Investigating the ecological risk of pharmaceuticals and personal care products (PPCPs) using recent data of the occurrence and contributions of PPCPs with potential ecological risks to ecotoxicological effects of chemicals on aquatic organisms in water environments is required. In the present study, preliminary ecological risk assessments of 10 PPCPs were conducted in the middle stream of Tama River and its tributaries using the hazard quotient. An algal growth inhibition test of concentrated river water samples using Pseudokirchneriella subcapitata was also conducted to evaluate the toxicity of each sample and the contributions of PPCPs to toxicity of the water sample to the algal species. The result of preliminary ecological risk assessment showed that the hazard quotients of five PPCPs were over one at some sampling locations. The relatively weak toxicities on P. subcapitata were observed in all the concentrated water samples. The relatively large contribution to relatively weak toxicity of the concentrated water samples on the growth of P. subcapitata was found for three of five PPCPs that show potential ecological risks in the middle basin of Tama River.
Calcium phosphate can precipitate from phosphate in urine and calcium carbonate, which is the main component of Mizuhopecten yessoensis shells. Precipitation tests, analyses of SEM-EDS and XRD were carried out to study the formation of calcium phosphate from the shells and synthetic urine, to identify the products, and to investigate the effect of operation conditions on the form of the obtained products. Two precipitation processes were observed at low Ca/P and at high Ca/P ratios. The former involved an increase in pH and a decrease in concentrations of phosphate and calcium to form dicalcium phosphate dihydrate (DCPD), while the latter involved three steps: 1. a rapid increase in pH and a decrease in the concentrations of phosphate and calcium to form DCPD, 2. a decrease in pH and an increase in the phosphate concentration, causing to change the crystal structure into poorly crystallized apatite, and 3. an increase in pH. The observations of the particle surface by SEM-EDS and powder XRD analysis of precipitates were consistent with these phenomena. Elemental analysis of the cross section of particles showed that the reaction that formed calcium phosphate started from the particle surface and then progressed to inside the particles.
In this study, to evaluate whether Clostridium perfringens could be a useful fecal indicator in aquatic environments and could be employed as a potential source-tracking indicator, the distribution of C. perfringens spores and their toxin types in sewage and livestock fecal samples were analyzed. A total of 804 C. perfringens spore isolates (366 from human-related sewage and effluents, 128 from cattle, 129 from pigs, 72 from chicken, and 109 from abattoir wastewaters) were analyzed using multiplex polymerase chain reaction (PCR) to detect six C. perfringens toxin genes. On the basis of the presence of toxin genes, most of the isolates from both human sewage and livestock samples were determined as C. perfringens type A and they expressed cpa alone or cpa and C. perfringens enterotoxin (cpe) with or without cpb2. Moreover, cpe-positive C. perfringens was detected with frequencies of 29% and 32% in human sewage and effluents, respectively. However, only one isolate (from cattle feces) was cpe-positive among all the livestock samples tested. Thus, the distribution of cpe-positive C. perfringens should be considered an important source tracking indicator for human fecal pollution. Furthermore, we conclude that sewage effluents are a significant source of cpe-positive C. perfringens pollution.