Characterization of chromium-containing wastes and soils affected by the production of chromium tanning agents

Purpose

Wastes of unknown composition derived from the production of trivalent chromium (Cr(III)) salts used as tanning agents are deposited in the area of Kanpur, India. The questions of whether these samples are chromite ore processing residue (COPR) and whether Cr occurs in its toxic hexavalent form (Cr(VI)) arise.

Materials and methods

Twenty-one samples from two disposal sites and surrounding soils were analyzed, specifically examining their elemental and mineralogical composition. Additionally, aqueous eluates with different liquid-to-solid ratios were performed and analyzed for Cr(VI).

Results and discussion

The samples were classified in accordance to the sum of silicon and aluminum and the sum of calcium and Cr contents: uncontaminated, moderately contaminated, and highly contaminated material. Highly contaminated material exhibited extremely alkaline pH values up to 12.5 and total Cr contents ranging from 65.7 to 110 g/kg, whereas uncontaminated material had comparatively moderate pH values and Cr contents <1 g/kg. In total, seven crystalline phases commonly found in COPR were identified in the contaminated samples, of which five phases (brownmillerite, hydrocalumite, hydrogarnet, magnesiochromite, and periclase) are known to be able to accommodate Cr whereas hydrogarnet and hydrocalumite are the main host phases for Cr(VI). Batch tests showed that dissolution controlled the Cr(VI) concentrations in the eluates.

Conclusions

Six samples were clearly identified as highly Cr-contaminated COPR. Leaching of Cr(VI) and resulting contamination of soils and water bodies is a key environmental risk arising from these COPR sites especially during the monsoon season. This situation is of particular concern as the local population use the highly Cr(VI)-contaminated water not only for the needs of livestock and irrigation but also as drinking water due to the absence of alternative water resources.     

Influences of ultra‐violet (UV)‐blue light radiation on the growth of cotton. II. Photosynthesis,leaf anatomy,and iron reduction

Cotton (Gossypium hirsutum L.) plants grown under low pressure sodium lamps (LPS) developed chlorosis which was similar in appearance to iron‐stress induced chlorosis, while plants under cool white fluorescent lamps (CWF) at the same level of photosynthetically active radiation (PAR) developed normally. These illumination sources differ in spectral irradiance; CWF lamps emit ultra violet (UV), whereas LPS lamps do not. Ultraviolet radiation is capable of reducing Fe³⁺ to Fe²⁺ through a chlorotic leaf which may be important in establishing an active iron fraction in the leaf. Root reduction of Fe³⁺ to Fe²⁺ was lacking in Fe‐stressed cotton under LPS light, but was present under CWF light. Net photosynthesis, photosynthetic electron transport, and leaf chlorophyll content were lower under LPS than CWF light in most of the growing media studies (soil or solutions with nitrate‐ or ammonium‐nitrogen supplied). Chloroplast ultrastructure and leaf thickness were also altered by LPS irradiance. Electron microscopic studies with plants grown in nutrient solutions for 4 weeks suggested that chioroplastic granal disorganization was more directly associated with diminished iron supplies than with light source. However, plants grown in soil for 6 weeks under LPS light had granal disorganization similar to that found in iron‐stressed plants. These studies suggest an important role for UV radiation in influencing the activity of iron in plants.     

Number of involved genes and heritability of clover rot (Sclerotinia trifoliorum) resistance in red clover (Trifolium pratense)

