Sand mining across the Ganges-Brahmaputra-Meghna catchment; assessment of activity and implications for sediment delivery

While issues of pollution, floods and drought in our rivers are widely studied, there is a hidden crisis with respect to the widespread global extraction of sand. Large volumes of sand are needed in the construction industry to make concrete. So far, calls for greater monitoring of sand mining activity have largely gone unmet. This is due to the fact mining is extensive, often hidden (e.g. underwater) and thus very difficult to properly assess. To meet this challenge, we use remote sensing methods to detect and monitor sand mining activities at the catchment scale, across the Ganges-Brahmaputra-Meghna river system (catchment size 1.72 million km2). Based on this analysis, here we show that mining activity is diverse and pervasive across the Ganges-Brahmaputra-Meghna catchment system for our study period of 2016-2021, with rates of extraction increasing within some of the rivers. Results show the total estimate for sand extraction is ~ 115 MTyr-1 +/- 20 MTyr-1, which is of a similar order of magnitude to the natural bedload flux of the catchment. While there are some limitations to deriving estimates based solely on imagery, this work highlights both the widespread spatial extent and large magnitude of sand mining for one of the world's biggest catchments. Furthermore, given our estimated scale of sand extraction, it demonstrates the need to properly account for mining activities when considering delivery of sediment to deltas in terms of the management of these vulnerable systems in the face of rising sea-levels. Overall, this work stresses the urgent requirement for further similar studies of sand extraction in the world's large rivers, which is vital to underpin sustainable management plans for the global sand commons

Sand mining across the Ganges-Brahmaputra-Meghna catchment; assessment of activity and implications for sediment delivery

While issues of pollution, floods and drought in our rivers are widely studied, there is a hidden crisis with respect to the widespread global extraction of sand. Large volumes of sand are needed in the construction industry to make concrete. So far, calls for greater monitoring of sand mining activity have largely gone unmet. This is due to the fact mining is extensive, often hidden (e.g. underwater) and thus very difficult to properly assess. To meet this challenge, we use remote sensing methods to detect and monitor sand mining activities at the catchment scale, across the Ganges-Brahmaputra-Meghna river system (catchment size 1.72 million km2). Based on this analysis, here we show that mining activity is diverse and pervasive across the Ganges-Brahmaputra-Meghna catchment system for our study period of 2016-2021, with rates of extraction increasing within some of the rivers. Results show the total estimate for sand extraction is ~ 115 MTyr-1 +/- 20 MTyr-1, which is of a similar order of magnitude to the natural bedload flux of the catchment. While there are some limitations to deriving estimates based solely on imagery, this work highlights both the widespread spatial extent and large magnitude of sand mining for one of the world's biggest catchments. Furthermore, given our estimated scale of sand extraction, it demonstrates the need to properly account for mining activities when considering delivery of sediment to deltas in terms of the management of these vulnerable systems in the face of rising sea-levels. Overall, this work stresses the urgent requirement for further similar studies of sand extraction in the world's large rivers, which is vital to underpin sustainable management plans for the global sand commons

Toxoplasma gondii Infection Is Associated with Low Birth Weight: Findings from an Observational Study among Rural Bangladeshi Women

Gestational Toxoplasma gondii (T. gondii) infection may cause substantial adverse effects on developing fetuses, newborns and also mothers. This study aims to estimate the seroprevalence of T. gondii among rural Bangladeshi pregnant women and determine the risk of a low birth weight (LBW). We followed a longitudinal design where 208 pregnant women were followed until the birth of their infants. Levels of IgG and IgM of T. gondii were assessed using chemiluminescent immunoassay. Modified Poisson regression was used to estimate crude and adjusted associations and multiple regression analysis was performed to understand the confounding and modifying effects of the variables. Thirty-nine (19%) children were born with LBW, among whom 15 (39%) mothers were positive for T. gondii IgG during pregnancy. After adjusting for several confounders and modifiers, pregnant women with T. gondii IgG or IgM seropositivity were significantly associated with LBW of infants (aRR: 2.00, 95% CI: 1.17-3.42). The strength of this association increased after adjusting for maternal education (aRR: 4.88, 95% CI: 1.74-13.69). The final model had an AROC of 0.84 with a sensitivity of 36% and specificity of 97%. Although causality is yet to be established, the study observed an association between T. gondii infection during pregnancy among rural Bangladeshi women and LBW of newborns

Hidden Depths:modelling the mining impact on sand-bed rivers

Sand is a critical natural resource used in the construction sector, in land reclamation and coastal protection schemes. Global consumption of aggregates is estimated to be c. 40 billion tonnes a year (Peduzzi, 2014) a large proportion of which is derived from fluvial sediment sources. This figure exceeds the mass of sediment delivered annually to the global ocean (Milliman and Syvitski,1992). Moreover, with urban populations projected to rise substantially over the next 20 years (UN, 2019), unsustainable extraction of alluvial sand represents a critical threat to the morphological and ecological integrity of rivers.<br/