Characterisation of domestic and industrial sewage in Southern California coastal sediments using nitrogen,carbon, sulphur and uranium tracers

A degradation-mixing model has been developed to aid in the interpretation of geochemical processes occurring in sewage-contaminated marine sediment near San Pedro, California. The nitrogen isotope ratio (${}^{15}{}^{14}\text{N}$) is shown to be an effective tracer of sewage discharge-on the San Pedro Shelf. Isotopic fractionation of ${}^{15}\text{N}{}^{14}\text{N}$ during release of amino compounds or ammonia (as a consequence of bacterial degradation of organic detritus) appears to be negligible. The nitrogen isotope ratio, therefore, may be considered a conservative component for tracing the source of organic matter deposited in marine sediment.Uranium enrichment from seawater is shown not to occur in the highly reducing sewage-contaminated sediments. The content of uranium in the effluent particulates (18 ppm) is large compared with the content in the uncontaminated sediment (3 to 5 ppm). This allows the content of uranium to also be used as a tool for tracing the deposition of sewage particles in marine sediment. Uranium and nitrogen are shown to be incorporated in the organic fraction of sewage effluent and are released during bacterial degradation of the organic matter. Cadmium and sulphur are shown not to be mobilised during sewage deposition and degradation. The stable isotope ratio of sulphur (${}^{34}\text{S}{}^{32}\text{S}$) is used to demonstrate that sulphur enrichment occurs in the sediment by in situ reduction of seawater sulphate. The data summarised by Morel et al. (1975) are presented and discussed in accordance with the above model.     

Nitrogen uptake,ammonium oxidation and nitrous oxide (N2O) levels in the coastal waters of western Cook Strait,New Zealand

Vertical measurements of $\text{NH}{}_4{}^{\mathrm{+}}$, $\text{NO}{}_3{}^{\mathrm{?}}$ and N₂O concentrations, $\text{NO}{}_3{}^{\mathrm{?}}$ and $\text{NH}{}_4{}^{\mathrm{+}}$ uptake, and $\text{NH}{}_4{}^{\mathrm{+}}$ oxidation rates were measured at 5 sites in western Cook Strait, New Zealand, between 31 March and 3 April 1983. Nitrate increased with depth at all stations reaching a maximum of 10.5 μg-atom $\text{NO}{}_3{}^{\mathrm{?}}\text{N l}{}^{\mathrm{?1}}$ at the most strongly stratified station whereas $\text{NH}{}_4{}^{\mathrm{+}}$ was relatively constant with depth at all stations (～0.1 μg-atom $\text{NH}{}_4{}^{\mathrm{+}}\text{N l}{}^{\mathrm{?1}}$). The highest rates of $\text{NH}{}_4{}^{\mathrm{+}}$ oxidation generally occurred in the near surface waters and decreased with depth. N₂O levels were near saturation with respect to the air above the sea surface and showed no obvious changes during 24 h incubation. $\text{NH}{}_4{}^{\mathrm{+}}$ oxidation by nitrifying bacteria may account for about 30% of the total $\text{NH}{}_4{}^{\mathrm{+}}$ utilization (i.e. bacterial+agal) and, assuming oxidation through to $\text{NO}{}_3{}^{\mathrm{?}}$, may supply about 40% of the algal requirements of $\text{NO}{}_3{}^{\mathrm{?}}$ in the study area. These results suggest that bacterial nitrification is of potential importance to the nitrogen dynamics of the western Cook Strait, particularly with respect to the nitrogen demands of the phytoplankton.     

Nitrogen and phosphorus concentrations within North Inlet,South Carolina—Speculation as to sources and sinks

The daily concentrations of $\text{NH}{}_4{}^{\mathrm{+}}$, $\text{NO}{}_3{}^{\mathrm{?}}$, and $\text{NO}{}_3{}^{\mathrm{?}}\text{+ NO}{}_2{}^{\mathrm{?}}$ within the North Inlet system are all negatively associated with tidal stage during the late summer, this association breaking down during the winter. The high concentrations of these constituents during low tide coupled with the lack of streamflow during the late summer suggests that there is an internal source for these species. Ammonium and orthophosphate most likely have their source in sediment diffusion from tidal creek sediments and/or seepage from the vegetated marsh surface during tidal exposure. It is hypothesized that high nitrate plus nitrite values at low tide are caused by nitrification within the tidal water or tidal creek sediments. During the summer there is evidence for a source of dissolved organic nitrogen and dissolved organic phosphorus within the North Inlet system, probably via diffusion from creek sediments. In general the main source of dissolved organic nitrogen is via stream-flow from the adjacent watershed. Particulate nitrogen and phosphorus concentrations are a function of: (1) wind and rain events which cause resuspension of particulate material from the tidal creek banks, (2) rain events which scour the marsh surface during tidal exposure, and (3) high tidal velocities which scour the creek bottoms.     

