河床内部的灰色和白色物质显示出是沉积物和盐结层。
Gray and white materials within the lake bed are exposed sediments and salt crusts.
他们对于一些来自冰川，河床以及珊瑚的岩心进行了分析并对可以随着岩层深度以及时间而变化的指示性化学物质的变化水平进行了测量。
They analysed cores from glaciers, lake bottoms and coral reefs and measured how the levels of some telltale chemicals changed with depth, and thus with time.
通过分析重庆江津白沙渗滤取水工程中渗透水水质表明，河水经过天然河床渗滤处理，其中的悬浮物质几乎可以被完全去除，并有较好的除菌效果。
River water of slight pollution and high turbidity was converted into seepage water by filter through which the suspended substance was removed, turbidity was depressed and bacteria reduced.
用小铲把河床表面的物质铲到金属筛里，将金属筛在水中轻轻转动。
Use a trowel, collect the top layer of the sediment. Place the sediment in a sieve and STIR it gently in the water.
用小铲把河床表面的物质铲到金属筛里，将金属筛在水中轻轻转动。
Use a trowel, collect the top layer of the sediment. Place the sediment in a sieve and STIR it gently in the water.
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