, in other words, the regions with high water footprint intensity are apt to be adjacent to the regions with high water footprint intensity, and the regions with low water footprint intensity are apt to be adjacent to the regions with low water footprint intensity. 3) From the aspect of local spatial difference, the regions with LL (low-low) or HH (high-high) correlation pattern have a large percentage in the 31 provinces (regions), and the number of this kind of regions are steadily increasing in the 15 years, which reflects the fact that the special cluster becomes more and more obvious, and a spillover effect of water footprint intensity may exist. Among these regions, the regions with LL (low-low) correlation pattern are mainly located in the eastern coast regions of China, and water footprint intensity in these regions has an obvious diffusing tendency. The regions with HH (high-high) correlation pattern are mainly located in the west China, which are steady in spatial distribution in these years.

水足迹强度是一个反映水的利用效率的指标,论文在对1995-2009年中国31个省(市、区)水足迹计算的基础上(因资料所限,未考虑香港、澳门和台湾地区),利用探索性空间数据分析(ESDA)对15 a来各地区水足迹强度空间分布格局以及演变态势进行了分析和探讨。结果表明:①中国水足迹强度整体呈现明显的下降趋势,说明水资源的利用效率明显提高,但是区域发展并不平衡;②从全局空间分异来看,中国各地区水足迹强度呈现出正的空间相关性特征,存在着空间集聚特征,即水足迹强度高的地区相互邻接,强度低的地区相互邻接;③从局部空间分异来看,空间正相关模式(LL集聚和HH集聚)所占比例很大,且在研究年份内逐渐增加,反映出水足迹强度的LL集聚和HH集聚变得越来越显著。LL集聚主要分布在东部沿海一带,在空间上有明显的向周边扩散的趋势;HH集聚主要分布在西部地区,在空间分布上较稳定。

... 在讨论造成灰水足迹的污染物时,学者普遍从工业、农业和生活三个部门进行分析^{[12,13,14,15,16]} ...

2010

0.0

孙才志, 刘玉玉, 陈丽新, 等. 基于基尼系数和锡尔指数的中国水足迹强度时空差异变化格局[J]. 生态学报, 2010, 30(5): 1312-1319.

[SUN

Cai-zhi

, LIU

Yu-yu

, CHEN

Li-xin

, et al. The spatial temporal disparities of water footprints intensity based on Ginicoefficient and Theil index in China. Acta Ecologica Sinica, 2010, 30(5): 1312-1319. ]

Water footprint can measure the real water resources consumption of the human being, and its intensity reflects the water utilization efficiency. Based on the calculated water footprint in different regions of China from 1997 to 2007, this paper analyzed the spatial distribution variations in the past 11 years using Gini coefficient and Theil index. The results show that water footprint intensity has declined on the whole in China which means the water utilization efficiency has improved, in spite of regional imbalance, the general regional difference of water footprint intensity has experienced a course of successive increase first and decrease next. The spatial development tends to polarize from 1997 to 2002 and be similar in the next few years, and the difference between the south and north reduced. The south concerning the share of contribution to water footprint intensity in regional differences is larger than that of the north, and the east share is lager than that of the west. The main factors causing the spatial distribution variations are the regional development strategy, the level of economic development and the degree of market development. In addition, it has been found that polarization in regional differences of water pollution footprint intensity is very serious in China, which reveals the fact that, with the economic development, the water pollution problems in some areas are very serious. At last, some corresponding suggestions responding to identified problems were put forward in order to coordinate the relations between economy development and water resources utilization in China.

水足迹可以衡量人类对水资源的真实占有量，而水足迹强度则表征了人类对水资源的利用效率水平。在计算出1997-2007年中国各地区水足迹的基础上，借助于基尼系数和锡尔指数计算方法，探索分析中国近11a水足迹强度发展的空间格局变化规律。结果表明：中国水足迹强度整体呈下降趋势，水资源利用效率有所提高，但是区域发展不平衡；水足迹强度区域总差异经历了“先增大后缩小”的过程，中东西三大地带空间发展呈先极化后趋同的态势，南北区差异总体有所缩小；对水足迹强度区域内部差异贡献份额南方大于北方、东部大于中西部；促使空间差异格局变化的主要因素为区域发展策略、经济发展水平和市场发育程度等；另外，发现中国水污染足迹强度区域差异极化现象非常严重，说明随经济的发展部分地区水污染问题很严峻。最后针对发现的问题提出了协调我国经济发展与水资源利用的相应建议。

... 在讨论造成灰水足迹的污染物时,学者普遍从工业、农业和生活三个部门进行分析^{[12,13,14,15,16]} ...

