Science Guarding Our Waters
Imagine a world where every river runs clear, where lakes teem with life, and where the water that sustains countless ecosystems remains unpolluted. This vision drives environmental scientists worldwide—and in China, this vision has taken the form of a critical scientific document: the Water Quality Criteria Green Book.
In a country experiencing rapid industrialization and facing significant environmental challenges, establishing scientifically sound water quality criteria isn't just academic—it's a matter of ecological survival. This article explores China's groundbreaking efforts to develop its own water quality standards, offering a fascinating glimpse into how science serves as the foundation for environmental protection.
For decades, China relied on water quality standards adapted from other countries, but these foreign-born regulations often failed to account for China's unique aquatic ecosystems and native species. The Green Book, formally titled "Water Quality Criteria Green Book of China," represents a monumental shift toward creating homegrown scientific standards that specifically protect China's diverse waterways and their inhabitants 1 .
Before diving into China's specific approach, it's essential to understand what water quality criteria are—and what they're not. Water quality criteria (WQC) are scientifically derived thresholds that indicate the maximum concentration of a pollutant that can be present in water without harming aquatic life or human health. These are not regulations themselves but rather the scientific foundation upon which legally enforceable water quality standards (WQS) are built.
The distinction is crucial: while standards are legal requirements, criteria represent scientific consensus about what levels protect ecosystems. Think of criteria as the research-based recommendations that inform policymakers who then create enforceable standards.
China's surface water quality management initially relied heavily on standards adapted from other countries without adequate consideration of China's unique ecological context 4 8 .
Environmental Quality Standards for Surface Water established five classes of water quality and specified parameters for 24 indicators plus 85 additional parameters for drinking water sources 4 8 .
China made developing national environmental criteria a national priority in its 12th Five-Year Plan for Environmental Protection Science and Technology Development .
The Water Quality Criteria Green Book of China was published, establishing China's first comprehensive system for developing scientifically defensible water quality criteria 1 .
Alarming declines in aquatic biodiversity were observed in major river systems, with species like the Yangtze river dolphin likely extinct and others like the Chinese Sturgeon becoming critically endangered 4 . Researchers estimated that 65 fish species in China were critically endangered, with another 101 species endangered—accounting for nearly 12% of all continental fish species identified in the country.
The Water Quality Criteria Green Book provides a comprehensive framework for deriving various types of water quality criteria, including:
Criteria derivation must include toxicity data for at least six species from three different phyla 1
Ten recommended species from four different phyla that are native to Chinese waters 1
Emphasis on native species represents a crucial advance over previous approaches 1
To understand how water quality criteria are developed in practice, let's examine a specific example: the derivation of criteria for cadmium, a toxic heavy metal that poses significant risks to aquatic ecosystems.
Following the Green Book's framework, researchers conducted a meticulous multi-step process 2 5 9 :
Gathered toxicity data for cadmium effects on native Chinese aquatic species
Tests on species from at least eight different families
Exposed organisms to varying concentrations under controlled conditions
Used species sensitivity distribution (SSD) method
The cadmium criteria derivation revealed fascinating patterns in species sensitivity. Some organisms proved far more vulnerable to cadmium than others, highlighting the importance of testing multiple species 9 .
| Species | Family | LC50 (μg/L) | Test Duration |
|---|---|---|---|
| Danio rerio (zebrafish) | Cyprinidae | 5,840 | 96 hours |
| Carassius auratus (goldfish) | Cyprinidae | 1,570 | 96 hours |
| Daphnia magna (water flea) | Daphniidae | 4.2 | 48 hours |
| Xenopus laevis (frog) | Pipidae | 1,680 | 96 hours |
| Species | Family | NOEC (μg/L) | Effects Observed |
|---|---|---|---|
| Gobiocypris rarus (rare minnow) | Cyprinidae | 3.8 | Reduced growth |
| Daphnia magna (water flea) | Daphniidae | 0.9 | Reduced reproduction |
| Chironomus dilutus (midge) | Chironomidae | 12.5 | Reduced emergence |
| Bellamya aeruginosa (snail) | Viviparidae | 5.6 | Reduced growth |
| Criterion Type | Value (μg/L) | Protection Goal |
|---|---|---|
| Acute criterion | 2.1 | Short-term exposure |
| Chronic criterion | 0.8 | Long-term exposure |
| Human health criterion | 0.03 | Protection from seafood consumption |
Developing water quality criteria requires specialized approaches and materials. Here are some essential components of the water quality scientist's toolkit:
| Research Tool | Function | Importance in Criteria Development |
|---|---|---|
| Native test species | Organisms naturally found in China's freshwater ecosystems | Ensures relevance to species being protected; accounts for unique sensitivities |
| Standard toxicity testing protocols | Guidelines for conducting exposure experiments | Ensures consistency and reliability of toxicity data |
| Water chemistry monitoring equipment | Measures parameters like pH, hardness, temperature | Accounts for how water conditions affect toxicity |
| Chemical analysis instruments | Precisely measures pollutant concentrations | Ensures accurate exposure concentrations in tests |
| Statistical software packages | Analyzes toxicity data and fits species sensitivity distributions | Derives final criteria values from raw toxicity data |
| Criteria derivation models | Mathematical frameworks for setting protective concentrations | Translates scientific data into usable criteria |
The Water Quality Criteria Green Book has already influenced China's environmental protection efforts in several important ways:
By identifying the most sensitive species and establishing protective concentrations, the criteria help prioritize protection efforts for vulnerable ecosystems 4 .
China's vast size and ecological diversity mean that nationally uniform standards may not always be appropriate. The Green Book's framework allows for developing region-specific criteria that account for local conditions .
Scientifically sound criteria help decision-makers strike an appropriate balance between environmental protection and socioeconomic development—a crucial consideration for a developing country like China 4 .
Perhaps most significantly, the development of China-specific water quality criteria represents an important shift in China's approach to environmental protection—from importing solutions from other countries to developing homegrown scientific approaches tailored to its unique ecological challenges .
The publication of the Green Book was a milestone, but it represents the beginning rather than the conclusion of China's water quality criteria journey. Since 2015, research has continued to refine and expand China's criteria development capabilities.
In 2017, China's Ministry of Ecology and Environment issued the Technical Guideline for Deriving Water Quality Criteria for Protection of Freshwater Organisms (HJ 831-2017), which was updated in 2022 to HJ 831-2022 2 5 . These guidelines incorporated important advances, including:
Developing criteria for new contaminants of concern
Addressing complex challenges like hormone-mimicking chemicals
Studying effects of multiple pollutants in combination
The Water Quality Criteria Green Book of China represents more than just a technical document—it symbolizes China's growing scientific capability and commitment to addressing its environmental challenges through rigorous, homegrown science. By developing criteria specifically tailored to protect China's unique aquatic ecosystems and native species, Chinese researchers are creating a scientific foundation for environmental protection that balances ecological health with human needs.
As water quality challenges evolve—with emerging pollutants, climate change impacts, and continuing development pressures—the systematic approach established by the Green Book provides a flexible framework for developing the scientific knowledge needed to protect China's waters for generations to come. The clear waters envisioned by China's environmental scientists may indeed be within reach, guided by the careful science documented in this remarkable green volume.
This article was based on scientific publications and government documents regarding China's water quality criteria development. For those interested in exploring this topic further, the Water Quality Criteria Green Book of China is available through academic booksellers and Springer Publishing. 1 6