1. The effects of added phosphorus (P) on the growth, P and RNA : DNA contents, and survivorship of snails grazing on laminated microbial mats (living ‘stromatolites’) were examined in the Rio Mesquites at Cuatro Ciénegas, Mexico (total P, c. 0.60 lmol L) to test the hypothesis that strong P-limitation of microautotroph growth produces a stoichiometric constraint on herbivores because of minera...

soil genesis and evolution studies are based on well understanding of geochemical processes involved in pedogenic processes and formation of soil. parent materials are main factors controlling soil properties in arid and semiarid regions. in this study, physicochemical and geochemical properties of 6 selected soil profiles developed on basalt rocks along arid (eshtehard), semiarid (qazvin) and ...

Streams store nutrients in standing stocks of organic matter (OM) and associated biologically sequestered elements. Unlike autotrophs, detritus is depleted by nutrient enrichment, potentially reducing areal storage detritus-associated nutrients. To test effects nutrient-loading on nitrogen (N) phosphorus (P) autotrophic detrital-pool compartments, we quantified the 2 yr continuous experimental ...

We develop a model for stochastic pre-enrichment and self-enrichment in globular clusters (GCs) during their formation process. GCs beginning their formation have an initial metallicity determined by the pre-enrichment of their surrounding protocloud, but can also undergo internal self-enrichment during formation. Stochastic variations in metallicity arise because of the finite numbers of super...