The speciation trend of dissolved copper (DCu) was studied for the first time in a Galician Ria across the estuarine zone of the Vigo Ria during the wet season and related to the copper levels in ...suspended particulate matter (PCu) and sediments. In the riverine and ocean end-members DCu concentrations can be defined as pristine (<4
nM in Oitaven River). DCu is not conservative during the estuarine mixing and its concentration increase (5–8
nM) cannot be only associated to PCu (0.5–1.0
nM) variations and the ria sediments may be an important DCu source. DCu speciation was mainly controlled by two types of ligands (
log
K
L
1
′
=
12.9
–
13.9
; and
log
K
L
2
′
=
10.8
–
12.1
). In all samples the concentration of L
1 (
C
L
1
=
15
–
34
nM
) was greater than that of copper, which speciation is so dominated by this strong organic ligand. The transport of copper contamination from the middle Ria to the San Simon Inlet is limited during the wet season; in spite of similar salinities, DCu in the inlet (6
nM) was much lower than at Rande Strait (15
nM).
Mariculture is an important economic activity in shallow marine areas of the Rías Baixas (Galicia, NW Spain). The maintenance of high product quality requires surveillance of environmental quality, ...including the risk of metal toxicity. In this study the redox status of intertidal sediments in the Bay of San Simón, and the risk of toxicity posed by their As, Cd, Cr, Cu, Mn, Ni, Pb and Zn contents, were evaluated by determination of operationally defined reactive, silicate-bound, organic and pyrite-related fractions of these elements and of Fe. The large silicate-bound fractions of most of these metals indicate their lithogenic origin; the main exception is Pb, which in all respects exhibits singular behaviour associated with its predominantly anthropogenic origin in a ceramics factory. In sediments with larger fine-grained particle contents, which are oxic only in the top few centimetres, greater proportions of the trace elements are present as sulphides or associated with sulphide minerals: the degree of pyritization of Fe (DOP) is 46% overall, and the pyrite fraction of some elements doubtless increases at the expense of the reactive fraction, most overall degrees of trace metal pyritization (DTMPs) lying in the range 10–50%. A decline in pyrite genesis at depths below about 18
cm in these sediments is attributed to the exhaustion of organic matter susceptible to metabolization by sulphide-generating bacteria. In coarse-grained, oxic sediments the oxidation of sulphides makes pyrite-related fractions very small, and reactive and silicate-bound fractions are negatively correlated; reactive fractions associated with Fe–Mn oxyhydroxides are large, and DOP and DTMPs are low (generally much lower than in mud-rich sediments), except for Pb. Most of the elements studied are mainly present in forms that are neither bioavailable nor potentially bioavailable, and so do not constitute a significant environmental threat. However, the high DTMPs of Cu and Pb indicate significant potential bioavailability, which should be taken into account in evaluations of environmental quality and the risk to bivalve cultures.
Four 2–3
m sediment cores were taken at the sites on the periphery of mussel raft concentrations in the subtidal zone of the inner Ría de Vigo (Galicia, NW Spain) with a view to evaluate the ...potential risk to mariculture from sediment-borne trace elements (As, Cd, Cr, Cu, Mn, Ni, Pb and Zn). The distribution of each of these elements in reactive, organic, pyrite and silicate-bound fractions was determined at 64 samples, and these data were used to calculate the degree of trace metal pyritization (DTMP) of each metal/metalloid. In the top 10–20
cm, relatively oxic conditions led to As, Cd, Cu, Pb and Zn having large reactive fractions due to their association with Fe and Mn oxyhydroxides. At lower levels, anoxic conditions favoured by intense diagenesis led to the precipitation of trace metals and metalloids as sulphides, with or without association with pyrite. Particularly large pyrite fractions in the 20–100
cm layer are attributed to the organic matter of this layer being more marine in origin than that of deeper sediments. DTMP was greatest for Cu and As, and least for Pb, Zn and Cr. The risk of trace element toxicity in the event of disturbances instituting oxic conditions in these sediments is discussed.
San Simon Bay in the innermost part of the Ria de Vigo is characterized by an abundance of very shallow gas accumulations and methane seeps. During the expeditions of April-June-September 2004 within ...the Spanish-funded Gs2G project, detailed very high-resolution seismic and field investigations were carried out to study the shallow gas and the seeps. Direct gas fluxes also were measured from bubble streams. For the first time, the surface area and gas front depth of a shallow gas field has been mapped and quantified in the inner bay of Ria de Vigo. This field overlaps spatially with the distribution of Holocene mud within the bay. Seismic data show 3.6 km2 affected by acoustic turbidity but this surface can be extended up to 9.5 km2 of San Simon's muddy subtidal area. Mounded turbidity superimposed on the main gas field has been mapped and characterized as anthropogenically (mussel rafts) mediated gas accumulations. Different acoustic anomalies have been identified and interpreted as being due to gas escapes from the present seabed sediment. The very high resolution of the seismic data makes it possible to identify a new type of seep, here named "acoustic smoke". A direct relationship can be observed between the gas front of accumulations and escape features, both acoustic seeps and pockmarks. The methane flux has been estimated from the subtidal environment in San Simon based on detected acoustic targets and direct measurements of current bubble flow. The total estimated methane flux from the seabed into the water column ranges from 10.1 to 48.8 t/year, and into the atmosphere from 7.0 to 34.2 t/year. The intertidal San Simon environment is also actively venting methane, as indicated by the presence of bubbling during high tide and white patches of Beggiatoa sp. PUBLICATION ABSTRACT
Opal concentrations in dry bulk sediment were measured in 43 sampling stations in the Ría de Vigo at 0–1, 1–2, 4–5, 10–11 and 14–15
cm sediment depths. The amount of opal was correlated with the ...biogenic silicon flux to the sediment obtained by means of a box model. The biosiliceous flux to the sediment (annual mean) is in good agreement with the content of opal found in the uppermost oxic layer, revealing that pelagic primary production is the main factor controlling the biogenic silica content in surface sediments. This correlation is illustrated by the equation: Opal (wt.%)
=
0.103BSiF
+
0.414 (
R
2
=
0.95) where BSiF is the biogenic silicon flux to the sediment in g
Si
m
−2
year
−1. In the innermost part of the ría, i.e. San Simón Inlet, the content of opal is higher than predicted by the equation, since other biogenic silica sources to the sediment may be involved, as benthic diatoms proliferation or freshwater diatoms input. Elevated percentages recorded in the inner ría in the subsuperficial sediment respond to the establishment of suboxic–anoxic conditions that enhance the preservation of opal. The input of faecal pellets to the surface sediment derived from mussel rafts also controls the opal distribution and concentration in the ría.