0.0

... 在讨论造成灰水足迹的污染物时,学者普遍从工业、农业和生活三个部门进行分析^{[12,13,14,15,16]} ...

2014

0.0

邓晓军, 韩龙飞, 杨明楠, 等. 城市水足迹对比分析——以上海和重庆为例[J]. 长江流域资源与环境, 2014, 23(2): 189-195.

[DENG

Xiao-jun

, HAN

Long-fei

, YANG

Ming-nan

, et al. Comparative analysis of urban water footprint—A case study of Shanghai and Chongqing. Resources and Environment in the Yangtze Basin, 2014, 23(2): 189-195. ]

Water is required for the production of nearly all goods. The water used in the production process of an agricultural or industrial product is called the ‘virtual water’ contained in the product. If one region exports a waterintensive product to another region, it exports water in virtual form. In this way some regions support other regions in their water needs. For waterscarce regions it could be attractive to achieve water security by importing waterintensive products instead of producing all waterdemanding products locally. Reversibly, waterrich regions could benefit from their abundance of water resources by producing waterintensive products for export. Water footprint concept is closely linked to the virtual water concept. The water footprint concept has been developed in order to have an indicator of water use in relation to consumption of people. The water footprint of a region is defined as the volume of water needed for the production of the goods and services consumed by the inhabitants in the region. The internal water footprint of a region is the volume of water used from the local water resources to produce the goods and services consumed by the inhabitants in the region. The external water footprint of a region is the volume of water used in other regions to produce goods and services imported and consumed by the inhabitants in the region. The water footprint of a region can be assessed by taking the use of the local water resources, subtracting the virtual water flow that leaves the region and adding the virtual water flow that enters the region. Based on the theories and methods of the virtual water and the water footprint, the concept of the urban water footprint was put forward and the calculation model of the urban water footprint was established, which was used to calculate the utilization of water resources of the Shanghai and Chongqing from 1999 to 2008 in order to reveal the effects and its differences of social and economic development on water resources system. The results showed that the total water footprint of Shanghai and Chongqing both showed an increasing tendency, and the gap between them was reducing in the recent decade. The water footprint structure changed little in Chongqing, while the proportion of virtual water net input quantity grew rapidly in Shanghai. Besides, the utilization of water resources was overloaded seriously in Shanghai, which was in a safe state in Chongqing. The selfsufficiency capacity of water resources was low in Shanghai, and the dependence on outside was much higher than Chongqing. Moreover, the efficiency in water resources utilized in Chongqing was much lower than Shanghai. Finally, several countermeasures to ensure the safety of urban water resources were proposed from the perspective of consumers, producers and managers

(1.School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210023, China;2.School of Environmental Science and Resources, Guangxi Normal University, Guilin 541004, China

基于虚拟水和水足迹的理论与方法，提出了城市水足迹的概念，构建了城市水足迹的计算模型，并对上海和重庆1999～2008年的水足迹进行对比分析，以揭示两市社会经济发展对水资源系统的影响及其差异。结果表明：近10 a来上海和重庆的水足迹总体均呈上升趋势，且两者的差距有缩小的趋势；重庆的水足迹结构变化不大，而上海的虚拟水净输入量所占比例快速增长；上海的水资源利用呈严重超载状态，重庆的水资源利用尚处于安全范围；上海的水资源自给能力较低，对外依赖的程度远高于重庆；重庆的水资源利用效益比上海低得多。最后，分别从消费者、生产者和管理者的角度提出了保障城市水资源安全的对策和建议

... 在讨论造成灰水足迹的污染物时,学者普遍从工业、农业和生活三个部门进行分析^{[12,13,14,15,16]} ...

2009

0.0

... 在讨论造成灰水足迹的污染物时,学者普遍从工业、农业和生活三个部门进行分析^{[12,13,14,15,16]} ...

