Wide Riparian Zones Inhibited Trace Element Loss in Mining Wastelands by Reducing Surface Runoff and Trace Elements in Sediment

Our plain-English summary of Wide Riparian Zones Inhibited Trace Element Loss in Mining Wastelands by Reducing Surface Runoff and Trace Elements in Sediment, by J. Deng, Z. Li, B. Li, et al (Toxics, 2024).

The study

• Authors: J. Deng, Z. Li, B. Li, C. Xu, L. Wang, Y. Li
• Journal: Toxics
• Published: 2024;12(4)
• Cited by: 2 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The diffusion of trace elements in mining wastelands has attracted widespread attention in recent years. Vegetation restoration is an effective measure for controlling the surface migration of trace elements. However, there is no field evidence of the effective riparian zone width in mining wastelands. Three widths (5 m, 7.5 m, and 10 m) of Rhododendron simsii/Lolium perenne L. riparian zones were constructed in lead-zinc mining wastelands to investigate the loss of soil, cadmium (Cd), copper (Cu), arsenic (As), lead (Pb), and zinc (Zn). Asbestos tiles were used to cut off connections between adjacent plots to avoid hydrological interference. Plastic pipes and containers were used to collect runoff water. Results showed that more than 90% of trace elements were lost in sediment during low coverage and heavy rainfall periods. Compared with the 5 m riparian zone, the total trace element loss was reduced by 69-85% during the whole observation period in the 10 m riparian zone and by 86-99% during heavy rain periods in the 10 m riparian zone, which was due to reduction in runoff and concentrations of sediment and trace elements in the 10 m riparian zone. Indirect negative effects of riparian zone width on trace element loss through runoff and sediment concentration were found. These results indicated that the wide riparian zone promoted water infiltration, filtered soil particles, and reduced soil erosion and trace element loss. Riparian zones can be used as environmental management measures after mining areas are closed to reduce the spread of environmental risks in mining wastelands, although the long-term effects remain to be determined.

In plain English

This field experiment looked at soil and trace element runoff from an abandoned lead–zinc mining wasteland in Lanping, Yunnan Province, China. It did not study asbestos exposure or any health effect; asbestos appears only as tiles dividing the test plots. In April 2021 the authors planted riverbank strips of Rhododendron simsii shrubs and Lolium perenne ryegrass 5 m, 7.5 m and 10 m wide, three plots per width. From April to September they measured sediment, cadmium, copper, arsenic, lead and zinc in rain runoff. Trace elements in sediment made up 94–99% of total loss. Compared with the 5 m strips, runoff fell by 40% in the 7.5 m strips and 47% in the 10 m strips, and sediment fell by 61% and 71%. Over the whole period, total trace element loss was 69–85% lower in the 10 m strips than in the 5 m strips. In a separate 60-minute rainfall observation, however, dissolved arsenic concentration was significantly higher in the 10 m strips than in the 5 m strips. The authors concluded that a 10 m strip is an effective control measure. They noted the brief observation period, so long-term effects remain undetermined.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: field experiment comparing three widths of planted riparian (riverbank) zones, three replicate plots per width, under natural rainfall
• Who was studied: nine experimental plots on the banks of the Momian River in an abandoned lead–zinc mining wasteland near Lanping County, Yunnan Province, China, constructed in April 2021 and observed April to September; no people were studied
• Exposure: loss of soil and the trace elements cadmium, copper, arsenic, lead and zinc in runoff from riparian zones 5 m, 7.5 m and 10 m wide; asbestos tiles were used only as plot dividers, and asbestos itself was not measured or studied
• Main results:
  • Trace elements carried in sediment accounted for 94–99% of total trace element loss
  • Compared with the 5 m zone, runoff yield was reduced by 40% (7.5 m) and 47% (10 m), and sediment yield by 61% (7.5 m) and 71% (10 m)
  • Compared with the 5 m zone, total trace element loss in the 10 m zone was reduced by 69–85% over the whole observation period and by 86–99% during heavy rain periods
  • Under heavy rainfall, sediment concentration in the 10 m zone was 80% lower than in the 5 m zone, and trace element concentrations were 53–98% lower
  • During a separate 60-minute observation under natural rainfall of 5.5 mm per hour, the concentration of dissolved arsenic was significantly higher in the 10 m zone than in the 5 m zone
  • Riparian zone width had no effect on plant biomass or on trace element accumulation in plants
• The authors' conclusion: The authors concluded that constructing a 10 m riparian zone is an effective measure for controlling trace element loss in mining wastelands, although long-term effects remain to be determined
• Limitations the authors state:
  • The observation period was brief, so the long-term effectiveness of riparian zones remains to be determined

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