A comparison of lignin and stable carbon isotope compositions in quaternary marine sediments

Organic matter in four Quaternary sediment cores from the Gulf of Mexico and one core from the Washington State coast have been analyzed for lignin and stable carbon isotope compositions. Holocene sequences of all five cores contain organic matter with high relative abundances of ¹³C ($\text{δ}{}^{13}\text{C = ?19.0 to ?22.5\% versus PDB}$) and low lignin concentrations, both of which are consistent with a marine origin. Distinctly lower ¹³C concentrations ($\text{δ}{}^{13}\text{C = ?24.0 to ?25.5\%}$) occur in underlying glacial-age sequences from four of the five cores, including the core from the Washington coast where such trends are previously unreported. Although the carbon isotopic compositions of these Pleistocene sediments are typical of predominantly land-derived organic matter, they contain only about 5% of the lignin found in modern sediments of similar $\text{δ}{}^{13}\text{C}$ from adjacent continental shelves. The lignin-poor organic matter in the glacial-age deposits appears to be either marine-derived or terrigenous material that likely was depleted in vascular plant debris at the time of deposition.     

Inhibition of sulphate reduction in anoxic marine sediment by Group VI anions

The addition of various concentrations (1, 10 and 20 mM) of Group VI anions to sediment slurry resulted in inhibition of the rate of sulphate reduction at the two higher concentrations, the degree of inhibition being in the order of molyb-date $\text{(MoO}{}_4{}^{\mathrm{=}}\text{)>selenate(SeO}{}_4{}^{\mathrm{=}}\text{)>tungstate(WO}{}_4{}^{\mathrm{=}}\text{)}$. The addition of 20 mM concentrations of these inhibitors almost entirely eliminated sulphate reduction. Doubling the sulphate concentration while using the highest concentration of inhibitors (20 mM) led to the re-establishment of some sulphate reduction in the $\text{SeO}{}_4{}^{\mathrm{=}}$ and $\text{WO}{}_4{}^{\mathrm{=}}$ treated slurries whereas no such reversal was noticed with $\text{MoO}{}_4{}^{\mathrm{=}}$. These observations suggested that $\text{SeO}{}_4{}^{\mathrm{=}}$ and $\text{WO}{}_4{}^{\mathrm{=}}$ are competitive inhibitors of sulphate reduction, while $\text{MoO}{}_4{}^{\mathrm{=}}$ is a non-competitive inhibitor.     

Nitrogen losses from a Louisiana Gulf Coast salt marsh

Losses of ¹⁵N labelled nitrogen in a Spartina alterniflora salt marsh was measured over three growing seasons. Labelled $\text{NH}{}_4{}^{\mathrm{+}}\text{N}$ equivalent to 100 μg ¹⁵N g^?1 of dry soil was added in four instalments over an eight week period. Recovery of the added nitrogen ranged from 93% 5 months after addition of the $\text{NH}{}_4{}^{\mathrm{+}}\text{N}$ to 52% at the end of the third growing season which represented a nitrogen loss equivalent to 3·4 gNm^?2. The availability of the labelled $\text{NH}{}_4{}^{\mathrm{+}}\text{N}$ incorporated into the organic fraction was estimated by calculation of the rate of mineralization. The time required for mineralization of 1% of the tagged organic N increases progressively with succeeding cuttings of the S. alterniflora and ranged from 152 to 299 days. Only 2% of the nitrogen applied as ¹⁵N labelled plant material to the marsh surface in the fall could be accounted for in S. alterniflora the following season.     

The density and expansibility of artificial seawater solutions from 0 to 40°C and 0 to 21‰ chlorinity