2002

0.0

... 2002）^[17]（以下简称《地表水标准》）中的地表水III类水质规定的各类污染物的浓度上限作为C_max代入公式计算,不考虑其他水体的水质标准 ...

2002

0.0

... 9）^[18]和《地表水环境质量标准》（GB 3838#cod#x02014 ...

2013

0.0

栾江, 仇焕广, 井月, 等. 我国化肥施用量持续增长的原因分解及趋势预测[J]. 自然资源学报, 2013, 28(11): 1869-1877.

[LUAN

Jiang

, QIU

Huan-guang

, JING

Yue

, et al. Decomposition of factors contributed to the increase of China’s chemical fertilizer use and projections for future fertilizer use in China. Journal of Natural Resources, 2013, 28(11): 1869-1877. ]

Intensive use of chemical fertilizer has largely contributed to the increase of China's agricultural production in the last 30 years, while in the same time, the excessive use of chemical fertilizer has also led to serious negative impacts on environment. There is a lot of debate on what causes continuous growth of fertilizer use in China and what would be the trend of future fertilizer use in China. Using the official statistical data of fertilizer use, this paper decomposed the factors that led to the increase of chemical fertilizer in China in the past 20 years. The results showed that the growth of fertilizer intensity is the major contributor to the overall growth of fertilizer use. But since 2007, the contribution from fertilizer intensity has decreased, while the expansion of cultivated area has begun to play a big role. On the basis of decomposition results and CHINAGRO model, this paper projects the national and provincial levels of fertilizer use in 2020. The results showed that in the next 10 years, China's total fertilizer use and per unit sown area of fertilizer use will continue to increase, and keep higher than the international limited standard which is 225 kg/hm 2 in a long period. The total fertilizer use and per hectare of cultivated land fertilizer usage in 2020 are expected to increase by 2% and 4.3% respectively compared with 2010. Per hectare of fertilizer use in Guangdong, Fujian, Tianjin and Beijing will be close to or more than 600 kg/hm 2 in 2020, which will exert great pressures on environment of these regions.

我国化肥大量使用在提高农业生产的同时也对环境产生了严重的负面影响。目前国内外学术界对我国化肥施用量持续增长的原因以及未来我国化肥使用的发展趋势还存在较大争议。论文利用过去20 a 间我国化肥施用量的相关数据, 对化肥施用量持续增长的成因进行了分解。研究结果表明:化肥使用强度的增长是我国化肥施用总量增长的主因, 但从2007 年以来, 使用强度的贡献不断下降, 播种面积调整的贡献有所提高。根据分解结果并利用“中国农业可持续发展决策支持系统”(CHINAGRO) 预测了2020 年全国和各省化肥使用量情况。模型分析结果表明如果不采取措施, 我国未来化肥的使用总量和单位播种面积化肥施用量将依然呈现增长趋势, 且单位面积化肥用量将长期高于225 kg/hm 2 的国际上限标准。预计到2020年我国化肥总施用量和单位播种面积化肥施用量比2010 年分别提高2%和4.3%。东部地区单位播种面积化肥施用量较高, 2020 年广东、福建、天津、北京等省(市) 化肥单位面积施用量将接近或超过600 kg/hm 2 , 这将对当地环境造成巨大压力。

... 在我国,化肥施用以氮、磷、钾肥和复合肥料为主,其中又以氮肥最多^[19] ...

2012

0.0

占丽平, 李小坤, 鲁剑巍, 等. 土壤钾素运移的影响因素研究进展[J]. 土壤, 2012, 44(4): 548-553.

[ZHAN

Li-ping

, LI

Xiao-kun

, LU

Jian-wei

, et al. Research advances on influence factors of soil potassium movement. Soils, 2012, 44(4): 548-553. ]

钾是植物必需的营养元素,土壤中钾素是作物所需钾素的主要来源.土壤中钾素通过质流、扩散和根系截获的方式到达根表被植物吸收.这些运移方式受一定因素的影响.本文简要综述了土壤钾素运移的影响因素,包括物理因素、化学因素和生物因素,归纳了土壤水分、质地、体积质量、温度、pH值、陪伴离子、钾离子的浓度和植物特性等因素对土壤钾素运移的影响,并展望了未来土壤钾素运移的重点研究方向.

