Add spaces: Therearemanyinvestigations,whichhavedocumentedcleanupfromabout2,000downtoabout200mgtotalPAH/kgwithtimescalesof6monthstoseveralyears.Generally,itisdifficulttocalculatethetimescaleforbiologicaltechniques.

Answer: There are many investigations, which have documented clean up from about 2,000 down to about 200 mg total PAH/kg with time scales of 6 months to several years. Generally, it is difficult to calculate the time scale for biological techniques.
TheentiredayisspentintheTobagoCays;AfterVarious.Islandtours,Youcanexplorewhilesnorkelinginacoralareaafascinatingunderwaterworld.

The entire day is spent in the Tobago Cays; After Various. Island tours, You can explore while snorkeling in a coral area a fascinating underwater world.
[Q]: [Theythinkaboutitconstantlyandbecomecompulsiveabouteatingrituals.]
[A]: [They think about it constantly and become compulsive about eating rituals.]
Problem: Add spaces: HEIhasrecentlyplayedbeachhandballinabigChampionsLeaguetournamentinSpain,wheretheteamhasmetlocalchampionsfromalloverEurope.HEIplaced5thandwasbeateninthequarterfinal.

Spaces added: HEI has recently played beach handball in a big Champions League tournament in Spain, where the team has met local champions from all over Europe. HEI placed 5 th and was beaten in the quarterfinal.
This text is missing some spaces, please add them: UnsureaboutwhichtypeofZ9fileyouhave?Doyouwanttoknowexactlywhatitis,whocreatedit,andhowtoopenit?
Unsure about which type of Z9 file you have? Do you want to know exactly what it is, who created it, and how to open it?
[Q]: [Theseelegantstructurescanbeusedastransparentflooring,dancefloors,fairstands,stagesorsteps.]
[A]:
[These elegant structures can be used as transparent flooring, dance floors, fair stands, stages or steps.]