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Park E. Sand mining in the Mekong Delta: Extent and compounded impacts. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 924:171620. [PMID: 38467261 DOI: 10.1016/j.scitotenv.2024.171620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 03/06/2024] [Accepted: 03/08/2024] [Indexed: 03/13/2024]
Abstract
Sand mining has accelerated in recent years primarily due to population increase and rapid urbanization. To meet demand, the rate of sand extraction often exceeds the rate of natural replenishment with serious environmental consequences. In this review paper, the Vietnamese Mekong Delta (VMD), a global hotspot for sand mining with a prolonged history of intensive riverbed extraction, is used as a representative case study to highlight the extent and compounded impacts of this activity. The sand mining budget of the VMD ranged from 8.5 to 45.7 Mm3/yr. The large difference is due to the use of different methods to determine the sand mining budget as well as the difficulties associated with measuring the volume of sand extracted from the riverbed. Widespread illegal mining in the region further exacerbates the mismatch. The environmental consequences of riverbed sand mining include deeply incised riverbeds that result in riverbank and coastal erosion. Massive sediment removal has also led to river water level reductions, disrupted hydrological connectivity, and diminished floodplain inundation. In addition, the augmented backwater effect that results from riverbed lowering, amplifies the extent of saltwater intrusion in the dry season. While the physical and hydrological impacts of sand mining is well studied, studies on the ecological and socio-economic ramifications remain sparse. In addition, the ways in which upstream dams, irrigation infrastructure, excessive groundwater extraction, and sea-level rise (SLR) have amplified the effects of sand mining was also considered in this review. This paper concludes by advocating for the adoption of remote sensing-based approaches for effective mapping of sand mining activities and the need to mine sustainably to balance developmental needs with environmental conservation.
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Affiliation(s)
- Edward Park
- National Institute of Education (NIE), Earth Observatory of Singapore (EOS), Asian School of the Environment (ASE), Nanyang Technological University (NTU), Singapore.
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Anh LH, Mihai FC, Belousova A, Kucera R, Oswald KD, Riedel W, Sekar NA, Schneider P. Life Cycle Assessment of River Sand and Aggregates Alternatives in Concrete. MATERIALS (BASEL, SWITZERLAND) 2023; 16:2064. [PMID: 36903179 PMCID: PMC10004002 DOI: 10.3390/ma16052064] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 02/21/2023] [Accepted: 02/23/2023] [Indexed: 06/18/2023]
Abstract
Urbanization processes in Asia are still ongoing; thus, aggregate demand is expected to increase in following years. Even though construction and demolition waste is a source for secondary building materials in industrialized countries, it is not yet an alternative construction material source in Vietnam as the urbanization process is still ongoing. Thus, there is a need for river sand and aggregates alternatives in concrete, namely manufactured sand (m-sand) from primary solid rock materials and secondary waste materials. The focus in the present study for Vietnam was on m-sand sand as alternative for river sand, and different ashes as alternatives for cement in concrete. The investigations comprised concrete lab tests according to the formulations of concrete strength class C 25/30 in accordance with DIN EN 206, followed by a lifecycle assessment study in order to identify the environmental impact of the alternatives. In total 84 samples were investigated, consisting of 3 reference samples, 18 samples with primary substitutes, 18 samples with secondary substitutes, and 45 samples with cement substitutes. This kind of holistic investigation approach comprising material alternatives and accompanying LCA was the first study for Vietnam, and even for Asia, and represents a substantial added value for future policy development in order to cope with resource scarcity. The results show that with the exception of metamorphic rocks, all m-sands meet the requirements for quality concrete. In terms of cement replacement, the mixes showed that a higher percentage of ash reduces the compressive strength. The compressive strength values of the mixes with up to 10% coal filter ash or rice husk ash were equivalent to the C25/30 standard concrete formulation. Higher ash contents up to 30% lead to the reduction of the concrete quality. The LCA study's results highlighted the better environmental footprints across environmental impact categories in the 10% substitution material in comparison to the use of primary materials. The LCA analysis results showed that cement as a component in concrete holds the highest footprint. The use of secondary waste as alternative for cement provides significant environmental advantage.
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Affiliation(s)
- Le Hung Anh
- Institute for Environmental Science, Engineering & Management, Industrial University of Ho-Chi-Minh City, Ho Chi Minh City 700000, Vietnam
| | - Florin-Constantin Mihai
- Environmental Research Center “CERNESIM”, Department of Exact Sciences and Natural Sciences, Institute of Interdisciplinary Research, “Alexandru Ioan Cuza” University of Iasi, Bulevardul Carol I 11, 700506 Iași, Romania
| | - Anna Belousova
- C&E Consulting und Engineering GmbH, Jagdschänkenstr. 52, 09117 Chemnitz, Germany
| | - Radek Kucera
- C&E Consulting und Engineering GmbH, Jagdschänkenstr. 52, 09117 Chemnitz, Germany
| | - Klaus-Dieter Oswald
- C&E Consulting und Engineering GmbH, Jagdschänkenstr. 52, 09117 Chemnitz, Germany
| | - Wolfgang Riedel
- C&E Consulting und Engineering GmbH, Jagdschänkenstr. 52, 09117 Chemnitz, Germany
| | - Naveedh Ahmed Sekar
- Department for Water, Environment, Civil Engineering and Safety, University of Applied Sciences Magdeburg-Stendal, 39114 Magdeburg, Germany
| | - Petra Schneider
- Department for Water, Environment, Civil Engineering and Safety, University of Applied Sciences Magdeburg-Stendal, 39114 Magdeburg, Germany
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Application of DPSIR and Tobit Models in Assessing Freshwater Ecosystems: The Case of Lake Malombe, Malawi. WATER 2022. [DOI: 10.3390/w14040619] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Inland freshwater shallow lake ecosystem degradation is indistinctly intertwined with human-induced factors and climate variability. Changes in climate and human-induced factors significantly influence the state of lake ecosystems. This study provides evidence of the driver, pressure, state, impact, and response (DPSIR) indicators for freshwater lake ecosystem dynamics, taking Lake Malombe in Malawi as a case study. We used the DPSIR framework and Tobit model to achieve the study’s objectives. The study’s findings indicate that top-down processes gradually erode Lake Malombe’s ecosystem state. The lake resilience is falling away from its natural state due to increasing rates of drivers, pressures, and impacts, indicating the lake ecosystem’s deterioration. The study shows that demographic, socio–economic, climatic drivers, pressures, state, and responses significantly (p < 0.05) influenced the lake ecosystem’s resilience. The study suggests that substantial freshwater ecosystem management under the current scenario requires a long-term, robust, and sustainable management plan. The findings from this study provide a roadmap for short-term and long-term practical policy-focused responses, particularly in implementing a freshwater ecosystem restoration programs in Malawi and Africa more broadly.
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