Sediment phosphorus forms and levels in two tropical floodplain wetlands

Abstract

Inorganic phosphorus is one of the critical nutrients determining trophic state and freshwater productivity. Sediment may act as a sink or source of phosphorus to the overlying water depending on its pH, redox state, various forms of phosphorus present, etc. To examine potential sorption or mobilization of sediment phosphorus in floodplain wetlands, the amount and distribution of phosphorus fractions were evaluated using a sequential chemical extraction procedure. Exceedingly high levels of total phosphorus (mean: 6040 § 344, 5470 § 363 mg kg ¡1 ), consisting largely of organic and refractory fraction (70 -98%), followed by calcium-phosphorus (mean: 584 § 31.3, 143 § 8.42 mg kg ¡1 ) and iron-phosphorus (mean: 108 § 10.1, 91.0 § 7.68 mg kg ¡1 ) were recorded respectively in Bhomra and Akaipur wetlands of West Bengal, India. The inorganic phosphorus, comprising the loosely sorbed phosphorus and all the mineral bound forms contributed only about 6-14% to the total phosphorus indicating their less significance in phosphorus sorption or desorption in these tropical wetlands. Although the loosely sorbed phosphorus was in moderate level (2.69 § 0.69, 1.54 § 0.53 mg kg ¡1 ), water dissolved phosphorus was recorded at higher concentrations (mean: 0.16 § 0.02 mg l ¡1 in Akaipur and 1.08 § 0.12 mg l ¡1 in Bhomra). However, the higher level of water available phosphorus was not reflected in plankton production since the dominance of weeds suppresses their growth. This study recorded large accumulation of organic matter and nutrients in the form of detritus in these wetlands which may be channelized for fish production through stocking of suitable detritivorous fishes and/or reducing macrophyte coverage that would give space and nutrients for phytoplankton growth.

Seasonal characteristics of phosphorus sorption by sediments from plain lakes with different trophic statuses

“…and environmental conditions (temperature, ionic strength, pH, P concentration in water body, etc. ), which are regarded as the main factors affecting P release flux through the sediment–water interface [ 11 , 12 ]. In the plain geomorphological region, shallow freshwater lakes with different trophic status exist commonly because of various factors.…”

Two‐Stage Agricultural Ditch Sediments Act as Phosphorus Sinks in West Michigan

“…Small amounts of loosely bound P suggest low cyclic exchange of the more bio‐available soil/sediment P between the water and periphyton interface and sediments (Samanta et al. ) or that P spends very little time within the loosely bound fraction. Drying and rewetting of soils (e.g., 2‐S benches between stormflow events) has been shown to increase the movement of loosely bound and pore water P compared to other fractions including redox sensitive P (Kinsman‐Costello et al.…”

Screening and evaluation of phosphate-solubilizing bacteria isolated from aquaculture ponds in a step-by-step strategy as potential biofertilizer

“…For TP, 0.5 g of dry sample was sequentially digested with 40 ml of 30% H 2 O 2 and tri‐acid mixtures (nitric acid, perchloric acid, sulfuric acid in ratio of 10:4:1 v/v) for two consecutive days, solubilized with water and after that P concentration was estimated. Org‐P was calculated by subtracting the inorganic P from the TP content (Murphy & Riley, 1962; Samanta et al, 2015). The sequential extraction method—detailed in Figure 2—was used to measure the concentration of P forms (Jackson, 1973; Samanta et al, 2015).…”

“…Org‐P was calculated by subtracting the inorganic P from the TP content (Murphy & Riley, 1962; Samanta et al, 2015). The sequential extraction method—detailed in Figure 2—was used to measure the concentration of P forms (Jackson, 1973; Samanta et al, 2015).…”