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 = "29 nov. 2020"