... 考虑钾素在土壤中部分为土壤胶体所吸附,部分存在于次生矿物层之间,水溶性钾占比例较小,且钾肥使用量相对较小的情况^[20,21,22],本文计算时排除了钾素的污染影响,只考虑氮肥使用造成的硝态氮的灰水足迹和磷肥使用产生磷素的灰水足迹 ...

1999

0.0

谢建昌, 周健民. 我国土壤钾素研究和钾肥使用的进展[J]. 土壤, 1999, 31(5): 244-254.

[XIE

Jian-chang

, ZHOU

Jian-min

. Study progress of potassium and potash fertilizer using in the soil. Soils, 1999, 31(5): 244-254. ]

回顾了建国以来我国土壤钾素研究和钾肥使用的历程，分别就钾肥效应，钾肥有效施用条件，土壤含钾矿物和钾的固定、释放，土壤钾素含量、状态和有效性，土壤钾素供给能力的评定，农田钾素循环和平衡等方面的研究进展作了综述。从全国来看，钾肥用量在逐年增长，钾肥所占比例在逐步增加，但与需求相比，仍有很大差距，应继续增加钾肥在化肥中的比重。在研究今后农业持续发展中的钾肥需求量时，除了应看到我国农田土壤钾素肥力下降、钾肥有效地区在不断扩大的趋势外，世界各国的用肥比例也可作为借鉴

2009

0.0

廖育林, 郑圣先, 鲁艳红, 等. 长期施钾对红壤水稻土水稻产量及土壤钾素状况的影响[J]. 植物营养与肥料学报, 2009, 15(6): 1372-1379. [LIAO Yu-lin, ZHENG Sheng-xian, LU Yan-hong, et al. Effects of long-term K fertilization on rice yield and soil K status in reddish paddy soil. Plant Nutrition and Fertilizer Science, 2009, 15(6): 1372-1379. ]

A 27 years of long-term experiment was conducted to evaluate the effects of K fertilizer application on rice yield and soil K status in reddish paddy soil. There were 5 treatments, namely, CK (without fertilization), NP (N, P fertilizers), NPK (N, P and K fertilizers), NP+RS (NP plus rice straw) and NPK+RS (NPK plus rice straw) in this study. The results show that the K fertilizer applications could obviously increase grain yields of early rice and late rice. The average yields of the early rice under the NPK and NPK+RS treatments are increased by 15.2% and 10.9%, respectively, and those of the late rice are increased by 17.2% and 9.1% compared with the NP and NP+RS treatments over 27 years. The 27-year yield change trends of both the early and late rice are different in various treatments. There are negative yield change trends with time in the CK and NP treatments, while there are the positive trends in the NPK, NP+RS and NPK+RS treatments. Contents of total K, slowly available K and available K in the different soil layers under the NPK and NPK+RS treatments are higher than those of corresponding soil layers under the NP and NP+RS treatments. Values of the apparent K balance in the soil-crop system are negative in all treatments except for the NPK+RS treatment, among which the values are highest in the CK and NP treatments. Long-term rational K fertilization could increase rice yield and sustain soil K fertility.

研究了长期定位施肥试验中连续27年（1981～2007）施用钾肥对水稻产量和土壤钾素状况的影响。本试验选择了其中5个处理：CK（不施肥）、NP（施氮、磷肥）、NPK（施氮、磷、钾肥）、NP+RS（施氮、磷肥和稻草）和NPK+RS（施氮、磷、钾肥和稻草）。结果表明，施钾能明显提高水稻产量，施钾肥的NPK和NPK+RS处理27年的早稻平均产量分别比NP和NP+RS处理增加15.2%和10.9%；晚稻增产17.2%和9.1%；在27年54季水稻种植期间，不同施肥处理早、晚稻产量的变化趋势不同。CK、NP处理的早、晚稻产量随时间的推移呈负变化趋势，而NPK、NP+RS和NPK+RS处理的早、晚稻产量呈正变化趋势。施钾的NPK和NPK+RS处理不同土层中土壤全钾、缓效钾和速效钾含量均高于NP和NP+RS处理的相同土层；除NPK+RS处理外，其它各处理表观钾平衡均为负值，其中CK和NP处理钾的负平衡值最大。长期施用钾肥能提高水稻产量和维持土壤钾素肥力。

1994

0.0

... 复合肥料中氮、磷的比重参考中国农业科学院土壤肥料研究所主编的《中国肥料》^[23]提出的复合肥料中氮磷钾的合理配比1:0 ...

