Dietary crude protein and tannin impact dairy manure chemistry and ammonia emissions from incubated soils

Excess crude protein (CP) in dairy cow diets is excreted mostly as urea nitrogen (N), which increases ammonia (NH) emissions from dairy farms and heightens human health and environmental concerns. Feeding less CP and more tannin to dairy cows may enhance feed N use and milk production, abate NH emissions, and conserve the fertilizer N value of manure. Lab-scale ventilated chambers were used to evaluate the impacts of CP and tannin feeding on slurry chemistry, NH emissions, and soil inorganic N levels after slurry application to a sandy loam soil and a silt loam soil. Slurry from lactating Holstein dairy cows (Bos taurus) fed two levels of dietary CP (low CP [LCP], 155 g kg; high CP [HCP], 168 g kg) each fed at four levels of dietary tannin extract, a mixture from red quebracho (Schinopsis lorentzii) and chestnut (Castanea sativa) trees (0 tannin [0T]; low tannin [LT], 4.5 g kg; medium tannin [MT], 9.0 g kg; and high tannin [HT], 18.0 g kg) were applied to soil-containing lab-scale chambers, and NH emissions were measured 1, 3, 6, 12, 24, 36, and 48 h after slurry application. Emissions from the HCP slurry were 1.53 to 2.57 times greater ( < 0.05) than from the LCP slurry. At trial's end (48 h), concentrations of inorganic N in soils were greater ( < 0.05) in HCP slurry-amended soils than in LCP slurry-amended soils. Emissions from HT slurry were 28 to 49% lower ( < 0.05) than emissions from 0T slurry, yet these differences did not affect soil inorganic N levels. Emissions from the sandy loam soil were 1.07 to 1.15 times greater ( < 0.05) than from silt loam soil, a result that decreased soil inorganic N in the sandy loam compared with the silt loam soil. Larger-scale and longer-term field trails are needed to ascertain the effectiveness of feeding tannin extracts to dairy cows in abating NH loss from land-applied slurry and the impact of tannin-containing slurry on soil N cycles.     

Use of HPGe gamma-ray spectrometry to assess the isotopic compositiion of uranium in soils

Gamma-ray spectrometry was used to determine uranium activity and investigate the presence of depleted uranium in soil samples collected from camping sites of the Greek expeditionary force in Kosovo. Assessment of 238U concentrations was based on measurements of the 63.3 keV and 92.38 keV emissions of its first daughter nuclide, 234Th. To determine the isotopic ratio of 238U/235U, secular equilibrium along the two radioactive series was first ensured and thereby the contribution of 235U under the 186 keV peak was deduced. The uranium activity in the samples varied from 48 to 112 Bq kg(-1), whereas the activity ratio of 238U/235U averaged 23.1+/-4.3.     

Activity concentration of caesium-137 in agricultural soils

In this study, we measured 137Cs activity concentrations in the soil samples taken from agricultural lands in the Buyuk Menderes Basin in Turkey in 1997 and 1998. The soil samples were collected from 42 sites in this Basin. The activity concentration of 137Cs was found to range between 2.81+/-0.17 Bq.kg(-1) and 20.75+/-0.29 Bq.kg(-1). The effect of organic matter, clay, silt and sand contents and pH of the soil on the relative adsorption of the 137Cs on the soil surface were also studied.     

Behavior of a surface applied radionuclide and a dye tracer in structured and repacked soil monoliths

