Massive shellfish farming might accelerate coastal acidification: A case study on carbonate system dynamics in a bay scallop (Argopecten irradians) farming area, North Yellow Sea

Seven cruises were carried out in a bay scallop (Argopecten irradians) farming area and its surrounding waters, North Yellow Sea, from March to November 2017 to study the dynamics of the carbonate system and its controlling factors. Results indicated that the studied parameters were highly variability over a range of spatiotemporal scales, comprehensively forced by various physical and biological processes. Mixing effect and scallop calcification played the most important role in the seasonal variation of total alkalinity (TAlk). For dissolved inorganic carbon (DIC), in addition to mixing, air-sea exchange and microbial activity, e.g. photosynthesis and microbial respiration processes, had more important effects on its dynamics. Different from the former, the changes of water pH_T, partial pressure of CO₂ (pCO₂) and aragonite saturation state (Ω_A) were mainly controlled by the combining of the temperature, air-sea exchange, microbial activity and scallop metabolic activities. In addition, the results indicated that massive scallop farming can significantly increase the DIC/TAlk ratio by reducing the TAlk concentration in seawater, thereby reducing the buffering capacity of the carbonate system in seawater especially for Ω_A. Preliminary calculated, ~75.7 and ~45.5 μmol kg^-1 of TAlk were removed from the surface and bottom waters respectively in one scallop cultivating cycle. If these carbonates cannot be replenished in time, it is likely to accelerate the acidification process of coastal waters. This study highlighted the control mechanism of the carbonate system under the influence of bay scallop farming, and provided useful information for revealing the potential link between human activities (shelled-mollusc mariculture) and coastal acidification.

The influence of summer hypoxia on sedimentary phosphorus biogeochemistry in a coastal scallop farming area, North Yellow Sea

In situ field investigations coupled with laboratory incubations were employed to explore the surface sedimentary phosphorus (P) cycle in a mariculture area adjacent to the Yangma Island suffering from summer hypoxia in the North Yellow Sea. Five forms of P were fractionated, namely exchangeable P (Ex-P), iron-bound P (FeP), authigenic apatite (CaP), detrital P (De-P) and organic P (OP). Total P (TP) varied from 13.42 to 23.88 μmol g^-1 with the main form of inorganic P (IP). The benthic phosphate (DIP) fluxes were calculated based on incubation experiments. The results show that the sediment was an important source of P in summer with ~39% of the bioavailable P (BioP) recycled back into the water column. However, the sediment acted a sink of P in autumn. The benthic DIP fluxes were mainly controlled by the remobilizing of FeP, Ex-P and OP under contrasting redox conditions. In August (hypoxia season), ~0.92 μmol g^-1 of FeP and ~0.52 μmol g^-1 of OP could be transformed to DIP and released into water, while ~0.36 μmol g^-1 of DIP was adsorbed to clay minerals. In November (non-hypoxia season), however, ~0.54 μmol g^-1 of OP was converted into DIP, while ~0.55 μmol g^-1 and ~0.28 μmol g^-1 of DIP was adsorbed to clay minerals and bind to iron oxides. Furthermore, scallop farming activities also affected the P mobilization through biological deposition and reduced hydrodynamic conditions. The burial fluxes of P varied from 11.67 to 20.78 μmol cm^-2 yr^-1 and its burial efficiency was 84.7-100%, which was consistent with that in most of the marginal seas worldwide. This study reveals that hypoxia and scallop farming activities can significantly promote sedimentary P mobility, thereby causing high benthic DIP flux in coastal waters.

