Nitrous oxide (N₂O) emissions from the South Plane River in Colorado were measured using closed chambers in the fall, winter, and summer of 1994-1995. The South Platte River was enriched in inorganic N (9-800µM) derived from municipal wastewater effluent and groundwater return flows from irrigated agricultural fields. River water was as much as 2500% supersaturated with N₂O, and median N₂O emission rates from the river surface ranged from less than 90 to 32 600 µg-N m^-2 d^-1. Seventy-nine percent of the variance in N₂O emission rates was explained by concentrations of total inorganic N in river water and by water temperature. The estimated total annual N₂O emissions from the South Platte River were 2 x 10¹³-6 x 10¹³ µg-N yr^-1. This amount of annual N₂O emissions was similar to the estimated annual N₂O emissions from all primary municipal waste water treatment processes in the United States (1). Results from this study indicate that N-enriched rivers could be important anthropogenic sources of N₂O to the atmosphere. However, N₂O emission measurements from other N-enriched rivers are needed to better quantify this source.

Concentrations of Zn, Cu, Fe. Cr, Ni, Pb and Cd were analyzed monthly for two years in different body parts (muscle, gill, hepatopancreas and exoskeleton) of edible prawns, Penaeus monodon and Penaeus inclicus sampled from Kulti brackish water wetland system. The area receives the municipal wastes from the highly urbanized and industrialized city of Calcutta, which brings considerable amount of conservative wastes in the wetland system. Shrimp culture with the wastewater is a common practice in this area and therefore the probability of bio-accumulation of conservative wastes in the prawn tissues cannot be ignored. The concentration of heavy metals in the prawn tissues exhibited unique seasonal variations and significant negative relationships with the aquatic pH and salinity of the study area.

Heavy metal pollution is one of the challenging problems to the scientists. In the search for alter-native adsorbents which can be used in place of costlier adsorbents, chemically treated charred saw dust has been investigated for its suitability in the removal of arsenic (80% ) and chromium ( 90 % ) from ground water. Mass transfer studies also revealed the detailed kinetics of the reactor and an effective filtration unit can be designed for simultaneous removal of both the heavy metals,

The study stretch of Ramganga river from Agwanpur township to down-stream confluence point with Gangan river, a tributary of Ramganga, is 36 km. It is considered for study of Cation exchange capacity, organic matter and distribution of heavy metals in river bed sediment. Due to alkaline nature of river water in this stretch most of the heavy metals have precipitated and settled into river bed as carbonates, oxides and hydroxides. The river receives industrial effluents from brass factories, stainless steel, electroplating units etc. through various drains including untreated sewage and human wastes from nearby villages directly into the river. It also receives agro-chemical run off and municipal wastes. The metal concentrations of Pb and Ni are found in maximum amounts at station no. 5 and minimum near station no. 1, whereas Cu, Cv, Zn and Cd the same is true at Station 6 and Station No. I respectively. Fe is found maximum at Station No. 4 and minimum at Station No. 1.

A bioassay test was conducted on polluted well waters and soils due to industrial effluents. The germination percentage and dry matter yields of various crops treated with polluted well waters and soils were reduced as compared to controls, due to accumulation of toxic substances from industrial effluents.