Charles R. Frink

Acid Rain on Acid Soil: A New Perspective

Acid rain is widely believed to be responsible for acidifying soil and water in areas of North America and northern Europe. However, factors commonly considered to make landscapes susceptible to acidification by acid rain are the same factors long known to strongly acidify soils through the natural processes of soil formation. Recovery from extreme and widespread careless land use has also occurred in regions undergoing acidification. There is evidence that acidification by acid rain is superimposed on long-term acidification induced by changes in land use and consequent vegetative succession. Thus, the interactions of acid rain, acid soil, and vegetation need to be carefully examined on a watershed basis in assessing benefits expected from proposed reductions in emissions of oxides of sulfur and nitrogen.

A perspective on metals in soils

Soil contaminated with metals from a variety of sources can be toxic to plants and animals, including humans. The extent of contamination is often determined by comparison with the total elemental composition of an uncontaminated soil, although some leaching tests have also been proposed. In any event, knowledge of the natural background concentrations of metals at the site is required. Analysis of a control sample from the site will provide some information, but soils are still inherently variable. This review summarizes the total elemental composition of soils not known to be contaminated from anthropogenic sources. The total concentrations of 50 metals reported for these soils were shown to be log‐normally distributed, making the geometric mean (GM) and geometric standard deviation (GS) appropriate. Thus, 99.7% of the data should fall between GM/GS3 and GM*GS3. Fifteen metals were above the upper 99.7% limit and eight were below the lower limit. Most fell between the 99.9% limits of GIWGS4 and GM*GS4. ...

Field-observed ethylene dibromide in an aquifer after two decades.

Abstract The fate and transport of the soil fumigant, 1,2-dibromoethane (EDB) was studied at a former tobacco field in Simsbury, Connecticut where it was last used in 1967. The subsurface consists of glacial deposits of stratified sand, gravel, and silt underlain by a fractured sandstone/siltstone bedrock. Contaminant plumes in the bedrock had migrated only slightly from beneath the tobacco field after nearly two decades, consistent with calculated flow velocities. Contaminant levels in the overburden aquifer were much lower, which was consistent with higher calculated flow velocities resulting in off-site discharge to a nearby stream, and possibly with faster biodegradation. EDB concentrations in both zones were stable over the study period (1.5–2yr). Earlier demonstration of relatively fast biodegradation of 14 C-EDB in aquifer core samples were contradicted by the plume stabilities observed here. EDB was found in vadose cores, particularly topsoils, at concentrations up to 32μg kg −1 . These residues could not be extracted with water, even after 20 d, and were unavailable for biodegradation. By contrast added 14 C-EDBwas mineralized almost completely in 22 d. EDB was also found in overburden aquifer cores, in some cases at concentrations much greater than predicted from equilibrium partition experiments. The results show that kinetically slow, nonequilibrium sorption is a factor in the decades-long persistence of this chemical in the topsoil and possibly in the aquifer.

Phosphorus and zinc fertilization of corn grown in a Connecticut soil

Abstract Deficiencies in soil zinc (Zn) may limit yield of corn (Zea mays L.) in parts of the northeastern United States. Because phosphorus (P) fertilizer is usually applied in excess of what is removed by the crop, buildup of P could reduce the plant availability of Zn. This study examines the effects of P and Zn fertilizer on yield of corn and levels of P and Zn in soil and tissue. Compared to corn that received no P or Zn, the yield of grain increased in three years when 66 kg/ha P + 0 kg/ha Zn and 66 kg/ha P + 15 kg/ha Zn was applied. When corn was fertilized with 0 kg/ha P + 15 kg/ha Zn, grain yield increased in one year. Similarly, an increase in grain yield occurred in only one year in plots fertilized with 66 kg/ha P + 15 kg/ha Zn compared to 66 kg/ha P + 0 kg/ha Zn. Increases in grain yields ranged between 5 and 22 percent for plots receiving P alone and P plus Zn, and between 5 and 10 percent for plots fertilized with Zn alone. Silage yields followed the same trends as the grain yields except t...