The density of artificial seawater has been measured with a magnetic float densitometer at 1 atm. from 0 to 40°C (in 5° intervals) and from 0 to 21‰ chlorinity. The densities at each temperature have been fitted to a modified Root (1933) equation, $\text{d = d}{}^0\text{+}\text{A}{}_{\mathrm{V}}\text{′ Cl}{}_{\mathrm{V}}\text{+ B}{}_{\mathrm{V}}\text{′ Cl}{}_{\mathrm{V}}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ and an equation based on the Debye-Hückel limiting law, $\text{d = d}{}^0\text{+}\text{A}{}_{\mathrm{V}}\text{Cl}{}_{\mathrm{V}}\text{+ B}{}_{\mathrm{V}}\text{Cl}{}_{\mathrm{V}}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{+ C}{}_{\mathrm{V}}\text{Cl}{}_{\mathrm{V}}{}^2$ where A_V′, B_V′, A_V, B_V and C_V are temperature-dependent constants (related to the ion-water and ion-ion interactions of the major components), d⁰ is the density of pure water and Cl_V is the volume chlorinity — $\text{Cl}{}_{\mathrm{V}}\text{= Cl (‰) × density}$. The densities fit these equations to ±9 p.p.m. from 0 to 25°C and ±18 p.p.m. from 30 to 40°C. The densities for artificial seawater are in good agreement with our measurements of Copenhagen seawater and the results for natural seawater obtained from Knudsen's tables.The expansibilities of the artificial seawater mixtures have been calculated from the temperature dependence of the densities. The resulting expansibilities at each temperature were fitted to the equations $\text{α = α}{}^0\text{+}\text{A}{}_{\mathrm{E}}\text{′ Cl}{}_{\mathrm{V}}\text{+ B}{}_{\mathrm{E}}\text{′ Cl}{}_{\mathrm{V}}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}$ and $\text{α = α}{}^0\text{+}\text{A}{}_{\mathrm{E}}\text{Cl}{}_{\mathrm{V}}\text{+ B}{}_{\mathrm{E}}\text{Cl}{}_{\mathrm{V}}{}^{\mathrm{<mtext>3</mtext><mtext>2</mtext>}}\text{+ C}{}_{\mathrm{E}}\text{Cl}{}_{\mathrm{V}}{}^2$ where A_E′, B_E′, A_E, B_E and C_E are constants (related to the effect of temperature on the ion-water and ion-ion interactions of the major components) and α⁰ is the expansibility of pure water. The expansibilities fit these equations to ±1 p.p.m. and at 35‰ S agree within ±1 p.p.m. with the expansibilities obtained for natural seawater from Knudsen's tables.Theoretical density and expansibility constants have been determined from the apparent equivalent volumes and expansibilities of the major components of seawater by using the additivity principle. The average deviations of the calculated densities and expansibilities are, respectively, ±20 and ±3 p.p.m. over the entire temperature range.     

Tidal exchange of nitrogen and phosphorus between a mesohaline vegetated marsh and the surrounding estuary in the lower Chesapeake Bay

A 22-month study was conducted to determine the exchange of nitrogen and phosphorus between a mesohaline vegetated marsh in the Carter's Creek area of Virginia and the surrounding estuary, focusing on the role of the vegetated marsh surface in the processing of these constituents. On an annual basis there was a removal of $\text{NH}{}_4{}^{\mathrm{+}}$, $\text{PO}{}_4{}^{\mathrm{3?}}$, $\text{NO}{}_3{}^{\mathrm{?}}$, dissolved organic nitrogen, dissolved organic phosphorus, particulate nitrogen and particulate phosphorus from the tidal water as it resided on the vegetated marsh. Only nitrite was transported from the marsh to the estuary. Most of the nitrogen and phosphorus species showed distinct seasonal trends with respect to the direction of transport except nitrate and orthophosphate. The ammonium flux data indicates that this nutrient was removed from the inundating water during late spring and fall, with a slight release of this constituent into the tidal water during the late summer. The transport of nitrite was from the estuary to the marsh for most of the year except during the fall. The large release of this nutrient into the tidal water at this time is associated with the senescence of the marsh vegetation. There was a large removal of DON from the tidal water during the fall, while the flux of DOP was from the estuary to the marsh for most of the year except during the summer. The largest removal of particulate nitrogen and phosphorus from the tidal water occurred during the summer months when the turbidity of the tidal water was highest, especially when wave scouring of the mudflats brings material into the water column. A loss of particulate nitrogen from the marsh to the estuary was evident during the fall and winter.     

Sodium fluoride ion-pairs in seawater

Laboratory investigations were conducted on the formation of NaF° ion-pairs at the ionic strength of seawater using specific ion electrodes. Sodium and fluoride ion electrodes produced results which are consistent with the ion-pairing model for these ionic interactions. The stoichiometric association constant for NaF°, $\text{K}{}^1{}_{\mathrm{<mtext>NaF</mtext>}}$, was determined at 15, 25, and 35°C. It was assumed that $\text{K}{}^1{}_{\mathrm{<mtext>NaF</mtext>}}$ was a function of temperature, pressure, and ionic strength but not of solution composition. The value for $\text{K}{}^1{}_{\mathrm{<mtext>NaF</mtext>}}$ at 25°C and I = 0.7 m is 0.045 ± 0.006. $\text{K}{}^1{}_{\mathrm{<mtext>NaF</mtext>}}$ increased with decreasing temperature. This result was used to recompute values of $\text{K}{}^1{}_{\mathrm{<mtext>MgF</mtext>}}$ and $\text{K}{}^1{}_{\mathrm{<mtext>CaF</mtext>}}$ accounting for the presence of NaF° ion-pairs. The value for $\text{K}{}^1{}_{\mathrm{<mtext>NaF</mtext>}}$ indicates that 1.1% of the fluoride in seawater is ion-paired with sodium at 25°C and 35‰ salinity. This fraction increases to approximately 2% at the lower temperatures found in the deep ocean. The percentage of free fluoride in natural seawater was measured at 15, 25, and 35°C to verify the speciation calculated from equilibrium constants.     

