Occurrence patterns of black water and its impact on fish in cutover areas of Eucalyptus plantations

Gairen Yang; Meijun Wen; Yusong Deng; Xiaolin Su; Daihua Jiang; Guan Wang; Youwen Chen; Guijin Chen; Sufang Yu

doi:10.1016/j.scitotenv.2019.07.199

Occurrence patterns of black water and its impact on fish in cutover areas of Eucalyptus plantations

Sci Total Environ. 2019 Nov 25:693:133393. doi: 10.1016/j.scitotenv.2019.07.199. Epub 2019 Jul 15.

Authors

Gairen Yang¹, Meijun Wen², Yusong Deng³, Xiaolin Su⁴, Daihua Jiang⁵, Guan Wang², Youwen Chen⁶, Guijin Chen⁷, Sufang Yu⁸

Affiliations

¹ Forestry College of Guangxi University, No. 100 Daxue Road, Nanning 530004, China. Electronic address: yanggr@gxu.edu.cn.
² Forestry College of Guangxi University, No. 100 Daxue Road, Nanning 530004, China.
³ Forestry College of Guangxi University, No. 100 Daxue Road, Nanning 530004, China. Electronic address: denny2018@gxu.edu.cn.
⁴ Forestry College of Guangxi University, No. 100 Daxue Road, Nanning 530004, China; Guangxi Liuwan State Owned Forest Farm, No. 3 Yunsong Road, Yulin 537000, China.
⁵ Agricultural college of Guangxi University, No. 100 Daxue Road, Nanning 530004, China. Electronic address: dhjiang2008@gxu.edu.cn.
⁶ Xingye Environmental Protection Bureau, No. 3 Yugui Road, Xingye 537800, China.
⁷ Guangxi Gaofeng State Owned Forest Farm, No. 10 Xingdong Road, Nanning 530001, China.
⁸ Forestry College of Guangxi University, No. 100 Daxue Road, Nanning 530004, China. Electronic address: yusufang@gxu.edu.cn.

PMID: 31374496
DOI: 10.1016/j.scitotenv.2019.07.199

Abstract

Black runoff occasionally flows from cutover areas of Eucalyptus plantations, polluting rivers and ponds, and resulting in fish death in severe cases. However, the occurrence patterns and environmental impacts of this black water remain unclear. Herein, we analyzed the major characteristics of black water at the occurrence sites, tested the complexation reaction of ground eucalyptus leaves with a solution of Fe³⁺, and determined the color and absorbance of the complex solution. The results showed that the water was dark blue, with weak acidity and strong light absorbance. The water contained a high level of dissolved organic matter content, while its chemical oxygen demand, total N, total P, NO₃^--N, and NH₄⁺-N concentrations were significantly higher than those in the stream water from Eucalyptus, Pinus massoniana Lamb., and Cunninghamia lanceolata stands during the growth period. Additionally, the tannic acid concentration in the black water was 1.0 mg L^-1 higher than that in the stream water from the Eucalyptus stand. The input of black water increases the concentration of tannic acid and NH⁴⁺-N, and the degradation of organic matter consumes dissolved oxygen in downstream ponds, leading to fish deaths. The presence of fresh logging residues and hot, humid weather also enable black water formation. Field investigations and simulation experiments revealed fresh Eucalyptus residues decompose rapidly under high-temperature and rainfall conditions, releasing large amounts of tannic acid, which reacts with Fe³⁺ to form a dark blue tannic acid‑iron complex and results in black water. These results indicate that the rich Fe³⁺ in runoff may be a key factor in the occurrence of black water. The logging of Eucalyptus plantations during the dry season or on non-rainy days and a reduction in the logging area could prevent the occurrence of black water or mitigate the extent of its environmental hazards.

Keywords: Black water; Eucalyptus plantation; Occurrence pattern; Tannic acid; Water-quality characteristics.

MeSH terms

Animals
China
Climate
Environment
Eucalyptus*
Fishes / physiology*
Forestry / methods*
Ponds / chemistry*
Water / chemistry*
Water Quality

Substances

Water