Evidence for Fossil Fuel PM1 Accumulation in Marine Biota

When fine particulates such as those with a diameter of approximately 1 μm (particulate matter, PM₁) are released from fossil fuel combustion into the air, they warm the atmosphere and contribute to millions of premature deaths in humans each year. Considerable quantities of PM₁ eventually enter the oceans as suspended particulates, yet subsequent removal mechanisms are poorly understood. In fact, the presence of PM₁ in marine biota has never been reported. Since sea anemones are opportunistic suspension feeders, they are anticipated to incorporate and accumulate PM₁ in their bodies. By histological examination, PM₁ was detected in 21 of the 22 sea anemones collected from Taiwan and Southeast China, with a depth of intertidal zone to 1000 m. PM₁, if present, was always detected in endodermal layers and had the same dominant color (i.e., black, brown, or green) in different species from the same site. The bioaccumulation factor of PM₁ in sea anemones was approximately 5-7 orders of magnitude. Based on radioisotope ¹⁴C results, the contribution of fossil fuel source PM₁ was 8-24%. Regardless of PM₁'s color, S and Fe were commonly detected by scanning electron microscopy and energy-dispersive spectrometry (SEM-EDS), suggesting anthropogenic sources. Furthermore, a maternal transfer of materials was suggested based on the existence of PM₁ in sea anemone eggs and in brooding and released juveniles. The significance of PM₁ accumulation by biota in aquatic ecosystems and the potential risk to living organisms via food webs warrant further investigation.

Submarine Groundwater Discharge helps making nearshore waters heterotrophic

Submarine groundwater discharge (SGD) is the submarine seepage of all fluids from coastal sediments into the overlying coastal seas. It has been well documented that the SGD may contribute a great deal of allochthonous nutrients to the coastlines. It is, however, less known how much carbon enters the ocean via the SGD. Nutrients (NO₃, NO₂, NH₄, PO₄, SiO₂), alkalinity and dissolved inorganic carbon (DIC) in the submarine groundwater were measured at 20 locations around Taiwan for the first time. The total N/P/Si yields from the SGD in Taiwan are respectively 3.28 ± 2.3 × 10⁴, 2.6 ± 1.8 × 10² and 1.89 ± 1.33 × 10⁴ mol/km²/a, compared with 9.5 ± 6.7 × 10⁵ mol/km²/a for alkalinity and 8.8 ± 6.2 × 10⁵ mol/km²/a for DIC. To compare with literature data, yields for the major estuary across the Taiwan Strait (Jiulong River) are comparable except for P which is extremely low. Primary production supported by these nutrient outflows is insufficient to compensate the DIC supplied by the SGD. As a result, the SGD helps making the coastal waters in Taiwan and Jiulong River heterotrophic.

Trace metals in surface sediments of the Taiwan Strait: geochemical characteristics and environmental indication

The concentration and geochemical fractionation of six trace metals related with environmental quality assessment, namely Cd, Cr, Cu, Ni, Pb, and Zn, in 30 surface sediments from both inshore and offshore areas of the Taiwan Strait were measured to investigate their distribution characteristics, evaluate their potential mobility, and assess their pollution status. The geoaccumulation index results indicated that, on average, the studied metals presented an order of Cd > Pb > Ni > Zn > Cu > Cr and were practically in uncontaminated status except Cd. The results of the sequential extraction analysis indicated that, on average, the studied metals were mostly accumulated in residual fraction except Cd whose concentration was the highest in the acid soluble fraction presenting a high risk to the environment, and their mobility decreased in the sequence of Cd > Pb > Ni > Cu > Zn > Cr. Based on the mean probable effect level quotients, the combination of the studied metals had an 8 % probability of being toxic at two sampling sites and had a 21 % probability of being toxic at the rest of sites. The spatial distribution of the studied metals in total concentrations and different geochemical fractions corroborated the previous findings about the possible sediment transportation routes in and around the Taiwan Strait.

Practice of breastfeeding and factors that affect breastfeeding in Hong Kong

OBJECTIVES

To describe the patterns of and factors affecting breastfeeding and to find out any significant relationship between breastfeeding and health of the child.

DESIGN

Cohort study.

SETTING

Postnatal ward of the Prince of Wales Hospital.

PARTICIPANTS

A total of 243 infants born in 1998 to 2001 at the hospital. Each infant was followed up for 3 years. Home visits were carried out at 3, 15, 24, and 36 months of age by medical students from the Chinese University of Hong Kong. A questionnaire was completed at each visit. Independent sample t-tests and Pearson Chi squared tests were used.

