Levels of heavy metals distribution near an urban wastewater in Southeastern Michigan – Nature

Report on Dissolved Heavy Metal Concentrations in the Detroit River Watershed in Relation to Sustainable Development Goals

1.0 Executive Summary

This report details a study on dissolved heavy metal concentrations in the Detroit River, focusing on areas upstream and downstream of the Detroit Wastewater Treatment Plant (WWTP). The study provides critical baseline data for assessing water quality and contributes directly to the monitoring of several United Nations Sustainable Development Goals (SDGs), particularly SDG 6 (Clean Water and Sanitation), SDG 3 (Good Health and Well-being), SDG 11 (Sustainable Cities and Communities), and SDG 14 (Life Below Water). The investigation found that while heavy metal concentrations were higher upstream, all measured levels were below the limits set by the U.S. Environmental Protection Agency (EPA). These findings suggest improvements in water quality, likely due to remediation efforts and changes in industrial activity, but underscore the need for continuous monitoring to ensure the long-term health of this vital urban watershed and its contribution to the Great Lakes ecosystem.

2.0 Introduction and Alignment with Sustainable Development Goals

The Detroit River watershed, a critical economic and social resource, has historically suffered from significant pollution due to intense urbanization and industrialization. This degradation directly challenges the achievement of the Sustainable Development Goals. This study was initiated to address a critical data gap concerning dissolved heavy metals near the Detroit WWTP, providing a scientific basis for strategies aimed at achieving key SDG targets.

2.1 Context: Water Quality and Urban Sustainability

Heavy metal pollution is a persistent threat to aquatic ecosystems and human health, undermining progress towards several SDGs:

• SDG 6 (Clean Water and Sanitation): The presence of heavy metals compromises water quality (Target 6.3) and threatens the health of water-related ecosystems (Target 6.6). Effective wastewater management is crucial for mitigating this impact.
• SDG 3 (Good Health and Well-being): Heavy metals are toxic and can bioaccumulate, posing significant health risks. Monitoring their levels is essential for reducing illnesses and deaths from water pollution (Target 3.9).
• SDG 11 (Sustainable Cities and Communities): As an urban watershed, the Detroit River’s condition reflects the environmental impact of the city. Managing industrial and municipal waste is fundamental to creating sustainable urban environments (Target 11.6).
• SDG 14 (Life Below Water): The Detroit River flows into Lake Erie, making its water quality vital for the health of the entire Great Lakes freshwater system. Reducing land-based pollution is critical for protecting aquatic biodiversity (Target 14.1).

2.2 Study Objectives

The primary objectives of this investigation were twofold, designed to provide actionable data for environmental management and SDG monitoring:

1. To determine and compare the concentrations of dissolved heavy metals (Cr, Fe, Cu, Zn, As, Cd, and Pb) at sites upstream and downstream of the Detroit WWTP.
2. To assess these concentrations against established U.S. EPA guidelines to evaluate potential risks to public health and the ecosystem, thereby measuring progress towards SDG 3 and SDG 6.

3.0 Methodology

3.1 Sampling Locations

Water samples were collected during the summer from five distinct sites chosen for their proximity to the Detroit WWTP and their ecological or recreational importance. These sites were categorized as either upstream or downstream of the treatment facility to assess its potential impact.

• Upstream Sites:
  • Site 1: Clinton River mouth
  • Site 3: Northeast Belle Isle
  • Site 4: Southwest Belle Isle
• Downstream Sites:
  • Site 5: Rouge River mouth
  • Site 6: Detroit River International Wildlife Refuge (DRIWR)/Trenton Channel

3.2 Sample Collection and Analysis

Water samples were collected using standardized protocols to prevent contamination. Physicochemical parameters, including pH, temperature, total dissolved solids (TDS), turbidity, and electrical conductivity (EC), were measured on-site. The concentrations of dissolved heavy metals were determined in a commercial laboratory using Inductively Coupled Plasma–Mass Spectrometry (ICP-MS) following U.S. EPA method 3005 A.

4.0 Results and Discussion

4.1 Physicochemical Water Quality Parameters

The physicochemical analysis indicated that most parameters were within acceptable ranges. However, Site 3 (upstream) exhibited elevated conductivity (929 µS/cm) and turbidity (676 ppm), suggesting higher levels of dissolved and suspended solids, potentially from industrial discharge or urban runoff. This highlights localized challenges in meeting SDG 6 targets for water quality.

4.2 Heavy Metal Concentrations and SDG Implications

The study’s findings on heavy metal concentrations provide a mixed but generally positive outlook on the region’s progress toward environmental sustainability.

