Articles describing environmental sensors built with Arduino:

Andrew D. Wickert 2014. The ALog: Inexpensive, Open-Source, Automated Data Collection in the Field. Bulletin of the Ecological Society of America 95:166–176. http://dx.doi.org/10.1890/0012-9623-95.2.68 [PDF @: http://www.esajournals.org/doi/full/10.1890/0012-9623-95.2.68]

Bo Yang, Mark C. Patsavas, Robert H. Byrne, Jian Ma, Seawater pH measurements in the field: A DIY photometer with 0.01 unit pH accuracy, Marine Chemistry, Volume 160, 20 March 2014, Pages 75-81, ISSN 0304-4203, http://dx.doi.org/10.1016/j.marchem.2014.01.005 [PDF @: http://www.sciencedirect.com/science/article/pii/S0304420314000061].

Leeuw T., E. S. Boss, and D. L. Wright. 2013. In situ measurements of phytoplankton fluorescence using low cost electronics. Sensors 13:7872–7883 [PDF @: http://www.mdpi.com/1424-8220/13/6/7872].

Some more resources:

http://playground.arduino.cc/Main/InterfacingWithHardware#envtop

Stroud Water Resource Center has a page with tutorials regarding Arduino based data loggers for sensors: http://czo.stroudcenter.org/sensors/introductio/