The remains of a mastodont and mammoth were recovered from Pleistocene deposits in southeastern Arizona. These new proboscidean remains have characteristics distinguishing them from their more ...typical late Pleistocene forms. The mastodont (Mammut americanum), has traits similar to those of other female mastodonts, but includes mandibular tusks. This may indicate an early Pleistocene Age or supports evidence that female mastodonts had mandibular tusks. The partial mammoth jaw and molar display characteristics similar to Mammuthus columbi, but appears to be a variant or earlier form approaching those displayed in Mammuthus meridionalis. The presence of different proboscideans with different diets, although within the same geologic unit, cannot be confirmed as being sympatric. If so, it would indicate a partitioning of resources. Mammoths are grazers, and more common in Arizona than the browsing mastodonts.
Palynological characterization of the pollen assemblages from core ZV-01 offers a reliable age record of shallow "gas seal" and "gas reservoir" sediments from the Ria de Vigo (NW Spain). Gassy ...sediments show a direct correspondence with the palynological assemblage zones (LPAZ) 2, 3 and 4, which range in age from 950 to 1510 a.d. for the interval 81-176 cm where gas is found. The facies acting as a seal would correspond to the sedimentation in the ria starting from 1510 a.d. These assemblages also provide significant data which make it possible to reconstruct the palaeoenvironmental changes recorded in the sedimentary infill of the Ria de Vigo. The gassy horizon corresponds to the phase when riparian and mesophilous forest were better represented. This coincides with a relative high abundance of Lingulodinium machaerophorum, which indicates that the waters of the ria had been less renewed by oceanic waters and had a plentiful supply of continental nutrients. At that time, anoxic conditions resulted from restricted vertical circulation of seawater and/or high biological productivity. The dinocyst assemblages overlying and underlying the gassy horizon in core ZV-01 are clearly different from those concomitant with the accumulation of the gassy sediments. This suggests that oceanographic conditions in the Ria de Vigo may have changed several times during the time interval covered by our record. The weaker relationship between L. machaerophorum/Spiniferites spp., and simultaneous significant increases in Impagidinium spp. and Bitectatodinium tepikiense may indicate a greater intrusion of colder, more oceanic waters into the Ria de Vigo, which may have provoked intensification in upwelling during two periods, ca. 700-850 a.d. and ca. 1500-1750 a.d. PUBLICATION ABSTRACT
Changes in the microbial flora of San Simón cheese, manufactured from raw milk without the addition of starter cultures, were studied during the manufacture and ripening, with the object of ...contributing to the characterization or typifying of this variety.
Microbial counts from cheese surface were, on the whole, 1 log unit lower with respect to the ones taken in the core of the cheese, with the exception of the counts in MSA and OGYEA media.
Lactic acid bacteria (major microbial group) reached their maximum counts in 4-week-old cheese from core samples, although on the surface of the cheese the maximum count of lactococci and leuconostoc were obtained after 2 weeks. Other microbial groups (Micrococcaceae, Enterococci and Enterobacteriaceae) reached their maximum counts in 1-week-old cheese and decreased slightly afterwards during ripening. The decrease of the Enterobacteriaceae was a little more striking, although they did not disappear completely at the end of the ripening process.
The evolution of major physico-chemical parameters investigated during manufacture and ripening of San Simón cheese, contribute to the slight decrease of all microbial groups, since the parameter values during ripening were not markedly dysgenic for any of the microbial groups investigated.
One focus of recent research on early agriculture (Late Archaic period—2000 B.C.–A.D. 150) in the southern Southwest of the United States and northwestern Mexico has been the debate surrounding the ...impact of these early farmers on their landscapes. In at least two places, the Tucson Basin in southern Arizona and northern Chihuahua in northwest Mexico, agriculture was relatively intensive, while in others such as the San Simon Basin in southeastern Arizona, it apparently was not. Using an historical ecology perspective, we examine the likely impact of early agriculture using faunal and projectile point data from the Tucson Basin, northern Chihuahua, and the San Simon Basin. Our analysis suggests that these early farmers had less impact on their landscapes than expected.
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