There has been increasing evidence in recent years about the impact of soil structure on vadose zone hydrology and the distribution of surface applied chemical substances. We have carried out a combined dye and radionuclide tracer study on two monoliths from the same location, one structured and one repacked, as part of an ongoing study to investigate the link between preferential flow, leaching of surface applied substances and their distribution within the soil.A tracer solution containing 1300 Bq/L (58)Co and 0.31 micromol/L Sulforhodamine B (SB) was added with roughly constant irrigation during a period of three weeks. The dye served as a tracer for water movement within the soil and thus allowed linkage of the radiotracer ((58)Co) with the flow pattern. Both were monitored in the outflow and measured within profile sections after monolith disassembly. Preferential flow in the structured monolith promoted the bypass and transport of both tracers, although transport was impeded at depths greater than 30 cm by compacted soil and reduced hydraulic conductivity. Eighty four percent of radiocobalt and 8% of SB were found in the upper 4 cm of the structured monolith. The homogenized monolith, on the other hand, showed mostly chromatographic infiltration and a more efficient soil filtering capacity with 91% of radiocobalt and 20% SB residing in the upper 4 cm. Furthermore no tracer was found in the outflow of the homogenized monolith during normal to high irrigation or at greater depth within the monolith. We have related flow characteristics and sorption of radiotracers by quantifying dye distributions and radionuclide activities throughout the profiles. Activities within the flow paths are up to 20-times higher than those measured in the soil matrix, and a fraction of radiocobalt follows the dye tracer in spite of cobalt's low mobility. The dye can thus be used to trace radionuclide distribution within the soil block.     

Anthropogenic radionuclides in the Japan Sea: their distributions and transport processes

The anthropogenic radionuclides, (90)Sr, (137)Cs and (239+240)Pu, were measured in the water column of the Japan Sea/East Sea during 1997-2000. The vertical profiles of radionuclide concentrations showed: exponential decrease with depth for (90)Sr and (137)Cs, and surface minimum/subsurface maximum for (239+240)Pu. These results do not differ substantially from results reported previously. The area-averaged concentrations of radionuclides in the Japan Sea are higher than those found in the Northwest Pacific Ocean below surface layer showing the accumulation of the radionuclides in the deep waters in the Japan Sea. Concerning spatial distributions, the area of high (137)Cs inventory extends from the Japan Basin into the Yamato Basin. It is suggested that wintertime convection of water, occurring mainly in the Japan Basin, causes the radionuclides to sink. The nuclides then advect into the Yamato Basin after detouring around the Yamato Rise.     

The effective and environmental half-life of 137Cs at Coral Islands at the former US nuclear test site

The United States (US) conducted nuclear weapons testing from 1946 to 1958 at Bikini and Enewetak Atolls in the northern Marshall Islands. Based on previous detailed dose assessments for Bikini, Enewetak, Rongelap, and Utirik Atolls over a period of 28 years, cesium-137 (137Cs) at Bikini Atoll contributes about 85-89% of the total estimated dose through the terrestrial food chain as a result of uptake of 137Cs by food crops. The estimated integral 30, 50, and 70-year doses were based on the radiological decay of 137Cs (30-year half-life) and other radionuclides. However, there is a continuing inventory of 137Cs and 90Sr in the fresh water portion of the groundwater at all contaminated atolls even though the turnover rate of the fresh groundwater is about 5 years. This is evidence that a portion of the soluble fraction of 137Cs and 90Sr inventory in the soil is lost by transport to groundwater when rainfall is heavy enough to cause recharge of the lens, resulting in loss of 137Cs from the soil column and root zone of the plants. This loss is in addition to that caused by radioactive decay. The effective rate of loss was determined by two methods: (1) indirectly, from time-dependent studies of the 137Cs concentration in leaves of Pisonia grandis, Guettarda specosia, Tournefortia argentea (also called Messerschmidia), Scaevola taccada, and fruit from Pandanus and coconut trees (Cocos nucifera L.), and (2) more directly, by evaluating the 137Cs/90Sr ratios at Bikini Atoll. The mean (and its lower and upper 95% confidence limits) for effective half-life and for environmental-loss half-life (ELH) based on all the trees studied on Rongelap, Bikini, and Enewetak Atolls are 8.5 years (8.0 years, 9.8 years), and 12 years (11 years, 15 years), respectively. The ELH based on the 137Cs/90Sr ratios in soil in 1987 relative to the 137Cs/90Sr ratios at the time of deposition in 1954 is less than 17 years. The magnitude of the decrease below 17 years depends on the ELH for 90Sr that is currently unknown, but some loss of 90Sr does occur along with 137Cs. If the 15-year upper 95% confidence limit on ELH (corresponding to an effective half-life of 9.8 years) is incorporated into dose calculations projected over periods of 30, 50, or 70 years, then corresponding integral doses are 58, 46 and 41%, respectively, of those previously calculated based solely on radiological decay of 137Cs.     

