Make sure it's clean river sand, not beach sand.

确保那是干净河沙，不是海滩的沙子。

youdao

River sand shall be paved with the progress of bricklaying and extensive paving in advance is forbidden.

河砂滑动层在砌筑时，要随砌随铺，禁止大面积预先铺放。

youdao

A subtle native "carpet"garden and olive grey colour palette responds to the white river sand walls reinforcing a sense of river foreshore.

精致的原生“地毯”花园和橄榄灰色调回应了加固河滩的白色河沙墙。

youdao

It lies between sand hills covered with pine trees and rich farmland near the Mississippi River.

VOA: special.2010.01.03

The first course at Dismal River, in the sand hills near tiny Mullen, Neb.

WSJ: Cabot Links, Streamsong, Bandon: When Building a Course Makes Sense | Golf Journal by John Paul Newport

The cassiterite makes up some fraction of the standard sand and river silt there.

FORBES: After Conflict Minerals Comes The Death Metal: Tin. And It's Apple's Fault Again.

The industry uses regulated amounts of water from the Athabasca River to separate bitumen from the sand.

BBC: Canada's 'dirty oil' challenge