European red clover (Trifolium pratense) crops are challenged by clover rot, a devastating disease caused by Sclerotinia trifoliorum or, in some cases by S. sclerotiorum. No completely resistant cultivars are available and resistance breeding is hampered by the lack of knowledge on the number of involved resistance genes and the heritability of clover rot resistance. In this study, we estimated the number of major genes contributing to clover rot resistance by analysing 15 F₁ progeny populations from pair crosses between ramets of resistant and susceptible genotypes. Parent plants were chosen from diverse, diploid populations, including wild material, landraces and cultivars. Young progeny plants were inoculated with ascospores, evaluated phenotypically and the segregation of disease scores was studied. Our results indicated that clover rot resistance may be conferred by three major effect genes, although segregation patterns suggested that there may be numerous minor effect genes involved as well. No proof was found for a maternal inheritance of clover rot resistance. To get insight in the heritability of clover rot resistance, we applied divergent selection by our high-throughput bio-test on an experimental diploid population: the original population (70.5 %), the first generation after selection for susceptibility (79.2 %) and the first generation after selection for resistance (62.3 %) differed significantly in susceptibility (p < 0.001). The second generation after selection for resistance (60.0 %) was not more resistant than the first generation after selection for resistance. In the first generation of selection the heritability (h²) was on average 0.34. In the second generation of selection h² was 0.07. These findings have important implications for resistance breeding.     

Cell-mediated and humoral immune responses in pigs following primary and challenge-exposure to Lawsonia intracellularis

ABSTRACT: To investigate immune responses upon re-infection with Lawsonia intracellularis, local and peripheral humoral and cell-mediated immune responses to primary and challenge inoculations were studied in 22 pigs. Pigs were orally inoculated with virulent L. intracellularis at the age of 5-6 weeks, treated with antibiotics and challenged with a re-inoculation (RE) at the age of 12 weeks. Treatment control (TC) pigs received only the primary inoculation and challenge control (CC) pigs received only the secondary inoculation at 12 weeks of age. Following this regimen, all RE pigs were protected against the re-infection as defined by reduced colonisation and pathology of intestinal mucosa, absence of bacterial shedding and without increase in serum acute phase protein response. In the protected RE pigs, serum IgG responses were variable with both high and low responders. Serum IgA responses were not boosted by the re-inoculation, since identical intestinal IgA responses developed in response to the inoculation in both the susceptible CC pigs and the protected RE pigs. A memory recall cell-mediated immune response developed in RE pigs which was significantly stronger compared to the primary response in age-matched CC pigs as assessed by whole blood IFN-γ assay and by calculation of IFN-γ integrated median fluorescence intensity (iMFI) after flow cytometry. The major IFN-γ producing cells were identified as CD8+ and CD4+CD8+ double positive lymphocytes. The results indicate that cell-mediated immune responses are likely mediators of protective immunity against L. intracellularis, with CD8+ effector cells and CD4+CD8+ double positive memory T cells as main contributors to the antigen-specific IFN-γ production.     

Field trial of six serological tests for bovine brucellosis

Serum agglutination (SAT), complement fixation (CFT), indirect ELISA (iELISA), competitive ELISA (cELISA), Rose Bengal (RBT) and EDTA-modified agglutination (EDTA) tests were used in parallel on serological samples from 19,935 cattle in 301 herds. The study herds were selected according to putative exposure to Brucellaabortus with cases defined by bacteriological culture or test agreement. No single test identified all infected cattle and, at diagnostic thresholds, relative sensitivity was highest in the iELISA (67.9%) or RBT (78.1%), using bacteriological culture or test agreement, respectively, to define cases. As screening tests, the relative sensitivity of the SAT was highest (75.9% by culture or 84.9% by test agreement), with an optimal threshold of 31 IU. The relative specificity of the diagnostic tests ranged from 99.6% (SAT 31IU) to 100% (iELISA, RBT and CFT). The trial confirmed the value of the SAT as a screening test and the value of parallel testing.     

Whole farm analysis of automatic section control for agricultural machinery

Automatic section control was analyzed in a whole farm decision-making framework when implemented on an agricultural sprayer and/or planter. In addition, various field types and navigational scenarios were examined to determine their impact on profitability. It was determined that automatic section control increased net returns under all scenarios; up to $36/ha. This investigation highlighted the importance of considering field size in addition to field shape as well as initial navigational scenarios when determining the profitability of automatic section control.