Conductivity and Suspended Sediments in Karst and Fractured Springs in Pennsylvania Cecilia Mejias and Laura Toran Department of Geology, Temple University  The properties of groundwater depend on the geology through which the groundwater travels  Three springs in southeastern Pennsylvania were compared: two karst springs and a spring discharging from sandstone  Conductivity, discharge, and suspended sediment were contrasted Problem Statement What’s going on? In Karst Systems:  Water seeps into the soil where it will react with the bedrock, (usually limestone or dolomite) exploit the weaknesses in the rock, and cause voids and fissures to form.  Water can easily pass through the fissures that will gradually become conduits which can lead to caves. If the overburden collapses it can make a sinkhole, which will make it easier for water to travel faster directly through the system.  When the water is dissolving the rock it will have a higher ionic content; when it travels fast through conduits it has a lower ionic content.  Water traveling through the karst will have higher sediment amounts since it can travel through the system faster. The water will respond to storms faster. In Nonkarst systems:  Water percolates through the soil where it may seep through a series of fractures.  The fractures are caused by stress or over burden.  Resistant bedrock such as sandstone does not easily react with water.  The water takes a long time to find its way through the network of fractures.  Therefore storm response will be slowed. The sediment and ion concentrations are also lower Nolte Stockton Bushkill Spring Locations Acknowledgements A special thanks to National Science Foundation Hydrologic Sciences Program for their support to make this project possible. Thank you to all the Temple student workers, especially Jen Tancredi whose work on the Nolte Spring and helpful input has proven invaluable. Conclusions SEDIMENT TRANSPORT  Higher at karst springs, Nolte and Bushkill (up to 50 mg/L)  Seemed to be season dependent: higher in fall than in the winter (some exceptions at Bushkill)  Stockton showed little or no variation (0 to 5mg/L) regardless of the season VARIATIONS IN Ca 2+  Nolte ranged from 95 to 115 mg/L  Bushkill ranged from 35 to 65 mg/L  Stockton less than 20 mg/L and little response to storms CONDUCITIVITY  Lowest in the fractured rock spring (Stockton)  Differences in response indicate that continuous monitoring is especially important in karst springs to predict contaminant transport Suspended Sediment Dissolved Ca 2+ /karst4.htm wellxsec.jpg Stockton Spring Site Bushkill Spring Site Nolte Spring Site Continuous Monitoring Biweekly Sampling Sample Analysis Stockton Spring (non-karst) Conductivity Bushkill Spring (karst) Nolte Spring (karst)  Located in Buckingham Township  Spring comes from a fracture in the sandstone in the Stockton formation  Stockton formation contains shale and sandstone  Discharges about 10 L/s at baseflow  Located in Lehigh Valley  This karst is composed of limestone and dolomite  Located in the Ordovian Epler formation  Discharges 3 L/s at baseflow Bushkill Spring Site  Located in Lancaster County  This karst is composed of limestone and dolomite  Occurs in the Ordovician Epler formation  Discharges 25 L/s at baseflow  Global Water GL400 Datalogger  Conductivity and water level recorded at 20- minute intervals  HOBO temperature logger  Data downloaded every two to four weeks  Measured unstable parameters (pH, T) in the field  Collected samples for sediment, alkalinity, and ions  Duplicates  pH, Temperature  Water level and flow measurements  Dionex ion chromatograph for dissolved ion concentrations  Sediment filtering  Alkalinity Titrations with H 2 SO 4 Stockton Spring house, built circa 1700 Methods Bimonthly samples