Key Takeaways & Executive Findings
- •• • In-situ remediation technologies offer lower costs and minimal disturbance compared to ex-situ methods, making them a priority for sustainable sediment management. • • Heavy metal contamination, particularly Cd and Hg, is prevalent in Chinese river and lake sediments, necessitating targeted remediation strategies. • • Combined in-situ technologies, integrating physical, chemical, and biological approaches, demonstrate enhanced efficiency and are a key research direction. • • Future development requires interdisciplinary integration and material innovations to overcome scalability and long-term effectiveness challenges.
Abstract
River and lake sediments, as both sources and sinks of water pollutants, significantly impact overlying water quality and aquatic ecosystems. In pollution treatment and ecological restoration, managing contaminated sediments is critical. Remediation technologies are categorized into ex-situ and in-situ methods; in-situ techniques have gained prominence due to lower costs and minimal environmental disturbance. This review summarizes sediment pollution status, comprehensively examines physical, chemical, biological, and combined in-situ remediation technologies, and discusses their mechanisms, applications, and future research needs. It proposes optimization strategies for emerging technologies, material improvements, and pathways for sustainable development, emphasizing interdisciplinary integration to enhance remediation efficacy. Key pollutants include heavy metals (e.g., Cd, Hg), persistent organic pollutants (POPs), and emerging contaminants like antibiotics and microplastics. In-situ methods such as capping, chemical oxidation, and bioremediation show promise but face challenges in long-term stability and scalability. The paper underscores the need for sustainable, cost-effective solutions and highlights recent advances in combined technologies, offering a reference for future research and engineering applications.
1. Introduction
Contaminated sediments in rivers and lakes act as long-term sources of pollutants, threatening aquatic ecosystems and water quality. Traditional ex-situ remediation, such as dredging, is effective but costly and disruptive, often causing secondary pollution. In-situ technologies have emerged as viable alternatives, offering reduced environmental footprint and cost efficiency. However, their application is hindered by limitations in remediation depth, uniformity, and long-term stability, particularly for complex contaminant mixtures.
This review addresses these bottlenecks by systematically analyzing recent advances in physical, chemical, and biological in-situ methods, including their mechanisms and field performance. It highlights innovative strategies such as combined technologies and material improvements that enhance remediation efficiency and sustainability. By synthesizing current knowledge, this work provides a framework for selecting appropriate technologies based on site-specific conditions and contaminant profiles, aiming to bridge the gap between laboratory research and full-scale implementation.
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DONG Yanting, YANG Jie, ZHU Nanwen, WANG Yan (2026). Pollution Status of River and Lake Sediments and Research Progress in In-situ Remediation Technologies. Journal of Environmental Engineering Technology. https://doi.org/10.13205/j.hjgc.202606012
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Frequently Asked Questions
What are the primary limitations of in-situ sediment remediation technologies in large-scale applications?
In-situ technologies often face challenges in achieving uniform treatment across heterogeneous sediments, limited depth penetration, and potential rebound of contaminants. For instance, chemical oxidation may be consumed by natural organic matter, reducing efficiency. Biological methods are slower and sensitive to environmental conditions. Scalability requires careful site assessment and adaptive management.
How do combined in-situ technologies improve remediation efficiency compared to single methods?
Combined approaches, such as coupling chemical oxidation with bioremediation, can synergistically enhance contaminant degradation. For example, chemical oxidants can break down recalcitrant compounds, making them more bioavailable for subsequent microbial degradation. This integration often results in higher removal rates and more complete mineralization, as evidenced by studies on PAH-contaminated sediments.
What are the cost implications of in-situ versus ex-situ remediation for heavy metal contaminated sediments?
In-situ methods generally have lower capital and operational costs due to reduced need for dredging, transport, and disposal. However, costs vary with technology: capping with reactive materials may be cost-effective for large areas, while electrokinetic remediation can be energy-intensive. A lifecycle cost analysis is essential, considering long-term monitoring and maintenance.
How do sediment characteristics influence the selection of in-situ remediation technologies?
Sediment properties such as organic content, grain size, and redox conditions dictate technology performance. For instance, high organic matter may sorb contaminants, reducing bioavailability and necessitating stronger oxidants or enhanced desorption. Fine-grained sediments with low permeability may hinder hydraulic delivery of amendments, favoring techniques like electrokinetics or in-situ chemical oxidation with pressure injection.
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