Solubility of hydrous ferric oxide and iron speciation in seawater

Iron solubility equilibria were investigated in seawater at 36.22‰ salinity and 25°C using several filtration and dialysis techniques. In simple filtration experiments with 0.05 μm filters and Millipore ultra-filters, ferric chlorides fluorides, sulfates, and FeOH²⁺ species were found to be insignificant relative to Fe(OH)₂⁺ at p[H⁺] = ?log [H⁺] greater than 6.0. Hydrous ferric oxide freshly precipitated from seawater yielded a solubility product of ${}^1\text{K}{}_{\mathrm{<mtext>so</mtext>}}\text{=}\text{[Fe}{}^{\mathrm{3+}}\text{][H}{}^{\mathrm{+}}\text{]}{}^{\mathrm{?3}}\text{= 4.7 · 10}{}^5$. Solubility studies based on the rates of dialysis of various seawater solutions and on the filtration of acidified seawater solutions indicated the existence of the Fe(OH)₃⁰ species. The formation constant for this species can be calculated as ${}^1\text{β}{}_3\text{=}\text{[Fe(OH)}{}_3{}^0\text{] [H}{}^{\mathrm{+}}\text{]}{}^3\text{/[Fe}{}^{\mathrm{3+}}\text{] = 2.4 · 10}{}^{\mathrm{?14}}$. The Fe(OH)₄^? species is present at concentrations which are negligible compared to Fe(OH)₂⁺ and Fe(OH)₃⁰ in the normal pH range of seawater. However, there is at least one other significant ferric complex in seawater above p[H⁺] = 8.0 (possibly with bicarbonate, carbonate, or borate ions) in addition to the Fe(OH)₂⁺ and Fe(OH)₃⁰ species.     

Postdepositional injections of uranium-rich solutions into East Pacific Rise sediments

An 8.5 m long apparently undisturbed core from a hilltop on the crest of the East Pacific Rise has uranium and thorium isotope distributions that are very unusual. The core is very poor in ²³²Th, and very rich in U, particularly at the 500-cm level, where a value of about 150 ppm is reached. At the same depth the ²³⁰Th_xs reaches very large negative values. These facts could be accounted for if one assumes that solutions rich in U and poor in Th had been postdepositionally injected into the sediments about 90,000–110,000 years ago. The top of the sediment received much of its U from seawater, judging from the ${}^{234}\text{U}{}^{238}\text{U}$ ratio. Possibly carbonate rich solutions were the carriers of the injected uranium.     

The refractive index of seawater — comparison of experimental values and estimates from binary solution data

The Tait-Gibson parameter, $\text{B}{}^1$, and the refractive index of seawater are estimated from binary solution data. The predicted and experimental values agree closely. The maximum deviations, at $\text{S = 40‰}$, are 1.7 bars for $\text{B}{}^1$ and 0.0001 for the refractive index. The results show that binary solution data, analysed on the basis of the Tammann-Tait-Gibson model for aqueous solutions, can be used to predict the properties of seawater of composition different to that of standard seawater.     

Uptake of nitrogenous nutrients by phytoplankton in a barrier Island estuary: Great South Bay,New York

The uptake of urea, nitrate and ammonium by phytoplankton was measured using ¹⁵N isotopes over a one-year period in Great South Bay, a shallow coastal lagoon. The bay is a unique environment for the study of nutrient uptake since ambient concentrations of $\text{NO}{}_3{}^{\mathrm{?}}\text{NH}{}_4{}^{\mathrm{+}}$ and urea remain relatively high through the year, and phytoplankton are probably never nutrient limited. Urea nitrogen averaged 52% of the total assimilated, while ammonium represented 33% and nitrate 13%. High rates of ammonium uptake occurred only at low urea concentrations (ca< 1-μg-atom urea l^?1). Over the sampling period urea was present in relatively high concentrations, averaging 5·35 μg-atom N l^?1, while means for ammonium and nitrate averaged 1·94 and 0·65 μg-atom N l^?1, respectively. Total N uptake measured with ¹⁵N averaged about 3·3 times the calculated (from elemental ratios and ¹⁴C productivity measurements) N needs of the phytoplankton population. Highest nitrogen uptake occurred in the summer and coincided with the primary production maximum.     