4.2.1 Comparison of Upstream and Downstream Sites

A consistent pattern emerged where heavy metal concentrations were higher at the upstream sites (1, 3, and 4) compared to the downstream sites (5 and 6). For example, mean concentrations of Chromium (Cr) and Lead (Pb) were approximately three to four times higher upstream. This spatial variation suggests that pollution sources are concentrated in the upper sections of the river, including the heavily industrialized Rouge River, which flows into the Detroit River near the downstream sampling sites. This points to the continued importance of managing industrial and non-point source pollution to achieve SDG 11 and SDG 12 (Responsible Consumption and Production).

4.2.2 Compliance with Environmental Standards

Crucially, the mean concentrations of all detected heavy metals (Cr, Fe, As, Zn, Pb) at both upstream and downstream locations were below the maximum limits set by the U.S. EPA. Copper (Cu) and Cadmium (Cd) were below the method detection limit at all sites. This finding is a positive indicator for SDG 3 and SDG 6, suggesting that current water conditions do not pose an immediate, acute risk based on these specific contaminants. The improved water quality may be attributed to several factors:

• Extensive sediment remediation and clean-up activities.
• Effective industrial pre-treatment programs.
• A general decline in heavy industrial activity in the region.

5.0 Conclusion and Recommendations for SDG Advancement

This study provides the first characterization of dissolved heavy metal distribution near the Detroit WWTP, offering valuable data for tracking progress towards a sustainable urban environment. The results indicate a significant improvement in the river’s water quality compared to previous decades, a positive step towards achieving SDG 6 (Clean Water and Sanitation) and protecting SDG 14 (Life Below Water).

However, the higher contaminant levels upstream confirm that pollution sources persist. The study’s limitations, including a short sampling period, highlight the need for a more comprehensive monitoring strategy. To ensure continued progress and fully realize the vision of the SDGs, the following is recommended:

1. Establish Long-Term Monitoring: Implement a continuous, year-round water quality monitoring program to understand seasonal variations and long-term trends in heavy metal concentrations. This will provide robust data for managing the watershed and reporting on SDG 6 and SDG 14 targets.
2. Identify and Mitigate Upstream Sources: Further investigation is needed to pinpoint specific point and non-point pollution sources in the upstream areas and the Rouge River watershed. This will enable targeted interventions aligned with SDG 11 and SDG 12.
3. Strengthen Public-Private Partnerships: Continue to foster collaboration between government agencies, industries, and community organizations to advance pollution prevention and remediation efforts, ensuring the Detroit River can support both a healthy ecosystem and a thriving, sustainable community.

Analysis of Sustainable Development Goals in the Article

1. Which SDGs are addressed or connected to the issues highlighted in the article?

The article on heavy metal contamination in the Detroit River watershed connects to several Sustainable Development Goals (SDGs) due to its focus on water quality, pollution from industrial and urban sources, ecosystem health, and potential impacts on human well-being.

• SDG 3: Good Health and Well-being

  The article directly links heavy metal pollution to health risks. It states that heavy metals “have toxic effects” and that their harmful effects on humans depend on dosage and exposure. The study’s purpose includes assessing “the potential public health and ecosystem impacts from any dissolved heavy metal contamination found,” connecting the environmental issue of water quality to human health outcomes.

• SDG 6: Clean Water and Sanitation

  This is the most central SDG addressed. The entire study is an assessment of water quality in the Detroit River. It focuses on “water pollution” from “urban, industrial, and agricultural development” and evaluates the role of the Detroit wastewater treatment plant (WWTP). The research aims to provide “a benchmark for future contaminant reduction strategies and remediation efforts,” which is fundamental to achieving clean water.

• SDG 9: Industry, Innovation, and Infrastructure

  The article identifies industrial activities as a major source of pollution. It mentions that the watershed has “numerous petrochemical plants, steel mills, petroleum refineries, and producers of automotive parts, rubbers, and plastics.” The study’s focus on the WWTP, a critical piece of infrastructure for managing waste from these sources, highlights the need for sustainable industrial practices and effective infrastructure to mitigate environmental impact.

• SDG 11: Sustainable Cities and Communities

  The article emphasizes the impact of urbanization on the river system. It notes that the watershed has experienced “a large amount of urban… development” and that “storm water runoff from a variety of impermeable surfaces, are additional sources of pollution in urban environments.” This connects the problem of water contamination directly to the environmental management of cities and urban areas.

• SDG 12: Responsible Consumption and Production

  This goal is relevant through its focus on the management of chemicals and waste. The article details how various heavy metals enter the environment from industrial processes and products, such as “paints, dyes, soaps, metals,” “car tires, anti-rust chemicals,” and waste from “smelting, textile manufacture.” The study of these pollutants in wastewater is a direct examination of the downstream consequences of production patterns and waste management practices.

• SDG 14: Life Below Water

  The article discusses the detrimental effects of heavy metal pollution on aquatic life. It notes that heavy metals “bioaccumulate in aquatic ecosystems” and have been “detected in the gills, liver, and muscle tissues of various species of fish and aquatic organisms.” By assessing the contamination that threatens these ecosystems, the study relates to the protection and restoration of freshwater ecosystems, which are connected to larger water bodies like the Great Lakes.