2009

0.0

... 46%）^[24] ...

2010

0.0

中华人民共和国环境保护部. 第一次全国污染源普查公报 [R]. 2010.

[Ministry of Environmental Protection of the People’s Republic of China. The first national pollution census bulletin. 2010. ]

... 87%^[25] ...

... 根据相关研究和统计资料^{[7,25,26,27,28]},并在咨询专业人员的基础上,确定农业生产中硝态氮、磷、石油类和COD的流失率分别为18%、15%、12%和22% ...

... 32%分解到地下水^[25] ...

2010

0.0

李学平, 邹美玲. 农田土壤磷素流失研究进展[J]. 中国农学通报, 2010, 26(11): 173-177.

[LI

Xue-ping

, ZOU

Mei-ling

. Advance of farmland soil phosphorus running off. Chinese Agricultural Science Bulletin, 2010, 26(11): 173-177. ]

本文对近些年来有关农田土壤磷素流失及其对水环境的影响进行综述。主要从农田土壤磷素的流失现状阐述磷素流失对水体的影响，讨论了磷肥的施用、土壤性质以及磷素的运输途径对土壤磷素流失的影响及其相关机理，同时阐述了土壤磷素流失的环境风险，最后该研究领域存在的若干问题。

... 根据相关研究和统计资料^{[7,25,26,27,28]},并在咨询专业人员的基础上,确定农业生产中硝态氮、磷、石油类和COD的流失率分别为18%、15%、12%和22% ...

2000

0.0

陈欣, 王兆骞, 杨武德, 等. 红壤小流域坡地不同利用方式对土壤磷素流失的影响[J]. 生态学报, 2000, 20(3): 374-377.

[CHEN

Xin

, WANG

Zhao-qian

, YANG

Wu-de

, et al. Effects of sloping land use patterns on phosphorus loss in a micro watershed of red soil area, Southern China. Acta Ecologica Sinica, 2000, 20(3): 374-377. ]

The study was conducted in a Paixichong micro watershed ecosystem of Deqing County,Zhejiang Province.The results obtained showed as follows:(1)Phosphorus loss varied obviously in different land use patterns.The order of phosphorus loss was bamboo field>upland field>newly exploited orchard>early tea plantation>China fir forest>waste grassland.(2)Particulate phosphorus(PP)was the major form of phosphorus loss with the run off.The average of PP in total phosphorus (TP)was 78 07% but varied with land use pa...

以浙江德清县排溪冲小流域生态系统为实例 ,采用定位土芯 Eu示踪和无界径流小区法研究了流域内坡地不同利用方式对土壤磷素流失的影响 ,结果表明 :( 1 )坡地不同利用方式磷素流失差异明显 ,流失最严重的是竹园 ,其次是旱地作物和新建果园 ,再次是幼龄茶园 ,林地和未开发利用的荒草地磷素的流失较轻 ;( 2 )泥沙结合态磷 ( Particulate phospho-rus,PP)随泥沙迁移流失是红壤坡地磷素流的主要形式 ,6种利用方式中 ,PP流失量占总磷流失量的平均值为 78.0 7%。但土地利用方式不同有差异 ,荒草地、林地和幼龄茶园流失的磷素中可溶性磷 ( Dissolved phosphorus,DP)的比重较大 ,分别为 3 5.2 9%、3 1 .4 9%和 2 7.65% ;( 3 )竹园、旱地作物和新开果园磷素流失严重的主要原因是农事活动和雨季相吻合 ,因而如何调整农事活动时间是减轻坡地磷素流失的关键。

... 根据相关研究和统计资料^{[7,25,26,27,28]},并在咨询专业人员的基础上,确定农业生产中硝态氮、磷、石油类和COD的流失率分别为18%、15%、12%和22% ...

