Impacts of inorganic turbidity on diquat efficacy against Egeria densa

In clear water, diquat [6,7-dihydrodipyrido (1,2-1a:2',1'-c) pyrazinediium dibromide] provides excellent submersed Plant control at low concentrations, such as <0.5 mg active ingredient (ai) L-1: however. turbid water conditions can interfere with the activity and effectiveness of this herbicide. Little work has been done to examine what ranges of turbidity caused by different Suspended sediment types affect diquat efficacy against a target species. A growth chamber study was conducted rising diquat against the submersed macrophyte -egeria (Egeria densa Planch.) under a range Of turbid conditions. Two materials were used to create turbid beater conditions: 100% bentonite clay for a "worst-case" scenario and a natural partial-clav (20% clay). Results indicated that a high rate of diquat (2 mg ai L-1) controlled egeria under relatively low levels of turbidity (5-10 NTU) using bentonite clay: however. higher levels (25 to 50 NTU) of turbidity essentially blocked effectiveness of diquat when applied at all rates tested (0.5. 1, 2 mg ai L-1). When using a natural partial-clay sediment, rates of 1 to 2 mg ai L-1 diquat provided good control of egeria in moderately turbid water (15 NTU). Additional evaluations rising different clay types would be useful to determine the effect of inorganic turbidity oil diquat efficacy.

In situ measurement of dissolved inorganic carbon speciation in natural waters, pH, pC02, TA, & TC02, Honolulu, Hawaii, February 16-18, 2005: workshop proceedings

The Alliance for Coastal Technology (ACT) convened a workshop on the in situ measurement of dissolved inorganic carbon species in natural waters in Honolulu, Hawaii, on February 16, 17, and 18, 2005. The workshop was designed to summarize existing technologies for measuring the abundance and speciation of dissolved inorganic carbon and to make strategic recommendations for future development and application of these technologies to coastal research and management. The workshop was not focused on any specific technology, however, most of the attention of the workshop was on in situ pC02 sensors given their recent development and use on moorings for the measurement of global carbon fluxes. In addition, the problems and limitations arising from the long-term deployment of systems designed for the measurement of pH, total dissolved inorganic carbon (DIC), and total alkalinity (TA) were discussed. Participants included researchers involved in carbon biogeochemistry, industry representatives, and coastal resource managers. The primary questions asked during the workshop were: I. What are the major impediments to transform presently used shipboard pC02 measurement systems for use on cost-eficient moorings? 2. What are the major technical hurdles for the in situ measurement of TA and DIC? 3. What specific information do we need to coordinate efforts for proof of concept' testing of existing and new technologies, inter-calibration of those technologies, better software development, and more precise knowledge quantzjjing the geochemistry of dissolved inoeanic carbon species in order to develop an observing system for dissolved inorganic carbon? Based on the discussion resulting from these three questions, the following statements were made: Statement No. 1 Cost-effective, self-contained technologies for making long-term, accurate measurements of the partial pressure of C02 gas in water already exist and at present are ready for deployment on moorings in coastal observing systems. Statement No. 2 Cost-effective, self-contained systems for the measurement of pH, TA, and DIC are still needed to both fully define the carbonate chemistry of coastal waters and the fluxes of carbon between major biogeochemical compartments (e.g., air-sea, shelf-slope, water column-sediment, etc.). (pdf contains 23 pages)

Growth response of Clarias gariepinus fry to organic and inorganic fertilizers

The growth response of Clarias gariepinus was investigated in various types of fertilizers. Fertilizer type was found to influence plankton abundance which in turn determine the growth and well being of C. gariepinus. The best weight increase recorded was in cow dung /NPK (1.37~c1.01g) followed by poultry (0.49~c0.31g), NPK/poultry (0.05~c0.25g) and NPK(0.03~c0.57g) The survival rate in these treatments were cow dung/NPK (100%), poultry (100%), NPK/cow/poultry (33%) and NPK (8%)