2. What specific targets under those SDGs can be identified based on the article’s content?

Based on the issues discussed, several specific SDG targets can be identified:

1. Target 3.9: Substantially reduce deaths and illnesses from hazardous chemicals and pollution

   The article’s objective to “assess the potential public health… impacts from any dissolved heavy metal contamination” directly aligns with this target. It investigates hazardous chemicals (Pb, As, Cd, Cr, etc.) in the water, which are known to cause illness, and compares their concentrations to established safety limits set by the US EPA to evaluate risk.

2. Target 6.3: Improve water quality by reducing pollution and treating wastewater

   This target is at the core of the study. The research evaluates “dissolved heavy metal concentrations” to assess water pollution. It specifically investigates the area “upstream and downstream of the Detroit WWTP,” which relates to the treatment of wastewater. The stated goal of creating a “benchmark for future contaminant reduction strategies” is a direct action towards improving water quality.

3. Target 6.6: Protect and restore water-related ecosystems

   The article highlights that the Detroit River is a critical ecosystem, designated as a “binational Great Lakes Area of Concern (AOC).” It discusses how pollution leads to a “loss of habitat” and threatens aquatic organisms through bioaccumulation. The study’s data is intended to inform “remediation efforts,” which contributes to the restoration of this vital water-related ecosystem.

4. Target 9.4: Upgrade infrastructure and retrofit industries for sustainability

   The article points to pollution from “petrochemical plants, steel mills, petroleum refineries,” and other industries. The focus on the WWTP, a key piece of environmental infrastructure, implies the need for effective treatment processes to handle industrial and municipal waste. The study’s findings can inform efforts to upgrade this infrastructure and encourage industries to reduce their discharges, aligning with the goal of making industrial processes more environmentally sound.

5. Target 11.6: Reduce the adverse environmental impact of cities

   The study explicitly links water pollution to urbanization, mentioning “storm water runoff” and “non-point source pollution from urban environments” as significant contributors. By measuring the levels of pollutants originating from the heavily urbanized Detroit area, the article provides data relevant to managing the environmental impact of the city, particularly its waste and water management.

6. Target 12.4: Achieve environmentally sound management of chemicals and wastes

   The article details the sources of various heavy metals, linking them to specific chemicals and industrial wastes (e.g., Cr from “tanning, wood preservation, chemical production,” and Pb from “batteries, ammunition, glass, paints”). The study of their concentration in the river is a direct assessment of how well these hazardous substances are being managed and the extent of their release into the environment.

7. Target 14.1: Prevent and reduce marine pollution from land-based activities

   While the Detroit River is a freshwater system, it is part of the Great Lakes, which are large inland seas. The principle of this target applies directly. The study investigates pollution from “land-based activities,” including “point and non-point source pollution” from industrial, urban, and agricultural development, which is the primary focus of this target.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

Yes, the article mentions and uses several specific indicators to measure the extent of the environmental issues, which align with official or logical measures of progress for the SDG targets.

• Concentrations of Specific Pollutants

  The primary indicator used throughout the study is the concentration of dissolved heavy metals (Cr, Fe, Cu, Zn, As, Cd, and Pb), measured in parts per billion (ppb) or micrograms per liter. This serves as a direct measure for assessing ambient water quality (Indicator 6.3.2: Proportion of bodies of water with good ambient water quality) and the release of hazardous chemicals (relevant to Targets 3.9, 12.4, and 14.1).

• Comparison with Regulatory Standards

  The article repeatedly measures progress and risk by comparing the observed heavy metal concentrations to the allowable limits set by the US Environmental Protection Agency (EPA). This comparison acts as a crucial indicator of whether the water is safe for human health and the ecosystem. For example, the finding that “the mean concentrations of all detected heavy metals at both sites were below the limits set by the US EPA” is a key indicator of the current state of water quality.

• Physicochemical Water Quality Parameters

  The study measures several other parameters that serve as indicators of overall water quality. These include pH, temperature, turbidity (ppm), and electrical conductivity (µS/cm). The article notes, for instance, that high turbidity and conductivity levels at certain sites could be due to “pollutants from nearby industries,” making these parameters useful indicators for monitoring pollution events and sources.

• Wastewater Treatment Assessment

  Although not a formal SDG indicator, the study’s design of sampling “upstream and downstream areas of the Detroit WWTP” is an implied method for indicating the effectiveness of wastewater treatment (relevant to Indicator 6.3.1: Proportion of… wastewater flows safely treated). The comparison of pollutant levels before and after the WWTP’s discharge point helps assess its contribution to, or mitigation of, river pollution.

4. Create a table with three columns titled ‘SDGs, Targets and Indicators” to present the findings from analyzing the article. In this table, list the Sustainable Development Goals (SDGs), their corresponding targets, and the specific indicators identified in the article.

Source: nature.com