2013

0.0

杨飞, 杨世琦, 诸云强, 等. 中国近30年畜禽养殖量及其耕地氮负荷污染分析[J]. 农业工程学报, 2013, 29(5): 1-9.

[YANG

Fei

, YANG

Shi-qi

, ZHU

Yun-qiang

, et al. Analysis on livestock and poultry production and nitrogen pollution load of cultivated land during last 30 years in China. Transactions of the CSAE, 2013, 29(5): 1-9. ]

In recent decades, China's livestock and poultry industry developed rapidly, and their wastes have become an important pollution source, and made a serious threat to China's environment. Due to the significant differences in natural conditions and economic development level in different provinces or regions, the scale and speed of livestock and poultry production show a large regional differences. Based on the statistical data of major livestock and poultry in recent 30 years of main provinces in China, we studied the spatial heterogeneity and temperal changes of livestock and poultry production and their annual growth rate, and further analzed their nitrogen pollution load per cultivated land area. The studied results show that, in recent years, China's livestock and poultry industry have developed rapidly, especially in the north and northeastern of China. The average annual growth rate of pigs, sheep and poultry generally increased grealtly all over the regions, which were even more than 12%. Relatively, the regional differences of the average annual growth rate of cattle or sheep exist in China, the North and Northeast China show the most obvious growth. During the last 30 years, the livestock and poultry development process can basically be divided into three stages: the steady development stage (1980-1995), the comprehensive development stage (1996-2006), the mordern development stage (2007-present). On the whole, the nitrogen excreted by the livestock and poultry are mostly distributed in north, middle, south, and southwestern of China, especially in Henan, Sichuan and Shandong provinces. These three provinces showed the largest growth rate, breeding production and nitrogen excretion of livestock and poultry. However, at present, the nitrogen pollution load for the unit cultivated land area in the middle, south and southwestern of China are the most, the farmland and water resource in these regions are facing the most serious pollution risk. In 2009, the average nitrogen load in unit cultivated land area in China were more than 138.13 kg/hm2. And for the six provinces including Sichuan, Beijing, Guizhou, Guangxi, Yunnan and Guangdong, they were above 202.98 kg/hm2, which have exceeded the cordon of 170 kg/hm2 regulated in the European Union policy. What is more, in most of other provinces of China, the nitrogen load in unit cultivated land area are being fast close to the cordon. Therefore, to avoid the cultivated land and water environment polluted by livestock and poultry manure, it is very necessary and urgent to control and manage the livestock and poultry production with the strong measures and means, and deal with the animals manure timely and effectively. This investigation can provide scientific support to the provinces on planing agriculture development and adjusting livestock and animals breeding structure.

为准确掌握近年来中国畜禽养殖发展的区域差异及畜禽粪便对环境的污染威胁，该研究利用年平均增长率方法，揭示畜禽养殖量及其氮污染的增长率的区域差异和时序变化规律，分析耕地的畜禽污染负荷。结果表明，近些年中国畜禽养殖业发展迅速，各地区的猪、羊、家禽养殖量的年平均增长率都普遍较高，增幅甚至超过12%；牛和羊的年平均增长率的区域差异较大。畜禽养殖发展基本可分为3个阶段：稳步发展阶段（1980－1995年），全面发展阶段（1996－2006年），现代化发展阶段（2007年-至今）。华北、华中、华南、西南地区畜禽氮污染产生量都较大，华北和东北各省的年平均增长率相对较高，其中河南、四川、山东三省的畜禽养殖的增幅较快、养殖量较大、耕地的氮污染负荷较重。全国平均单位耕地面积的畜禽氮污染负荷达138.13 kg/hm2，其中四川等6省市已达202.98 kg/hm2以上。该研究为全国和各省区农业发展规划和畜禽养殖结构调整提供参考。

... 根据相关研究和统计资料^{[7,25,26,27,28]},并在咨询专业人员的基础上,确定农业生产中硝态氮、磷、石油类和COD的流失率分别为18%、15%、12%和22% ...

1978

0.0

... 农业生产是非点源污染的主要污染源,没有固定的排污地点,污染物通过地表径流或地下渗漏过程进入水体而造成污染^[29],参考统计数据,确定将农业生产污染物的60 ...