生态环境部发布全国地表水空气质量报告与小学生低碳环保作文启示自然保护意识

一、地表水

（一）总体情况

2020年10月，1940个国家地表水考核断面中，水质优良（Ⅰ-Ⅲ类）断面比例为83.3%，同比上升7.5个百分点；劣Ⅴ类断面比例为0.8%，同比下降2.1个百分点。主要污染指标为化学需氧量、总磷和高锰酸盐指数。

图1 2020年10月全国地表水水质类别比例

2020年1-10月，1940个国家地表水考核断面中，水质优良（Ⅰ-Ⅲ类）断面比例为81.8%，同比上升6.4个百分点；劣Ⅴ类断面比例为0.8%，同比下降2.4个百分点。主要污染指标为化学需氧量、总磷和高锰酸盐指数。

图2 2020年1-10月全国地表水水质类别比例

（二）主要江河水质状况

2020年10月，长江、黄河、珠江、松花江、淮河、海河、辽河等七大流域及西北诸河、中南诸河和浙闽片河流Ⅰ-Ⅲ类water quality ratio for the seven major river basins and western, central China's rivers, and Zhejiang-Fujian River Basin was 86.7%, an increase of 6.4 percentage points compared with the same period last year; the proportion of Grade V water quality was 0.4%, a decrease of 1.7 percentage points compared with the same period last year.

The main pollution indicators were chemical oxygen demand (COD), permanganate index (CODmn) and total phosphorus.

Figure 3: Water Quality Classification Ratios for Seven Major River Basins and Western, Central China's Rivers, and Zhejiang-Fujian River Basin in October 2020.

In October this year, the water quality in the Yangtze River basin was good; that in the Yellow River basin was fair; that in other river basins was light pollution.

From January to October this year, long-term monitoring stations found that CODcr levels exceeded Class II standards at some sites along sections of rivers such as Yili Lake on Qinghai-Tibet Plateau.

China has set up a network of more than one thousand surface water monitoring stations across its territory to ensure continuous observation of water environmental conditions.

The Ministry said it will continue to strengthen supervision over enterprises' sewage treatment facilities so as to reduce pollutant discharge into rivers.

（三）重要湖泊的营养状态分析

In terms of nutrient status analysis for important lakes:

There are currently over one hundred key lakes monitored by Chinese authorities which are categorized into different grades based on their trophic state index values ranging from zero (oligotrophic) to five (eutrophic).

Accordingly, we can see that there have been improvements made towards reducing eutrophication levels within these lakes during recent years but still face challenges related primarily due mainly due to human activities such as agricultural runoff or wastewater discharges from industrial processes without proper treatment systems installed before they reach these bodies natural habitats where aquatic life thrives alongside plant growth while nutrients accumulate leading eventually causing algal blooms when too much nitrogen enters system triggering increased photosynthesis rates among algae populations thereby depleting dissolved oxygen content making environment less suitable even dangerous for most living organisms present inside it including fish species & other wildlife who rely heavily upon clear waters & healthy ecosystems overall maintenance healthiness balance nature itself maintains delicate balance between all components involved including humans whose actions influence outcomes whether directly indirectly through consumption choices lifestyle practices resource management strategies implemented policies enacted regulations enforced etcetera...