Repeated trans-Arctic invasions in littoral bivalves: molecular zoogeography of the<Emphasis Type="Italic"> Macoma balthica</Emphasis> complex

From a geographical survey of allozyme variation, a history of repeated trans-Arctic invasions since the Plio-Pleistocene is suggested for circumboreal bivalves of the Macoma balthica complex. A principal genetic subdivision, involving several nearly diagnostic loci and Nei's distance D=0.6, distinguishes the clams of the NE Pacific from those of the NE Atlantic. The Pacific taxon is however also present in Europe, in disjunct isolates in the Baltic Sea and White Sea basins. Nevertheless, these populations have marked Atlantic introgressive elements in their gene pools (ca. 30%). Two further population types are recognized, one in the St. Lawrence estuary, Quebec, the other in Varangerfjorden, NE Norway; the latter appears a mixture of Pacific and Atlantic components in almost equal proportions, in local genetic equilibrium (a hybrid swarm). Populations in temperate North America fall outside the circumboreal M. balthica complex discussed here (D=1.0), and are referred to M. petalum. In a scenario of the history and evolution of the M. balthica complex and the similarly subdivided Mytilus edulis complex, the divergence between Pacific and Atlantic taxa started after an initial introduction of Pacific ancestors to the Atlantic basin, enabled by the Pliocene opening of the Bering Strait. During the Pleistocene and Holocene, the ocean basins were, for the most part, effectively isolated, but occasional re-invasions have taken place, causing secondary contacts of the diverged bivalve types on the Atlantic coasts. The recently re-invaded Pacific taxa in northern Europe now seem to thrive only in the extreme marginal environments. Exact dating of the re-invasions is not possible from current data. Apart from the divergence through isolation, hybridization and introgression have significantly molded the present affinities within the M. balthica complex. A formal taxonomic treatment of reticulate and hybridizing lineages is problematic; yet to recognize the evolutionary and systematic diversity within the M. balthica complex, a subspecies distinction between the NE Atlantic clams and those from the Pacific, Baltic and White Sea basins is suggested.Communicated by L. Hagerman, Helsingør     

The role of grazing by the lysianassid amphipod<Emphasis Type="Italic"> Orchomenella aahu</Emphasis> in dieback of the kelp<Emphasis Type="Italic"> Ecklonia radiata</Emphasis> in north-eastern New Zealand

The lysianassid amphipod Orchomenella aahu was associated with small-scale mass mortality of Ecklonia radiata, the dominant laminarian alga in north-eastern New Zealand. O. aahu burrowed into and hollowed out stipes with severe bleaching, accelerating mortality by 12–14 months. Meristoderm tissue of bleached plants contained approximately one-third of the phlorotannin content (~4% dry mass) present in unbleached, apparently healthier, sporophytes (~12% dry mass). Unbleached stages consistently lacked amphipod damage. O. aahu also colonised plants when non-lethal storm damage afforded entry into the cortical layers of the primary lamina, and ultimately the stipe. O. aahu typically consumed both medullary and cortical tissue of the stipes, forming networked brood-chambers within them, with increasing populations often reducing the plant to the holdfast. There was synchronised mortality across sites and between depths over spatial scales of metres. Following loss of the mature canopy, recruitment of E. radiata was generally within 2 months at most study sites where mortality had occurred.Communicated by G.F. Humphrey, Sydney