Date of Award
Master of Science (MS)
The chemical and biological properties of ponds artifically created as a result of the strip-mining process, were studied in Mercer County, North Dakota. The water in four of these ponds was analyzed for 25 chemical variables, pH and electrical conductivity. These same variables were also analyzed in bottom sediments and spoils surrounding the four ponds. Invertebrates were collected and identified from these ponds, as well as measuring certain attributes of community structure, including species composition, density, biomass and species diversity. Both the chemical and biological properties documented in strip-mine ponds were compared to a naturally occurring pond nearby (NBUN).
The strip-mine ponds studied showed high salinites (819-2029 ppm), with sodium and sulfate, as the dominant ions. Though salinities are higher than NBUN (250 ppm), they are not at levels which exceed the normal range (100-100,000 ppm) for alkaline ponds in North Dakota, Wyoming and Saskatchewan, Canada. Other chemical variables (Ca, Mg, K, Li, Mn, Ni, Sr, Cl and NO3) which were also higher in strip-mine ponds when compared to NBUN, still were not unlike typical prairie potholes. Several ions (Al, Cu, Fe, Mo, NH4, Pb, PO^, Si and Zn) were essentially no different from NBUN. Heavy metal toxicity, which is a potential problem, is minimal because these metals are quickly precipitated into the bottom sediment as they are leached from surrounding spoil.
When a strip-mine pond is formed, it is almost immediately used by wildlife and soon becomes inhabited with aquatic organisms. A total of 97 species were identified in three strip-mine ponds and NBUN. The most common phyla in these ponds are Mollusca and Arthropoda. The class Insecta comprises almost 80% of all species identified, with Diptera (26 species) and Coleoptera (24 species) the most common orders. Cnidaria, Nematomorpha, Bryozoa and Annelida are not common to stripmine ponds. As amount of vegetation increases, it has a moderating effect on water chemistry, as well as providing food, shelter and support for aquatic invertebrates. This causes an increase in the various properties of community structure. Density increases from 2 2 1,337 ind./m at NB1 to 13,453 ind./m at DS30. Biomass increases from 15.4 lbs/acre to 1,133.1 lbs/acre. Species diversity at NB1 is 1.81 and 2.53 at DS30, using the Shannon-Wiener index. A similarity index comparing strip-mine ponds and NBUN shows that as the strip-mine pond increases in age, the more it resembles NBUN.
In general, surface mined waters will tend to resemble naturally occurring ponds, both chemically and biologically, within a few years.
Batema, Donald Llewllyn, "Aquatic Invertebrates and Water Chemistry of Strip-Mine Ponds in Western North Dakota" (1979). Theses and Dissertations. 2643.