@Article{LoboCostNovoTelm:2017:EfSmGo,
author = "Lobo, Felipe de Lucia and Costa, Maycira and Novo, Evlyn
M{\'a}rcia Le{\~a}o de Moraes and Telmer, Kevin",
affiliation = "{Instituto Nacional de Pesquisas Espaciais (INPE)} and {University
of Victoria} and {Instituto Nacional de Pesquisas Espaciais
(INPE)} and {University of Victoria}",
title = "Effects of small-scale gold mining tailings on the underwater
light field in the Tapaj{\'o}s River Basin, Brazilian Amazon",
journal = "Remote Sensing",
year = "2017",
volume = "9",
number = "8",
pages = "Article number 861",
month = "Aug.",
keywords = "optical properties, biogeochemical data, inorganic particles,
light attenuation, critical depth.",
abstract = "Artisanal and Small-scale Gold Mining (ASGM) within the Amazon
region has created several environmental impacts, such as mercury
contamination and changes in water quality due to increased
siltation. This paper describes the effects of water siltation on
the underwater light environment of rivers under different levels
of gold mining activities in the Tapaj{\'o}s River Basin.
Furthermore, it investigates possible impacts on the phytoplankton
community. Two field campaigns were conducted in the Tapaj{\'o}s
River Basin, during high water level and during low water level
seasons, to measure Inherent and Apparent Optical Properties
(IOPs, AOPs), including scattering (b) and absorption (a)
coefficients and biogeochemical data (sediment content, pigments,
and phytoplankton quantification). The biogeochemical data was
separated into five classes according to the concentration of
total suspended solids (TSS) ranging from 1.8 mg L-1 to 113.6 mg
L-1. The in-water light environment varied among those classes due
to a wide range of concentrations of inorganic TSS originated from
different levels of mining activities. For tributaries with low or
no influence of mining tailings (TSS up to 6.8 mg L-1), waters are
relatively more absorbent with b:a ratio of 0.8 at 440 nm and b660
magnitude of 2.1 m-1. With increased TSS loadings from mining
operations (TSS over 100 mg L-1), the scattering process prevails
over absorption (b:a ratio of 10.0 at 440 nm), and b660 increases
to 20.8 m-1. Non-impacted tributaries presented a critical depth
for phytoplankton productivity of up to 6.0 m with available light
evenly distributed throughout the spectra. Whereas for greatly
impacted waters, attenuation of light was faster, reducing the
critical depth to about 1.7 m, with most of the available light
comprising of red wavelengths. Overall, a dominance of diatoms was
observed for the upstream rivers, whereas cyanobacteria prevailed
in the low section of the Tapaj{\'o}s River. The results suggest
that the spatial and temporal distribution of phytoplankton in the
Tapaj{\'o}s River Basin is not only a function of light
availability, but rather depends on the interplay of factors,
including flood pulse, water velocity, nutrient availability, and
seasonal variation of incoming irradiance. Ongoing research
indicates that the effects of mining tailings on the aquatic
environment, described here, are occurring in several rivers
within the Amazon River Basin.",
doi = "10.3390/rs9080861",
url = "http://dx.doi.org/10.3390/rs9080861",
issn = "2072-4292",
language = "en",
targetfile = "remotesensing-09-00861.pdf",
urlaccessdate = "06 maio 2024"
}