A potentiometric study of ferric ion complexes in synthetic media and seawater

An investigation of ferric ion complexing has been conducted in synthetic media and seawater at 25°C. Formation constants were potentiometrically determined for the species FeCl²⁺, FeCl₂⁺, FeOH²⁺, and Fe(OH)₂⁺ at an ionic strength of 0.68 m. Formation constants for the ferric chloride complexes were determined as _Clβ₁ = 2.76 and _Clβ₂ = 0.44. In a study of the reaction Fe³⁺ + nH₂O ? Fe(OH)_n^(3?n)+ + nH⁺ in NaClO₄, NaNO₃ and NaCl the formation constants ${}^1\text{β}{}_1\text{and}{}^1\text{β}{}_2$ were shown to be relatively independent of medium when the effects of nitrate and chloride complexing were taken into account. The average values obtained for these constants are ${}^1\text{β}{}_1\text{= 1.93 · 10}{}^{\mathrm{?3}}\text{and}{}^1\text{β}{}_2\text{= 8.6 · 10}{}^{\mathrm{?8}}$. Reasonable agreement with these values was obtained when these constants were determined in seawater by accounting for the effects of chloride, fluoride and sulfate complexing.     

Landward migration of inner bars

A field investigation was carried out to collect data of inner bar migration. Profiles were measured once or twice a week for a two-year period at Naka Beach, Ibaraki Prefecture, Japan. It was found that the onshore migration of inner bars could be described by two dimensionless quantities as: $\text{5D}\text{(H}{}_{\mathrm{<mtext>b</mtext>}}\text{)}{}_{\mathrm{<mtext>max</mtext>}}\text{<}\text{(H}{}_{\mathrm{<mtext>b</mtext>}}\text{)}{}_{\mathrm{<mtext>max</mtext>}}\text{gT}{}^2{}_{\mathrm{<mtext>max</mtext>}}\text{<}\text{20D}\text{(H}{}_{\mathrm{<mtext>b</mtext>}}\text{)}{}_{\mathrm{<mtext>max</mtext>}}$ where (H_b)_max is the maximum value of daily average breaker height during one interval between surveys, T_max is the average wave period of the day giving (H_b)_max, D is the mean size of the beach sediment, and g is the acceleration due to gravity. Analyses based on surfzone sediment dynamics yields $\text{v}\text{?}\text{(}\text{wD}\text{b}\text{)}\text{= 2 × 10}{}^{\mathrm{?11}}\text{(}\text{(}\text{H}\text{?}{}_{\mathrm{<mtext>b</mtext>}}\text{D}\text{)}{}^3$, where $\text{v}\text{?}$ is the average speed of onshore bar-migration, b is the bar height, $\text{H}\text{?}{}_{\mathrm{<mtext>b</mtext>}}$ is the average breaker height, and w is the fall velocity of the beach sediment. Nomographs for the speed of landward migrating bars are also presented.     

MgSO4 ION association in seawater

Examination of the consequences of the stoichiometric association constant $\text{K}{}^1{}_{\mathrm{<mtext>a</mtext>}}\text{= 41.7}$ for MgSO₄ in seawater as advocated by Johnson and Pytkowicz (1979) leads to a thermodynamic association constant K_a = 212.6, a value 32% greater than K_A = 160 derived from conductance data. Use of K_a = 160 leads to a $\text{K}{}^1{}_{\mathrm{<mtext>a</mtext>}}$ in essential agreement with the value of 10.2 reported by Kester and Pytkowicz (1969).     

Apparent dissociation constants of hydrogen sulfide in chloride solutions

Spectrophotometric measurements are reported for the first apparent dissociation constant of hydrogen sulfide in seawater over the temperature range 7.5–25°C and 2–35.8‰ salinity. These data are described by the expression $\text{p}\text{K}{}_1\text{′ = 2.527 ? 0.169 Cl}{}^{\mathrm{<mtext>1</mtext><mtext>3</mtext>}}\text{+ 1359.96/T}$. The second apparent dissociation constant in potassium chloride solution was estimated potentiometrically using a sulfide specific ion electrode. A value of ～13.6 was found for pK₂′ at a KCl concentration of 0.67 M. It is suggested that explicit reference to the sulfide ion, S^2?, in describing equilibria in marine waters be dropped in favor of a formulation involving the bisulfide ion, HS^?.