RESULTS

Of the 243 subjects, 213 provided data on the method of infant feeding. There were 66.7% of mothers initiating breastfeeding, with a median duration of 1 month. Only 13.4% met the World Health Organization's recommendations on breastfeeding. Breastfeeding was found to have a statistically significant relationship with (i) the infant's birth order and (ii) the mother's and father's education level. During follow-up, 44.6% of the infants were hospitalised but there was no significant relationship between breastfeeding and number of hospitalisations.

CONCLUSIONS

The current breastfeeding rate in Hong Kong falls below expectations when compared with other developed nations. To raise this rate, more support is needed for families with parents having a lower education level or more than two children, as they are the least likely to breastfeed. This might be achieved by encouraging antenatal class attendance, counselling of husbands, and more support for breastfeeding from doctors.

Magnetic resonance imaging for the detection of nasopharyngeal carcinoma

BACKGROUND

Endoscopic guided biopsy (EGB) is performed after an initial endoscopy for the investigation of patients with suspected nasopharyngeal carcinoma (NPC). The aim of the study was to determine whether MR imaging has the potential to replace invasive EGB in patients with a normal endoscopy.

PATIENTS AND METHODS

Data from 2 groups of patients was reviewed, group 1 with proved NPC for MR staging (n = 456) and group 2 with suspected NPC (n = 77). The sensitivity was calculated for group 1 and sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for group 2.

RESULTS

In group 1, which included 118 of 456 (26%) with stage 1 disease, cancer was detected in all patients, giving a sensitivity of 100%. In group 2, MR imaging was negative for NPC in 70 (91%) patients, and no cancer has been detected on follow-up (follow-up range, 1-90 months; mean, 36 months). MR imaging was positive for NPC in 7 (9%) patients and NPC was confirmed by biopsy in 3 (4%). Two of these 3 patients had undergone negative endoscopy and biopsy before the MR imaging. NPC was not present in the remaining 4 patients, 2 of whom were found to have lymphoid hyperplasia. MR imaging had a sensitivity of 100%, specificity of 95%, NPV of 100%, PPV of 43%, and accuracy of 95%.

CONCLUSION

MR imaging has the potential to screen healthy patients who do not require EGB and direct the site of biopsy in small cancers that may be missed by endoscopy. On the basis of these results, a prospective study is planned.

Effect of glycoprotein IIb/IIIa receptor inhibition on angiographic complications during percutaneous coronary intervention in the ESPRIT trial

OBJECTIVES

We sought to determine whether eptifibatide decreases the incidence of in-laboratory angiographic complications and to determine the relationship of angiographically evident complications to elevations of creatine kinase-MB (CK-MB) enzyme levels during percutaneous coronary intervention.

BACKGROUND

In the Enhanced Suppression of the Platelet IIb/IIIa Receptor with Integrilin Therapy (ESPRIT) trial, eptifibatide during coronary intervention was associated with decreased ischemic complications at 48 h and 30 days.

METHODS

Patients (n = 2,064) were randomized to placebo versus eptifibatide (two 180 microg/kg boluses 10 min apart and as a continuous infusion of 2 microg/kg per min) during percutaneous coronary stenting. Angiographic complications including major dissection, distal embolization, residual thrombus, abrupt closure, residual stenosis >50% and side-branch occlusion were prospectively recorded by the operator. Creatine kinase-MB levels were measured after the procedure and every 6 h thereafter. The incidence of angiographic complications and CK-MB elevation was determined for eptifibatide versus placebo groups.

RESULTS

Eptifibatide-treated patients demonstrated nonsignificant trends toward fewer angiographic complications (10 vs. 12% for placebo patients, p = 0.13) and, for patients with angiographic complications, fewer subsequent CK-MB elevations (43 vs. 50% for placebo patients, p = 0.31). In patients without any angiographic complications, the incidence of CK-MB elevation >3 times the normal was 7% with placebo and 4% with eptifibatide (p = 0.003).

