TREND WATCH : <i> A roundup of business developments spotted by other publications.</i>

Temporary Prosperity: The U.S. temporary-employee payroll has grown 20 times over since 1970--to $10.8 billion from $540 million. Temporary services expect flat business this year compared to last but are not concerned about an economic downturn. One temp executive says short-term secretarial services are frequently part of the rebuilding process after a slowdown. It seems that the relatively inexpensive solution of using temps is a habit that American businesses are not going to give up. Another executive noted, “We’ve moved from the position of supplying bodies to providing a business service.” Atlanta Constitution

Bartering Crude: Global Natural Resources has found a way to make money while cleaning up the environment--in the Soviet Union. The Houston-based company has entered into a deal with Tatneft, a Soviet oil and gas company, to recover crude evaporating from Tatneft’s facilities in Tataria. In exchange, it will receive crude exports. Global and its partner, Core Resources of San Antonio, will put up about $3.2 million and the technology for the vapor-recovery facilities. The Soviets will provide some capital and support staff. Houston Chronicle

S ulfur Deposit: Chemical maker Freeport-McMoRan of New Orleans has discovered a huge sulfur deposit at the mouth of the Mississippi River that it will begin mining as soon as equipment is in place, likely 1992. The amount of sulfur is estimated at 67 million tons--$10 billion worth. Six interconnected platforms will be erected to remove the mineral. Four others will produce oil and gas at the site. Industry watchers say it will take 30 years to remove the sulfur, which Freeport uses to make phosphate fertilizers. New Orleans Times-Picayune