"Warning:explode()…" appears on each page of my website. Please help.

Please let me know how I may remove the following message that appears on top of all of my website’s pages:

Warning: explode() expects parameter 2 to be string, array given in /nfs/c09/h04/mnt/139922/domains/asilm.org/html/wp-content/themes/pk2011_itis/parkerandkent2011/functions/theme/pk_filters.php on line 214

I updated some of my plug-ins recently, so maybe the “PK 2011 Itis” theme may not have been able to support them and that is why the above message may have appeared. I am not sure though. Please help me figure out how to fix this problem.

Thank you.