CONCLUSIONS

Eptifibatide during nonurgent coronary stent intervention only minimally (and insignificantly) reduces the incidence of angiographic complications and subsequent CK-MB elevations in patients developing an angiographic complication. The greater effect is to reduce myocardial infarction in patients undergoing otherwise uneventful coronary stent implantation as well as in the overall study population.

Mitral valve replacement and endocavitary patch repair for a giant left ventricular pseudoaneurysm

We present a case of a giant inferior left ventricular (LV) wall pseudoaneurysm. The patient had New York Heart Association class IV heart failure due to severe mitral valve regurgitation and poor LV function. Our operative approach included right thoracotomy, excision of the mitral valve, and patch repair of the pseudoaneurysm neck from inside of the dilated LV cavity followed by mitral valve replacement. Surgery was performed without aortic cross-clamping on a normothermic perfused beating heart. The patient had an uncomplicated cardiac recovery and is doing well 15 months after surgery.

Comparison of intravenous mexiletine and lidocaine for the treatment of ventricular arrhythmias

The efficacy and safety of intravenous loading of mexiletine was compared to lidocaine in patients with ventricular premature depolarizations (VPDs). Seventeen men and five women, average age 63 years, completed this randomized parallel study. Twelve patients received mexiletine intravenously at (5 to 10 mg/min) until greater than or equal to 95% VPD suppression was achieved or a total of 450 mg of drug was given. The average loading dose of mexiletine was 4.4 mg/kg, at an infusion rate of 0.1 mg/kg/min. Ten patients received lidocaine (1 mg/kg) given over 3 minutes, with a second similar bolus given if after 10 minutes greater than or equal to 95% VPD suppression was not achieved. Total VPDs were determined for the 60 minutes before drug administration, during drug infusion, and 60 minutes thereafter. Eleven of 12 (92%) patients receiving mexiletine were full responders (greater than or equal to 95% suppression) and one was a partial responder (greater than or equal to 75% greater than or equal to 95% suppression). Five of 10 lidocaine patients (50%) were full responders, three (30%) were partial responders, and two failed to respond. At peak suppression, mexiletine reduced mean VPD from 37 +/- 33/5 minutes (mean +/- S.D.) to 0.8 +/- 0.9/5 minutes (p less than 0.01) and lidocaine decreased mean VPDs from 28 +/- 47/5 minutes to 4.7 +/- 2.2/5 minutes (p less than 0.01). Mexiletine resulted in greater suppression of VPDs than lidocaine in terms of mean percent reduction (96% vs 68%, p less than 0.01). All lidocaine patients had therapeutic plasma levels (range 1.6 to 3.5 micrograms/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Reduction of ventricular ectopic beats with oral acebutolol: a double-blind, randomized crossover study

The antiarrhythmic efficacy of oral acebutolol, a new cardioselective beta-blocking agent, was assessed in a randomized double-blind, placebo-controlled study. Twenty-five patients with greater than or equal to 30 ventricular ectopic beats (VEB) per hour on three control ambulatory monitorings were studied. Mean VEB reduction from the control period was 35% with placebo and 45% and 50% with the use of acebutolol 200 mg and 400 mg, respectively. Eleven patients had greater than or equal to 70% reduction in VEB with acebutolol and nine of them had greater than or equal to 90 VEB reduction. Among these 11 patients, the mean VEB suppression was 51% after placebo but significantly higher following the two doses of acebutolol at 71% (p less than 0.05) and 86% (p less than 0.01). The mean reduction of paired VEB compared to placebo was 71% (p less than 0.05) and 75% (p less than 0.01) following 200 mg and 400 mg of acebutolol and only 49% after placebo. Complete suppression of paroxysmal ventricular tachycardia was also noted in five patients. Mean PR interval only increased slightly when patients took 400 mg of acebutolol, but there was no significant change in either the QRS or QTc intervals. A significant decrease in heart rate from that during control periods was noted after acebutolol. No significant adverse reactions were noted during the study. Acebutolol appears to be an effective and well-tolerated antiarrhythmic agent in the treatment of VEB and higher grades of ventricular ectopy.